ANTIBACTERIAL AND/OR ANTIFOULING POLYMERS

Abstract

The present disclosure provides a copolymer comprising monomer units represented by formulas (I) and/or (II) as disclosed and defined herein which are useful in antibacterial and/or antifouling coatings. The present disclosure further provides methods of synthesizing said copolymers.

Claims

1. A copolymer comprising monomer units represented by formulas (I) and (II): ##STR00035## wherein the copolymer is terminated on one end by R.sub.1 and on the other end by R.sub.4; R.sub.1 comprises an antifouling moiety; R.sub.4 is H, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted carbocycle, or optionally substituted heterocarbocycle; R.sub.2 and R.sub.3 are independently optionally substituted hetero-C.sub.1-10-alkyl, wherein one or more chain carbon atoms is optionally replaced by a heteroatom; R.sub.2a and R.sub.3a are independently optionally substituted hetero-C.sub.1-10-alkyl, wherein one or more chain carbon atoms is optionally replaced by a heteroatom; R.sub.2b comprises an anchoring moiety; R.sub.3b comprises an antibacterial moiety; m is an integer in the range of 2 to 20; and n is an integer in the range of 0 to 100.

2. The copolymer according to claim 1, wherein R.sub.1 is a polymer residue comprising an antifouling moiety, optionally the antifouling moiety comprises an alkoxyalkylene.

3.-39. (canceled)

40. The copolymer according to claim 2, wherein said copolymer is a diblock copolymer, wherein one block consists of R.sub.1, and the other block consists of repeating units of Formula (I); optionally wherein said copolymer is a diblock copolymer, wherein one block consists of R.sub.1, and the other block consists of randomly arranged monomer units of Formulas (I) and (II); more optionally wherein said copolymer is a triblock copolymer, wherein one block consists of R.sub.1, the second block consists of Formula (I), and the third block consists of Formula (II); and further optionally wherein said copolymer is a triblock copolymer, wherein one block consists of R.sub.1, the second block consists of Formula (II), and the third block consists of Formula (I).

41. The copolymer according to claim 1, wherein R.sub.1 is a polymer residue selected from the group consisting of poly(oxyalkylene), methoxypoly(oxyalkylene), and poly(alkoxy acrylate); and optionally R.sub.1 is a polymer residue selected from the group consisting of poly(ethylene glycol) (PEG), methoxypoly(ethylene glycol) (mPEG), poly(methoxyethyl methacrylate) and poly(ethoxyethyl methacrylate).

42. The copolymer according to claim 1, wherein R.sub.1 is a polymer residue with a molecular weight in the range of 2,000 to 20,000, of about 2,400, about 10,000.

43. The copolymer according to claim 1, wherein the anchoring moiety comprises an α-β-unsaturated carbonyl group; optionally the anchoring moiety is selected from the group consisting of maleic acid, maleamic acid and maleimide groups.

44. The copolymer according to claim 1, wherein the antibacterial moiety comprises a cation; and optionally the antibacterial moiety comprises a quaternary ammonium.

45. The copolymer according to claim 1, wherein Formula (I) is of Formula (IA) and Formula (II) is of Formula (IIA): ##STR00036## wherein m and n are as defined in claim 1; R.sub.a, R.sub.b, R.sub.c, R.sub.d, R.sub.e and R.sub.f are independently C(R.sub.5).sub.2, O or N(R.sub.5); R.sub.5 is H, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted carbocycle, or optionally substituted heterocarbocycle; R.sub.g comprises an anchoring moiety; and R.sub.h comprises an antibacterial moiety.

46. The copolymer of claim 45, wherein R.sub.g is of formula (i): ##STR00037## wherein * is the point of attachment; R.sub.6 and R.sub.7 are independently H, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted carbocycle, or optionally substituted heterocarbocycle; R.sub.8 is an anchoring moiety comprising a α-β-unsaturated carbonyl group; and y is an integer in the range of 1 to 5.

47. The copolymer of claim 46, wherein R.sub.8 is selected from the group consisting of maleic acid, maleamic acid and maleimide.

48. The copolymer of claim 45, wherein R.sub.h is of formula (ii): ##STR00038## wherein R.sub.9 and R.sub.10 are independently H, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted carbocycle, or optionally substituted heterocarbocycle; R.sub.11 is an aryl or heteroaryl substituted with at least one cation; and Z is an integer in the range of 1 to 5; and optionally R.sub.11 is selected from the group consisting of aryl or heteroaryl substituted with at least one quaternary ammonium cation.

49. The copolymer of claim 1, wherein Formula (I) is of Formula (IB): ##STR00039## wherein m is as defined in claim 1; and optionally wherein Formula (II) is selected from the group consisting of: ##STR00040## wherein n is as defined in claim 1.

50. The copolymer according to claim 1, selected from the group consisting of: ##STR00041## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.2a, R.sub.2b, R.sub.3a, R.sub.3b, m and n are as defined in any one of claims 1 to 12; and p is an integer in the range of 1 to 50.

51. The copolymer of claim 1, wherein m is in the range of 2 to 7; and optionally wherein n is in the range of 70 to 95.

52. A method of synthesizing a copolymer comprising monomer units represented by formulas (IIIA) and (IIIB): ##STR00042## wherein the copolymer is terminated on one end by R.sub.1 and on the other end by R.sub.4; R.sub.1 is a polymer residue comprising an antifouling moiety; R.sub.4 is H, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted carbocycle, or optionally substituted heterocarbocycle; R.sub.a, R.sub.b, R.sub.c, R.sub.d, R.sub.e and R.sub.f are independently C(R.sub.5).sub.2, O or N(R.sub.5); R.sub.5 is H, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted carbocycle, or optionally substituted heterocarbocycle; R.sub.g′ represents protected R.sub.g, and R.sub.h′ represents aryl or heteroaryl substituted with at least one substituent capable of being quaternized, wherein R.sub.g comprises an anchoring moiety; in the range of 2 to 20; and n is an integer in m is an integer the range of 0 to 100, the method comprising the operation of: (i) performing a ring-opening polymerization reaction in a reaction mixture comprising compounds of Formula (IC), H—R.sub.1, and compounds of Formula (IIC): ##STR00043## with the proviso that compounds of Formula (IIC) are present only when n≠0, thereby forming a copolymer comprising monomer units of Formula (IIIA) and/or (IIIB); optionally the copolymer is selected from the group consisting of: ##STR00044## wherein Ra, Rb, Rc, Rd, Re, Rf, Rg′, Rh′, R.sub.1, R.sub.4, m and n are as defined herein; R.sub.R is a block consisting of randomly arranged monomer units of ##STR00045## and p is an integer in the range of 1 to 50; more optionally further comprising (ii) performing a deprotection reaction on the copolymer formed herein, thereby exposing the R.sub.g anchoring moiety(s); and (iii) when n≠0, performing a quaternization reaction, thereby forming a copolymer comprising monomer units represented by formulas (IA) and/or (IIA): ##STR00046## wherein the copolymer is terminated on one end by R.sub.1 and on the other end by R.sub.4; R.sub.1, R.sub.2, Ra, Rb, Rc, Rd, Re, Rf, Rg, m and n are as defined herein; and R.sub.h comprises a cation.

53. The method according to claim 52 wherein operation (i) further comprises a ring opening polymerization catalyst; and optionally the ring-opening polymerization catalyst is selected from the group consisting of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), tin(II) 2-ethylhexanoate (Sn(Oct).sub.2) and tin(II) trifluoromethanesulfonate (Sn(OTf).sub.2).

54. The method according to claim 52, wherein H—R.sub.1 is selected from the group consisting of poly(ethylene glycol) (PEG), methoxypoly(ethylene glycol) (mPEG), poly(methoxyethyl methacrylate) and poly(ethoxyethyl methacrylate).

55. The method according to claim 52, wherein the deprotection is carried out by dissolving the copolymer formed in operation (i) in toluene; and optionally the quaternization reagent is selected from the group consisting of amine, dimethylbutylamine, dimethyloctylamine, dimethylbenzylamine, and trimethylamine.

56. A method of attaching a copolymer to a substrate, comprising attaching the anchoring moiety of said copolymer to an anchoring segment on said substrate; wherein the copolymer comprises monomer units represented by formulas (I) and (II): ##STR00047## wherein the copolymer is terminated on one end by R.sub.1 and on the other end by R.sub.4; R.sub.1 comprises an antifouling moiety; R.sub.4 is H, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted carbocycle, or optionally substituted heterocarbocycle; R.sub.2 and R.sub.3 are independently optionally substituted hetero-C.sub.1-10-alkyl, wherein one or more chain carbon atoms is optionally replaced by a heteroatom; R.sub.2a and R.sub.3a are independently optionally substituted hetero-C.sub.1-10-alkyl, wherein one or more chain carbon atoms is optionally replaced by a heteroatom; R.sub.2b comprises an anchoring moiety; R.sub.3b comprises an antibacterial moiety; m is an integer in the range of 2 to 20; and n is an integer in the range of 0 to 100; optionally wherein the anchoring segment comprises one or more thiol groups; more optionally wherein the copolymer is attached to the substrate via a Michael addition.

57. An article comprising a substrate and a coating comprising a copolymer comprising monomer units represented by formulas (I) and (II): ##STR00048## wherein the copolymer is terminated on one end by R.sub.1 and on the other end by R.sub.4; R.sub.1 comprises an antifouling moiety; R.sub.4 is H, optionally substituted alkyl, optionally substituted alkenyl, optionally substituted alkynyl, optionally substituted aryl, optionally substituted heteroaryl, optionally substituted carbocycle, or optionally substituted heterocarbocycle; R.sub.2 and R.sub.3 are independently optionally substituted hetero-C.sub.1-10-alkyl, wherein one or more chain carbon atoms is optionally replaced by a heteroatom; R.sub.2a and R.sub.3a are independently optionally substituted hetero-C.sub.1-10-alkyl, wherein one or more chain carbon atoms is optionally replaced by a heteroatom; R.sub.2b comprises an anchoring moiety; R.sub.3b comprises an antibacterial moiety; m is an integer in the range of 2 to 20; and n is an integer in the range of 0 to 100.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0221] The accompanying drawings illustrate a disclosed embodiment and serves to explain the principles of the disclosed embodiment. It is to be understood, however, that the drawings are designed for purposes of illustration only, and not as a definition of the limits of the invention.

[0222] FIG. 1 shows the general process of a polymer coating process with triblock copolymers of PEG, cationic polycarbonate (CPC) and maleimide-functionalized polycarbonate (PMC).

[0223] FIG. 2 shows the general process of a polymer coating process with diblock copolymers of PEG and cationic polycarbonate containing maleimide groups (i.e. 2.4 k-MC and 10 k-MC) and copolymers of PEG and maleimide-functionalized polycarbonate (i.e. 2.4 k-M and 10 k-M).

[0224] FIG. 3 shows a graph of viable surface colonies analysis of S. aureus (S.a.) and E. coli (E.c) at 1 and 7 days on pristine, thiol-functionalized and surfaces coated with triblock copolymers of PEG, cationic polycarbonate (CPC) and maleimide-functionalized polycarbonate (PMC).

[0225] FIG. 4 shows a graph of viable surface colonies analysis of S. aureus and E. coli at 1 and 7 days on pristine, thiol-functionalized and surfaces coated with diblock copolymers of PEG and cationic polycarbonate containing maleimide groups (i.e. 2.4 k-MC and 10 k-MC) and copolymers of PEG and maleimide-functionalized polycarbonate (i.e. 2.4 k-M and 10 k-M).

[0226] FIG. 5a is a .sup.1H spectra of protected polymer 2.4 k-V.

[0227] FIG. 5b is a .sup.1H spectra of deprotected polymer 2.4 k-V.

[0228] FIG. 5c is a .sup.1H spectra of quarternized polymer 2.4 k-V.

[0229] FIG. 6 is a depiction of static water contact angles of a pristine surface, a thio-functionalized surface, a 2.4 k-V coated surface and a 2.4 k-S coated surface.

[0230] FIG. 7 is a graph showing the antibacterial activity of pristine, thiol-functionalized silicone rubber surfaces and surfaces coated with the disclosed polymers against (a) Gram-positive S. aureus; and (b) Gram-negative E. coli.

[0231] FIG. 8 is a graph showing the metabolic activity of (a) S. aureus; and (b) E. coli fouling on pristine, thiol-functionalized surfaces and surfaces coated with the disclosed polymers with various treatments by (a) XTT; and (b) Cell Titer-Blue® Assay analyses.

[0232] FIG. 9 shows a study of protein fouling on uncoated and coated PDMS surfaces via observation of BSA-FITC using spectroscopy, showing prevention of protein fouling.

[0233] FIG. 10 is a graph showing hemolysis data for rat red blood cells incubated with various polymer coated PDMS surfaces.

[0234] FIG. 11a is a .sup.1H NMR spectra of protected polymer 2.4 k-MC. FIG. 11b

[0235] FIG. 11b is a .sup.1H NMR spectra of deprotected polymer 2.4 k-MC.

[0236] FIG. 11c is a .sup.1H NMR spectra of quaternized polymer 2.4 k-M.

[0237] FIG. 12a is a .sup.1H NMR spectra of protected non-cationic polymer 2.4 k-M.

[0238] FIG. 12b is a .sup.1H NMR spectra of deprotected non-cationic polymer 2.4 k-M.

[0239] FIG. 13 is a depiction of static water contact angles of a pristine surface, a thio-functionalized surface, a 2.4 k-MC coated surface, a 10 k-MC coated surface, a 2.4 k-M coated surface, and a 10 k-M coated surface.

[0240] FIG. 14 is a N1s spectra of 2.4 k-MC and 2.4 k-M polymer-coated surfaces.

[0241] FIG. 15 is a graph showing the antibacterial activity of pristine, thiol-functionalized silicone rubber surfaces and surfaces coated with the disclosed polymers against (a) Gram-positive S. aureus (S.a); and (b) Gram-negative E. coli (E.c).

[0242] FIG. 16 is a graph showing the metabolic activity of (a) S. aureus; and (b) E. coli fouling on pristine, thiol-functionalized surfaces and surfaces coated with the disclosed polymers.

[0243] FIG. 17 shows a study of protein fouling on uncoated and coated PDMS surfaces via observation of BSA-FITC using spectroscopy, showing prevention of protein fouling.

[0244] FIG. 18 is a graph showing hemolysis data for rat red blood cells incubated with various polymer coated PDMS surfaces.

EXAMPLES

[0245] Non-limiting examples of the invention will be further described in greater detail by reference to specific Examples, which should not be construed as in any way limiting the scope of the invention.

[0246] Materials CH.sub.3O-PEG-OH (known as MPEG, Mn 2400 g.Math.mol.sup.−1, PDI 1.05) was purchased from Polymer Source™, lyophilized and transferred to a glove-box one day prior to use. N-(3,5-trifluoromethyl)phenyl-N′-cyclohexylthiourea (TU) was prepared according to a procedure described below. TU was dissolved in dry tetrahydrofuran and dried over CaH.sub.2 overnight. The mixture was filtered, and the solvent removed in vacuo. 1,8-Diazabicyclo[5,4,0]undec-7-ene (DBU) was dried over CaH.sub.2 overnight, and dried DBU was obtained after vacuum distillation. Both dried TU and DBU were transferred to a glove-box prior to use. FITC-conjugated bovine serum albumin (FITC-BSA), 3-mercaptopropyltrimethoxysilane and all other chemicals were purchased from Sigma-Aldrich, and used as received unless stated otherwise. Silicone Kit Sylgard 184 was bought from Dow Corning, and used according to the manufacturer's protocols. LIVE/DEAD Baclight bacterial viability kit (L-7012) was obtained from Invitrogen. S. aureus (ATCC No. 6538) and E. coli (ATC No. 25922) were purchased from ATCC (U.S.A).

Experimental

Preparation of N-(3, 5-trifluoromethyl)phenyl-N′-cyclohexylthiourea (TU)

[0247] Thiourea co-catalyst was synthesized via addition of cyclohexylamine (1.85 g, 18.5 mmol) dropwise at room temperature to a stirring solution of 3,5-bis(trifluoromethyl)phenyl isothiocyanate (5.0 g, 19 mmol) in tetrahydrofuran (THF) (20 mL). After stirring for 4 hours, the solvent was evaporated. The white residue was recrystallized from chloroform to give TU as a white powder. Yield: 5.90 g (86%). .sup.1H NMR (400 MHz, CDCl.sub.3, 22° C.) δ: 7.52 (s, 1H, 5-ArH), 7.33 (s, 2H, 2,6-ArH), 6.50 (s, 1H, ArNH), 5.17 (s, 1H, CyNH), 4.40 (br m, 1H, NCyH), 2.03-0.86 (m, 10H, CyH).

[0248] Gel Permeation Chromatography (GPC):

[0249] Polymer molecular weights were analysed by GPC using a Waters HPLC system equipped with a 2690D separation module, two Styragel HR1 and HR4E (THF) 5 mm columns (size: 300×7.8 mm) in series arrangement, coupled with a Waters 410 differential refractometer detector. THF was employed as the mobile phase at a flow rate of 1 mL.Math.min.sup.−1. Number-average molecular weights, as well as polydispersity indices of polymers were calculated from a calibration curve based on a series of polystyrene standards with molecular weights ranging from 1350 to 151700.

[0250] 1H NMR Analysis:

[0251] 1H NMR spectra of monomers and polymers were recorded on a Bruker Advance 400 NMR spectrometer, operated at 400 MHz and at room temperature. The 1H NMR measurements were performed using an acquisition time of 3.2 s, a pulse repetition time of 2.0 s, a 300 pulse width, 5208-Hz spectral width, and 32 K data points. Chemical shifts were referred to solvent peaks (δ=7.26 and 1.94 ppm for CDCl.sub.3 and CD.sub.3CN-d.sub.6, respectively).

[0252] Preparation of Polydimethylsiloxane (PDMS) Silicone Rubber:

[0253] PDMS silicone rubber was prepared by mixing 10 base parts to 1 curing part thoroughly, followed by degassing under vacuum for 30 min. The mixture was spin coated onto a Petri dish (for LIVE/DEAD cell staining and SEM studies) using SAWATECH AG Spin Module SM-180-BT, or it was cast into a 48-well plate for XTT, Titer Blue® cell viability and colony assays. Both the Petri dish and plate were placed overnight in a vacuum oven at 70° C. for curing. After curing, the PDMS sample formed in the Petri dish was cut into square pieces (0.5 cm×0.5 cm with a thickness of about 1 mm). The disc-like PDMS samples were gently removed from the bottom of the 48-well plate with flat forceps. All PDMS samples were first sonicated with de-ionized (DI) water, followed by isopropanol and DI water. The samples were dried under a stream of nitrogen before use.

[0254] Vapour Deposition of PDMS Surface:

[0255] Clean PDMS surface was exposed to ultraviolet/ozone (UVO) radiation for 1 hour in a commercial PSD-UVT chamber (Novascan). The surface was then briefly exposed to humid air, and dried under a stream of nitrogen. Subsequently, the dried PDMS surface was placed on a clean piece of weighing paper in a small vacuum desiccator, together with 1 mL of 3-mercaptopropyltrimethoxysilane loaded in a clean vial. The vapour deposition process was carried out overnight with the desiccator sealed under vacuum at 70° C. to provide thiol-functionalized surface. The treated surface was dried under a stream of nitrogen, and kept in a sealed desiccator at room temperature prior to use.

[0256] Polymer Coating:

[0257] The polymers of different composition (2 mg) were first dissolved in 400 μL of HPLC grade water, 500 μL of PBS (pH 7.4), and 100 μL of SDS solution. Subsequently, the clean PDMS surface treated with 3-mercaptopropyltrimethoxysilane was immersed in the polymer solution for 1 day at room temperature (˜22° C.). The polymer-coated PDMS samples were sonicated in a mixture of isopropropanol and water (1:1 volume ratio), and dried under a stream of nitrogen before further use or characterization.

[0258] X-Ray Photoelectron Spectroscopy (XPS) Measurements:

[0259] The difference in chemistry between uncoated and polymer-coated PDMS surfaces was analyzed by X-ray photoelectron spectroscopy (XPS, Kratos Axis HSi, Kratos Analytical, Shimadzu, Japan) with Al Ka source (hν=1486.71 eV). The angle between the surface of the sample and the detector was kept at 90°. The survey spectrum (from 1100 to 0 eV) was acquired with pass energy of 80 eV. All binding energies were calculated with reference to C 1s (C—C bond) at 284.5 eV.

[0260] Static Contact Angle Measurements:

[0261] The static contact angles of both uncoated and polymercoated surfaces were measured by an OCA15 contact angle measuring device (Future Digital Scientific Corp., U.S.A.). DI water (20 μL) was used for all measurements. All samples were analyzed in triplicates, and the static contact angle data were presented as mean±SD.

[0262] Killing Efficiency of Polymer-Coated Surfaces (Colony Assay):

[0263] The concentration of S. aureus or E. coli in Mueller-Hinton broth (MHB, cation-adjusted) was adjusted to give an initial optical density (O.D.) reading of 0.07 at the wavelength of 600 nm on a microplate reader (TECAN, Switzerland), which correlates to a concentration of Mc Farland 1 solution (3×10.sup.8 CFU.Math.mL.sup.−1). The bacterial solution was diluted by 1000 times to achieve a loading of 3×10.sup.5 CFU.Math.mL.sup.−1. Subsequently, 20 μL of this bacterial solution was added to the surface of an uncoated or coated disc-like PDMS sample, which was placed in a 48-well plate. Additionally, 60 μL of MHB was added to the surface, and the 48-well plate was incubated at 37° C. for 24 hours. The bacterial solution (10 μL) was then taken out from each well and diluted with an appropriate dilution factor. The bacterial solution was streaked onto an agar plate (LB Agar from 1st Base). The number of colony-forming units (CFUs) was tabulated and recorded after an incubation of about 18 hours at 37° C. Each test was conducted in triplicates.

[0264] Antifouling Analysis of Pristine, Thiol-Functionalized and Polymer-Coated PDMS Surfaces by Surface Viable Colonies:

[0265] Quantitative measurement of live S. aureus cells attached onto PDMS surface was performed by directly enumerating the bacteria adhering to the surface. Briefly, S. aureus or E. coli in MHB (20 μL, 3×105 CFU.Math.mL.sup.−1) was seeded onto uncoated and polymercoated PDMS surfaces, topped up with 60 μL of MHB, and cultured at 37° C. for 24 hours. Each surface was washed thrice with sterile PBS, and was carefully placed in individual 8-ml tube containing 1.5 ml PBS. Each tube was sonicated for 8 sec and viable counts in the resulting suspensions was performed by plating on agar medium to enumerate bacteria that were attached to the disc-like PDMS surface.

[0266] Antifouling Analysis of Uncoated and Polymer-Coated PDMS Surfaces by XTT Assay:

[0267] Another quantitative measurement of live bacteria cells attached onto the disc-like PDMS surface was performed by studying 2,3-bis (2-methoxy-4-nitro-5-sulfo-phenyl)-2H-tetrazolium-5-carboxanilide (XTT) reduction.[2] XTT reduction assay measures the mitochondrial enzyme activity in live cells. The optical density (O.D.) of formazan dye produced by XTT reduction within mitochondrial enzymes of viable cells was recorded, and the experiment was conducted in triplicates. Briefly, S. aureus in MHB (20 μL, 3×10.sup.5 CFU.Math.mL.sup.−1) was seeded onto uncoated and polymer-coated PDMS surfaces, topped up with 60 μL of MHB, and cultured at 37° C. for 24 hours. Each surface was washed thrice with sterile PBS, followed by incubation with 100 mL of PBS, 10 μL of XTT and 5 μL of menadione at 37° C. for 2 hours. The mitochondrial dehydrogenase of the bacterial cells reduced XTT tetrazolium salt to formazan, and the colorimetric change was correlated to cell metabolic activity (cell viability). The absorbance of each sample was measured at 490 nm with a reference wavelength of 660 nm using a microplate reader (TECAN, Sweden).

[0268] Antifouling Analysis of Uncoated and Polymer-Coated PDMS Surfaces by Cell Titer Blue® Assay:

[0269] The Cell Titer-Blue® cell viability assay provided quantitative analysis of live E. coli cells attached onto the disc-like PDMS surface. The fluorescence intensity of resorufin produced after reduction within mitochondrial enzymes of viable cells was recorded, and the experiment was conducted in triplicates. E. coli in MHB (20 μL, 3×10.sup.5 CFU.Math.mL.sup.−1) was seeded onto the uncoated and polymer-coated PDMS surfaces, topped up with 60 μL of MHB, and cultured at 37° C. for 24 hours. The surface was washed twice with sterile PBS, followed by incubation with 100 mL of PBS and 20 μL of Cell Titer Blue Reagent at 37° C. for 2 hours. The fluorescence intensity readings of the wells were determined at excitation wavelength of 560 nm and emission wavelength of 590 nm using the microplate reader.

[0270] LIVE/DEAD Baclight Bacterial Viability Assay:

[0271] A LIVE/DEAD Baclight bacterial viability kit (L-7012, Invitrogen), containing both propidium iodide and SYTO® fluorescent nucleic acid staining agents, was used to label bacterial cells on the uncoated and polymer-coated PDMS surfaces. Briefly, the red-fluorescent nucleic acid staining agent propidium iodide, which only penetrates damaged cell membrane, was used to label dead bacterial cells. SYTO® 9 greenfluorescent nucleic acid staining agent, which can penetrate cells both with intact and damaged membranes, was used to label all bacterial cells. Bacteria solution (3×10.sup.5 CFU.Math.mL.sup.−1, 20 μL) was seeded onto the uncoated and polymer-coated PDMS surfaces, followed by incubation at 37° C. for 24 hours or 7 days. The surfaces were washed thrice with clean PBS after the bacteria solution was removed. Subsequently, each PDMS sample was placed individually into a 48-well plate with 200 μL of a dye solution, prepared from a mixture of 3 μL of SYTO® (3.34 mM) and 3 μL of propidium iodide (20 mM) in 2 mL of PBS. The procedure was conducted at room temperature in the absence of light for 15 minutes. Eventually, the stained bacterial cells attached to the surfaces were examined under a Zeiss LSM 5 DUO laser scanning confocal microscope (Germany), and the images were obtained using an oil immersed 40× object lens at room temperature.

[0272] Analysis of Bacteria Attachment and Biofilm Formation by Field-Emission Scanning Electron Microscopy (FE-SEM):

[0273] FE-SEM was employed to evaluate the attachment and biofilm formation of S. aureus or E. coli on the uncoated and coated PDMS surfaces. Bacteria solution (3×10.sup.5 CFU.Math.mL.sup.−1, 20 μL) was seeded onto the uncoated and polymer-coated PDMS surfaces, followed by incubation at 37° C. for 1, 7 or 14 days. An additional 20 μL of MHB was added after every 24 hours to prevent the bacteria culture medium from drying out. At the predetermined time points, the PDMS surfaces were washed thrice with sterile PBS, followed by fixation with 2.5% glutaraldehyde in PBS overnight. The fixed bacteria were dehydrated with a series of graded ethanol solution (25%, 50%, 75%, 95%, and 100%, 10 min each) before the PDMS samples were mounted for platinum coating. Finally, a field emission scanning electron microscope (FE-SEM, JEOL JSM-7400F, Japan) was used to observe PDMS surfaces.

[0274] Analysis of Platelet Adhesion:

[0275] Fresh rat blood was centrifuged at 1000 rpm.Math.min.sup.−1 and at room temperature for 10 minutes to obtain platelet rich plasma (PRP) in the supernatant. Uncoated and polymer-coated PDMS surfaces were immersed in PRP and incubated at 37° C. for 30 minutes. The samples were then washed thrice with PBS, followed by the same bacteria fixation and FE-SEM analysis procedures described above.

[0276] Fluorescence Analysis for Protein Fouling:

[0277] Individual surfaces were incubated overnight with 20 μL of FITC-BSA solution (1 mg/mL) at 37° C. The surfaces were then washed thrice with clean sterile PBS solution before they were observed under an inverted fluorescence microscope (Olympus IX71, U.S.A). Meanwhile, the FITC-BSA solutions were removed from the respective surfaces, dissolved in 1 mL of sterile PBS solution. The fluorescence intensity of the solution was investigated using a Perkin-Elmer-LS55 luminescence spectrometer with Jobin Yvon Fluorolog-3 at 495 and 525 nm excitation and emission wavelengths respectively.

[0278] Hemolysis Test:

[0279] Freshly obtained rat blood was diluted to 4% (by volume) with PBS buffer. The red blood cell suspension in PBS (500 μL) was added into a 2 mL eppendorf tube, which contained uncoated or polymer-coated PDMS samples individually. The tube was incubated for 1 h at 37° C. for hemolysis to proceed. After incubation, the tube was centrifuged at 2200 rpm for 5 min at room temperature. Aliquots (100 mL) of the supernatant from each tube were transferred to a 96-well plate, and hemoglobin release was measured at 576 nm using the microplate reader (TECAN, Sweden). In this procedure, the red blood cells in PBS were used as a negative control, while the red blood cells lysed with 0.2% Triton-X were used as a positive control. The absorbance analysis for red blood cells lysed with 0.2% Triton X was taken as 100% hemolysis. The calculation for percentage of hemolysis was as follow: Hemolysis (%)=[(OD576 nm of the sample−OD576 nm of the negative control)/(OD576 nm of the positive control−OD576 nm of the negative control)]×100. The data was analyzed and expressed as mean and standard deviation of three replicates for quantification of each type of PDMS surface.

Example 1: Synthesis of Monomers MTC-OCH.SUB.2.BnCl and MTC-FPM

[0280] The detailed procedure for the synthesis of the monomers MTC-OCH.sub.2BnCl and MTC-FPM are shown below Examples 1a and 1b. In general, the polymers were synthesized via metal-free organocatalytic ring-opening polymerization of MTC-OCH.sub.2BnCl and MTC-FPM using MPEG as the macroinitiator in the presence of the co-catalysts DBU and TU. The reaction was quenched with trifluoroacetic acid and left to stir for 5 minutes. Subsequently, the quenched polymer was dissolved in a minimal amount of dichloromethane, and precipitated twice in cold diethyl ether before lyophilization. The dried polymer was first deprotected to expose the maleimide pendant groups, and completely quaternized with N,N-dimethylbutylamine to achieve a cationic polycarbonate polymer for surface attachment. Detailed procedures for the synthesis of 2.4 k-V and 2.4 k-S are given below.

Example 1a: Synthesis of MTC-OCH.SUB.2.BnCl Monomer

[0281] Briefly, in a dry two-neck 500 mL round bottom flask equipped with a stir bar, MTC-OH (3.08 g, 19.3 mmol) was first dissolved in dry THF (50 mL) with 5-8 drops of dimethylformamide (DMF). Subsequently, oxalyl chloride (3.3 mL) was added in one shot (pure form), followed by an additional 20 mL of THF. The solution was stirred for 90 minutes, after which volatiles were blow dried under a strong flow of nitrogen to yield a pale yellow solid intermediate (5-chlorocarboxy-5-methyl-1,3-dioxan-2-one, MTC-Cl). The solid then subjected to heat at 60° C. for 2-3 minutes for the removal of residual solvent, and was re-dissolved in dry CH.sub.2Cl.sub.2 (50 mL), followed by immersing the flask in an ice bath at 0° C. A mixture of para-chloromethylbenzyl alcohol (2.79 g, 17.8 mmol) and pyridine (1.55 mL, 19.3 mmol) were dissolved in dry CH.sub.2Cl.sub.2 (50 mL), which was added dropwise to the flask over a duration of 30 minutes, and allowed to stir at room temperature immediately after complete addition for an additional 2.5 hours (and not more than 3 hours). The reacted mixture was quenched by addition of 50 mL of brine, and the organic solvent was collected after separation. After removal of solvent, the crude product was purified by silica-gel flash column chromatography via a hexane-ethyl acetate solvent system (gradient elution up to 80% vol. ethyl acetate) to yield MTC-OCH2BnCl as a white solid. The crude product was further purified by recrystallization. The solid was dissolved in 1 mL of dichloromethane and ethyl acetate respectively, followed by addition of 50 mL of diethyl ether. The crystals were allowed to form at 0° C. for 2 days, and were subsequently obtained by washing the crystals with cold diethyl ether.

[0282] 1H NMR (400 MHz, CDCl3, 22° C.): δ 7.37 (dd, J=20.2, 8 Hz, 4H, Ph-H), 5.21 (s, 2H, —OCH.sub.2), 4.69 (d, J=13.6 Hz, 2H, —OCH.sub.2C—), 4.59 (s, 2H, —CH.sub.2Cl), 4.22 (d, J=14.8 Hz, 2H, —OCH.sub.2C—), 1.32 (s, 3H, —C.sub.2CH.sub.3).

Example 1b: Synthesis of MTC-FPM Monomer

[0283] Briefly, in a dry two-neck 500 mL round bottom flask equipped with a stir bar, MTC-OH (3.08 g, 19.3 mmol) was first dissolved in dry THF (50 mL) with 5-8 drops of dimethylformamide (DMF). Subsequently, oxalyl chloride (3.3 mL) was added in one shot (pure form), followed by an additional 20 mL of THF. The solution was stirred for 90 min, after which volatiles were blow dried under a strong flow of nitrogen to yield a pale yellow solid intermediate (5-chlorocarboxy-5-methyl-1,3-dioxan-2-one, MTC-Cl). The solid was then subjected to heat at 60° C. for 2-3 minutes for the removal of residual solvent, and re-dissolved in dry CH.sub.2Cl.sub.2 (50 mL), followed by immersing the flask in an ice bath at 0° C. A mixture of exo-3a,4,7,7a-Tetrahydro-2-(3-hydroxypropyl)-4,7-epoxy-1H-isoindole-1,3(2H)-dione (3.97 g, 17.8 mmol) and triethylamine (1.77 mL, 19.3 mmol) were dissolved in dry CH.sub.2Cl.sub.2 (50 mL), which was added dropwise to the flask over a duration of 30 minutes, and allowed to stir at room temperature immediately after complete addition for an additional 24 hours. The reacted mixture was quenched by addition of 50 mL of water, and the organic solvent was collected after separation. After removal of solvent, the crude product was dissolved in 4 mL of CH.sub.2Cl.sub.2, followed by addition of 50 mL of diethyl ether for recrystallization. The crystals were allowed to form at room temperature, and were subsequently obtained by washing with cold diethyl ether.

[0284] 1H NMR (400 MHz, CDCl.sub.3, 22° C.): δ 6.51 (s, 2H, —CH═CH), 5.25 (s, 2H, —OCHC.sub.2—), 4.74 (d, 2H, J=14.4 Hz, —OCH.sub.2CC.sub.2—), 4.22 (d, 2H, J=14.8 Hz, —OCH.sub.2CC.sub.2—), 4.11 (t, 2H, J=6.0 Hz, —OCH.sub.2CH.sub.2—), 3.58 (t, 2H, J=6.6 Hz, CH.sub.2CH.sub.2NC—), 2.85 (s, 2H, —COCHC—), 1.96 (quin, 6.4 Hz, 2H, —CONCCOCHC—), 1.38 (s, 3H, —C.sub.2CH.sub.3).

Example 2: General Synthesis of Disclosed Polymers

[0285] In general, a macroinitiator was used to ring-open cyclic carbonate monomers. The product was then deprotected to expose anchoring groups. The deprotected product may be followed by subsequent quaternization to yield the disclosed copolymers (Scheme 1 or Scheme 2).

##STR00030##

##STR00031##

[0286] wherein R.sup.1, R.sup.4, Ra, Rb, Rc, Rd, Re, Rf, Rg, Rh, Rg′, Rh′, m and n are defined above.

Example 2a: 2.4 k-V and 2.4 k-S

[0287] ##STR00032##

TABLE-US-00001 TABLE 1 Compositions of tri-block copolymers consisting of PEG and polycarbonates Feed molar ratio (PEG:MTC-FPM:MTC- OCH.sub.2BnCl) with Composition after Polymer TU/DBU 5% mol Composition.sup.a Mw.sup.a (PDI) Quaternization.sup.a 2.4k-V 1:10:140 PEG-(MTC-FPM).sub.7- 34829 (1.20) PEG-P(MC).sub.5-CP(C).sub.90 (MTC-OCH.sub.2BnCl).sub.100 2.4k-S 1:10:140 PEG-(MTC-FPM).sub.3- 27394 (1.28) PEG-P(MC).sub.3-CP(C).sub.80 (MTC-OCH.sub.2BnCl).sub.80 .sup.aDetermined from .sup.1H NMR Spectrum

[0288] Monomethylether PEG (MPEG) with 2.4 kDa was used as a macroinitiator to ring-open the cyclic carbonate monomers MTC-Furan protected maleimide (MTC-FPM) and MTC-benzyl chloride (MTC-OCH.sub.2BnCl) in a sequential order, followed by deprotection to expose the maleimide anchoring groups, and subsequent complete quaternization with dimethyl butyl amine to yield triblock copolymers of PEG, maleimide-functionalized polycarbonate (PMC) and cationic polycarbonate (CPC), i.e. PEG-PMC-CPC and PEG-CPC-PMC (Scheme 4, Table 1). Each of the polymers had PEG of the same molecular weight for providing antifouling function, cationic polycarbonates of comparable length for antibacterial property and maleimide-functionalized polycarbonate for surface attachment via Michael addition reaction. .sup.1H NMR integration values of monomers against the PEG initiator were correlated, hence confirming controlled polymerization via initial monomer to initiator feed ratio. In addition, the proton NMR analysis displayed all the peaks associated with both initiator and monomers. Both polymers had narrow molecular weight distribution with polydispersity index (PDI) ranging between 1.20 to 1.28. Subsequently, after precipitating twice in cold diethyl ether, the two polymers were isolated and dried. The polymers were subsequently dissolved in toluene and heated to 110° C. overnight for the deprotection of pendant furan-protected maleimide. The deprotected polymers were reprecipitated in cold diethyl ether twice, and .sup.1H NMR showed a downfield shift from 6.49 to 6.68 ppm, which was correlated to the deprotected maleimide pendant groups. Excess quantity of N,N-dimethylbutylamine was then added to the polymers dissolved in 20 mL of acetonitrile to achieve complete quaternization. The fully quaternized polymers were purified via dialysis in acetonitrile/isopropanol (1:1 in volume) for 2 days. From 1H NMR analysis, the presence of a new distinct peak at 2.99 ppm confirmed that quaternization of —OCH.sub.2BnCl pendant groups took place (FIGS. 7a to 7c).

Example 2b: 2.4 k-M, 2.4 k-MC, 10 k-M, and 10 k-MC

[0289] ##STR00033## ##STR00034##

TABLE-US-00002 TABLE 2 Compositions of di-block copolymers consisting of PEG and polycarbonates Feed molar ratio (Initiator:MTC-FPM:MTC- OCH.sub.2BnCl) with Composition after Polymer TU/DBU 5% mol Composition.sup.a Mw.sup.a (PDI) Quaternization.sup.a 2.4k-MC 1:10:140 MPEG 2.4K-P(MTC-FPM).sub.8- 28623 (1.28) MPEG 2.4K-P(MC).sub.5-CP(C).sub.72 P(MTC-OCH.sub.2BnCl).sub.78 10k-MC 1:10:140 MPEG 10K-P(MTC-FPM).sub.9- 37783 (1.16) MPEG 10K-P(MC).sub.6-CP(C).sub.72 P(MTC-OCH.sub.2BnCl).sub.82 2.4k-M 1:10:0 MPEG 2.4K-P(MTC-FPM).sub.8  5251 (1.08) MPEG 2.4K-P(MC).sub.6 10k-M 1:10:0 MPEG 10K-P(MTC-FPM).sub.4 11425 (1.10) MPEG 10K-P(MC).sub.3 .sup.aDetermined from .sup.1H NMR Spectrum

[0290] Diblock copolymers (2.4 k-M and 10 k-M) of PEG and maleimide-functionalized polycarbonate (PMC) were prepared via organocatalytic ring-opening polymerization (ROP). In order to study the antifouling effect of PEG, MPEGs of different lengths (2.4 kDa and 10 kDa) were utilized as macroinitiators as shown in Scheme 3. In addition, two diblock copolymers (2.4 k-MC and 10 k-MC) consisting of MPEG (2.4 kDa or 10 kDa) and cationic polycarbonate with maleimide functional groups randomly copolymerized (CP(M-C)) were as a comparison. For 2.4 k-M and 10 k-M polymers, there are 6 and 3 maleimide groups respectively (Table 2). In 2.4 k-MC and 10 k-MC polymers, there are 72 cationic repeat units and 5-6 maleimide groups (Table 2). .sup.1H NMR integration values of monomers against the MPEG initiator are well correlated, hence confirming controlled polymerization via strict initial monomer to initiator feed ratio. In addition, the proton NMR analysis displayed all the peaks associated with both initiator and monomers. All polymers had narrow molecular weight distribution with polydispersity index (PDI) ranging between 1.09 to 1.28. Subsequently, after precipitating twice in cold diethyl ether, the four polymers were isolated and dried. The polymers were subsequently dissolved in toluene and heated to 110° C. overnight in order to deprotect pendant furan-protected maleimide. The deprotected polymers were re-precipitated into cold diethyl ether twice, and .sup.1H NMR showed a downfield shift from 6.49 to 6.68 ppm, correlating to the deprotected maleimide pendant groups. Excess quantity of N,N-dimethylbutylamine was then added to the two polymers containing OCH.sub.2BnCl pendant groups, which were dissolved in 20 mL of acetonitrile to achieve complete quaternization. The fully quaternized polymers were further purified via dialysis in acetonitrile/isopropanol (1:1, volume by volume) for 2 days. From .sup.1H NMR analysis, the presence of a new distinct peak at 2.99 ppm demonstrated that quaternization of OCH.sub.2BnCl pendant groups took place (FIGS. 16a to 16c).

Example 3: Polymer Synthesis of Polymer 2.4 k-V

[0291] Details of the metal-free organocatalytic ring opening polymerization for polymer 2.4 k-V are given as an example. In a glove-box, 24.1 mg (0.010 mmol) of 2.4 kDa MPEG-OH initiator and 36.7 mg (0.10 mmol) of MTC-FPM were charged in a 20 mL glass vial equipped with a stir bar. Dichloromethane was added and the concentration was adjusted to 2 M with respect to the monomer. Once the initiator and monomers were completely dissolved, 1.5 μL (0.01 mmol) of DBU was added to initiate the polymerization. After 45 minutes, the last block was adjoined to the polymer by adding 0.3 g (1.0 mmol) of MTC-OCH.sub.2BnCl. Additional catalysts, 6 μL (0.040 mmol) of DBU and 18.6 mg (0.050 mmol) of TU, were added to the pot and left to stir at room temperature for another 40 minutes before quenching with 30 μL of trifluoroacetic acid. Subsequently, the polymer intermediate was purified immediately via precipitation twice in cold diethyl ether, and was dried on a vacuum line until a constant weight was achieved.

[0292] 1H NMR (400 MHz, CDCl.sub.3, 22° C.) δ 7.38-7.27 (m, 400H, —C.sub.6H4CH.sub.2Cl), 6.51-6.42 (m, 14H, —CHOC.sub.2H.sub.4CHO—), 5.27-5.21 (m, 14H, —R.sub.2CHOCHR.sub.2—), 5.15-5.12 (m, 200H, —COOCH.sub.2—), 4.64-4.49 (m, 200H, —C.sub.6H.sub.4CH.sub.2Cl), 4.46-4.39 (m, 14H, —COOCH.sub.2CH.sub.2—), 4.37-3.96 (m, 426H, —CH.sub.2OCOO—), 3.87-3.60 (m, 217H, —OCH.sub.2CH.sub.2— from 2.4 kDa MPEG), 3.56-3.51 (m, 14H, —CH.sub.2CH.sub.2NR.sub.2), 2.91-2.81 (m, 14H, —CC.sub.2HCC.sub.2H—), 2.17-1.98 (m, 14H, —OCH.sub.2CH.sub.2CH.sub.2—), 1.26-1.19 (m, 321H, —CH.sub.3).

[0293] The protected polymer was then deprotected by dissolving in 10 mL of toluene and heated to 110° C. overnight. After that, the toluene was removed under vacuum and the deprotected polymer was dissolved in 2 mL of dichloromethane and precipitated in cold diethyl ether. The polymer was subsequently dried on a vacuum line until a constant weight was achieved.

[0294] 1H NMR (400 MHz, CDCl3, 22° C.) 7.40-7.24 (m, 396H, —C6H.sub.4CH.sub.2Cl), 6.72-6.65 (m, 12H, —COC.sub.2H.sub.4CO—), 5.21-5.02 (m, 198H, —COOCH.sub.2—), 4.59-4.48 (m, 198H, —C.sub.6H.sub.4CH.sub.2Cl), 4.45-4.40 (m, 12H, —COOCH.sub.2CH.sub.2—), 4.38-3.94 (m, 420H, —CH.sub.2OCOO—), 3.83-3.60 (m, 217H, —OCH.sub.2CH.sub.2— from 2.4 kDa MPEG), 3.59-3.54 (m, 12H, —CH.sub.2CH.sub.2NR.sub.2), 2.17-1.98 (m, 12H, —OCH.sub.2CH.sub.2CH.sub.2—), 1.27-1.14 (m, 315H, —CH.sub.3).

[0295] Finally the polymer was dissolved in 20 mL of acetonitrile, and an excess (2 mL) of N,N-dimethylbutylamine was added to fully quaternize the OBnCl pendant groups. The reaction mixture was stirred overnight in a 50 mL round bottom flask at room temperature, and the solvent was then removed in vacuo. The obtained product was dissolved in a mixture of acetonitrile and isopropanol (1:1 in volume), and dialysis in acetonitrile/isopropanol (1:1, volume by volume) for 2 days. Finally, the solvent was removed under reduced pressure, and the final product was dried in a vacuum oven until a constant mass was achieved.

[0296] Polymer 2.4 k-V:

[0297] 1H NMR (400 MHz, (CD.sub.3)2CO, 22° C.) 7.65-7.34 (m, 360H, —C.sub.6H.sub.4CH.sub.2Cl), 7.18-6.22 (m, 10H, —COC.sub.2H.sub.4CO—), 5.46-5.29 (m, 10H, —COOCH.sub.2CH.sub.2—), 5.25-5.04 (m, 180H, —COOCH.sub.2—), 4.80-4.52 (m, 180H, —C.sub.6H.sub.4CH.sub.2Cl 4.40-3.90 (m, 380H, —CH.sub.2OCOO—), 3.70-3.56 (m, 10H, —CH.sub.2CH.sub.2NR.sub.2), 3.54-3.38 (m, 217H, —OCH.sub.2CH.sub.2— from 2.4 kDa MPEG), 3.34-3.20 (m, 180H, —N.sup.+ CH.sub.2CH.sub.2CH.sub.2—), 2.99 (s, 540H, —N.sup.+[CH.sub.3]2), 2.29-2.10 (m, 10H, —OCH.sub.2CH.sub.2CH.sub.2—), 1.81-1.70 (m, 180H, —N.sup.+ CH.sub.2CH.sub.2CH.sub.2—), 1.34-1.25 (m, 180H, —N.sup.+ CH.sub.2CH.sub.2CH.sub.2—), 1.23-1.10 (m, 270H, —N.sup.+ CH.sub.2CH.sub.2CH.sub.2CH.sub.3), 1.05-0.84 (m, 285H, —CH.sub.3).

Example 4: Polymer Synthesis of Polymer 2.4 k-S

[0298] Polymer 2.4 k-S was synthesized in similar fashion, with slight modification to the sequence of monomer addition to the reaction pot. In a glove-box, 24.1 mg (0.010 mmol) of 2.4 kDa MPEGOH initiator and 0.3 g (1.0 mmol) of MTC-OCH.sub.2BnCl were charged in a 20 mL glass vial equipped with a stir bar for the first and second block polymer synthesis. Dichloromethane was added and the concentration was adjusted to 2 M with respect to the monomer. Once the initiator and monomers were completely dissolved, 7.5 μL (0.05 mmol) of DBU and 18.6 mg (0.050 mmol) of TU were added to initiate the polymerization. After 15 minutes, the last block of the polymer was completed by adding 36.7 mg (0.10 mmol) of MTC-FPM. The reaction pot was left to stir at room temperature for another 40 min before quenching with 30 μL of trifluoroacetic acid. Subsequently, the polymer intermediate was purified immediately via precipitation twice in cold diethyl ether, and was dried on a vacuum line until a constant weight was achieved.

[0299] Polymer 2.4 k-S (Protected Maleimide):

[0300] 1H NMR (400 MHz, CDCl.sub.3, 22° C.) 7.39-7.25 (m, 320H, —C.sub.6H.sub.4CH.sub.2Cl), 6.59-6.40 (m, 6H, —CHOC.sub.2H.sub.4CHO—), 5.26-5.21 (m, 6H, —R.sub.2CHOCHR.sub.2—), 5.18-5.02 (m, 160H, —COOCH.sub.2—), 4.81-4.63 (m, 160H, —C.sub.6H.sub.4CH.sub.2Cl), 4.62-4.48 (m, 6H, —COOCH.sub.2CH.sub.2—), 4.49-3.99 (m, 332H, —CH.sub.2OCOO—), 3.85-3.61 (m, 217H, —OCH.sub.2CH.sub.2— from 2.4 kDa MPEG), 3.59-3.53 (m, 6H, —CH.sub.2CH.sub.2NR.sub.2), 2.91-2.75 (m, 6H, —CC.sub.2HCC.sub.2H—), 1.92-1.87 (m, 6H, —OCH.sub.2CH.sub.2CH.sub.2—), 1.27-1.20 (m, 249H, —CH.sub.3).

[0301] Polymer 2.4 k-S (Deprotected Maleimide):

[0302] 1H NMR (400 MHz, CDCl.sub.3, 22° C.) 7.41-7.24 (m, 320H, —C.sub.6H.sub.4CH.sub.2Cl), 6.73-6.63 (m, 6H, —CHOC.sub.2H.sub.4CHO—), 5.25-5.03 (m, 160H, —COOCH.sub.2—), 4.65-4.46 (m, 160H, —C.sub.6H.sub.4CH.sub.2Cl), 4.44-4.40 (m, 6H, —COOCH.sub.2CH.sub.2—), 4.38-3.97 (m, 332H, —CH.sub.2OCOO—), 3.84-3.61 (m, 217H, —OCH.sub.2CH.sub.2— from 2.4 kDa MPEG), 3.57-3.52 (m, 6H, —CH.sub.2CH.sub.2NR.sub.2), 1.91-1.88 (m, 6H, —CH.sub.2CH.sub.2CH.sub.2—), 1.34-1.14 (m, 249H, —CH.sub.3).

[0303] Polymer 2.4 k-S:

[0304] 1H NMR (400 MHz, (CD.sub.3)2CO, 22° C.) 7.69-7.25 (m, 320H, —C.sub.6H.sub.4CH.sub.2Cl), 7.17-6.55 (m, 6H, —COC.sub.2H.sub.4CO—), 5.42-5.27 (m, 6H, —COOCH.sub.2CH.sub.2—), 5.26-4.92 (m, 160H, —COOCH.sub.2—), 4.89-4.47 (m, 160H, —C.sub.6H.sub.4CH.sub.2Cl), 4.45-3.81 (m, 332H, —CH.sub.2OCOO—), 3.61-3.54 (m, 6H, —CH.sub.2CH.sub.2NR.sub.2), 3.54-3.40 (m, 217H, —OCH.sub.2CH.sub.2— from 2.4 kDa MPEG), 3.35-3.24 (m, 160H, —N.sup.+ CH.sub.2CH.sub.2CH.sub.2—), 2.98 (s, 480H, —N.sup.+[CH.sub.3].sub.2), 2.23-2.00 (m, 6H, —OCH.sub.2CH.sub.2CH.sub.2—), 1.87-1.61 (m, 160H, —N.sup.+ CH.sub.2CH.sub.2CH.sub.2—), 1.36-1.07 (m, 405H, —N.sup.+ CH.sub.2CH.sub.2CH.sub.2— & —N.sup.+ CH.sub.2CH.sub.2CH.sub.2CH.sub.3), 1.05-0.83 (m, 249H, —CH.sub.3).

Example 5: Polymer Synthesis of Polymer 2.4 k-MC

[0305] Details of the metal-free organocatalytic ring opening polymerization for polymer 2.4 k-MC are given below as an example.

[0306] In a glove-box, 17.2 mg (0.0072 mmol) of 2.4 kDa MPEG-OH initiator, 0.3 g (0.001 mol) of MTC-CH.sub.2OBnCl and 26.2 mg (0.072 mmol) of MTC-FPM were charged in a 20 mL glass vial equipped with a stir bar. Dichloromethane was added and the concentration was adjusted to 2 M with respect to the monomer. Once the initiator and monomers were completely dissolved, 6.3 μL of DBU and 18.6 mg of TU (0.05 mmol) were added to initiate the polymerization. After 20 minutes, the reaction was quenched with 30 μL of trifluoroacetic acid. Subsequently, the polymer intermediate was purified immediately via precipitation twice in cold diethyl ether, and was dried on a vacuum line until a constant weight was achieved.

[0307] 1H NMR (400 MHz, CDCl.sub.3, 22° C.): δ 7.42-7.26 (m, 312H, —C.sub.6H.sub.4CH.sub.2Cl), 6.51-6.46 (m, 16H, —CHOC.sub.2H.sub.4CHO—), 5.27-5.19 (m, 16H, —R.sub.2CHOCHR.sub.2—), 5.17-5.06 (m, 156H, —COOCH.sub.2—), 4.62-4.49 (m, 156H, —C.sub.6H.sub.4CH.sub.2Cl), 4.47-4.39 (m, 16H, —COOCH.sub.2CH.sub.2—), 4.35-3.99 (m, 312H, —CH.sub.2OCOO—), 3.90-3.61 (m, 217H, —OCH.sub.2CH.sub.2— from 2.4 kDa MPEG), 3.57-3.49 (m, 16H, —CH.sub.2CH.sub.2NR.sub.2), 2.88-2.78 (m, 16H, —CC.sub.2HCC.sub.2H—), 1.82-1.72 (m, 16H, —OCH.sub.2CH.sub.2CH.sub.2—), 1.32-1.13 (m, 234H, —CH.sub.3).

[0308] The furan-protected maleimide polymer was then deprotected by dissolving the polymer in 10 mL of toluene and heated to 110° C. overnight. After that, the toluene was removed under vacuum and the deprotected polymer was dissolved in 2 mL of dichloromethane and precipitated in cold diethyl ether. The polymer was subsequently dried on a vacuum line until a constant weight was achieved.

[0309] 1H NMR (400 MHz, CDCl.sub.3, 22° C.) δ 7.40-7.23 (m, 308H, —C.sub.6H.sub.4CH.sub.2Cl), 6.72-6.61 (m, 12H, —COC.sub.2H.sub.4CO—), 5.18-5.05 (m, 154H, —COOCH.sub.2—), 4.60-4.49 (m, 154H, —C.sub.6H.sub.4CH.sub.2Cl), 4.47-4.35 (m, 12H, —COOCH.sub.2CH.sub.2—), 4.34-4.00 (m, 308H, —CH.sub.2OCOO—), 3.88-3.60 (m, 217H, —OCH.sub.2CH.sub.2— from 2.4 kDa MPEG), 3.59-3.53 (m, 12H, —CH.sub.2CH.sub.2NR.sub.2), 1.96-1.87 (m, 12H, —OCH.sub.2CH.sub.2CH.sub.2—), 1.33-1.14 (m, 231H, —CH.sub.3).

[0310] Finally the polymer was dissolved in 20 mL of acetonitrile, and an excess (2 mL) of N,N-dimethyl-butylamine was added to fully quaternize the OBnCl pendant groups. The reaction mixture was stirred overnight in a 50 mL round bottom flask at room temperature, and the solvent was then removed in vacuo. The resulting crude product was dissolved in a mixture of acetonitrile and isopropanol (1:1 in volume), and dialysed in acetonitrile/isopropanol (1:1, volume by volume) for 2 days. Finally, the solvent was removed under reduced pressure, and the final product was dried in a vacuum oven until a constant mass was achieved.

[0311] 1H NMR (400 MHz, (CD.sub.3)2CO, 22° C.) 7.90-7.26 (m, 288H, —C.sub.6H.sub.4CH.sub.2Cl), 7.22-6.05 (m, 6H, —COC.sub.2H.sub.4CO—), 5.52-5.30 (m, 6H, —COOCH.sub.2CH.sub.2—), 5.29-4.90 (m, 144H, —COOCH.sub.2—), 4.81-4.52 (m, 144H, —C.sub.6H.sub.4CH.sub.2Cl), 4.46-3.89 (m, 288H, —CH.sub.2OCOO—), 3.84-3.44 (m, 6H, —CH.sub.2CH.sub.2NR.sub.2), 3.43-3.41 (m, 217H, —OCH.sub.2CH.sub.2-from 2.4 kDa MPEG), 3.33-3.21 (m, 144H, —N+CH.sub.2CH.sub.2CH.sub.2—), 2.99 (s, 432H, —N.sup.+[CH.sub.3]2), 2.26-2.12 (m, 6H, —OCH.sub.2CH.sub.2CH.sub.2—), 1.89-1.68 (m, 144H, —N.sup.+CH.sub.2CH.sub.2CH.sub.2—), 1.43-0.99 (m, 360H, —N+CH.sub.2CH.sub.2CH.sub.2— and —N+CH.sub.2CH.sub.2CH.sub.2CH.sub.3), 0.98-0.71 (m, 216H, —CH.sub.3).

Example 6: Polymer Synthesis of Polymer 10 k-MC

[0312] Polymer 10 k-MC was synthesized in similar fashion to polymer 2.4 k-MC, with slight modification to the amount of macroinitiator used. In a glove-box, 71.7 mg (0.0072 mmol) of Mn 10 kDa MPEG-OH initiator, 0.3 g (0.001 mol) of MTC-CH.sub.2OBnCl and 26.2 mg (0.072 mmol) of MTC-FPM were charged in a 20 mL glass vial equipped with a stir bar. Dichloromethane was added and the concentration was adjusted to 2 M with respect to the monomer. Once the initiator and monomers were completely dissolved, 6.3 μL of DBU and 18.6 mg of TU (0.05 mmol) were added to initiate the polymerization. After 20 minutes, the reaction was quenched with 30 μL of trifluoroacetic acid. Subsequently, the polymer intermediate was purified immediately via precipitation twice in cold diethyl ether, and was dried on a vacuum line until a constant weight was achieved. Deprotection and purification protocols for 10 k-MC are similar to that of 2.4 k-MC described above.

[0313] Polymer 10 k-FPMC (Protected Maleimide):

[0314] 1H NMR (400 MHz, CDCl3, 22° C.) δ 7.43-7.25 (m, 328H, —C6H4CH2Cl), 6.52-6.41 (m, 14H, —CHOC2H4CHO—), 5.28-5.19 (m, 14H, —R2CHOCHR2-), 5.18-5.06 (m, 164H, —COOCH2-), 4.61-4.51 (m, 164H, —C6H4CH2Cl), 4.48-4.34 (m, 14H, —COOCH2CH2-), 4.33-3.99 (m, 328H, —CH2OCOO—), 3.90-3.61 (m, 908H, —OCH2CH2- from 10 kDa MPEG), 3.59-3.50 (m, 14H, —CH2CH2NR2), 2.88-2.78 (m, 14H, —CC2HCC2H—), 1.81-1.75 (m, 14H, —OCH2CH2CH2-), 1.30-1.15 (m, 246H, —CH3).

[0315] Polymer 10 k-MC (Deprotected Maleimide):

[0316] 1H NMR (400 MHz, CDCl3, 22° C.) δ 7.41-7.25 (m, 312H, —C6H4CH2Cl), 6.77-6.56 (m, 12H, —COC2H4CO—), 5.18-5.06 (m, 156H, —COOCH2-), 4.61-4.50 (m, 156H, —C6H4CH2Cl), 4.45-4.35 (m, 12H, —COOCH2CH2-), 4.33-3.96 (m, 312H, —CH2OCOO—), 3.89-3.58 (m, 908H, —OCH2CH2- from 10 kDa MPEG), 3.57-3.53 (m, 12H, —CH2CH2NR2), 1.82-1.75 (m, 12H, —OCH2CH2CH2-), 1.33-1.11 (m, 234H, —CH3).

[0317] Polymer 10 k-MC (Quaternized):

[0318] 1H NMR (400 MHz, (CD3)2CO, 22° C.) δ 7.75-7.38 (m, 288H, —C6H4CH2Cl), 7.21-6.50 (m, 12H, —COC2H4CO—), 5.31-5.05 (m, 144H, —COOCH2-), 4.80-4.53 (m, 144H, —C6H4CH2Cl), 4.39-4.37 (m, 12H, —COOCH2CH2-), 4.36-3.88 (m, 288H, —CH2OCOO—), 3.71-3.45 (m, 12H, —CH2CH2NR2), 3.43-3.39 (m, 908H, —OCH2CH2- from 10 kDa MPEG), 3.34-3.23 (m, 144H, —N∘+CH2CH2CH2-), 2.99 (s, 432H, —N∘+[CH3]2), 2.28-1.90 (m, 12H, —OCH2CH2CH2-), 1.85-1.63 (m, 144H, —N∘+CH2CH2CH2-), 1.38-1.00 (m, 360H, —N∘+CH2CH2CH2- & —N∘+CH2CH2CH2CH3), 0.99-0.70 (m, 216H, —CH3).

Example 7: Polymer Synthesis of Polymer 2.4 k-M

[0319] Details of the metal-free organocatalytic ring opening polymerization for the polymer 2.4 k-M without cationic polycarbonate are given below as an example.

[0320] In a glove-box, 13.1 mg (0.055 mmol) of 2.4 kDa MPEG-OH initiator and 0.2 g (0.55 mmol) of MTC-FPM were charged in a 20 mL glass vial equipped with a stir bar. Dichloromethane was added and the concentration was adjusted to 2 M with respect to the monomer. Once the initiator and monomers were completely dissolved, 4.1 μL (0.027 mmol) of DBU was added to initiate the polymerization. After 24 hours, the reaction was quenched with excess benzoic acid. Subsequently, the polymer intermediate was purified immediately via precipitation twice in cold diethyl ether, and was dried on a vacuum line until a constant weight was achieved.

[0321] 1H NMR (400 MHz, CDCl.sub.3, 22° C.): δ 6.56-6.46 (m, 16H, —CHOC.sub.2H.sub.4CHO), 5.29-5.20 (m, 16H, —R.sub.2CHOCHR.sub.2—), 4.47-4.16 (m, 32H, —COOCH.sub.2—), 4.11-4.00 (m, 16H, —COOCH.sub.2CH.sub.2—), 3.84-3.60 (m, 217H, —OCH.sub.2CH.sub.2— from 2.4 kDa MPEG), 3.59-3.52 (m, 16H, —CH.sub.2CH.sub.2NR.sub.2), 2.93-2.80 (m, 16H, —CC.sub.2HCC.sub.2H—), 1.95-1.86 (m, 16H, —OCH.sub.2CH.sub.2CH.sub.2—), 1.35-1.24 (m, 24H, —CH.sub.3).

[0322] The furan-protected maleimide polymer was then deprotected by dissolving the polymer in 10 mL of toluene and heated to 110° C. overnight. After that, the toluene was removed under vacuum and the deprotected polymer was dissolved in 2 mL of dichloromethane and precipitated in cold diethyl ether. The polymer was subsequently dried on a vacuum line until a constant weight was achieved.

[0323] 1H NMR (400 MHz, CDCl3, 22° C.) δ 6.76-6.69 (m, 12H, —COC.sub.2H.sub.4CO—), 4.47-4.18 (m, 24H, —COOCH.sub.2—), 4.14-4.04 (m, 12H, —COOCH.sub.2CH.sub.2—), 3.91-3.62 (m, 217H, —OCH.sub.2CH.sub.2— from 2.4 kDa MPEG), 3.61-3.51 (m, 12H, —CH.sub.2CH.sub.2NR.sub.2), 2.00-1.88 (m, 12H, —OCH.sub.2CH.sub.2CH.sub.2—), 1.35-1.23 (m, 18H, —CH.sub.3).

Example 8: Polymer Synthesis of Polymer 10 k-M

[0324] Polymer 10 k-M was synthesized in similar fashion to polymer 2.4 k-M, with slight modification to the amount of macroinitiator used. In a glove-box, 0.55 mg (0.055 mmol) of 10 kDa MPEG-OH initiator and 0.2 g (0.55 mmol) of MTC-FPM were charged in a 20 mL glass vial equipped with a stir bar. Dichloromethane was added and the concentration was adjusted to 2 M with respect to the monomer. Once the initiator and monomers were completely dissolved, 4.1 μL (0.027 mmol) of DBU was added to initiate the polymerization. After 24 hours, the reaction was quenched with excess benzoic acid. Subsequently, the polymer intermediate was purified immediately via precipitation twice in cold diethyl ether, and was dried on a vacuum line until a constant weight was achieved. Deprotection and purification protocols for polymer 10 k-M are similar to those of polymer 2.4 k-M described above.

[0325] FIG. 1 shows the general process of a polymer coating process with triblock copolymers of PEG, cationic polycarbonate (CPC) and maleimide-functionalized polycarbonate (PMC). FIG. 2 shows the general process of a polymer coating process with diblock copolymers of PEG and cationic polycarbonate containing maleimide groups (i.e. 2.4 k-MC and 10 k-MC) and copolymers of PEG and maleimide-functionalized polycarbonate (i.e. 2.4 k-M and 10 k-M). PEG: on the top of the molecule; maleimide-functionalized polycarbonate block: anchoring point, close to the surface; cationic carbonate moiety: randomly copolymerized with maleimide-functionalized carbonate moiety.

[0326] Polymer 10 k-FPM (Protected Maleimide):

[0327] 1H NMR (400 MHz, CDCl.sub.3, 22° C.): δ 6.64-6.40 (m, 8H, —CHOC.sub.2H.sub.4CHO—), 5.33-5.16 (m, 8H, —R.sub.2CHOCHR.sub.2—), 4.39-4.22 (m, 16H, —COOCH.sub.2—), 4.10-4.01 (m, 8H, —COOCH.sub.2CH.sub.2—), 3.85-3.58 (m, 908H, —OCH.sub.2CH.sub.2— from 10 kDa MPEG), 3.52-3.49 (m, 8H, —CH.sub.2CH.sub.2NR.sub.2), 2.92-2.78 (m, 8H, —CC.sub.2HCC.sub.2H—), 2.00-1.84 (m, 8H, —OCH.sub.2CH.sub.2CH.sub.2—), 1.37-1.18 (m, 12H, —CH.sub.3).

[0328] Polymer 10 k-M (Deprotected Maleimide):

[0329] 1H NMR (400 MHz, CDCl.sub.3, 22° C.) δ 6.77-6.68 (m, 6H, —COC.sub.2H.sub.4CO—), 4.56-4.20 (m, 12H, —COOCH.sub.2—), 4.13-4.05 (m, 6H, —COOCH.sub.2CH.sub.2—), 3.91-3.51 (m, 217H, —OCH.sub.2CH.sub.2— from 2.4 kDa MPEG), 3.49-3.42 (m, 6H, —CH.sub.2CH.sub.2NR.sub.2), 2.01-1.86 (m, 6H, —OCH.sub.2CH.sub.2CH.sub.2—), 1.47-0.90 (m, 9H, —CH.sub.3).

Example 9: General Procedure for Coating/Functionalization

[0330] 2.4 k-V and 2.4 k-S

[0331] Clean samples of PDMS silicone rubber were exposed to ultraviolet/ozone (UVO) radiation for 1 hour, and then dried with nitrogen gas. 3-Mercaptopropyltrimethoxysilane was deposited onto the surface to provide thiol functional groups. These thiol-functionalized samples were immersed in polymer solution (2 mg dissolved in 1 mL of phosphate-buffered saline, pH 7.4), and left at room temperature for 1 day. Subsequently, the thiol functional groups on the PDMS surface reacted with the maleimide pendant groups on the polymer via Michael addition. The unreacted polymers were washed off the surface with isopropanol/water solution before use.

Example 10: Contact Angles

[0332] 2.4 k-V and 2.4 k-S

[0333] The static water contact angles of treated and untreated PDMS surfaces were measured to study wettability change after coating. As shown in FIG. 6, the contact angle of silicone rubber surface decreased drastically after UV/ozone passivation (108.6±0.7° vs. 22.3±1.00). After functionalizing with mercaptopropyltrimethoxysilane, the PDMS surface regained partial hydrophobicity (83.8±2.4°). Cationic polymer coating led to decreased wettability (2.4 k-S polymer-coated surface: 74.1±0.7°; 2.4 k-V polymer-coated surface: 75.1±0.4°). These findings demonstrate that the cationic polymer coatings increased the wettability of silicone rubber surface.

[0334] 2.4 k-M, 2.4 k-MC, 10 k-M, and 10 k-MC

[0335] The static water contact angles of treated and untreated PDMS surfaces were measured to study wettability change. As shown in FIGS. 17a and 17b, the contact angle of silicone rubber surface decreased drastically after UV/ozone passivation (108.6±0.7° vs. 22.3±1.0°). After functionalizing with mercaptopropyltrimethoxysilane, the PDMS surface regained partial hydrophobicity (83.8±2.4°). All polymer coatings led to decreased wettability, with 10 k-MPEG incorporated polymer coatings (10 k-MC: 71.1±1.1°, 10 k-M: 70.5±0.9°) giving rise to slightly more hydrophilic surfaces as compared to shorter 2.4 k-MPEG incorporated polymer coated surfaces (2.4 k-MC: 74.7±0.6°, 2.4 k-M: 73.8±0.4°). The presence of cationic polycarbonates did not change the surface wettability significantly. These results indicate successful polymer coating and that polycarbonates confer hydrophobicity to the surface.

Example 11: Grafting of Polymers 2.4 k-V and 2.4 k-S

[0336] 2.4 k-V and 2.4 k-S

[0337] The XPS spectra of silicone rubber before and after polymer coatings were obtained and analyzed to affirm successful grafting of the polymers onto the thiol-functionalized PDMS surface. The atomic content of C1s, O1s, N1s and S2p peaks were analyzed and compared among the pristine, thiol-functionalized, 2.4 k-V and 2.4 k-S grafted surfaces. After successful vapour deposition of 3-mercaptopropyltrimethoxysilane onto the pristine surface, S2p peak appeared with an atomic content of 2.35%. Moreover, the surface grafted with 2.4 k-V and 2.4 k-S had comparable nitrogen atomic contents (i.e. 0.61% and 0.45 respectively). In the high resolution N1s spectrum of the coated surface, there are two distinct peaks. The first peak at 396.2 eV represents the amine from the maleimide pendant group (Scheme 3), and the second peak at 398.7 eV is from N,N-dimethylbutylammonium functional groups. These findings demonstrated successful grafting of the polymers onto the thiol-functionalized surface.

[0338] 2.4 k-M, 2.4 k-MC, 10 k-M, and 10 k-MC

[0339] The XPS spectra of silicone rubber before and after polymer coating were obtained and analyzed to further affirm the successful grafting of the polymers onto the thiol-functionalized PDMS surface. The atomic content of C1s, O1s, N1s and S2p peaks were analyzed and compared among the pristine, thiol-functionalized, 2.4 k-M and 2.4 k-MC grafted surfaces. After successful vapour deposition of 3-mercaptopropyltrimethoxysilane onto the pristine surface, the thiol functionalized surface provided linker groups for Michael addition reaction with the pendantmaleimide moieties on the various polymers. The surface grafted with 2.4 k-M was observed with 1.85% nitrogen atomic content, while surface grafted with 2.4 k-MC recorded lower nitrogen content (0.26%) due to lower nitrogen content in CPC segment as compared to PMC segment and a higher content of CPC segment. In the high resolution N1s spectrum of the surface coated with 2.4 k-MC, there are two distinct peaks (FIG. 13). The first peak at 396.8 eV represents the amine from the maleimide pendant group (Scheme 4). The second peak at 399.2 eV correlated to the presence of N,N-dimethylbutylammonium functional groups. The surface coated with 2.4 k-M only displayed a single sharp peak at 396.9 eV, correlating to the presence of the amine from the maleimide moiety. These findings further confirm the successful coating of the polymers onto the thiol-functionalized surface.

Example 12: Antibacterial Activity

[0340] 2.4 k-V and 2.4 k-S

[0341] Pristine PDMS silicone and thiol-functionalized control surfaces, and surfaces coated with 2.4 k-V and 2.4 k-S, were tested against Gram-positive S. aureus and Gram-negative E. coli after incubation with the respective bacteria solution at 37° C. for 24 hours. With the pristine surface serving as the control, killing efficiency for the thiol-functionalized surface, as well as surfaces coated with the two copolymers was studied. The number of S. aureus in solution increased by 4.8 and 4.2 Log.sub.10 after 24 hours of incubation for the pristine and thiol-functionalized PDMS surfaces, respectively (FIG. 7a). In contrast, the surfaces coated with cationic polymers showed a reduction in the number of bacteria in solution as compared to both the pristine and thiol-functionalized PDMS surfaces (8.0 Log.sub.10 for 2.4 k-V and 8.9 Log.sub.10 for 2.4 k-S), demonstrating 98.5% and 89.4% killing efficiencies, respectively, in the solution as compared to the pristine control. Moreover, there was significant reduction in viable colonies derived from E. coli solution (FIG. 7b) seeded on polymer-coated surfaces (7.4 Log.sub.10 for 2.4 k-V and 8.0 Log.sub.10 for 2.4 k-S) as compared to the pristine and thiol-functionalized surfaces (˜8.7 Log.sub.10). The results translated to killing efficiencies of 93.9% and 82.5% for surfaces coated with 2.4 k-V and 2.4 k-S, respectively. The 2.4 k-V polymer coating had a greater killing effect against both S. aureus and E. coli than the 2.4 k-S polymer coating, possibly due to a greater contact of the cationic moieties with the bacteria (FIG. 1).

[0342] 2.4 k-M, 2.4 k-MC, 10 k-M, and 10 k-MC

[0343] Pristine PDMS silicone surface and surfaces coated with the 4 polymers respectively were tested against both Gram-positive bacteria S. aureus and Gram-negative bacteria E. coli. All samples were incubated with the respective bacteria solution at 37° C. for 24 hours, after which the solution was diluted to respective concentrations for colony counting. Bacterial solution seeded on pristine (10.1 Log CFU.Math.ml.sup.−1), thiol functionalized (9.6 Log CFU.Math.ml.sup.−1) and non-cationic polymer surfaces 2.4 k-M (10.0 Log CFU.Math.ml.sup.−1) and 10 k-M (10.0 Log CFU.Math.ml.sup.−1) had a large amount of live S. aureus cells as seen in FIG. 15. In contrast, the solution on the surfaces coated with the cationic polymers 2.4 k-MC (8.8 Log CFU.Math.ml.sup.−1) and 10 k-MC (8.3 Log CFU.Math.ml.sup.−1) had an approximated 2 logarithmic reduction in bacteria colonies as compared to the pristine surface, demonstrating that 95.5% and 98.4% of killing efficiencies respectively. This trend was held constant when the surfaces were tested against E. coli. Significant reduction of viable colonies derived from E. coli solution was observed for the surfaces coated with 2.4 k-MC (8.4 Log CFU.Math.ml.sup.−1) and 10 k-MC (8.2 Log CFU.Math.ml.sup.−1), recording killing efficiencies of 92.7% and 95.5% respectively. These results demonstrated that 2.4 k-M and 10 k-M without cationic polycarbonate were unable to eradicate bacteria in solution, while 2.4 k-MC and 10 k-MC with cationic polycarbonate killed bacteria in solution that was in contact with the coated surfaces.

Example 13: Antifouling Activity

[0344] 2.4 k-V and 2.4 k-S

[0345] Antifouling activity is the most important property that ideal catheters should possess to prevent catheters-associated infections. To quantitatively investigate bacteria fouling on the uncoated thiol- and polymer-coated silicone rubber surfaces, the number of viable bacterial cells fouled on the surfaces was measure (FIG. 3). A high number of S. aureus and E. coli cells were fouled onto both pristine and thiol-functionalized surfaces after 7 days of incubation (S. aureus: 8.8 Log.sub.10 and 8.6 Log.sub.10, respectively. E. coli: 8.5 Log.sub.10 and 8.2 Log.sub.10, respectively). There was no significant difference in the number of viable cells observed on the pristine and thiol-functionalized surfaces. In contrast, the polymer-coated surfaces showed significant antifouling activity with 2.4 k-S being more effective. For example, the number of S. aureus and E. coli was lower by ˜3 Log.sub.10 on the 2.4 k-S coated surface at 7 days as compared to that on the pristine surface.

[0346] A complementary XTT assay, which measures bacterial cell viability, was performed to further evaluate antifouling activity of the coated and uncoated surfaces, and the results are well correlated to the viable surface colonies determined by agar plating (FIG. 8a). Cell Titer-Blue@ cell viability assay was employed to quantify fouling of E. coli as XTT assay was unable to detect E. coli. Similar to S. aureus, the pristine and thiol-functionalized surfaces showed extensive E. coli fouling, while polymer coatings inhibited E. coli fouling with 2.4 k-S coating being more promising (FIG. 8b). LIVE/DEAD bacterial cell staining was performed to further confirm the antifouling property of polymer coatings against both S. aureus and E. coli. Live and dead (a) S. aureus; and (b) E. coli cell staining on uncoated silicone PDMS surface and surfaces coated with thiol, 2.4 k-V and 2.4 k-S was performed. The surfaces were imaged under confocal laser scanning microscopy after 1 and 7 days of incubation. It was found that the pristine and thiol-functionalized surfaces showed significant fouling of bacteria, and a large number of live cells were seen after 1 day and 7 days of incubation. The surface coated with the polymer 2.4 k-S had significantly less fouling, as compared to surface coated with polymer 2.4 k-V, which is in agreement with both viable surface colonies (FIG. 3) and XTT assay results (FIG. 8).

[0347] Biofilm on surfaces consists of bacteria, their secretions and organic debris, and is extremely difficult to remove. From SEM analysis, the control surfaces without polymer coating developed biofilm especially at 7 days. In sharp contrast, no biofilm was formed on the polymer 2.4 k-S coating. Taken together, this data suggests that the polymer 2.4 k-S with the optimal composition inhibited bacteria fouling, effectively preventing biofilm formation.

[0348] 2.4 k-M, 2.4 k-MC, 10 k-M, and 10 k-MC

[0349] To quantitatively investigate bacteria fouling on uncoated and polymer-coated silicone rubber surfaces, surviving S. aureus and E. coli cells left on the surfaces after washing were counted (FIG. 4). The pristine surface, thiol-functionalized surface, and the surfaces coated with cationic polymers had a higher amount of S. aureus and E. coli cells. Live and dead (a) S. aureus; and (b) E. coli cell staining on uncoated silicone PDMS surface and surfaces coated with thiol, 2.4 k-MC, 2.4 k-M, 10 k-MC and 10 k-M was performed. The surfaces were imaged under confocal laser scanning microscopy after 1, 7 and 14 days of incubation. From the presence of dead cells as shown by LIVE/DEAD bacterial viability staining (FIG. 4), the thiol functional groups killed the bacteria on the surface, and live cells were also attached to the surface by anchoring onto the underlying dead cells. The coatings of the cationic polymers 1.4 k-MC and 10 k-MC were unable to prevent bacteria fouling. In contrast, 1.4 k-M and 10 k-M inhibited bacteria fouling with 10 k-M being more effective against both S. aureus and E. coli over 14 days. For example, 20 k-M coating led to more than 4 Log.sub.10 reduction for live S. aureus fouling and -3 Log.sub.10 reduction for E. coli as compared to the pristine surface (FIG. 4). Complementary XTT (and cell titer blue assays which measure viability of S. aureus and E. coli respectively, were performed and the results are well correlated to FIG. 4 and FIG. 15, with surfaces coated with solely PEG components recorded the strongest antifouling activity.

[0350] Prevention and removal of biofilm is notoriously difficult. Pristine and thiol-functionalized surfaces developed biofilm after 7 and 14 days of incubation, confirmed by SEM (FIG. 17) and viable surface colony (FIG. 4) analyses. Moreover, after 7 days of incubation with S. aureus bacteria, surfaces coated with 2.4 k-MC and 10 k-MC started to foul, with the former surface fouling most extensively. S. aureus biofilm was observed on 2.4 k-MC coated surface after 14 days of incubation. Compared to S. aureus, E. coli started to foul earlier and biofilm was seen on both 2.4 k-MC and 10 k-MC coated surfaces after 14 days of incubation. For 2.4 k-M coated surface without cationic polycarbonate, significant S. aureus and E. coli fouling was observed after 7 and 14 days of incubation, respectively. However, 10 k-M coating effectively prevented S. aureus and E. coli biofilm formation over 14 days. These results further demonstrated that 10 k-M coating effectively prevented fouling of both Gram-positive and Gram-negative bacteria, inhibiting biofilm formation.

Example 14: Protein Adsorption, Platelet Adhesion and Hemolysis

[0351] 2.4 k-V and 2.4 k-S

[0352] The uncoated and coated surfaces were examined for their protein adsorption, platelet adhesion and hemolysis to study blood compatibility. Proteins are present in blood and adsorption of the proteins may mask the antifouling function of the polymer coatings. FITC-labeled BSA was used as a model protein. BSA-FITC solution was incubated with the coated and uncoated pristine PDMS rubber surfaces for one day at 37° C. From the fluorescence microscopic images of the surfaces the pristine surface showed the greatest degree of protein adsorption. Protein adsorption was greatly decreased on the surface coated with the polymer 2.4 k-S as shown by fluorescence spectroscopy studies (FIG. 9), which may be attributed to the structure of the polymer.

[0353] The PEG block was positioned at the top most position within the covalently tethered tri-block copolymer 2.4 k-S (FIG. 1), preventing proteins from fouling onto the surface. Meanwhile, the surface coated with the 2.4 k-V copolymer demonstrated a higher amount of bacteria and protein fouling, which was most likely due to insufficient coverage of the surface by PEG since the PEG block was positioned at the periphery of the tethered tri-block polymer. The large disparity in molecular size between the cationic block in relation to the PEG block may also shield the smaller PEG block on the surface coated with 2.4 k-V polymer, compressing the antifouling PEG component closer to the PDMS surface as compared to the PEG block on the surface coated with 2.4 k-S polymer.

[0354] Platelet adhesion may cause thrombus formation. Platelet adhesion on the pristine and copolymer-coated surfaces was examined by SEM analysis. Platelet fouling was seen on the entire pristine surface. Moreover, the surface coated with 2.4 k-V was shown to attract a number of platelets. However, very few platelets were observed on the surfaces coated with the polymer 2.4 k-S coated surface, implying that 2.4 k-S coating successfully prevented platelet fouling. Hemolytic activity of the untreated and polymer-coated surfaces was evaluated using rat red blood cells. All surfaces, coated or uncoated, exhibited almost no or minimal hemolysis after incubation with red blood cells (FIG. 10), which is ideal for use as antibacterial and antifouling coatings especially for intravenous catheters.

[0355] 2.4 k-M, 2.4 k-MC, 10 k-M, and 10 k-MC

[0356] Proteins present in blood and subsequent adsorption of these blood proteins may act as an underlying anchoring layer for adhesion of surrounding bacteria, hence masking the antifouling/antimicrobial functions of the polymer coatings. Therefore, FITC-labeled BSA was used as a standard protein to study protein adsorption on the polymer-coated silicone rubber surfaces. BSA-FITC solution was incubated with the treated and pristine PDMS rubber surfaces for one day at 37° C. Consequently, the pristine surface showed the greatest protein adsorption, analyzed by both florescence microscopy and spectroscopy. Protein adsorption was greatly reduced on all other coated surfaces.

[0357] Blood platelet adhesion may also compromise the antibacterial and antifouling functions of the polymer coatings via clotting. It is evident from FE-SEM analysis that the pristine surface had significant blood platelet fouling. The 10 k-M coating with the optimal composition showed almost no presence of blood platelets, indicating that the polymer coating may reduce occurrence of thrombosis. Moreover, all surfaces, coated or uncoated, had almost no or minimal hemolysis after treatment with red blood cells from rats (FIG. 18).

INDUSTRIAL APPLICABILITY

[0358] In conclusion, triblock copolymers of antifouling PEG, antibacterial cationic polycarbonate and maleimide-functionalized polycarbonate (for anchoring onto silicone rubber surface) may be successfully synthesized with different molecular structure but similar molecular length for each block via metal-free organocatalytic ring-opening polymerization for surface coating. The polymers may be grafted onto thiol-functionalized PDMS silicone rubber surfaces through Michael addition reaction. The surface coated with 2.4 k-S was the most effective against S. aureus and E. coli fouling over one week, preventing biofilm formation. This polymer coating was also able to resist protein fouling and platelet adhesion, and did not cause significant hemolysis. This polymer coating holds great potential for prevention of bacterial fouling and catheter-associated bloodstream infections.

[0359] Additionally, diblock copolymers of PEG with different chain length and maleimide-functionalized polycarbonate, and diblock copolymers of PEG with different chain length and cationic polycarbonate having maleimide groups randomly distributed were successfully synthesized. The polymer having PEG of Mn 10 kDa without cationic polycarbonate effectively inhibited fouling of both Gram-positive and Gram-negative bacteria, preventing biofilm formation without inducing protein adsorption, platelet adhesion or hemolysis. The polymer coating further has great potential for use as catheter coating to prevent various infections.

[0360] It will be apparent that various other modifications and adaptations of the invention will be apparent to the person skilled in the art after reading the foregoing disclosure without departing from the spirit and scope of the invention and it is intended that all such modifications and adaptations come within the scope of the appended claims.