PROCESS AND SOLUTION FOR PREPARING A SURFACE WITH BACTERIOSTATIC AND BACTERICIDAL ACTIVITY, SURFACE THUS PREPARED AND USES THEREOF

Abstract

A method for conferring bacteriostatic or bactericidal properties on a surface of an object, comprising: (a) putting the surface into contact with an aqueous solution comprising an ionene-type polymer functionalised by at least one radically polymerisable function, an organic compound with two radically polymerisable functions, an organic compound with three radically polymerisable functions and a photoinitiator, (b) subjecting the surface coated with the aqueous solution to irradiation by means of which a radical polymerisation is initiated and a grafted three-dimensional polymer network comprising ionene-type polymers is obtained. The aqueous solution and the object thus obtained as well as uses thereof in particular for preparing protective garments, for packaging and/or storing fresh food products but also for purifying or decontaminating a solution or a surface.

Claims

1) A method for conferring bacteriostatic or bactericidal properties on a surface of an object, comprising: (a) putting said surface into contact with an aqueous solution comprising: at least one ionene-type polymer functionalised by at least one radically polymerisable function, at least one organic compound with two radically polymerisable functions, at least one organic compound with three radically polymerisable functions, and a photoinitiator, (b) subjecting said surface coated with said aqueous solution to an irradiation by means of which a radical polymerisation is initiated and a grafted three-dimensional polymer network comprising polymers of the ionene type is obtained.

2) The method according to claim 1, in wherein, prior to said step a), said step is subjected to an oxidising treatment and/or an organic sublayer is formed on said surface.

3) The method according to claim 1 , wherein said ionene-type polymer functionalised by at least one polymerisable function is prepared via a polyaddition involving at least one diamine of formula (I): $\left(\text{R1}\right)\left(\text{R2}\right)\text{N-A-N}\left(\text{R3}\right)\left(\text{R4}\right)$ wherein R1, R2, R3 and R4, identical or different, represent a hydrogen atom, an alkyl group, optionally substituted, or an aryl group, optionally substituted; and A is a chain selected from the group consisting of an alkylene chain, optionally substituted, an alkenylene or alkynylene chain, optionally substituted, an arylene chain, optionally substituted, an alkylarylene chain, optionally substituted, and an arylalkylene chain, optionally substituted, and at least one dihalide of formula (II): $\left(\text{R5}\right)\text{-B-}\left(\text{R6}\right)$ wherein R5 and R6, identical or different, represent a halogen; and B is a chain selected from the group consisting of an alkylene chain, optionally substituted, an alkenylene or alkynylene chain, optionally substituted, an arylene chain, optionally substituted, an alkylarylene chain, optionally substituted, and an arylalkylene chain, optionally substituted.

4) The method according to claim 3, wherein said polyaddition step is followed by an operation during which a function or a plurality of functions, identical or different, substituting the ionene-type polymer is/are replaced by one or more radically polymerisable functions.

5) The method according to claim 1 , wherein said organic compound with two radically polymerisable functions is ethylene glycol dimethacrylate, optionally in a mixture with a poly(ethylene glycol) diacrylate such as a poly(ethylene glycol) diacrylate the molar mass of which is 700 g.mol-.sup.1.

6) The method according to claim 1 , wherein said organic compound with three radically polymerisable functions is trimethylolpropane triacrylate or a trimethylolpropane ethoxylate triacrylate such as a trimethylolpropane ethoxylate triacrylate the molar mass of which is 428 g.mol.sup.-1, a trimethylolpropane ethoxylate triacrylate the molar mass of which is 692 g.mol.sup.-1 or a trimethylolpropane ethoxylate triacrylate the molar mass of which is 912 g.mol.sup.-1.

7) The method according to claim 1 , wherein said photoinitiator is 2 hydroxy-4′-(2-hydroxyethoxy) 2 methylpropiophenone.

8) The method according to claim 1 te-7, wherein the solvent of said aqueous solution is a mixture of water and ethanol and in particular a mixture of deionised water and ethanol.

9) The method according to claim 1 , wherein, in said step a), the aqueous solution is deposited on said surface by inkjet printing.

10) The method according to claim 1 , wherein the irradiation in said step b) is a photonic annealing comprises subjecting said surface coated with aqueous solution obtained following said step a) to a succession of light pulses of UV radiation.

11) An queous solution used during step a) of a method according to claim 1 , comprising: at least one ionene-type polymer functionalised by at least one radically polymerisable function, at least one organic compound with two radically polymerisable functions, at least one organic compound with three radically polymerisable functions, and a photoinitiator.

12) The aqueous solution according to claim 11, wherein it comprises or consists of: deionised water, ethanol, the mass ratio between deionised water and ethanol being between 0.5 and 0.65, an ionene-type polymer functionalised by at least one radically polymerisable function comprising, in its main chain, a concatenation of repetitive units of formula (III): ${\text{-N}}^{\text{+}}\left(\text{R1}\right)\left(\text{R2}\right){\text{-A-N}}^{\text{+}}\left(\text{R3}\right)\left(\text{R4}\right)\text{-B-}$ wherein R1 = R2 = R3 = R4 = CH.sub.3 and A = B = C.sub.6H.sub.12, said polymer being in a quantity of between 2% and 7% by mass with respect to the total mass of the aqueous solution, ethylene glycol dimethacrylate in a quantity of between 8% and 12% by mass with respect to the total mass of the aqueous solution, trimethylolpropane ethoxylate triacrylate the molar mass of which is 428 g.mol.sup.-1, in a quantity of between 2% and 13% by mass with respect to the total mass of the aqueous solution, and 2 hydroxy-4′-(2-hydroxyethoxy) 2 methylpropiophenone in a quantity between 2% and 3% with respect to the total mass of the aqueous solution.

13) An object having a surface on which bacteriostatic or bactericidal properties have been conferred in accordance with a method as defined in claim 1.

14) The object according to claim 13, wherein said object is selected from the group consisting of a film, a packaging film, a box, a tray, a case, a lid, a sachet, dialysis equipment, a rod, a probe, paper, a textile, a membrane and a filter.

15) A_use of an object according to claim 13 , for preparing garments and protective coatings, for packaging and/or storing food products such as fresh food products, or for purifying and/or decontaminating a solution, an object or a surface in the environmental or hospital field.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0135] FIG. 1 presents the FTIR spectrum of an ink according to the present invention (ink 6-1B) printed on a PE film and then subjected to photonic annealing, after ultrasound cleaning.

[0136] FIG. 2 presents the FTIR spectrum of native PVC and PVC with the 6-1B ink according to the present invention.

[0137] FIG. 3 presents the global spectra of the surfaces of native PVC and PVC with the 6-1B ink (FIG. 3A) and the high-resolution spectrum of the N 1 s of PVC with the 6-1B ink (FIG. 3B).

[0138] FIG. 4 presents the FTIR spectrum of native PET and PET with the 6-1B ink according to the present invention.

[0139] FIG. 5 presents the global spectra of the surfaces of native PET and PET with the 6-1B ink (FIG. 5A) and the high-resolution spectra of the N 1 s on these same surfaces (FIG. 5B).

[0140] FIG. 6 presents the global spectra of the surfaces of PE with the 6-1B ink according to the present invention and the 7-1B ink without PI with at least one radically polymerisable function and therefore not forming part of the invention (FIG. 6A) and the high-resolution spectrum of the N 1 s on PE with the 6-1B ink (FIG. 6B).

[0141] FIG. 7 presents the 3 h adhesion at 37° C. of S. aureus on a film of native PE and on a film of PE modified with 6-1B ink in accordance with the method according to the invention with FT = total flora and VC = cultivatable viable.

[0142] FIG. 8 presents the count of the adhesion supernatants of S. aureus on a film of native PE and on a film of PE modified with 6-1B ink in accordance with the method according to the invention.

[0143] FIG. 9 presents the cytotoxicity results on cell layers of mouse fibroblasts (L929) after exposure for 48 h to films of PE modified with the 6-1B ink (ink 6-1B PE) in accordance with the method according to the invention (n = 3). The control corresponds to the same culture medium but without PE film modified or not.

[0144] FIG. 10 presents the cytotoxicity results on human epidermises reconstructed after exposure of 24 h in the presence of PBS to films of non-modified PE (native PE) and to films of PE modified with the 6-1B ink (ink 6-1B PE) in accordance with the method according to the invention (n = 3). The negative control corresponds to PBS alone and the positive control to PBS with a latex glove extract.

DETAILED DISCLOSURE OF PARTICULAR EMBODIMENTS

I. Preparation of Inks According to the Present Invention

I.1. Materials

[0145] With a view to preparing inks according to the invention, the reagents listed in Table 1 below were ordered from Sigma-Aldrich. The solvents were ordered from CARLO ERBA Reagents. After receipt, all the reagents were used as such, without additional purification.

TABLE-US-00001 Products necessary for manufacturing the ink Product Raw formula M (g. mol.sup.-1) CAS 1,6 dibromohexane C.sub.6H.sub.12Br.sub.2 243.98 629-03-8 N,N,N′,N′-tetramethyl-1,6-diaminohexane C.sub.10H.sub.24N.sub.2 172.32 111-18-2 Methanol CH.sub.4O 32.0 67-56-1 Acetone C.sub.3H.sub.6O 58.08 64-17-5 DMAEMA (2-(Dimethylamino)ethyl methacrylate) C.sub.8H.sub.15O.sub.2N 157.21 2867-47-2 Poly(ethylene glycol) diacrylates 700 / 700 26570-48-9 Ethylene glycol dimethacrylate C.sub.10H.sub.14O.sub.4 198.2 97-90-5 Trimethylpropane triacrylates C.sub.15H.sub.20O.sub.6 296.3 15625-89-5 Trimethylolpropane ethoxylate triacrylate 428 / 428 28961-43-5 Trimethylolpropane ethoxylate triacrylate 692 / 692 28961-43-5 Trimethylolpropane ethoxylate triacrylate 912 / 912 28961-43-5 2 hydroxy-4′-(2-hydroxyethoxy) 2 methylpropiophenone C.sub.12H.sub.16O.sub.4 224.3 106797-53-9

I.2. Synthesis of Polyionene: PI 6-6

[0146] All the compounds are introduced by means of a syringe into a 50 mL three-necked flask under inert atmosphere surmounted by a refrigerant, in the following order: N,N,N′,N′-tetramethyl-1,6-diaminohexane (4.3 mL, 0.0224 mol), 11 mL of methanol, 1,6-dibromohexane (3.4 mL, 0.0224 mol) and 11 mL of methanol.

[0147] The reaction mixture, homogeneous and clear, is heated at 65° C. for 17 h under stirring. The reaction is stopped by putting the flask in an ice bath. The mixture obtained is precipitated by adding it dropwise in 300 mL of acetone. The precipitate obtained is filtered over a Büchner flask and dried.

[0148] A white solid is obtained with a mass m = 8.86 g. .sup.1H NMR (D.sub.2O, δ in ppm): 1.39 (s, 8H); 1.74 (s, 8H); 2.83 (s, 0.27H, amine end); 3.01 (s, 12H); 3.23-3.30 (m, 8H); 3.46-3.49 (t, 0.38H, brominated end).

[0149] The polyionene thus obtained is the PI 6-6 of formula:

##STR00006##

I.3. Synthesis of Functionalised PI 6-6

[0150] With a view to functionalising PI 6-6 implemented on the brominated ends of this polymer, it is sought first of all to increase the brominated chain ends thereof.

[0151] In a 350 mL three-neck flask surmounted by a refrigerant, PI 6-6 (8.0214 g, 0.0028 mol) is introduced and then, once the assembly is closed, the solid is put under inert atmosphere. 100 mL of methanol is added with a glass syringe and complete dissolution of the solid is obtained. 1,6-dibromohexane (9 mL, 0.059 mol) is introduced by means of a syringe, and then 18 mL of methanol.

[0152] The reaction mixture is heated at 65° C. for 24 h under stirring. The reaction is stopped by putting the flask in an ice bath. The mixture is next poured, dropwise, into 300 mL to 1300 mL of acetone. The precipitate obtained is then filtered on a Büchner flask and then dried.

[0153] A white solid is obtained with a mass m = 6.56 g. .sup.1H NMR (D.sub.2O, δ in ppm): 1.39 (s, 8H); 1.74 (s, 8H); 2.83 (s, 0.22H, amine end); 3.01 (s, 12H); 3.23-3.30 (m, 8H); 3.46-3.49 (t, 0.49H, brominated end).

[0154] The polyionene with brominated ends thus obtained is the PI 6-6 Br of formula:

##STR00007##

[0155] In a 250 mL three-necked flask surmounted by a refrigerant, the PI 6-6 Br (6.00 g, 0.0021 mol) is introduced and then, once the assembly is closed, the solid is put under inert atmosphere. 90 mL of methanol is added with a glass syringe and complete dissolution of the solid is awaited. 2-(Dimethylamino)ethyl methacrylate (36 mL, 0.2137 mol) is introduced by means of a glass syringe, and then 16 mL of methanol.

[0156] The reaction mixture is heated at 65° C. for 48 h under stirring. The reaction is stopped by putting the flask in an ice bath. The mixture is next poured, dropwise, into 300 mL to 1400 mL of acetone. The precipitate obtained is filtered on a Büchner flask and then dried.

[0157] A white solid is obtained of mass m = 5.56 g. .sup.1H NMR (D.sub.2O, δ in ppm): 1.39 (s, 8H); 1.74 (s, 8H); 2.15 (s, 0.07H, DMAEMA end); 2.66-2.69 (t, 0.12H, DMAEMA end); 2.81 (s, 0.07H, amine end); 3.01 (s, 12H); 3.23-3.30 (m, 8H); 3.46-3.49 (t, 0.03H, brominated end); 3.97 (s, 0.21H, DMAEMA end); 5.37 (1, 0.004H, DMAEMA end); 5.57 (s, 0.004H, DMAEMA end).

[0158] The functionalised polyionene thus obtained is the functionalised PI 606 of formula:

##STR00008##

[0159] The functionalised PI 6-6 used in the inks according to the invention has a molar mass of around 3000 g.mol.sup.-1.

1.4. Formulations of the Inks

[0160] The functionalised PI 6-6 is soluble only in water or methanol, and the other components of the inks in ethanol. Consequently, the solvent of the inks was selected so as to be capable of solubilising all the compounds, evaporating rapidly during crosslinking and conferring to the ink an ideal viscosity for deposition in inkjet printing. This solvent is a mixture of ethanol and deionised water.

[0161] Each of the inks is prepared by weighing the liquid and solid compounds precisely and separately. Next, the mixture of the liquid compounds is left to stir for at least 1 h. This mixture is added to the mixture of solids and the formulation is left to stir for at least 1 night.

[0162] Finally, the ink is filtered on a 13 mm diameter syringe filter made of PTFE with a porosity of 0.45 .Math.m. The formulation is next stored away from light at 4° C. to preserve the activity of the photoinitiator. It can thus be stored for several months. It should be noted that a test was carried out with an ink reused 2 months after manufacture thereof.

[0163] The formulations of the various inks produced are supplied in Tables 2 to 8 below.

TABLE-US-00002 Formulation of ink 6-1B Components Mass % Mass (g) Mn (g.mol.sup.-1) Deionised water 27.4% 2.500 18 Ethanol 48.6% 4.440 46.1 Double-bond functionalised polyionene 4.2% 0.380 3212 Ethylene glycol dimethacrylate 10.9% 1.000 198.2 Trimethylolpropane ethoxylate triacrylate 428 6.2% 0.566 428 2 hydroxy (4′ hydroxyethoxy) 2 methylpropio phenone 2.7% 0.250 224.3

TABLE-US-00003 Formulation of ink 4-5 Components Mass % Mass (g) Mn (g.mol.sup.-1) Deionised water 26.8% 2.500 18 Ethanol 47.6% 4.440 46.1 Poly(ethylene glycol) diacrylates 700 5.4% 0.500 700 Double-bond functionalised polyionene 6-6 4.1% 0.380 3212 Ethylene glycol dimethacrylate 10.7% 1.000 198.2 Trimethylpropane triacrylates 2.7% 0.250 296.3 2 hydroxy (4′ hydroxyethoxy) 2 methylpropio phenone 2.7% 0.250 224.3

TABLE-US-00004 Formulation ink 6-1A Components Mass % Mass (g) Mn (g.mol.sup.-1) Deionised water 26.5% 2.500 18 Ethanol 47.1% 4.440 46.1 Poly(ethylene glycol) diacrylates 700 5.3% 0.500 700 Double-bond functionalised polyionene 6-6 4.0% 0.380 3212 Ethylene glycol dimethacrylate 10.6% 1.000 198.2 Trimethylolpropane ethoxylate triacrylate 428 3.8% 0.361 428 2 hydroxy (4′ hydroxyethoxy) 2 methylpropio phenone 2.7% 0.250 224.3

TABLE-US-00005 Formulation of ink 6-2A Components Mass % Mass (g) Mn (g.mol.sup.-1) Deionised water 25.9% 2.500 18 Ethanol 46.0% 4.440 46.1 Poly(ethylene glycol) diacrylates 700 5.2% 0.500 700 Double-bond functionalised polyionene 6-6 3.9% 0.380 3212 Ethylene glycol dimethacrylate 10.4% 1.000 198.2 Trimethylolpropane ethoxylate triacrylate 692 6.1% 0.585 692 2 hydroxy (4′ hydroxyethoxy) 2 methylpropio phenone 2.6% 0.250 224.3

TABLE-US-00006 Formulation of ink 6-2B Components Mass % Mass (g) Mn (g.mol.sup.-1) Deionised water 26.4% 2.500 18 Ethanol 46.8% 4.440 46.1 Double-bond functionalised polyionene 6-6 4.0% 0.380 3212 Ethylene glycol dimethacrylate 10.5% 1.000 198.2 Trimethylolpropane ethoxylate triacrylate 692 9.6% 0.915 692 2 hydroxy (4′ hydroxyethoxy) 2 methylpropio phenone 2.6% 0.250 224.3

TABLE-US-00007 Formulation of ink 6-3A Components Mass % Mass (g) Mn (g.mol.sup.-1) Deionised water 25.4% 2.500 18 Ethanol 45.1% 4.440 46.1 Poly(ethylene glycol) diacrylates 700 5.1% 0.500 700 Double-bond functionalised polyionene 6-6 3.9% 0.380 3212 Ethylene glycol dimethacrylate 10.2% 1.000 198.2 Trimethylolpropane ethoxylate triacrylate 912 7.8% 0.770 912 2 hydroxy (4′ hydroxyethoxy) 2 methylpropio phenone 2.5% 0.250 224.3

TABLE-US-00008 Formulation of ink 6-3B Components Mass % Mass (g) Mn (g.mol.sup.-1) Deionised water 25.6% 2.500 18 Ethanol 45.4% 4.440 46.1 Double-bond functionalised polyionene 6-6 3.9% 0.380 3212 Ethylene glycol dimethacrylate 10.2% 1.000 198.2 Trimethylolpropane ethoxylate triacrylate 912 12.3% 1.205 912 2 hydroxy (4′ hydroxyethoxy) 2 methylpropio phenone 2.6% 0.250 224.3

[0164] It should be noted that by selecting trimethylolpropane ethoxylate triacrylate as compound with three radically polymerisable polyethylene glycol functions, it was possible to dispense with the presence of polyethylene glycol diacrylate used in the first ink formulations.

II. Printing and Annealing of the Inks According to the Present Invention

[0165] The inks are next used on a DIMATIX inkjet printer. Approximately 2 mL of each of the inks is introduced into cartridges with a print head having 16 nozzles each delivering 10 picolitres. The printings are performed with a drop spacing of 50 .Math.m to 1 mm of the surface to be printed (PE, PVC, PET).

[0166] Once printed, the surface undergoes an annealing under the Xenon S2200 lamp that covers all the wavelengths from 250-300 nm to 1000-1200 nm with 2000 V flashes for 150 milliseconds and then an absence of flash for 300 milliseconds. The series of flashes is repeated 20 times.

[0167] Once the annealing has been carried out, the printed crosslinked surfaces are introduced into a mixture of deionised water and ethanol (50/50) and put under ultrasound at full power for 10 minutes.

[0168] For all the inks the formulations of which are supplied in Tables 2 to 8, a film of the crosslinked solid deposit type is obtained after photonic annealing, consisting of a three-dimensional network, obtained from the various compounds with radically polymerisable functions, contained in the ink. Polyionene is thus incorporated covalently in this network.

[0169] Among the various inks tested, ink 6-1B allows to obtain the most homogeneous coating.

III. Characterisation of the Crosslinked Solids Deposit

III.1. Covalent Grafting on the Printed Surface

[0170] After the printings, the samples with the deposits resulting from the 6-1B ink were cleaned with ultrasound for 10 minutes in a water/ethanol mixture (50/50). These cleaned samples were next analysed by infrared spectroscopy (FTIR) and XPS, to attest to the presence of the deposits and maintenance thereof after ultrasound cleaning.

PE Surface

[0171] The analyses by XPS and FTIR spectroscopies show that the films obtained are grafted covalently on the printed PE surface.

[0172] Indeed, on FIG. 1, the presence of the ink is observed on the polyethylene after a cleaning of 10 minutes in an ultrasound bath in a water/ethanol mixture (50/50).

PVC Surface

[0173] The FTIR spectrum attests to the maintenance of the 6-1B ink on the PVC through the presence of the characteristic peaks, which can be attributed to the ink (FIG. 2). The peak at 3500 cm.sup.-1 corresponds to the elongation of the O—H bonds. The peak at 1728 cm.sup.-1 corresponds to the elongation of the C═O bonds (esters). The peak at 1601 cm.sup.-1 corresponds to the elongation of the C═C bonds (alkenes). The peaks at 1173 and 1103 cm.sup.-1 correspond to the elongation of the C—O—C bonds (ethers).

[0174] The global XPS spectrum at N 1 s high resolution of the PVC 6-1B ink (FIG. 3) also corroborates the presence of the deposit on the PVC. The nitrogen contribution, characteristic of the presence of PI, is in fact visible only on the global spectrum of the 6-1B ink PVC (FIG. 3A). In addition, the N 1 s high-resolution spectrum indicates that the contribution of the C—N.sup.+ bonds, at 402 eV, is in the majority (FIG. 3B). This contribution is characteristic of the quaternary ammoniums present in the skeleton of the PI.

[0175] The atomic percentages determined on the global spectra and the high-resolution spectrum of the nitrogen are set out in Tables 9 and 10 below.

TABLE-US-00009 Chemical compositions of the native PVC and 6-1B ink PVC (atomic %) determined on the global spectra Layer C1s O1s CI2p Si2p N1s Native PVC 69.2 7.5 18.1 5.2 - PVC + 6-1B ink 70.1 17.6 7.7 4.2 0.5

TABLE-US-00010 N 1.sub.S contributions (atomic %) determined on the high-resolution spectrum of the 6-1B ink PVC Layer C-N 399 eV C—N.sup.+ 402 eV PVC + 6-1B ink 16.8 83.2

PET Surface

[0176] In the case of the 6-1B ink PET, the FTIR spectrum does not make it possible to confirm the presence of ink, after ultrasound cleaning, since the spectrum obtained is similar to that of the native PET (FIG. 4).

[0177] On the other hand, the XPS analyses show clearly the presence of the deposit of 6-1B ink, after ultrasound cleaning. The nitrogen contribution is present both on the global spectrum of the native PET and the global spectrum of the 6-1B ink PET (FIG. 5A). Nevertheless, the N 1 s high-resolution spectra make it possible to note a difference in contribution (FIG. 5B). Indeed, on the N 1 s high-resolution spectrum of the native PET, the contribution is a single peak that corresponds to the C—N bonds, whereas on the 6-1B ink PET spectrum the contribution consists of two peaks corresponding to the C-N and C—N.sup.+ bonds. This double peak is characteristic of the presence of PI. Thus, through these analyses, the deposit of ink on the PET films is also established.

[0178] The atomic percentages determined on the global spectra and the high-resolution spectra of nitrogen are set out in Tables 11 and 12 below.

TABLE-US-00011 Chemical compositions of the native PET and 6-1B ink PET (atomic %) determined on the global spectra Layer C1s O1s Si2p N1s Native PET 59.4 25.8 11.9 2.9 PET + 6-1B ink 70.4 25.8 2.3 1.6

TABLE-US-00012 N1s contributions (atomic %) determined on the high resolution spectra of native PET and 6-1B ink PET 6-1B Layer C-N 399 eV C—N.sup.+ 402 eV Native PET 100 - PET + 6-1B ink 73.0 27.0

III.2. Importance of the Functionalisation of the Polyionenes

[0179] In order to demonstrate the importance of the functionalisation of the Pls in the crosslinking step of the method according to the invention, a supplementary ink without functionalised PI 6-6 was produced. This ink, called 7-1B, is a formulation with the same reagents and proportions as the 6-1B ink as defined in Table 2 above but, for the 7-1B ink, a PI 6-6 without crosslinkable function (double bonds) is used rather than the functionalised PI 6-6 as in the 6-1B ink. These two inks were next printed and crosslinked on PE films in accordance with the protocol described at point II above.

[0180] Once the inks have been printed and crosslinked, the printed PE substrates are cleaned with ultrasound in a water/ethanol mixture (50/50) and then dried under a vacuum bell jar, before XPS analysis.

[0181] Among all the components of the ink, only the PI 6-6 has nitrogens in its structure. Thus, the presence of a nitrogen contribution on the global spectrum (FIG. 6A) attests to the presence of PI 6-6 in the deposit made with the 6-1B ink. No nitrogen contribution is on the other hand detected in the deposit obtained from the 7-1B ink.

[0182] The need for the functionalisation of the PI 6-6 with a double bond for allowing the integration of the polymer in the network, during the crosslinking of the ink and anchoring thereof on the surface, is thus demonstrated. Without this functionalisation, the PI 6-6 is eliminated by the ultrasound cleaning since it does not form covalent bonds with the crosslinked ink.

[0183] The atomic percentages determined on the global spectra and the high-resolution spectrum of the nitrogen are set out in Tables 13 and 14 below. The high-resolution spectrum of the N 1 s of the PE with the 6-1B ink can be divided into two contributions (FIG. 7B). The contribution at 402 eV is characteristic of the C—N.sup.+ bonds and is in the majority with respect to the contribution at 400 eV of the C-N bonds.

TABLE-US-00013 Chemical compositions of the PEs with 6-1B ink and 7-1B ink (atomic %) determined on the global spectra ‘Layer C1s O1s N1s Si2p 6-1B ink PE 76.2 22.4 0.8 0.6 7-1B ink PE 95.9 2.4 - 1.6

TABLE-US-00014 Contributions (atomic %) N 1 s determined on the high-resolution spectrum of the 6-1B ink PE Layer C-N 399 eV C—N.sup.+ 402 eV 6-1B ink PE 13.7 86.3

111.3. Bacterial Adhesion Tests

[0184] The adhesion tests are tests that allow to study the pro- or anti-adhesive effect of the surfaces modified according to the method of the invention and their bactericidal character, by depositing bacteria on these surfaces.

[0185] Firstly, the total quantity of bacteria that adhered to the surface, called total flora (FT), is evaluated, by means of a microscope observation and a counting of the bacteria on the photographic exposures.

[0186] Secondly, the quantity of living bacteria capable of multiplying after the exposure to the modified surfaces, referred to as adherent cultivatable viable bacteria (VC), is evaluated, by detaching them and counting them on a gelose culture medium.

[0187] The first biological tests are adhesion tests implemented with Staphylococcus aureus (S. aureus) in distilled water for 3 h at 37° C. with a bacterial suspension at 10.sup.6 UFC.mL.sup.-1 (Unit Forming Colonies.mL.sup.-1). These tests make it possible to attest to the pro-adhesive properties of the ink since, in FIG. 1, an increase is noted in the total flora present on the PE film modified with the 6-1B ink compared with the PE film without treatment.

[0188] These tests also reveal a bactericidal effect of the ink. On FIG. 7, it is observed that the difference between the quantity of adherent cultivatable viable bacteria with respect to the total flora on the PE film modified with the 6-1B ink is greater than this same difference for the PE film without treatment. This reduction is approximately 1.7 log for the PE sample modified with the 6-1B ink as against 0.5 log for the PE without treatment. Which corresponds to inhibition efficiencies (calculated by taking account of the total flora) of 97.9% for the PE modified with the 6-1B ink, as against 69.9% for the untreated PE.

III.4. Salting-Out Test

[0189] To study a possible salting out of polyionene from the crosslinked solid, the supernatants of the adhesion tests were counted. It is a case of checking whether the bacteria are inhibited by the PE film with the crosslinked 6-1B ink, in contact with the surface and/or by the suspension submerging the material.

[0190] The counting of the cultivatable viable bacteria on FIG. 8 shows that there is no difference between the supernatants of the PE film without treatment and the PE film modified via the bacteriostatic ink. It is deduced from this that there is no salting out of the polyionenes in the supernatant and that the bacterial inhibition is solely due to the contact with the PE film modified with the crosslinked 6-1B ink.

III.5. Cytotoxicity Test

[0191] Cytotoxicity tests were performed according to two distinct methods: [0192] firstly, on cell layers of mouse fibroblasts (L929) after an exposure of 48 h to the PE films modified with PI ink (6-1B ink PE); and [0193] secondly, on reconstructed human epidermises (Skin+) after an exposure of 24 h to the films of 6-1B ink PE. The tests were repeated three times for each of the tests.

[0194] For the test on the L929, the 6-1B ink PE floats above the cell layer in the wells, and therefore the effect of the salting out is evaluated in this case (FIG. 9). The tests do not indicate cytotoxicity of the 6-1B ink PE since the cell viability is above 70% and is comparable with that of the control. This is because the statistical tests (Student) gave a p-value > 0.05, and therefore the difference is not significant between the two conditions.

[0195] In tests on the reconstructed human epidermises, the native PE and the 6-1B ink PE are in direct contact with the epidermises. The tests do not indicate cytotoxicity of the native PE and of the 6-1B ink PE since the cell viabilities are above 70% (FIG. 10).

[0196] The Student test however indicates a significant difference between the negative control and the native PE (p-value = 0.03), as well as a significant difference between the negative control and the 6-1B ink PE (p-value = 0.01). The test being performed on only three materials, it can be considered that this significant difference is probably due to experimental error. In particular in the case of the 6-1B ink PE where an increase in the cell viability is rather observed, rather than a reduction, compared with the negative control.

[0197] Thus, these two types of cell test indicate clearly that no cytotoxicity is shown for the PE films with deposits of 6-1B ink (containing bacteriostatic PI 6-6 polyionene).

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