Method for modifying surface of polymer substrate and polymer substrate having surface modified thereby

Abstract

The present invention relates to a method for modifying the surface of a polymer substrate. Specifically, the present invention provides a method for modifying the surface of a polymer substrate using a plasma treatment, a hydrophilic primer and a coating agent including a hydrophobic fluorine compound.

Claims

1. A method for modifying a surface of a polymer substrate, the method comprising: treating the surface of the polymer substrate with plasma; applying a hydrophilic primer, under a wet process, comprising a polymer of aminoalkylsilane and a first functional organic or inorganic silane compound onto the surface of the plasma-treated polymer substrate; and hydrophobic coating the plasma-treated polymer substrate with a coating agent, under a wet process, containing a hydrophobic fluorine compound in a fluorine-based solvent comprising a condensed polymer of a fluorine-based polymer and a second functional organic or inorganic silane compound, wherein at least one of the first functional organic or inorganic silane compound and the second functional organic or inorganic silane compound is at least one compound selected from the group consisting of phenylaminopropyltrimethoxysilane, γ-aminopropyldimethoxysilane, γ-aminopropyldiethoxysilane, chlorotrimethylsilane, trichloroethylsilane, trichloromethylsilane, trichlorophenylsilane, trifluoropropyltrimethoxysilane, bis(trimethoxysilylpropyl)amine, bis(3-triethoxysilylpropyl)tetrasulfide, bis(triethoxysilylpropyl)disulfide, and p-styryltrimethoxysilane.

2. The method of claim 1, wherein the polymer substrate is a siloxane-based polymer.

3. The method of claim 2, wherein the siloxane-based polymer is silicone rubber.

4. The method of claim 1, wherein the plasma is plasma of argon, nitrogen, oxygen, or a mixed gas in which two or more of these gases are mixed.

5. The method of claim 1, wherein in the treating of the surface of the polymer substrate with plasma, the plasma is formed from a mixed gas by applying power using RF power at 700 to 800 W in a device in which pressure is maintained at an atmospheric pressure (760 Torr).

6. The method of claim 1, wherein the fluorine-based polymer is selected from the group consisting of a polymer comprising tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, trifluoroethylene, vinylidene fluoride, octafluorobutylene, pentafluorophenyl trifluoroethylene, pentafluorophenyl ethylene, a fluoro-containing acrylate polymer, and perfluoro polyether.

7. The method of claim 1, wherein the second functional organic or inorganic silane compound comprises one or more functional groups selected from the group consisting of an amino group, a halogen group, and a sulfide group.

8. The method of claim 1, wherein the second functional organic or inorganic silane compound is at least one compound selected from the group consisting of phenylaminopropyltrimethoxysilane, aminopropyldimethoxysilane, γ-aminopropyldiethoxysilane, chlorotrimethylsilane, trichloroethylsilane, trichloromethylsilane, trichlorophenylsilane, trifluoropropyltrimethoxysilane, bis(trimethoxysilylpropyl)amine, bis(3-triethoxysilylpropyl)tetrasulfide, bis(triethoxysilylpropyl)disulfide, and p-styryltrimethoxysilane.

9. The method of claim 1, wherein the hydrophobic fluorine compound is selected from the group consisting of polytetrafluoroethylene, an ethylene-tetrafluoroethylene copolymer, a perfluoropolyether group-containing silane, a tetrafluoroethylene-hexafluoropropylene copolymer, a partial hydrolysis condensate of a fluorooxyalkylene group-containing polymer composition, a fluoropolymer composition, polyvinylidene fluoride, and a fluorine-containing organopolysiloxane.

10. The method of claim 1, wherein the first functional organic or inorganic silane compound is at least one compound selected from the group consisting of phenylaminopropyltrimethoxysilane, aminopropyldimethoxysilane, γ-aminopropyldiethoxysilane, chlorotrimethylsilane, trichloroethylsilane, trichloromethylsilane, trichlorophenylsilane, trifluoropropyltrimethoxysilane, bis(trimethoxysilylpropyl)amine, bis(3-triethoxysilylpropyl)tetrasulfide, bis(triethoxysilylpropyl)disulfide, and p-styryltrimethoxysilane.

11. A polymer substrate whose surface is modified by the method for modifying a surface of a polymer substrate according to claim 1.

12. A biochip comprising the polymer substrate of claim 11.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIGS. 1 and 2 illustrate fluorescence photographs and relative fluorescence intensities exhibiting the adsorption degrees of FITC-BSA proteins of each of the PDMS biochips according to the present invention and Comparative Examples before and after the surface modification thereof.

(2) FIG. 3 illustrates the adsorption degree of an oil-based ink of each of the PDMS biochips according to the present invention and the Comparative Examples before and after the surface modification thereof, and the left side and the right side illustrate graphs of the case where a BSA protein is adsorbed and the case where a BSA protein is not adsorbed, respectively.

(3) FIG. 4 illustrates the light transmittance of each of the PDMS biochips according to the present invention and the Comparative Examples before and after the surface modification thereof, and a) and b) illustrate graphs of the case where a BSA protein is adsorbed and the case where a BSA protein is not adsorbed, respectively.

(4) FIG. 5 illustrates morphological observation results of the MDA cell lines cultured on a petri dish (control), a PDMS whose surface is not modified, and the PDMS biochip according to the present invention (0 hour, 48 hours, and 72 hours).

(5) FIGS. 6 and 7 illustrate the life and death determination test results of cells attached to the bottom and cells floating in the medium, in the MDA cell lines cultured on a petri dish (control), a PDMS whose surface is not modified, and the PDMS biochip according to the present invention. The green color and the red color illustrate living cells and dead cells, respectively, and the number of the corresponding cells is proportional to the fluorescence intensity.

(6) FIG. 8 illustrates a numerical comparison of the cell viability through the fluorescence intensities in FIGS. 6 and 7.

(7) FIG. 9 illustrates PEEL test results of the PDMS substrate according to the present invention (a) during the experiment and b) after completion of the experiment.

BEST MODE

(8) An aspect of the present invention provides a method for modifying a surface of a polymer substrate, the method including: treating the surface of the polymer substrate with plasma; applying a hydrophilic primer onto the surface of the plasma-treated polymer substrate; and coating the plasma-treated polymer substrate with a coating agent containing a hydrophobic fluorine compound.

MODE FOR INVENTION

(9) Hereinafter, the present invention will be described in more detail through one or more Examples. However, these Examples are provided only for exemplarily explaining one or more Examples, and the scope of the present invention is not limited by these Examples.

Example 1

Surface Modification of PDMS Coin

(10) 1.1. Plasma Treatment of Surface of PDMS Coin

(11) First, a PDMS coin with a diameter of 1.5 cm and a height of 0.5 cm was manufactured and subjected to a plasma treatment under an atmospheric pressure at room temperature, and the plasma-treated PDMS coin was used for the cleaning of organic contaminants and the surface modification.

(12) For the plasma treatment, a mixed gas of 25 sccm of an argon (Ar) gas and 30 sccm of an oxygen (O.sub.2) gas was used at an atmospheric pressure of 1 atm (760 Torr), and the formation of plasma was induced by applying power using RF power at 700 to 800 W, thereby treating the PDMS coin with plasma reciprocally at a speed of 15 mm/sec.

(13) 1.2. Coating of Surface of PDMS Coin Using Coating Agent WNP/WAF Containing Fluorine Compound

(14) After the PDMS coin which was plasma-treated in Example 1.1. was taken out of the plasma reactor and coated to have a thickness of about 10 to 20 nm by spraying Nano-Primer (NP, product name: CK-WNP, manufactured by CEKO, Inc.), purchased as an attachment reinforcing agent, at 40 ml/m.sup.2 under a wet process, the resulting product was spray-coated with Wet Anti-fingerprint (WAF, product name: CK-WAF, manufactured by CEKO, Inc.), which is a hydrophobic compound purchased as a fluorine compound, at 35 ml/m.sup.2 under a wet process, and then the coated-PDMS coin was dried by hot wind for about 1 hour (WNP/WAF method, in this case, W before NP and AF indicates that the coating is performed under a wet process). In the present Example 1.2., the Nano-Primer (NP) served as a buffer layer for enhancing attachment.

Comparative Example 1

Surface Modification 1 of PDMS Coin Using AF

(15) The PDMS coin which was plasma-treated in Example 1.1. was taken out of the plasma reactor, coated to have a thickness of 12 nm using SiO.sub.2, and then coated with 0.3 g of AF, as a hydrophobic compound, by an evaporative deposition using e-beam under a dry process (AF1 method). In this case, the formed hydrophobic coating foil had a thickness of about 20 to 30 nm. In the present Comparative Example 1, SiO.sub.2 served as a buffer layer for enhancing attachment.

Comparative Example 2

Surface Modification 2 of PDMS Coin Using AF

(16) The PDMS coin which was plasma-treated in Example 1.1. was taken out of the plasma reactor, coated to have a thickness of 5 nm using SiO.sub.2, and then coated with 0.3 g of AF, as a hydrophobic fluorine compound, by a resistance heating element under a dry process (AF2 method). In the present Comparative Example 2, SiO.sub.2 served as a buffer layer for enhancing attachment.

Comparative Example 3

Surface Modification of PDMS Coin Using WNP

(17) The PDMS coin which was plasma-treated in Example 1.1. was taken out of the plasma reactor and sufficiently spray-coated with the resulting product obtained by completely dissolving 0.5 g of NP, as a hydrophilic compound containing a fluorine compound, in 100 g of ethanol as a solvent, such that the surface thereof was uniformly coated under a wet process, and then the coated-PDMS coin was dried by hot wind for 10 minutes (WNP method).

Experimental Example 1

Evaluation of Protein Adsorption after Surface Modification

(18) A 0.01% (0.1 mg/ml) FITC-BSA stock was prepared by dissolving an FITC-BSA powder in DPBS, and 600 μl of a 0.01% FITC-BSA solution or 600 μl of a DPBS solution was placed on the coating surface of the PDMS coin that was surface-modified in Example 1, and then left to stand for 3 minutes. The PDMS coin was washed with DPBS for 1 minute, and then strongly washed with distilled water contained in a squeeze bottle for 1 minute, and the residual moisture thereof was removed by a blower. Thereafter, optical images and fluorescence images of the surface of the PDMS coin were captured, and the fluorescence quantification was performed using the ImageJ program.

(19) As a result, it could be confirmed that when the surface of the PDMS coin was coated with AF exhibiting hydrophobicity (Example 1 and Comparative Examples 1 and 2), the protein was scarcely adsorbed (<1%), whereas when the surface of the PDMS coin was coated with NP exhibiting hydrophilicity (Comparative Example 3), the protein was adsorbed at a high proportion (>400%). Further, when the surface of the PDMS coin was coated with NP (Comparative Example 3), cracks could be found in the absorption experiment (see FIGS. 1 and 2).

Experimental Example 2

Evaluation of Oil-Based Ink Adsorption after Surface Modification

(20) On the surfaces of the PDMS coin onto which the protein was adsorbed (the PDMS coin that was left to stand in the 0.01% FITC-BSA solution) and of the PDM coin onto the protein was not adsorbed (the PDMS coin that was left to stand in the DPBS solution), which were prepared in Experimental Example 1, marks were drawn with a black oil-based ink pen at a predetermined speed, and the degree to which the oil-based ink was adsorbed onto the PDMS coin was observed.

(21) As a result, it could be confirmed that when the surface of the PDMS coin was coated with AF exhibiting hydrophobicity (Example 1 and Comparative Examples 1 and 2), the ink took the form of water droplets, whereas when the surface of the PDMS coin was coated with NP exhibiting hydrophilicity (Comparative Example 3), the ink was adsorbed in the form of the mark drawn with the oil-based ink pen. In particular, even among the hydrophobic coatings, it could be confirmed that the WNP/WAF method in which the PDMS coin was coated under a wet process had the strongest hydrophobicity, and simultaneously, the oil-based ink was aggregated in a form most similar to a perfect circle (see FIG. 3).

Experimental Example 3

Evaluation of Light Transmittance after Surface Modification

(22) The change in light transmittance of each of the PDMS coin onto which the protein was adsorbed (the PDMS coin that was left to stand in the 0.01% FITC-BSA solution) and the PDM coin onto the protein was not adsorbed (the PDMS coin that was left to stand in the DPBS solution), which were prepared in Experimental Example 1, was observed using a UV-VIS spectrophotometer (HITACHI U-4100, 240 to 1,300 nm).

(23) As a result, when the protein was not adsorbed, the transmittance of the PDMS coin which was not treated was the best, the transmittance of Example 1 in which the PDMS coin was coated by the WNP/WAF method (the transmittance of the PDMS, subjected to surface modification coating, as compared to the bare PDMS: 98.27 to 99.89%) was the second best, and the transmittance of Comparative Example 3 in which the PDMS coin was coated by the WNP method (the transmittance of the PDMS, subjected to surface modification coating, as compared to the bare PDMS: 97.94 to 99.14%) was the third best (see FIG. 4A).

(24) In contrast, it was determined that when the protein was adsorbed, the adsorption of the protein affected the light transmittance of the substrate (see FIG. 4B).

Experimental Example 4

Evaluation of Cell Viability after Surface Modification

(25) Except that a PDMS sheet with a 100-pi dish size and a height of about 1 mm was used instead of the PDMS coin with a diameter of 1.5 cm and a height of 0.5 cm, the surface of the PDMS sheet was modified in the same manner as in the method described in Example 1.

(26) The surface-modified PDMS sheet was disinfected with alcohol, and then washed with a medium to remove the residual alcohol. After the surface-modified PDMS sheet was placed on the bottom of the petri dish and 12 ml of the medium was put thereinto, about 4×10.sup.6 MDA cells were inoculated thereto, and the resulting PDMS sheet was cultured for 3 days. After 3 days, cell attachment morphology and life and death determination tests were performed.

(27) As a result of observation of the cell attachment morphology, the MDA cells cultured on the PDMS coin sheet that was surface-modified by the method of the present invention were aggregated without being attached onto the surface of the PDMS to form a plurality of spheroids, and no significant difference were exhibited between the number and morphological shape of the observed cells and those of the cells cultured in the petri dish during the same period (see FIG. 5).

(28) As a result of the cell life and death determination test, no significant difference was exhibited between the life and death of the attached cells cultured for 3 days in the PDMS coin sheet that was surface-modified by the method of the present invention and that of the cells cultured in the petri dish (88.4% as compared to the control). It could be confirmed that in the life and death of the cells floating in the medium, the cells cultured in the PDMS coins sheet that was surface-modified by the method of the present invention had a higher viability than that of the cells cultured in the petri dish (see FIGS. 6 to 8).

(29) In addition, through the present experiment, it could be confirmed that the coating agent of the present invention did not show severe toxicity to the MDA cell line.

Experimental Example 5

Evaluation of Elasticity after Surface Modification

(30) A PEEL test of measuring the elasticity by fixing the tension degree for 10 minutes was performed using a substrate prepared using a 20:1 PDMS.

(31) It was confirmed that when both sides of the substrate were pulled out, the surface thereof was blurred, but a portion which was not tensioned maintained the transparency as it was (see FIG. 9A). After completion of the tension experiment for 10 minutes, it was confirmed that when the PDMS substrate returned to the original state thereof, the transparency returned to be almost equal to that before the experiment (see FIG. 9B).

Experimental Example 6

Preparation of Biocompatibility Biochip Having Modified Surface

(32) First, a subspot material layer was formed by applying a dielectric material onto a substrate formed of PDMS, a photoresist was applied onto the subspot material layer, and then a specific pattern was formed by a lithography process. A biochip substrate having a desired structure was manufactured by etching the subspot material layer exposed by the pattern.

(33) The biochip substrate was put into a plasma reactor under an atmospheric pressure at room temperature, and then treated with plasma as described in Example 1.1. Next, the plasma-treated biochip was sprayed with the resulting product obtained by completely dissolving 1 g of AF, as a fluorine compound, in 100 g of a fluorine-based solvent (HFE7200, 3 M), and the resulting biochip was dried, thereby completing a biochip substrate.

(34) From the foregoing, the present invention has been reviewed mainly based on the preferred examples thereof. A person with ordinary skill in the art to which the present invention pertains will be able to understand that the present invention may be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed examples should be considered not from a restrictive viewpoint, but from an explanatory viewpoint. The scope of the present invention is represented by the claims to be described below rather than the foregoing detailed description, and it should be interpreted that the meaning and scope of the claims and all the changes or modified forms derived from the equivalent concepts thereto fall within the scope of the present invention.