Creating Bioinert Surface by pH-Sensitiveeak Electrolyte-Sulfobetaine Copolymer
Date Issued
2009
Date
2009
Author(s)
Wu, Che-Cheng
Abstract
Nonfouling surface has been widely used in both biomaterials and biosensor, due to its resistancy in non-specific adsorption. In our study, non-fouling materials were used to fabricate bioinert surfaces, where effect on the interface with different pH values and salt concentration was investigated. Sulfobetaine methacrylate (SBMA), with its zwitterionic character, was polymerized into two oppositely charged random copolymers. It was either polymerized with a weak electrolytic acrylic acid, or 2-aminoethyl methacrylate by a conventional free radical polymerization. Through this method, electrostatic interaction may aid in adsorption of the copolymers on the polyelectrolyte-modified surface for obtaining the ideal resistance in biological adsorption. The objective is that the use of polyelectrolytic mechanism is applied on the all substrates. Examinations were done on the copolymers with different content of SBMA at 0 % (polyelectrolyte), 25%, 50%, 75% and 100 %, mainly investigating the effect of pH and salt content on the adsorption of the surface. Methods such as Quartz Crystal Microbalance (QCM) was used to examine the changes on surface adsorption in order to correlate it with the protein adsorption and L929 cell adhesion on the different surfaces through cell culture experiments. From previous studies, 4 layer of P(SBAA-co-AA) with PAH were examined to show resistancy in protein adsorption and cell adhesion, though the influence of surrounding factor on the biological adhesion was not further discussed. Thus, the goal of this study is to explore environmental factors on its influence for cell adhesion.Using the negatively charged character of copolymer, copolymer with different ratio of SBMA and acrylic acid were adsorbed to form surfaces with 3 layers of PEI/PAA. As result, resistancy on cell adhesion was observed under acidic environment, where the resistance increases with increment in SBMA ratio, and the surface with 50% SBMA copolymer showed most resistancy in protein adsorption and cell adhesion without addition of salt. Inhibition of cell adhesion was also demonstrated in acidic environment under different salt concentration, where best cell adhesion resistancy was observed under high salt content. As for the other copolymer of positive-charged Poly(SBMA-co-AEMA) (poly(sulfobetaine methacrylate-co-2-aminoethyl methacrylate)), copolymer with different composition of SBMA were adsorbed to 4 layers of PEI/PSS surface. As result, only 75% SBMA copolymer showed 40% resistancy for cell adhesion, suggesting better resistance effect by the direct adsorption of the copolymer to the TCPS without polyelectrolyte modification as indicated on 75% SBMA copolymer. Nevertheless, great efficiency in decrement of cell adhesion was also observed under neutral environment for the 75% SBMA copolymer to low ionized PAA surface. Thus, through this research, bioinert surface were successfully created by electrostatic interaction to immobilize two types of opposite-charged poly(electrolyte-co-SBMA) copolymer.
Subjects
bioinert
sulfobetaine methacrylate
cell attachment
protein adsorption
Type
thesis
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