Redox phospholipid polymer microparticles as doubly functional polymer support for immobilization of enzyme oxidase

Abstract: We prepared redox phospholipid polymer microparticles for immobilizing an enzyme in order to maintain activity for a long time and obtain highly effective electron transfer to a gold substrate as an electrode. To achieve these double functions, an amphiphilic redox phospholipid polymer, poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate-co-p-nitrophenyloxycarbonyl oligo(ethylene glycol) methacrylate (MEONP)-co-vinylferrocene (VFc)) (PMBNF) was synthesized. The polystyrene (PS) microparticles were modified by employing a simple solution dip-coating technique to form the PMBNF layer on the surface. As one of the model enzyme oxidases, a glucose oxidase (GO x ) was immobilized on the PMBNF/PS microparticles by the reaction between the MEONP units in the PMBNF layer and the amino group in the GO x . The activity of immobilized GO x is maintained well; for example, activity of more than 80% of the initial activity was observed even after storage at both 4°C and 25°C (ionic strength: 0.10mol/L, phosphate buffer solution, pH 7.0) for at least one month. The GO x /PMBNF/PS microparticles were arrayed on a gold substrate in a monolayer, and then, crosslinked to each other with a polymeric diamine compound. The PMBNF/PS microparticles demonstrated an efficient electron transfer from immobilized GO x to the gold surface. From these results, we concluded that the PMBNF layer on the PS microparticles possessed double functions such as stable enzyme immobilization ability and efficient electron transfer ability. [Copyright &y& Elsevier]