Surface chemical modification for the immobilization of biomolecules.

摘要

Surface engineering in biochip technology has received great interest since the high-throughput analysis of biological assay showed a promising potential in biomedical research. The way to immobilize biomolecules should consider the biocompatibility of solid substrate so that the intrinsic activity of the biomolecules remains intact. Our group developed a two step approach to graft poly(ethylene glycol) (PEG) on a silicon surface. It takes advantages of the well-known biocompatible poly(ethylene glycol) and the microfabrication-available silicon surface. DNA is first introduced to test this engineered surface. p-Maleiimide phenyl isocyanate (PMPI) is used as a cross linker. The efficient hybridization of complementary DNA on this template will be discussed. In a next step, we tailor the grafted PEG to introduce Cu2+-IDA complex at the surface. This strategy is originated from immobilized metal affinity chromatographic technique (IMAC) which enables the adsorbed proteins to retain their conformation and orientation. It shows the specificity between the protein and the engineered surface, and the binding specificity in the assay of the immobilized sulfotransferase (ST) with low background. In addition, enzymatic activity is also demonstrated with their orientation upon immobilization. At the end, the behavior of adsorbed lipid vesicles is investigated with functional groups (e.g. NH2, CO2H, OH) at surfaces as a step toward the immobilization of membrane proteins. Unlike soluble proteins, membrane proteins are associated with lipid membranes. It shows the phase change of adsorbed lipid from planar to vesicle configuration by the number of charge groups at surface. Fluorescence recover after photobleaching (FRAP) measurement will be employed to explain this phase transition.