(269a) Modifying Antibody Immobilization Density with Mechanical Assembled Monolayers

The surface density of spacer molecules can be one of the principal factors in determining the bioactivity in the process of antibody immobilization. Higher surface densities of bound antibody may also result in a lower capture efficiency of antibody by preventing the flexible rotation of spacer. It is important to identify the optimal surface density, which can allow maximum flexibility of spacers to orient themselves, and increase the probability of antibody to capture target.

In this study, poly(dimethylsiloxane) (PDMS) substrates are treated with (tridecafluoro-1,1,2,2-tetrahydrooctyl)-1-trichlorosilane (FAS) by chemical vapor deposition and incubated in a 0.1% solution of Pluronic F108 to generate brittle thin films on PDMS substrates. The coated substrates were stretched by the uniaxial tensile strains (from 10%, 20%, 40% to 60%) in two dimensions, and formed a criss-crossing crack patterns. The cracks exposed underlying materials which can be used to immobilize antibody using covalent immobilization, to illustrate the spacer density effects.

Poly(ethylene glycol) (PEG) spacers were employed for tethering Escherichia Coli (E.Coli) K99 pilus antibody to surfaces for the purpose of increasing the flexibility of antibody as well as reducing the steric hindrance. X-ray photoelectron spectroscopy (XPS) and Atomic Force Microscopy (AFM) were used to characterize the surface morphology and chemical composition at each reaction step. The effect of spacer density in improving the specificity of immobilized antibody and the recognition process for bacteria-antibody was investigated by Scanning Electronic Microscopy (SEM).