Micro-assembly of functionalized particulate monolayer on C₁₈-derivatized SiO₂ surfaces

This work describes a simple approach to immobilize functionalized colloidal microstructures onto a C₁₈-coated SiO₂ substrate via specific or non-specific biomediated interactions. Biotinylated bovine serum albumin pre-adsorbed onto a C₁₈ surface was used to mediate the surface assembly of streptavidin-coated microbeads (2.8 μm), while a bare C₁₈ surface was used to immobilize anti-Listeria antibody-coated microbeads (2.8 μm) through hydrophobic interactions. For a C₁₈ surface pre-adsorbed with bovine serum albumin, hydrophobic polystyrene microbeads (0.8 μm) and positively charged dimethylamino microbeads (0.8 μm) were allowed to self-assemble onto the surface. A monolayer with high surface coverage was observed for both polystyrene and dimethylamino microbeads. The adsorption characteristics of Escherichia coli and Listeria monocytogenes on these microbead-based surfaces were studied using fluorescence microscopy. Both streptavidin microbeads preadsorbed with biotinylated anti-Listeria antibody and anti-Listeria antibody-coated microbeads showed specific capture of L. monocytogenes, while polystyrene and dimethylamino microbeads captured both E. coli and L. monocytogenes non-specifically. The preparation of microbead-based surfaces for the construction of microfluidic devices for separation, detection, or analysis of specific biological species is discussed.