Figure 3.

(a) A top-view high-resolution scanning electron microscope (HRSEM) image of a typical PSiO₂ film demonstrating the porous nanostructure morphology with typical pores in the range of 60–100 nm. (b) Schematic illustration of the synthesis steps for the biofunctionalizion of PSiO₂ with IgG. (I) PSiO₂ was reacted with APTES and catalyzed by an organic base to create an amine-terminated surface. (II) The amine-terminated PSiO₂ was reacted with one of the aldehyde groups of the cross-linker GluAld. (III) Grafting of SA onto the aldehyde-terminated surface. (IV) Biotinylated-IgG (E. coli) was conjugated via biotin-SA binding.