Surface modification and characterization of polycarbonate microdevices for capture of circulating biomarkers, both in vitro and in vivo.

Herein, we report the fabrication, characterization, and testing of a polymer microprojection array, for the direct and selective capture of circulating biomarkers from the skin of live mice. First, we modified polycarbonate wafers using an electrophilic aromatic substitution reaction with nitric acid to insert aromatic nitro-groups into the benzene rings, followed by treatment with sodium borohydride to reduce the nitro-groups to primary amines. Initial characterization by ultraviolet–visible (UV–vis) spectroscopy suggested that increasing acid concentration led to increased depth of material modification and that this was associated with decreased surface hardness and slight changes in surface roughness. Chemical analysis with X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance fourier transform infrared (ATR-FT-IR) spectroscopy showed nitrogen species present at the surface for all acid concentrations used, but subsurface nitrogen species were only observed at acid concentrations >3...