Micron-Sized Protein Patterning on Diazonaphthoquinone/Novolak Thin Polymeric Films

Abstract

Protein patterns at 2-μm resolution were surface-printed on the unprofiled surface of diazonaphthoquinone/novolak thin polymeric films through positive-tone and reversed negative-tone lithography. The possible mechanisms responsible for selective protein patterning, that is, (i) linkage of the amino end of the protein to the photoinduced indenecarboxylic acid via NH2-to-COOH cross-linking mediated by carbodiimide, (ii) linkage of the amino end of the protein via in-situ addition to the photoinduced ketene, and (iii) hydrophobic interaction with unexposed surfaces, were assessed through the use of ESCA, contact angle, AFM, and fluorescence microscopy. Of these, the first two mechanisms, in conjunction with diazonaphthoquinone/novolak photopolymers (a class of conventional microlithographic materials) and microlithographic equipment and techniques, can be used for bottom-to-top biomolecular architecture construction. The study proves that photolithographic materials (used for light-assisted selective surface protein attachment) can be easily transferred to bio-microlithography, with potential applications ranging from biodevice fabrication to diagnostic and combinatorial chemistry.