Simple micropatterning of biomolecules on a diazoketo-functionalized photoresist

Abstract

A simple strategy for the patterning of cells and biomolecules including DNA and protein was developed, employing novel diazoketo-functionalized photoresists in conjunction with a simplified lithographic process that does not require photoacid generator, post-exposure bake or development steps. The diazoketo functional groups present in the polymers undergo Wolff rearrangement upon UV light irradiation to generate carboxylic groups. This chemistry was used to create patterns of alternate hydrophilic/hydrophobic regions on the surface of diazoketo-functionalized polymers. The in vitro cell culture on the patterned surfaces of the polymer showed good alignment of cells on the UV-exposed regions, where carboxylic groups were predominant. Furthermore, cells were found to maintain their alignment during proliferation. In addition to this, the photogeneration of carboxylic groups by diazoketo functional groups was exploited for DNA and streptavidin patterning. For DNA patterning, amine-modified probe DNA was successfully immobilized on the photopatterned regions of the polymer by amide bond formation using EDC/NHS coupling chemistry. Successful hybridization with complementary DNA proved the selectivity and functionality of the immobilized probe DNA. Biotin-amine was also immobilized on the photopatterned regions of the diazoketo-functionalized polymer in a similar manner to that of probe DNA to study streptavidin patterning. Biotin-specific streptavidin binding proved the successful patterning of biotin-amine by amide bond formation. These results showed that diazoketo-functionalized photoresist is biocompatible and simple to use for biomolecular patterning, which can be used in further approaches for high-throughput screening assays.