Protein patterning via radiation-assisted surface functionalization of conventional microlithographic materials

Several technological options available for protein high resolution pattern ing on conventional microlithographic materials were investigated: (i) two mechanisms for radiation-assisted selective attachment on polymer surface, i.e. chemical linkage and hydrophobicity-controlled patterning; (ii) two cl asses of microlithographic materials, i.e. diazonaphto-quinone (DNQ)/novola k and poly(tert-butyl-methacrylate-co-methyl-methacrylate) [P(tBuMA-co-MMA) ] resists; (iii) two pattern exposure techniques, i.e. contact printing usi ng near-UV light on DNQ/novolak resist, and projection printing using e-bea m lithography on P(tBuMA-co-MMA) resist; and (iv) two patterning tones, i.e . positive and negative tone lithography. The mechanism based on crosslinki ng protein amino groups to carboxylic groups generated by photolysis can be used to print (i) high contrast, positive or negative tone, protein featur es on DNQ/novolak resists; and (ii) good contrast, positive tone protein fe atures on P(tBuMA-co-MMA) resist. The hydrophobicity-controlled mechanism b ased on the hydrophobic interaction between the protein and hydrophobic une xposed polymer surface can be used to print high contrast, negative tone, p rotein features on P(tBuMA-co-MMA) resist with 125 nm resolution. It was fo und that optical and e-beam lithography materials and techniques can be eas ily transferred in bio-microlithography, with impact on biodevices fabricat ion and combinatorial chemistry. (C) 1999 Elsevier Science B.V. All rights reserved.