Microstamping on an activated polymer surface: Patterning biotin and streptavidin onto common polymeric biomaterials

Microstamping on an activated polymer surface (MAPS) is a methodology that enables biomolecules to be patterned on polymers with micrometer spatial re solution. MAPS combines homogeneous surface derivatization of a polymer to introduce a reactive functional group followed by reactive microcontact pri nting (mu CP) of a biological ligand of interest, linked to an appropriate reactive group. We demonstrate here that polyethylene, polystyrene, poly(me thyl methacrylate), and poly(ethylene terephthalate) films can be successfu lly modified to introduce COOH groups on their surfaces, which can be subse quently patterned by reactive mu CP of amine-terminated biotin after deriva tization. of the COOH groups with pentafluorophenol. X-ray photoelectron sp ectroscopy and time-of-flight secondary ion mass spectrometry (TOF-SIMS) co nfirmed the chemistry of MAPS at each stage of the derivatization of the po lymer surfaces and reactive mu CP of biotin. Micropatterned biotin surfaces fabricated by MAPS were patterned with streptavidin by exploiting molecula r recognition between biotin and streptavidin. The formation of streptavidi n patterns was examined by fluorescence microscopy of Alexa488-labeled stre ptavidin and by TOF-SIMS imaging of N-15-labeled recombinant streptavidin, bound to biotin patterns. The contrast in the streptavidin micropatterns wa s optimized by examining the effect of blocking agents and streptavidin inc ubation time. Maximum contrast was obtained for binding of 0.1 muM streptav idin from a buffer containing 0.02% (v/v) Tween 20 detergent for an incubat ion time of 1 min.