Micropatterning of gold substrates based on poly(propylene sulfide-bl-ethylene glycol), (PPS–PEG) background passivation and the molecular-assembly patterning by lift-off (MAPL) technique

Poly(propylene sulfide-bl-ethylene glycol) (PPS–PEG) is an amphiphilic block copolymer that spontaneously adsorbs onto gold from solution. This results in the formation of a stable polymeric layer that renders the surface protein-resistant when an appropriate architecture is chosen. The established molecular-assembly patterning by lift-off (MAPL) technique can convert a prestructured resist film into a pattern of biointeractive chemistry and a non-interactive background. Employing the MAPL technique, we produced a micron-scale PPS–PEG pattern on a gold substrate, and then characterized the patterned structure with time-of-flight secondary ion mass spectrometry (ToF-SIMS) and atomic force microscopy (AFM). Subsequent exposure of the PPS–PEG/gold pattern to protein adsorption (full human serum) was monitored in situ; SPR-imaging (i-SPR) shows a selective adsorption of proteins on gold, but not on PPS–PEG areas. Analysis shows a reduction of serum adsorption up to 93% on the PPS–PEG areas as compared to gold, in good agreement with previous analysis of homogenously adsorbed PPS–PEG on gold. MAPL patterning of PPS–PEG block copolymers is straightforward, versatile and reproducible, and may be incorporated into biosensor-based surface analysis methods.