Graft-Then-Shrink: Simultaneous Generation of Antifouling Polymeric Interfaces and Localized Surface Plasmon...

Antifouling polymer coatings that are simple to manufacture are crucial for the performance of medical devices such as biosensors. "Grafting-to", a simple technique where presynthesized polymers are immobilized onto surfaces, is commonly employed but suffers from nonideal polymer packing leading to increased biofouling. Herein, we present a material prepared via the grafting-to method with improved antifouling surface properties and intrinsic localized surface plasmon resonance (LSPR) sensor capabilities. A new substrate shrinking fabrication method, Graft-then-Shrink, improved the antifouling properties of polymer-coated Au surfaces by altering graft-to polymer packing while simultaneously generating wrinkled Au structures for LSPR biosensing. Thiol-terminated, antifouling, hydrophilic polymers were grafted to Au-coated prestressed polystyrene (PS) followed by shrinking upon heating above the PS glass transition temperature. Interestingly, the polymer molecular weight and hydration influenced Au wrinkling patterns. Compared to Shrink-then-Graft controls, where polymers are immobilized post shrinking, Graft-then-Shrink increased the polymer content by 76% in defined footprints and improved the antifouling properties as demonstrated by 84 and 72% reduction in macrophage adhesion and protein adsorption, respectively. Wrinkled Au LSPR sensors had sensitivities of ∼200-1000 Δλ/ΔRIU, comparing favorably to commercial LSPR sensors, and detected biotin-avidin and desthiobiotin-avidin complexation in a concentration-dependent manner using a standard plate reader and a 96-well format.