Dual Biomolecule Patterning on Micropatterned Polylactide Surfaces Bearing Oppositely Charged Polymer Brushes at Neighboring Sites

Suitably functionalized polymer brush-modified micropatterned surfaces may enable precise control over interfacial interactions with multiple biomolecules, potentially leading to the creation of proteins/DNA microarrays, biosensors, diagnostics, tissue engineering, etc. Herein, we present a facile strategy to construct oppositely charged polymer brushes installed at their designated domains on the micropatterned biodegradable polymeric substrate PLA (polylactide) via SIATRP (surface-initiated atom transfer radical polymerization). Generally, it is challenging to graft polycationic and polyanionic brushes on a micropatterned surface with alternate domains of positive and negative charges. To avoid the inherent interactions between the opposite charges, this study demonstrates a unique strategy to fabricate micropatterned cationic (poly([2-(methacryloyloxy) ethyl] trimethylammonium chloride)) (PMETA) and anionic (poly(3-sulfopropyl methacrylate potassium)) (PSPMA) polymer brushes on the PLA surface. After grafting of the PSPMA brush on the desired region of the micropatterned surface (using the masking/demasking technique), tributylamine was employed to block the anionic sulfonate groups so that grafting of the cationic PMETA brush became feasible in the neighboring domain in the subsequent step. Following the polymerization of META, the anionic brushes were simply unblocked by reducing the pH of the medium, producing a micropatterned surface modified with oppositely charged polyelectrolyte brushes. As examples, oppositely charged brushes were employed to form proteins and DNA microarrays. Interestingly, while being cytocompatible and hemocompatible, the oppositely charged dual-brush-modified micropatterned surfaces were found to be highly antibacterial.