Device-associated infections are a leading cause of extended hospitalization, readmission to surgery, and healthcare economic burden. Bacterial microadherence to plastic surfaces can lead to occlusion of many indwelling devices, which is further complicated by blood-surface interactions and can lead to septicemia. Nitric oxide (NO) is gasotransmitter critical to immune response that possesses potent antibacterial properties, such that polymers embedded with NO donor compounds are capable of remarkable antibacterial properties. Despite being able to control NO evolution, difficulty remains in preventing microbial adherence to these surfaces. Mussel-inspired polydopamine (pDA) surface coatings are an efficacious strategy to combatting bacterial surface infection, as pDA possesses highly tunable structure-function relationships and near universal substrate scope. In this study, roughened pDA coatings were applied to NO-releasing silicon rubber (SR) substrates. The afforded rpDA-NO-SR composites were characterized for NO release using chemiluminescence-based detection, hydrogen peroxide generation via fluorometric assay, and NO donor leaching via colorimetric assay. Surface analysis was performed using scanning electron microscopy and contact angle goniometry. Finally, the materials were assessed for plasma protein adsorption, bacterial surface adhesion, and cellular cytocompatibility. The addition of the rPDA layering to NO-SR resulted in an over 100% increase in NO surface flux while maintaining cellular compatibility in fibroblasts and vascular endothelial cells. The rPDA modification exhibited enhanced pDA nanoaggregate deposition on NO-SR substrates compared to SR controls, with paralleled increase in surface wettability and nearly 40% reduction in plasma protein adsorption relative to untreated SR. In a 24 h antibacterial study, rpDA-NO-SR exhibited near 2.0-log reductions in adhered <i>E. coli </i>and methicillin-resistant <i>S. aureus</i>. This simple yet efficacious method of functionalizing medical grade SR may have promise for reducing surface contamination of medical devices and the endemic burden of healthcare associated infection.

Versatile antifouling, antibacterial coatings from polydopamine surface functionalization of a nitric oxide-releasing substrate

ACS Fall 2021

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