Triethoxysilyl-Functionalized Polyethylenimine: Its Spontaneous Cross-Linking and Drug Retention

Effective antibacterial and antiviral coatings are expected to serve as effective infection control measures in medical and public environments. In this study, we investigated polyethylenimine functionalized with triethoxysilyl groups (Si-PEI) as a promising platform material to implement such coatings feasibly. Si-PEI, synthesized in ethanol in a one-pot reaction, was coated onto the material surface as a diluted solution and then spontaneously cross-linked after solvent evaporation at room temperature. The resulting water-resistant coating layer retained water-soluble antimicrobial components such as copper-(II) ions and sulfonamide antibiotics within the cross-linked network, thereby moderately suppressing their leaching due to casual water exposure. Similar retention was also implemented for the antiviral agent didecyldimethylammonium chloride, and the coating layer demonstrated effective and stable suppression of viral infectivity of deposited droplets under realistic conditions.