Dual-functional antireflection and antimicrobial PA/Cu²⁺/PDA silica coating via interface charge assembly

SiO₂ antireflection coating holds great promise in the optimization of optical lenses. However, their inherent hydrophilic and porous properties cause their surface to be susceptible to contamination by microorganisms. Herein, a SiO₂ antireflection coating with an antimicrobial surface is designed and fabricated by interface assembling polydopamine (PDA), Cu²⁺ and phytic acid (PA) on the SiO₂ coating to obtain a sustained antibacterial property. The phenolic hydroxyl group in PDA provides a large number of active sites for the chelating of Cu²⁺, thus endowing the coating with antibacterial properties (GSP-Cu²⁺). Further coordination with PA controls the release rate of Cu²⁺ and prolongs the service life of the antimicrobial coating (GSPP). Under the optimal conditions, the GSPP_0.1 coating achieved an antibacterial efficacy exceeding 99.99 % (E. coli and S. aureus antimicrobial rate > 99.9 % at 6 h). Compared to the GSP-Cu²⁺ coating (0 %), the GSPP_0.1 coating still maintains an antibacterial efficacy of more than 80 % against E. coli and S. aureus after 12 days’ immersion in water, while maintaining the light transmittance above 96 %. These results demonstrate a promising potential for the practical functional antireflection.