SterilShield: Mechanically Robust, Fluorine-Free SiO2–CuO Nanocomposite Coatings with Combined Superhydrophobicity, Optical Transparency, and Antimicrobial Activity

Abstract

Highly transparent superhydrophobic coatings have emerged as essential materials across electronics, energy, and healthcare sectors, where cleanliness, durability, and optical performance are critical. Integrating antimicrobial functionality into such coatings further broadens their applicability in consumer electronics, biomedical devices, and food packaging. Herein, we report SterilShield, a fluorine-free, cost-effective, and scalable nanocoating fabricated via a single-step dip-coating process using a composite of silica (SiO2) nanoparticles (NPs) and cupric oxide (CuO) NPs, followed by surface treatment with trimethylchlorosilane. By precisely controlling the coating composition and thickness, the resulting surfaces exhibit superhydrophobicity with a water contact angle of 160°, optical transmittance of 91.6%, and broad-spectrum antibacterial and antibiofilm activity against Gram-negative (E. coli, P. aeruginosa, and K. pneumoniae) and Gram-positive (MRSA). The coating also demonstrates mechanical robustness, biocompatibility, and fluorine-free chemistry, addressing long-standing challenges of cytotoxicity and environmental sustainability. The unique integration of mechanical durability, antimicrobial protection, superhydrophobicity, and high optical transparency establishes SterilShield as a promising candidate for next-generation multifunctional coatings in healthcare, photonics, and transparent electronic interfaces.