Oxide anchored multi-charged metal complexes with binary nanoparticles for stable and efficient anti-bacterial coatings on cotton fabrics

Abstract

Personal protective equipment (PPE), especially face masks, has received much attention as a quick reaction to pandemic outbreaks to prevent infections caused by airborne microorganisms. Single-use masks are generally made of synthetic polymers such as polypropylene. Discarding the used masks causes serious environmental pollution. Incineration is an energy-intensive process for treating used masks. Therefore, in order to meet the urgent requirement to minimize the use of synthetic polymers in single-use masks, we developed a combination coating comprising of multi-charged metal complexes anchored on TiO₂ and binary nanoparticles containing silver and copper on cotton substrates as anti-bacterial inserts in face masks. The coatings have shown excellent activity against both Gram-negative and Gram-positive bacteria. >99.9% activity against bacteria under standard test conditions and after exposure to extreme conditions of humidity (>90% RH, 45 °C, 6 h), temperature (>110 °C, 6 h), and multiple cycles of washing confirms high anti-bacterial action combined with excellent environmental stability. The combination coatings exhibited excellent activity against bacterial strains that were partially resistant to already proven anti-bacterial agents like silver-copper nanoparticles. With differential partial pressure as low as 1.1 Pa cm⁻² confirming excellent breathability, good shelf life (exceeding 5 months under ambient conditions), comfort, and cooling effects, these coatings are promising candidates for anti-microbial inserts in cloth-based and otherwise all-polymeric PPE.