Silver-based hybrid nanomaterials are gaining interest as potential alternatives for conventional antimicrobial agents. Herein, we present a simple, facile and eco-friendly approach for the deposition of silver nanoparticles (AgNPs) on ZnO nanorods, which act as a nanoreactor for in situ synthesis and as an immobilizing template in the presence of arginine. The presence of arginine enhanced the stability of ZnO deposition on the glass substrate by hindering the dissolution of zinc under alkaline conditions. Various Ag/ZnO hybrid nanorod (HNR) samples were screened to obtain a high amount of silver immobilization on the ZnO substrate. Ag/ZnO HNRs displayed potent antibacterial ability and could achieve 100% kill for both Escherichia coli and Bacillus subtilis strains under various test conditions. The hybrid material mediated its dual mode of antibacterial action through direct contact-killing and release of silver ions/nanoparticles and showed superior bactericidal performance compared to pure ZnO nanorods and colloidal AgNPs. No significant decline in antibacterial efficacy was observed even after the same substrate was repeatedly reused multiple times. Interestingly, the amount of Ag and Zn release was much below their maximal limit in drinking water, thus preventing potential health hazards. Immobilized AgNPs showed no cytotoxic effects on the human hepatocarcinoma cell line (HepG2). Moreover, treating cells with the antibacterial substrate for 24 hours did not lead to significant generation of reactive oxygen species (ROS). The good biocompatibility and bactericidal efficacy would thus make it feasible to utilize this immobilization strategy for preparing new-generation antibacterial coatings.

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Rapid and sustained disinfection of surfaces is necessary to check the spread of pathogenic microbes. The current study proposes a method of synthesis and use of copper nanoparticles (CuNPs) for contact disinfection of pathogenic microorganisms. Polyphenol stabilized CuNPs were synthesized by successive reductive disassembly and reassembly of copper phenolic complexes. Morphological and compositional characterization by transmission electron microscope (TEM), selected area diffraction and electron energy loss spectroscopy revealed monodispersed spherical (ϕ 5–8 nm) CuNPs with coexisting Cu, Cu(I) and Cu (II) phases. Various commercial grade porous and non-porous substrates, such as, glass, stainless steel, cloth, plastic and silk were coated with the nanoparticles. Complete disinfection of 107copies of surrogate enveloped and non-enveloped viruses: bacteriophage MS2, SUSP2, phi6; and gram negative as well as gram positive bacteria: Escherichia coli and Staphylococcus aureus was achieved on most substrates within minutes. Structural cell damage was further analytically confirmed by TEM. The formulation was well retained on woven cloth surfaces even after repeated washing, thereby revealing its promising potential for use in biosafe clothing. In the face of the current pandemic, the nanomaterials developed are also of commercial utility as an eco-friendly, mass producible alternative to bleach and alcohol based public space sanitizers used today.