Antimicrobial and toxicological behavior of montmorillonite immobilized metal nanoparticles

Highlights: • Ag and Cu NPs are deposited in situ over montmorillonite with different reductants. • Stronger reductants produce smaller NP size in presence of montmorillonite. • The nanohybrids have excellent antimicrobial and antifungal behaviour. • The nanohybrids show compatibility with human RBC and dermal fibroblast cells. - Abstract: With increasing demand for novel and potent antimicrobial agents to combat cross-infections and infectious diseases, silver and copper based nanoparticles (NPs) deposited over supports such as montmorillonite (MMT) are playing a crucial role in shaping the current research scenario. Although materials based on Ag NP and Cu NP on MMT have been reported, its toxicological properties on human cell lines have not been accounted for. This paper reports a comparative study on synthesis, antibacterial, antifungal and toxicological behavior of Ag and Cu NPs deposited over MMT nanosheets synthesized by employment of different reduction media. The effect of synthesized NP-MMT hybrids on human erythrocytes and fibroblast cells has been evaluated. The NP formation was facilitated using borohydride and ethyl alcohol (wet chemical route) and photo-reduction and thermal treatment (physical reduction route). The NP-MMT hybrids showed NP formation over supporting silicate layers with particle size ~10–50 nm confirmed by TEM micrographs and loading of ~6–22 wt% of metallic element by EDX analysis. The MMT layers were peeled apart to accommodate NPs inside its galleries, confirmed by increased d-value in powder WAXD. The NP-hybrids showed excellent inhibition zone against bacteria E.coli and S. aureus and fungi A. niger. RBC hemolysis and cytocompatibility assay were performed in vitro to advocate its safety to live human cells. These hybrid materials are potential candidates for new generation advanced antimicrobial materials with less toxicity and highly potent behavior.