Modification of Natural Clays with Magnetite to Provide Boosted Antimicrobial Properties and Chemopreventive Activity Against Melanoma

Historically, clays have been widely used for the treatment of wounds and to stop hemorrhaging. The aim of this study was to combine four natural clay minerals (kaolinite, glauconite, montmorillonite, and bentonite) with magnetite (Fe₃O₄) nanoparticles to produce Fe₃O₄-clay complexes with enhanced antimicrobial properties and chemopreventive activity against melanoma. The magnetite-clay complexes were synthesized by the chemical co-precipitation method and characterized using XRD, TEM, STEM-EDS, SEM, and SQUID magnetometer. Antimicrobial properties were determined by evaluation of MIC values. The most promising materials were also subjected to direct contact antibacterial test according to the OECD standard for porous materials. Cytotoxicity of the complexes towards melanoma cells and normal human skin fibroblasts was assessed by MTT assay. We performed XRD, which confirmed the formation of Fe₃O₄-clay complex materials. It was also proven that complexes exhibited superparamagnetic properties. Microbiological experiments clearly revealed that modification of natural clays with magnetite significantly boosted their antimicrobial properties. Fe₃O₄-montmorillonite and Fe₃O₄-bentonite showed the strongest antimicrobial activity. Moreover, the mentioned complexes had the ability to reduce the viability of melanoma cells by 35-40%, while exhibiting no cytotoxicity against the normal human fibroblast (BJ) cell line, which is an extremely desirable feature. Thus, it may be concluded that Fe₃O₄-montmorillonite and Fe₃O₄-bentonite complexes hold promise for use in the management of infected wounds and wounds after melanoma excision.