Eco-Friendly Fabrication of Silver Sulphide Nanostructures via Microwave Irradiation: Structural Characterization and Pharmacologically Relevant Cytotoxicity Studies

Abstract

In this study, we present a rapid, template -free, and environmentally benign synthetic strategy for the fabrication of structurally diverse silver sulphide (Ag2S) nano structures under ambident conditions. This synthesis is based on a microwave assisted thermal decomposition of a macrocyclic ligand -coordinated silver (I) complex employed as a single-source molecular precursor. This ecofriendly method enables the synthesis of silver sulphide nanostructures with different morphologies, including nano spheres and nanotubes, composed primarily of assembled nano plates and nanoparticles. Synthetic parameters-precursor stoichiometry, and the nature of counterions -revealed that ionic species significantly influence the resultant morphology specifically sulphate, nitrate, bromide, hydroxide ions favoured the formation of tubular nanostructures, whereas chloride ions predominantly yielded spherical architectures. The resulting ecofriendly nanomaterials were extensively characterized using elemental analysis, Fourier -transform infrared spectroscopy (FT-IR),UV-Vis spectroscopy (UV-Vis), thermogravimetric analysis (TGA),X-ray diffraction(XRD),transmission electron microscopy(TEM),and scanning electron microscopy(SEM).FT-IR spectral data indicated notable shifts in vibrational bands, in silver (I) complex, affirming successful coordination of the ligand to the silver ion in +1 oxidation state. XRD confirmed the crystalline phase purity of silver sulphide nanostructures, while SEM revealed monodisperse spherical particles averaging ~ 78 nm in diameter. A prominent absorption peaks at 353 & 378 nm in UV spectrum further corroborated the optical and nano scale features of the synthesized particles. SEM analysis displayed agglomerated, grain-like surface textures characteristic of Ag2S nano structures.  The incorporation of non-polar solvents like DMSO (dimethyl sulfoxide) under microwave irradiation was found to significantly enhance reaction kinetics, reduce by-products of reaction and improve the overall quality of the nanomaterials. In addition to structural and optical characterization, the bioactive potential of the synthesised silver sulphide nano particles was evaluated. The materials exhibited notable pharmacological properties, including anticancer, antioxidant, and anti-inflammatory activities likely arising from the electronic characteristics of the substituent groups on the molecular precursor. Furthermore, cytotoxic assays against MCF -7 breast cancer cell lines, revealed significant biological activity, under scoring the therapeutic promise of the nano structures. This ecofriendly, microwave-assisted route represents a robust and efficient methodology for producing bio-functional Ag2S nanostructures, holding great potential for future applications in biomedicine, particularly in cancer therapy and molecular diagnostics.