Curcumin-mediated synthesis of silver nanoparticles immobilized on chitosan-modified kaolin: Investigation of its catalytic activity, antioxidant and anti-lung cancer effects

In this research, Curcumin, a naturally occurring pigment, was utilized to synthesize silver nanoparticles (AgNPs), serving as a reducing agent, and stabilizer, through an environmentally friendly, cost-effective, and straightforward method. This process occurred on the surface of kaolin; a mineral clay modified with chitosan. The study revealed that the phenolic hydroxyl and carbonyl functional groups of Curcuma played a significant role in reducing silver ions to form AgNPs with a characteristic ginger hue. Additionally, the presence of kaolin minerals promoted the in-situ nucleation of AgNPs on both the surface and within the interlayers of the modified kaolin. This approach successfully inhibited aggregation and ensured a uniform distribution of AgNPs, with particle sizes ranging from 20 to 30 nm across the kaolin surface. The resulting Kaolin@CS-Cur/AgNPs nanocomposite was thoroughly characterized using various analytical techniques, including TEM, SEM, FT-IR, EDX-elemental mapping, ICP-OES, and XRD. The composite demonstrated promising catalytic activity in the solvent-free preparation of 1-substituted-1H-tetrazoles via a three-component coupling reaction (MCR) involving NaN₃, amines, and triethyl orthoformate. Catalyst performance was further validated by conducting eight catalyst recycling cycles, drain tests, and hot filtration experiments. DPPH assay indicates the power antioxidant efficacy of Kaolin@CS-Cur/AgNPs nanocomposite. After undergoing 3-4 passages, the lung cancer cells as well as the normal cell were meticulously prepared in regards to their morphology and quantity through in vitro experiments. After separating the flask surface cells through trypsin-EDTA, we evaluated and enumerated the cell viability, and subsequently cultured 3 × 10³ cells in 96 wells with or without NPs. IC₅₀ of Kaolin@CS-Cur/AgNPs nanocomposite was 110, 96, and 38 on HLC-1, LC-2/ad and PC-14 lung cancer cells.