Microwave-assisted green synthesis of silver nanoparticles using alkaline extracted crude polysaccharide of C. Nutans: Optimisation, characterisation, toxicity, anticancer potential and antibacterial studies

Green synthesised metal nanoparticles have been identified as promising materials for the development of nanomedicine due to their cost effectiveness, toxic-free and sustainable attributes. Studies have shown that silver nanoparticles (AgNP) combined with natural extracts can be useful in treating various diseases. Our study aims to prepare AgNP using alkaline extracted Clinacanthus nutans (C. nutans) crude polysaccharides (ALK_CNP) by the microwave-assisted method. The ALK_CNP synthesised silver nanoparticles (ALK_AgNP) were characterised by the UV–Visible spectroscopy, dynamic light scattering technique, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and transmission electron microscopy. The toxicity of the ALK_AgNP was tested against brine shrimp. The anticancer activity of AgNP was assessed on MCF-7 and HT-29 cell lines. The antibacterial efficacy of AgNP was determined against pathogenic bacteria (Escherichia coli and Staphylococcus aureus). Also, the DNA synthesis mechanism was tested via the mRNA expression of both bacteria strains. The obtained results demonstrated that synthesised ALK_AgNP had an average diameter of 7.48 ± 2.88 nm and had lower toxicity and higher anticancer and antibacterial potential than commercially available AgNP.