Piperonal-coated silver nanoparticles: A study on cytotoxicity and protein binding

Silver nanoparticles are broadly acknowledged for their medicinal potential. Various research groups, including ours, have explored the functionalization of nanoparticles with natural compounds, revealing promising applications in biomedicine. The current study focuses on synthesizing silver nanoparticles capped with piperonal (P-Ag). We successfully produced spherical piperonal-capped silver nanoparticles, with size range of 20-35 nm, demonstrating good stability. We assessed the cytotoxicity of these nanoparticles and found them to exhibit low toxicity. Further anticancer studies revealed significant antitumor activity against lung cancer cell lines, indicated by low IC₅₀ values. Encouraged by these findings, we investigated the protein binding of P-Ag nanoparticles, using human serum albumin (HSA) as a model protein due to its abundance and importance in the human body. UV-visible and photoluminescence spectroscopy demonstrated a moderate binding affinity of P-Ag for HSA, with a binding constant in the range of 10³ M^-1. Isothermal titration calorimetry indicated that the interaction is spontaneous, favourable and endothermic. Despite the moderately strong binding, circular dichroism spectroscopy showed minimal disruption to the secondary structure and negligible conformational changes in HSA upon interaction with P-Ag. In short, the comprehensive study suggests that P-Ag nanoparticles are promising candidates for therapeutic applications.