In vitro anticancer activity of silver nanoparticles entrapped in gelatin-alginate, synthesized using Calendula officinalis flower extract

Cancer remains a leading cause of global mortality, and conventional therapies are often limited by toxicity and poor selectivity. Green nanotechnology provides an eco-friendly approach to developing biocompatible and efficient anticancer agents. In this study, we developed silver nanoparticles (AgNPs) encapsulated in gelatin-alginate (Gel-Alg) hygrogel using Calendula officinalis (CO) flower extract (Gel-Alg-Ag-CO) to evaluate their therapeutic potential. The hydrogel formulation was synthesized using AgNPs derived from the aqueous extract of CO as a reducing and stabilizing agent. The nanocomposite was characterized by UV-vis spectroscopy, dynamic light scattering (DLS), zeta potential analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD). Phytochemical and gas chromatography-mass spectrometry (GC-MS) analyses were performed to identify bioactive compounds. Biocompatibility was assessed in vivo using zebrafish embryos. Anticancer activity was evaluated in HepG2 liver cancer cells through morphological assessment and MTT assay. The Gel-Alg-Ag-CO nanohydrogel displayed an average hydrodynamic size of 97.68 nm, a negative zeta potential (-31.03 mV), and a crystalline face-centered cubic structure. FTIR confirmed the involvement of functional groups in the stabilization process. Phytochemical and GC-MS analyses revealed the presence of flavonoids, terpenoids, glycosides, and fumaric acid derivatives, with fumaric acid, 2,2,3,3,4,4,5,5-octafluoropentyl tridecyl ester, as the major compound (25.79%). The formulation demonstrated 93 ± 3.3% viability in fibroblast cells at 80 µg/mL, minimal hemolysis (0.4–1.06%), and no significant developmental toxicity in zebrafish embryos up to 5 µg/mL; however, hatchability declined to 75 ± 4.8% at 10 µg/mL. Against HepG2 cells, Gel-Alg-Ag-CO exhibited dose-dependent cytotoxicity with 63 ± 3.5% inhibition at 80 µg/mL and an IC 50 of 18.2 µg/mL. The study demonstrated that Gel-Alg-Ag-CO is a safe, biocompatible, and potent anticancer nanocomposite. Its synergistic effects, combining silver nanoparticles, biopolymer encapsulation, and phytochemicals from CO, highlight its promise as a green, multifunctional platform for targeted cancer nanotherapy. Future in vivo tumor studies are warranted to validate its therapeutic potential.