Geometry-dependent cytotoxicity of silver nanoparticles modulates apoptotic signaling in HCT-116 colorectal cancer cells

This study investigated the biological effects of size-and shape-controlled silver nanoparticles on HCT-116 colon carcinoma cells. Silver decahedral nanoparticles (AgNDs), with average diameters of 41 nm and 90 nm, were synthesized photochemically, while silver pentagonal nanorods (AgNRs), with a length of approximately 90 nm, were synthesized thermochemically. UV-vis spectroscopy, transmission electron microscopy (TEM), and scanning electron microscopy were used to confirm and characterize the synthesized nanoparticles. The cytotoxic effects of the nanoparticles were evaluated using a viability assay (MTT assay) at 72 h following exposure to a range of concentrations. Results demonstrated that nanoparticle size and shape influence cellular responses. Among the AgNDs, the 41 nm AgNDs were more cytotoxic than the 90 nm AgNDs, reflected by their lower IC50 value, demonstrating a size-dependent difference in cytotoxicity. However, 90 nm AgNRs displayed even greater cytotoxicity despite their larger length dimensions, suggesting that particle geometry strongly influences nanoparticle-cell interactions and biological activity. To further investigate potential molecular responses associated with nanoparticle-induced cytotoxicity, Western blot analysis was performed to evaluate the expression of key proteins associated with apoptotic pathways, proliferation, and survival signaling cascades. Exploratory analysis showed treatment-associated differences in these proteins, including a higher relative p53 signal in the 90 nm AgNR-treated condition. As these observations were obtained from a single biological experiment, they provide preliminary mechanistic context and require independent quantitative validation. Collectively, these findings demonstrate that nanoparticle size and morphology play critical roles in mediating the anticancer activity of silver nanoparticles and emphasize the importance of precise structural development when designing nanoparticle-based therapeutic strategies. These findings shed new light on nanoparticles-based therapeutics: To optimize the efficacy of these approaches, nanoparticles geometry should be carefully designed, taking into consideration the size and shape of nanoparticles.