In vitro localization of modified zinc oxide nanoparticles showing selective anticancer effects against colorectal carcinoma using biophysical techniques

In recent decades, despite advancements in conventional cancer therapies, their serious side effects on both healthy and tumor cells remain a major concern. Aiming to address indiscriminate drug distribution, unwanted toxicity, and high chemotherapy doses, this study explores the targeted delivery of zinc oxide nanoparticles (ZnO NPs). ZnO NPs were synthesized and coated with bovine serum albumin (BSA) and tetraethoxysilane (TEOS) to control cellular uptake and enhance anticancer activity. Characterized by UV-visible spectroscopy, DLS, FTIR, XRD, and TEM, ZnO, ZnOB, and ZnOT particles displayed sizes of 140 ± 13.6 nm, 342 ± 8.4 nm, and 145 ± 23.8 nm, respectively, with ZnOT showing a positive charge of + 19.3 ± 4.16 mV, enhancing stability and cellular interaction. Cytotoxicity assays revealed ZnO's potent anticancer effect in Caco-2 cells with an IC50 of 219 µg/ml, while ZnOB and ZnOT showed moderate toxicity (IC50 values of 308 µg/ml and 235 µg/ml). HepG2 cells maintained viability close to 100%, highlighting ZnO NPs' selectivity for Caco-2 cells. Flow cytometry and confocal microscopy indicated differential uptake, with ZnOB showing the highest uptake in Caco-2 cells after 24 h at 37 °C, increasing fluorescence intensity by over 80% compared to ZnO. ZnOT notably increased late apoptotic cells by 65% in Caco-2 lines and caused a 40% rise in G2/M phase arrest. Mitochondrial function assays showed that ZnO reduced mitochondrial membrane potential by over 30%, indicating stress induction. These results support the potential of ZnO-based nanoparticles in colorectal cancer treatment, offering selective cytotoxicity, enhanced cellular uptake, and clear apoptotic activity, making them a promising alternative to conventional chemotherapy.