Efficient composite partnering of crab shell-derived chitosan with tin oxide for anticancer and other biomedical...

Chitosan and metal oxide-based nanocomposites are useful for several applications, especially in biomedical-related studies such as diabetes and cancer. This research focuses on the synthesis of SnO₂/chitosan (SnO₂/CS) nanocomposites with varying weight proportions of SnO₂/CS (1:0.5, 1:1, and 1:2 g) and their health-related applications. The nanocomposites prepared using the soft chemical method were characterized using XRD, FTIR, PL, FESEM, EDS with mapping, TEM, XPS, DLS and BET analysis. The nanocomposite synthesized with 2 g of chitosan (SnO₂/CS(2)) functioned the best in biomedical applications. The SnO₂/CS(2) nanocomposite showed inhibition percentages of 92.36 % (IC₅₀ = 61.83 ± 0.73 μg/mL) and 93.28 % (IC₅₀ = 75.43 ± 0.51 μg/mL) in the ABTS and superoxide radical scavenging assays, respectively. Similarly, its antidiabetic potential was demonstrated by its inhibition of α-glucosidase by 91.85 % with an IC₅₀ value of 60.57 ± 0.33 μg/mL. The nanocomposite showed notable anti-inflammatory effects in both the protein denaturation assay (IC₅₀ = 77.61 ± 0.88 μg/mL) and in H₂O₂-induced RAW 264.7 cells. Cytotoxicity studies against A-549 lung cancer cells revealed dose-dependent inhibition (IC₅₀ = 20.405 ± 2.298 μg/mL), while no significant toxicity was observed in normal fibroblast 3T3-L1 cells. The cell morphological studies and AO/EtBr fluorescence staining confirmed apoptosis-induced cell death. Gene expression analysis indicated downregulation of Bcl-2 and upregulation of Bax, p53, and Caspase-3, confirming the activation of the intrinsic apoptotic pathway. These results suggest that the SnO₂/CS(2) nanocomposite is a promising candidate for antioxidant, antidiabetic, anti-inflammatory, and anticancer therapeutic applications.