Natural sunlight driven photocatalytic dye degradation by biogenically synthesized tin oxide (SnO2) nanostructures using Tinospora crispa stem extract and its anticancer and antibacterial applications

In the present study, tin oxide (SnO2) was synthesized by advocating the principles of green chemistry for the photo-mediated degradation of pollutants, antimicrobial, and as an antitumor agent. Bioactive SnO2 (nanorods & nanospheres) were fabricated using Tinospora crispa stem extract (TCSE) via sol-gel technique and characterized extensively. XRD, UV-VIS, FTIR, and XPS studies confirmed the formation of crystalline and well stoichiometric pure phase of SnO2 nanostructures with optical bandgap 3.2 to 3.5 eV. The transmission electron microscopy (TEM) results demonstrated the effect of secondary phytoconstituents on the shape of SnO2 in a concentration dependent manner. The morphological variations in the obtained nanostructures attributed to the nucleation density and coalescence effect leading to the formation of nanorods with an average diameter 23-25 nm whereas the average particle size of the nanospheres obtained was found to be 23-30 nm. The zeta potential value of SnO2 nanorods was high (- 58.9 mV) indicating the higher stability compared to nanospheres (- 15.6 mV). The SnO2 nanostructures were investigated for the simultaneous degradation of methylene blue with degradation efficiency of 92.3% and 47.3% for rhodamine B in mono system and 72.3%, 47.7% respectively for binary dye system. The anticancer activity of SnO2 nanorods explored against human breast cancer (MCF-7) cells revealed a concentration dependent cytotoxic effect reactive oxygen species (ROS) induced cell death. Additionally, efficient antibacterial activity of SnO2 was established using E.coli.