Sustainable Green for the Synthesis of TiO₂ Nanoparticles Using Solanum Melongena Extract

In this study, a sustainable and environmentally benign methodology was developed for the synthesis of titanium dioxide (TiO₂) nanoparticles utilizing Solanum melongena (eggplant) extract as a natural reducing and stabilizing agent. The proposed biosynthetic route was intentionally designed to substitute conventional chemical pathways that commonly involve hazardous precursors and high-energy consumption. The synthesized TiO₂ nanomaterials were subjected to comprehensive structural and morphological characterization through X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), and Fourier-transform infrared spectroscopy (FTIR). XRD patterns verified the formation of a highly crystalline anatase phase with an estimated mean crystallite size of approximately 13.6 nm. The FE-SEM micrographs revealed nearly spherical to quasi-spherical morphologies with an average particle diameter of about 29 nm, indicating that the bio mediated process enabled controlled nucleation and moderate particle-size homogeneity. The FTIR spectra exhibited characteristic Ti–O–Ti stretching vibrations together with residual phytochemical functional groups originating from the eggplant extract, confirming their involvement as surface-capping species that enhanced nanoparticle stability. In addition to the structural investigation, the electrical sensing performance of the TiO₂ nanomaterials toward DNA molecules was evaluated at ambient temperature. A comparative analysis between uncalcined and calcined (400 °C) TiO₂ samples demonstrated a pronounced improvement in sensitivity following calcination. The thermally treated TiO₂ displayed enhanced electrical conductivity, increased surface activity, and improved crystallinity, achieving DNA-sensing sensitivities in the range of 45–70%, compared with 12–18% for the uncalcined samples. The observed enhancement is attributed to the generation of oxygen vacancies and the phase transformation from amorphous to anatase, which collectively facilitated more efficient charge transfer across the TiO₂–biomolecule interface.