Facile synthesis of carbon/titanium oxide quantum dots from lignocellulose-rich mandarin orange peel extract via microwave irradiation: Synthesis, characterization and bio-imaging application.

A nanohybrid prepared from the lignocellulosic residue is a feasible approach to synthesize blue light emitting fluorescent doped TiO quantum dot nanocomposite (C-TiO QDs) by microwave techniques using Mandarin orange (Citrus reticulata) peel powder with titanium isopropoxide precursors. With a greater orange peel colloidal medium, the structure of the TiO-NPs changed from a mixture of rutile and anatase phases to exclusively the anatase phase. The optical and morphological properties of as-prepared C-TiO QDs were characterized by HR-TEM, XRD, FT-IR, UV-visible, PL spectra, DLS, and Zeta potential techniques. The reaction condition was optimized by changing substrate composition, pH, and reaction time. C-TiO QDs exhibit outstanding stability at pH 7 and remain sustained for at least 180 days without aggregation. As prepared C-TiO QDs have distinct emission and excitation activities with an average particle size of 2.8 nm. Cell viability was performed on normal L929 cells, where it showed excellent biocompatibility (<90 %) even at the concentration of 200 μg/mL after 24 h treatment. Additionally, the synthesized C-TiO QDs were used with L929 cells as a fluorescent probe for bio-imaging applications. The results revealed that neither of the cell lines' morphologies had significantly changed, proving the biocompatibility of the synthetic C-TiO QDs.