Protection of neuronal cell lines, antimicrobial and photocatalytic behaviours of eco-friendly TiO2 nanoparticles

[Display omitted] •Green synthesize of TiO2 nanoparticles is using Citrus aurantium fruit peel extract for the first time.•The average size of the green synthesized nanoparticles is around 24−34 nm.•The bio synthesized TiO2 nanoparticles have shown excellent antimicrobial, neuronal cell line and photocatalytic activities. Eco-friendly synthesis of nanoparticles is promising as a futuristic alternative for chemical and physical protocols. In the present investigation, TiO2 nanoparticles were synthesised using the peel extract of Citrus aurantium fruit for the first time. The biosynthesised TiO2 nanoparticles were characterized by various techniques such as X- ray diffraction (XRD), UV–vis spectrophotometer, Fourier Transform Infra-Red Spectroscopy (FT-IR), Field Emission Scanning Electron Microscope (FE-SEM), Energy dispersive X-ray (EDAX), Transmission Electron Microscope (TEM) and Atomic Force Microscope (AFM). The crystal structure and phase purity of TiO2 nanoparticles were analysed using XRD. The optical properties and functional groups of TiO2 nanoparticles were investigated with the help of UV visible absorption and FT-IR analysis. The morphology and topography of TiO2 nanoparticles were examined through FE-SEM, TEM and AFM measurements. Biosynthesised TiO2 nanoparticles were evaluated for their antimicrobial activities against Staphylococcus aureus and Staphylococcus epidermidis (Gram-positive), Pseudomonas aeruginosa and Klebsiella pneumonia (Gram- negative), Candida albicans and Aspergillus niger (Fungi) using agar well method. In addition, cytotoxicity study was performed through MTT assay, the cell cycle analysis, and apoptosis assays of cells by flow cytometry and DNA fragmentation analysis. The photocatalytic behaviour against methylene blue dye was studied. Results of the present study revealed that biosynthesised TiO2 nanoparticles with an average size of 34 nm showed excellent antimicrobial, cell viability in PC12 cell lines (a combination of neuroblastic and eosinophilic cell lines) with IC50 ranged between 31.2–62.5 μg/ mL and excellent photo degradation property. Therefore, the present study concluded that biosynthesised TiO2 nanoparticles have potential antimicrobial, anti-apoptotic and photocatalytic behaviours towards neuronal cell lines.