Endophytic fungi-mediated biosynthesis of titanium dioxide nanoparticles: characterization and evaluation of their antimicrobial, antioxidant, and anticancer activities

Herein, the different biological activities of green-fabricated titanium dioxide nanoparticles (TiO 2 -NPs) were assessed. The cell-free filtrate (CFF) of the endophytic fungus Penicillium chrysogenum was utilized as a biocatalyst for the green production of TiO 2 -NPs. GC-MS was used to identify CFF metabolites containing alkaloids, terpenoids, organic compounds, carotenoids, and steroids. The characterization of the nanoscale structure was achieved by UV analysis, TEM, FT-IR, EDX, XRD, zeta potential, and DLS. The colorless CFF was transformed into a white precipitate as an indicator of TiO 2 -NPs synthesis, which showed maximum surface plasmon resonance at 360 nm. TEM exhibited spherical shapes with sizes ranging from 10 to 40 nm. EDX confirmed that the main components of the nanoscale sample were oxygen (weight% of 15.32%) and titanium (weight% of 44.1%) ions. XRD and DLS showed the formation of an anatase crystalline structure and a negative surface charge with a ζ-value of − 28.42. The biological applications of TiO 2 -NPs, including antimicrobial, antioxidant, and cytotoxic activities, were concentration-dependent. Different strains of Gram-positive and Gram-negative bacteria, as well as unicellular and multicellular fungi, were inhibited by the formed nanostructure, with low MIC values ranging from 25 to 50 µg mL −1 . The synthesized nanostructure exhibited DPPH scavenging activity with a percentage of 90.4 ± 0.6% compared to 96.1 ± 0.8% for ascorbic acid (positive control) at 1000 µg mL −1 . Myco-fabricated TiO 2 -NPs targeted the cancer cells Caco-2 and MCF7 to inhibit their viability, with low IC 50 and selectivity index (SI) values of 242 and 287 µg mL −1 and 1.67 and 1.41, respectively, compared to their activity toward the normal cell line WI38, which had an IC 50 value of 405 µg mL −1 . Overall, these results highlight the efficacy of the endophytic fungal strain Penicillium chrysogenum in producing TiO 2 -NPs with multifunctional activities, including inhibition of microbial growth, scavenging of free radicals, and selective activity against cancer cells.