Therapeutic Potential of Sol-Gel ZnO Nanocrystals: Anticancer, Antioxidant, and Antimicrobial Tri-Action.

Zinc oxide nanocrystals (ZnO NCs) hold great promise in nanomedicine with fascinating multifunctional properties. We investigated the therapeutic potential of sol-gel synthesized ZnO NCs with crystal sizes of 52.65 and 25.11 nm, focusing on their anticancer effects on HepG2 and HT29 cells, antioxidant properties, and antimicrobial activity. Both samples displayed a hexagonal wurtzite ZnO structure, wherein the crystal sizes diminished with lower calcination temperatures according to X-ray diffraction. The scanning electron microscopy analysis revealed that lowering the calcination temperature resulted in a decrease in the grain size of the ZnO NCs, as expected. This reduction in grain size combined with a decrease in crystal size resulted in a significant 40% reduction in the reflectance of the ZnO NCs in UV-vis-NIR spectroscopy. It was also observed that the ZnO NCs calcined at higher temperatures exhibited larger particle sizes with a reduced surface area mean of 69.30 µm and a stable negative zeta potential of -11.2 mV. In contrast, the ZnO NCs calcined at lower temperatures exhibited a larger surface area mean of 34.56 µm and a positive zeta potential of +10 mV. In both cell lines, the cytotoxic potential was found to be higher in HepG2 cells. Specifically, when ZnO nanocrystals (NCs) with a crystal size of 52.65 nm were used, the lowest cell viability was observed at a concentration of 5.74 µg/mL. Based on oxidative stress index values, a lower crystal size of ZnO NCs displayed greater effectiveness in HT29 cells, while a higher crystal size of ZnO NCs had pronounced effects in HepG2 cells. Moreover, both ZnO NCs exhibited significant antimicrobial activity against Gram-positive bacteria (Enterococcus faecalis and Staphylococcus aureus) and Candida parapsilopsis fungus. These findings emphasize sol-gel ZnO NCs' potential as versatile agents in nanomedicine, spurring research on targeted cancer therapies and antimicrobial innovations.

A Novel Label-Free Optical Biosensor Using Synthetic Oligonucleotides from E. coli O157:H7: Elementary Sensitivity Tests.

SiO(2)-TiO(2) thin films for use as fiber optic guiding layers of optical DNA biosensors were fabricated by the sol-gel dip coating technique. The chemical structure and the surface morphology of the films were characterized before immobilization. Single probe DNA strands were immobilized on the surface and the porosity of the films before the hybridization process was measured. Refractive index values of the films were measured using a Metricon 2010 prism coupler. On the surface of each film, 12 different spots were taken for measurement and calculation of the mean refractive index values with their standard deviations. The increased refractive index values after the immobilization of single DNA strands indicated that immobilization was successfully achieved. A further refractive index increase after the hybridization with target single DNA strands showed the possibility of detection of the E. coli O157:H7 EDL933 species using strands of 20-mers (5'-TAATATCGGTTGCGGAGGTG -3') sequence.