Highly effective suppression of herpes simplex virus type 1 by titanium dioxide nanoparticles

Herpes simplex virus type 1 (HSV-1) is an important clinical problem due to its drug resistance and reactivation of infections, and new antiviral agents are required. Titanium dioxide (TiO₂) nanoparticles, due to their high photocatalytic activity, lack of toxicity and biocompatibility, were claimed possible candidates in antiviral therapy. The purpose of this work was to investigate the antiviral effect of TiO₂ nanoparticles in HSV-1 infection, and evaluate their biocompatibility on Vero cells.

TiO₂ nanoparticles were characterized for their structure by X-ray diffraction analysis, Fourier transform infrared spectroscopy, zeta potential measurement, and field emission scanning electron microscopy. Cytotoxicity studies were performed on Vero cells using the neutral red cytotoxicity assay with concentrations varying from 200 to 1600 μg/mL. Virucidal and post-treatment testing was also applied to measure virucidal efficacy against HSV-1. Viral load was measured by real-time PCR with targets on the UL30 gene.

TiO₂ nanoparticles showed no cytotoxicity up to 1200 μg/mL, and at concentrations of 1400 μg/mL (20%) and 1600 μg/mL (68%), the viability of cells was reduced. In virucidal tests, at TiO₂ concentrations of 400, 800, and 1200 μg/mL, the percentage inhibition of HSV-1 was 95.1%, 98%, and 98.8%, respectively (P < 0.001). Results of post-treatment tests showed percentage inhibition of 99.2%, 99.8%, and 99.9%, respectively (P < 0.001).

In this in vitro investigation, the high antiviral efficacy of TiO₂ nanoparticles has been established in Vero cell culture infected with HSV-1, which was found to have good biocompatibility up to 1200 μg/mL. Further clarification of the antiviral mechanism of TiO₂ nanoparticles can be achieved through in vivo studies.