A nano perspective behind the COVID-19 pandemic.

The global pandemic scenario has definitely pushed the scientific community to develop COVID-19 vaccines at unprecedented speed. Nevertheless, a worldwide vaccination campaign is still far from being achieved, making the usual precautionary measures as necessary as at the beginning of the outbreak. Many aspects of the SARS-CoV-2 infectious potential and disease severity do not solely rely on interactions at the molecular level but also on physical-chemical parameters that often involve nanoscale effects. Here the SARS-CoV-2 journey to infect a susceptible host is reviewed, focusing on the nanoscale aspects that play a role in the viral infectivity and disease progression. These nanoscale-driven interactions are essential to establish mitigation-related strategies.

Dose-dependent cell necrosis induced by silica nanoparticles.

In recent years, much attention has been given to nanoparticles (NPs) due to their many possible applications, and as research has progressed, these NPs have become valuable tools for medical purposes. Among many different types of NPs, silica nanoparticles (SiO2NPs) have been specifically evaluated for medical purposes and have also been used in many different types of products. Although SiO2NPs have already been applied and are believed to be nontoxic, there is still a concern regarding possible adverse effects that may be triggered after SiO2NP exposure. Therefore, in the present study, we employed a recommended cell line (BALB/c 3T3) for the toxicity evaluation to investigate the cytotoxic effects of SiO2NPs produced by chemical synthesis at a laboratory scale. First, we employed OECD guideline 129 in order to evaluate cytotoxicity effects and also estimate the starting doses for acute oral systemic toxicity tests. We evaluated the cytotoxic effects of two types of SiO2NPs (nonfluorescent and fluorescent) and found that they were not significantly different (IC50 = 1986.39 ± 237 µg/mL and IC50 = 1861.13 ± 186.72 µg/mL, respectively). Then, we used the predicted LD50 of both types of SiO2NPs to suggest that they could be categorized as GHS category 4 substances. By ultrastructural evaluation, we found that SiO2NPs are internalized by 3 T3 cells and are located in vacuole-like structures with no other significant changes in cell structure. We also found that SiO2NPs lead to cell necrosis in a dose-dependent manner.