Theoretical investigation on the interactions of microplastics with a SARS-CoV-2 RNA fragment and their potential impacts on viral transport and exposure.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes the coronavirus disease-19 (COVID-19) pandemic spread across the world and remains difficult to control. Environmental pollution and habitat conditions do facilitate SARS-CoV-2 transmission as well as increase the risk of exposure to SARS-CoV-2. The coexistence of microplastics (MPs) with SARS-CoV-2 affects the viral behavior in the indoor and outdoor environment, and it is essential to study the interactions between MPs and SARS-CoV-2 because they both are ubiquitously present in our environment. To determine the mechanisms underlying the impact of MPs on SARS-CoV-2, we used molecular dynamic simulations to investigate the molecular interactions between five MPs and a SARS-CoV-2 RNA fragment at temperatures ranging from 223 to 310 K in vacuum and in water. We furthermore compared the interactions of MPs and SARS-CoV-2 RNA fragment to the performance of SARS-CoV-1 and Hepatitis B virus (HBV) RNA fragments in interacting with the MPs. The interaction affinity between the MPs and the SARS-CoV-2 RNA fragment was found to be greater than the affinity between the MPs and the SARS-CoV-1 or HBV RNA fragments, independent of the environmental media, temperature, and type of MPs. The mechanisms of the interaction between the MPs and the SARS-CoV-2 RNA fragment involved electrostatic and hydrophobic processes, and the interaction affinity was associated with the inherent structural parameters (i.e., molecular volume, polar surface area, and molecular topological index) of the MPs monomers. Although the evidence on the infectious potential of SARS-CoV-2 RNA is not fully understood, humans are exposed to MPs via their lungs, and the strong interaction with the gene materials of SARS-CoV-2 likely affects the exposure of humans to SARS-CoV-2.