Fig. 5.

Nanoparticles are used to strengthen the intestinal barrier against SARS-CoV-2 invasions. SARS-CoV-2 can interact with intestinal microbes, resulting in decreased microbial diversity. At the same time, intestinal microbes can regulate the expression level of ACE2 and affect the virus's ability to invade. Moreover, the expression levels of inflammatory cytokines also increase accordingly. However, targeted nanoparticles can block these pathways, and then restore intestinal microbial diversity, reduce inflammation levels, and improve intestinal barrier capabilities.