Multivalent nanomedicines to treat COVID-19: A slow train coming.

The high transmission rate and serious consequences of the unprecedented COVID-19 pandemic make it challenging and urgent to identify viral pathogens and understand their intrinsic resistance mechanisms, to pave the way for new approaches to combat severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Multivalent interactions are responsible for performing a broad range of biological functions in normal cells, such as cell-cell communication and adhesion. Multivalency underlies the reversibility of ligand-receptor interactions during infections. Previous studies into multivalent nanomedicines used against viruses, have revealed their ability, not only to probe the molecular processes of viral infections, but also to target pathogen-host cell binding with minimal collateral damage to normal cells. Nanomedicines are comparable in size to viruses and to cell receptor complexes (that mediate viral uptake), and can function as safe and accurate armoured vehicles to facilitate the transport of anti-viral drugs. Multivalent nanomedicines can be designed to avoid binding to extracellular serum proteins, and ultimately lead to destruction of the viruses. This brief perspective highlights the potential of innovative smart and safe multivalent nanomedicines that could target multiple viral factors involved in infections at cellular levels. For instance it is possible to target viral spike protein mediated entry pathways, as well as viral replication and cell lysis. Nanomedicine-based approaches could open new opportunities for anti-coronavirus therapies.