Biomimetic nanoplasmonic sensor for rapid evaluation of neutralizing SARS-CoV-2 monoclonal antibodies as antiviral therapy.

Monoclonal antibody (mAb) therapy is one of the most promising immunotherapies that have shown the potential to prevent or neutralize the effects of COVID-19 in patients at very early stages, with a few formulations recently approved by the European and American medicine agencies. However, a main bottleneck for their general implementation resides in the time-consuming, laborious, and highly-specialized techniques employed for the manufacturing and assessing of these therapies, excessively increasing their prices and delaying their administration to the patients. We propose a biomimetic nanoplasmonic biosensor as a novel analytical technique for the screening and evaluation of COVID-19 mAb therapies in a simpler, faster, and reliable manner. By creating an artificial cell membrane on the plasmonic sensor surface, our label-free sensing approach enables real-time monitoring of virus-cell interactions as well as direct analysis of antibody blocking effects in only 15 min assay time. We have achieved detection limits in the 102 TCID50/mL range for the study of SARS-CoV-2 viruses, which allows to perform neutralization assays by only employing a low-volume sample with common viral loads. We have demonstrated the accuracy of the biosensor for the evaluation of two different neutralizing antibodies targeting both Delta and Omicron variants of SARS-CoV-2, with half maximal inhibitory concentrations (IC50) determined in the ng/mL range. Our user-friendly and reliable technology could be employed in biomedical and pharmaceutical laboratories to accelerate, cheapen, and simplify the development of effective immunotherapies for COVID-19 and other serious infectious diseases or cancer.