Plastic antibodies that see viruses: optical sensing with molecularly imprinted polymers.

The need for rapid, sensitive, and selective detection of viral pathogens has never been more apparent. Molecularly imprinted polymers have emerged as robust synthetic receptors that rival biological antibodies in affinity and specificity, while offering superior chemical stability, low cost, and design flexibility. This Feature Article focuses on recent advances in the integration of virus-imprinted polymers with optical transducers, creating powerful platforms for viral diagnostics. We discuss key imprinting strategies including solid-phase synthesis, epitope imprinting, and nanogel approaches that enable precise recognition of whole viruses or their surface proteins. The optical readout mechanisms-fluorescence, resonance light scattering, colorimetric/visual detection, and surface plasmon resonance-are critically reviewed, with emphasis on signal amplification, multiplexing, and point-of-care deployment. Special attention is paid to the work of our group and others in engineering paper-based sensors, ratiometric probes, and smartphone-readable devices that detect viruses from Hepatitis A and B to SARS-CoV-2 and influenza at femtomolar or even attomolar levels. Current challenges and future directions for virus-imprinted optical sensors are discussed, highlighting the road toward commercial and clinical translation.