A dual-functional localized surface plasmon resonance (LSPR) biosensor combining a photothermal effect in concert with plasmonic sensing transduction shows promise as the basis for accurate real-time detection of SARS-CoV-2 viral nucleic acid, according to Swiss and Chinese researchers. However, as to actually employing the proposed biosensor in situations such as monitoring air in public spaces, Dr. Jing Wang said in a statement that "This still needs development work." Nevertheless, say the investigators "Biosensors are ideal for providing an alternative and reliable solution to clinical diagnosis, real-time detection, and continuous monitoring." In an online paper in ACS Nano, Dr. Wang of the Swiss Federal Laboratories for Materials Science and Technology, Dubendorf, and colleagues observe that "LSPR is a strong photon-driven coherent oscillation of the surface conduction electrons, which can be modulated when coupling occurs at the surface of the plasmonic material." Compared to routinely used reverse transcription polymerase chain reaction (RT-PCR), the LSPR technique for genetic testing and nucleic acid detection in clinical practices, they go on to say, "could be an interesting alternative for SARS-CoV-2 detection and COVID-19 diagnosis." The sensor the researchers developed is based on gold nanoislands (AuNIs) on a glass substrate. Grafted onto the AuNIs are artificially produced DNA receptors that match specific RNA sequences of the SARS-CoV-2 via nucleic acid hybridization. "For better sensing performance," say the investigators, "the thermoplasmonic heat is generated on the same (nanoabsorbers, or AuNIs) chip when illuminated at their plasmonic resonance frequency." Following initial testing, the team validated the dual-functional LSPR sensing system by selective hybridization detection of several different genome sequences from both SARS-CoV-2 and SARS-CoV. "Tests showed that the sensor can clearly distinguish between the very similar RNA sequences of the two viruses," Dr Wang further stated. And the results are ready in a matter of minutes. "Current RT-PCR-based detection methods," say the investigators, demand high manpower and long processing time, which may not be able to provide the capacity to test all the suspected cases during full-scale outbreaks." In light of these findings the researchers conclude that "this proposed dual-functional LSPR biosensor can provide a reliable and easy-to-implement diagnosis platform to improve the diagnostic accuracy in clinical tests and relieve the pressure on PCR-based tests." —David Douglas Source
