The new coronavirus is extremely contagious and spreads rapidly around the world, The number of confirmed cases of COVID-19 in the world has exceeded 2 million, and the epidemic situation in foreign countries is very serious. Virus detection is the key to the prevention and treatment of  COVID-19.

Novel coronavirus detection methods include novel coronavirus pneumonia (RT-PCR) and antibody detection. Nucleic acid detection is directly used to detect virus nucleic acids in samples collected, with high specificity and sensitivity. Antibody detection is the detection of antibody levels in human blood, including colloidal gold method and magnetic particle chemiluminescence method. The average detection time of colloidal gold method is about 15 minutes. It has the characteristics of simple and fast operation. Antibody testing is used to assist in the diagnosis of cases with negative nucleic acid tests, and can also be used for screening and screening of cases.

Because nucleic acid testing has false positive and false negative problems, and antibody testing has a window period, under the situation of rapid spread of the global epidemic, nucleic acid testing alone cannot meet the testing needs. So scientists are committed to developing faster and more accurate detection methods.

Researchers from several research institutions in Switzerland have developed a dual-functional plasmonic biosensor combining the plasmonic photothermal (PPT) effect and localized surface plasmon resonance (LSPR) sensing transduction provides an alternative and promising solution for the clinical COVID-19 diagnosis.

The two-dimensional gold nanoislands (AuNIs) functionalized with complementary DNA receptors can perform a sensitive detection of the selected sequences from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) through nucleic acid hybridization. For better sensing performance, the thermoplasmonic heat is generated on the same AuNIs chip when illuminated at their plasmonic resonance frequency. The localized PPT heat is capable to elevate the in situ hybridization temperature and facilitate the accurate discrimination of two similar gene sequences.

The dual-functional LSPR biosensor exhibits a high sensitivity toward the selected SARS-CoV-2 sequences with a lower detection limit down to the concentration of 0.22 pM and allows precise detection of the specific target in a multigene mixture.

In summary, nucleic acid detection is still the mainstream method for the diagnosis of new coronary pneumonia. The new method developed by Swiss scientists may help relieve the current pressure on nucleic acid detection.

References:

Guangyu Qiu et al. Dual-Functional Plasmonic Photothermal Biosensors for Highly Accurate Severe Acute Respiratory Syndrome Coronavirus 2 Detection. ACS Nano, Publication Date:13 April 2020, doi:10.1021/acsnano.0c02439.

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