The new SERS-PCR technique could enable more rapid COVID-19 diagnosis, which will help in curtailing the spread of the disease. (Credit: Chung-Ang University)

Researchers are using gold nanoparticles to develop a new molecular diagnostic platform that considerably reduces the time required for COVID-19 detection. The RT-PCR test, the current diagnostic standard for COVID-19, is considerably time-consuming.

To shorten the time required for SARS-CoV-2 detection, researchers have developed a nanotechnology-based platform called “SERS-PCR” using a “gold nanoparticle-internalized nanodimple” substrate. This new molecular diagnostic platform reduces the number of PCR cycles required to amplify and detect viral genes as compared to conventional RT-PCR, allowing more rapid diagnosis and helping in the mitigation of COVID-19 transmission.

The newly developed SERS-PCR assay uses SERS signals to detect “bridge DNA” — small DNA probes that slowly break down in the presence of target viral genes. Therefore, in samples from patients positive for COVID-19, the concentration of bridge DNA (and therefore the SERS signal) continuously decreases with progressive PCR cycles. In contrast, when SARS-CoV-2 is not present in the sample, the concentration of bridge DNA and the resultant SERS signal remain unchanged. In this way, SARS-CoV-2 can be rapidly detected in patient samples.

The team tested the effectiveness of their system using two representative target markers of SARS-CoV-2, namely, the envelope protein (E) and RNA-dependent RNA polymerase (RdRp) genes of SARS-CoV-2. While 25 cycles were required for RT-PCR-based detection, the AuNDS-based SERS-PCR platform required only 8 cycles, considerably reducing the testing duration.