Chung-Ang University researchers show gold-paved path towards faster COVID-19 diagnosis

In a bid to shorten the time required for SARS-CoV-2 detection, researchers have developed a nanotechnology-based platform called “SERS-PCR” using a “gold nanoparticle-internalised 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, a statement from the Chung-Ang University notified.

The statement mentioned that a recent study has been published in Biosensors and Bioelectronics, in which researchers from Korea and China have introduced a novel nanotechnology-based platform that can shorten the time required for COVID-19 diagnosis. Their Surface-Enhanced Raman Scattering (SERS)-PCR detection platform—prepared using gold nanoparticles (AuNPs) in the cavities of Au ‘nanodimple’ substrates (AuNDSs)—can detect viral genes after only eight cycles of amplification. That is almost one-third of the number required with the conventional RT-PCR.

“Conventional RT-PCR is based on the detection of fluorescence signals, so three-to-four hours are required to detect SARS-CoV-2. This speed is not enough considering how rapidly COVID-19 spreads. We wanted to find a way to cut this time at least by half,” the statement quoted a professor as saying.

In a previous study published in 2021, the professor’s team had developed a novel detection platform in which high-sensitivity SERS signals are produced by AuNPs uniformly arranged in the cavities of AuNDSs through a technique called DNA hybridisation. Based on this previous discovery, the professor and his team developed the novel SERS-PCR platform for COVID-19 diagnosis, the statement further mentioned.

It also said that 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 eight cycles, considerably reducing the testing duration, the statement added.

“Although our results are preliminary, they provide an important proof-of-concept for the validity of SERS-PCR as a diagnostic technique. Our AuNDS-based SERS-PCR technique is a promising new molecular diagnostic platform that can considerably shorten the time required for gene detection compared to conventional RT-PCR techniques. This model can be further expanded by incorporating an automatic sampler to develop a next-generation molecular diagnostic system,” the professor explained.