In today's new crown pneumonia epidemic, in order to be able to travel normally, nucleic acid testing has become a common thing. At present, the nucleic acid detection of the new crown virus is mainly based on nasopharyngeal swabs, using fluorescence quantitative PCR, that is, polymerase chain reaction (PCR) technology, and the detection time is usually 2-24 hours.
Photo credit: Zhejiang Provincial People's Government
The growing demand for travel and the ongoing epidemic situation, which is not a short testing time, have put the nucleic acid test of the new crown virus under considerable pressure. Therefore, in the case of ensuring the accuracy of the results, it is necessary to make the detection more rapid.
Recently, the research team of Liu Yunxi and Wei Dacheng of Fudan University published a study in the journal Nature Biomedical Engineering (a sub-journal of Nature Biomedical Engineering). The new crown detection equipment and method developed can obtain nucleic acid test results within 5 minutes with higher accuracy.
In the current common polymerase chain reaction (PCR) detection method, the nucleic acid (RNA) of the new coronavirus needs to be reverse-transcribed into DNA, so in nucleic acid detection, if the virus concentration is too low, it will affect the accuracy of the test results.
Image from: People's Daily News
In an article published by the fudan university research team, it is mentioned that microelectromechanical systems (MEMS) are highly integrated, small, inexpensive and efficient, and have the feasibility of commercialization. But MEMS, NEMS, and FET-based biosensors struggle to maintain sensitivity in some cases.
Therefore, the research team of Fudan University developed a transistor sensing chip based on MolEMS (Molecular Electromechanical System). The MolEMS (Molecular Electromechanical System) proposed by them is a miniature device that is self-assembled by DNA molecules and driven by an external electric field to accurately regulate the process of molecular recognition and signal transformation.
MolEMS and MolEMS g-FET, Image courtesy of Nature Biomedical Engineering
In practice, most biosensors cannot achieve ultra-high sensitivity in biological fluids. The unique structure of MolEMS enables ultra-precise bioassays, enabling efficient biometrics and signal transduction for ultra-high sensitivity.
The findings also mention that SARS-CoV-2 (novel coronavirus) RNA has approximately 30,000 nucleotides, and that measuring clinical samples has higher biological complexity, patient-to-patient differences, and uncertainties in sample collection and preparation procedures.
MolEMS detects nucleic acid samples without the need for complex and time-consuming nucleic acid extraction and amplification processes, and can directly detect SARS-CoV-2 RNA in nasopharyngeal swab samples. The time to diagnose COVID-19 is approximately 0.1-4 minutes, with an average of 60 seconds.
The researchers used MolEMS g-FET to assemble the COVID-19 test system for both on-site and bedside testing. The test system consists of two parts: the MolEMS g-FET integrated test module and the main system. To avoid cross-interference between different samples, a module is used to test one sample.
SARS-CoV-2 nucleic acid testing, image courtesy of Nature Biomedical Engineering
Simply replace the MolEMS test module and reuse the main system for multiple tests. The operation of the system is divided into three steps: the first step is to connect the test module to the main system, and connect the computer or smartphone to the test system via USB, Wifi or Bluetooth. The second step is to open the seal covering the test module PDMS well. The third step is to add the test sample to the PDMS well and read the results from a computer or smartphone.
In terms of findings, compared to MEMS and NEMS, MolEMS reduces cost, volume and weight, and allows for molecular-level manipulation. And the operation is simple, the sensitivity and specificity are high and portable. The probability of false negatives and false positives is extremely low and faster than PCR detection.
Ultra-sensitive biological detection and long-term stability, courtesy of Nature Biomedical Engineering
With the further development of portable systems, it can be used to perform on-site and bedside testing at airports, clinics and local emergency departments, even at home. It helps to improve the efficiency of nucleic acid detection and slow the spread of the virus.
It is worth mentioning that the development of MolEMS can also achieve ultra-precise diagnosis of other diseases in minutes without the goal of purification, amplification or culture, which typically takes hours or days. In addition to biosensing, the design principles of MolEMS can be used to design other higher precision electromechanical devices and functional systems.
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