Nanomaterial testing breakthroughs set to boost pandemic resilience



The ongoing outbreak of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic has posed significant challenges in early viral diagnosis. Hence, it is urgently desirable to develop a rapid, inexpensive, and sensitive method to aid point-of-care SARS-CoV-2 detection. In this work, we report a highly sequence-specific biosensor based on nanocomposites with aggregation-induced emission luminogens (AIEgen)-labeled oligonucleotide probes on graphene oxide nanosheets (AIEgen@GO) for one step-detection of SARS-CoV-2-specific nucleic acid sequences (Orf1ab or N genes). A dual “turn-on” mechanism based on AIEgen@GO was established for viral nucleic acids detection. Here, the first-stage fluorescence recovery was due to dissociation of the AIEgen from GO surface in the presence of target viral nucleic acid, and the second-stage enhancement of AIE-based fluorescent signal was due to the formation of a nucleic acid duplex to restrict the intramolecular rotation of the AIEgen. Furthermore, the feasibility of our platform for diagnostic application was demonstrated by detecting SARS-CoV-2 virus plasmids containing both Orf1ab and N genes with rapid detection around 1 h and good sensitivity at pM level without amplification. Our platform shows great promise in assisting the initial rapid detection of the SARS-CoV-2 nucleic acid sequence before utilizing quantitative reverse transcription-polymerase chain reaction for second confirmation.

Period6 Apr 2023

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Media coverage

  • TitleNanomaterial testing breakthroughs set to boost pandemic resilience
    Degree of recognitionLocal
    Media name/outletPolyU Vibrant@FENG eNewsletter Issue 4
    Media typeWeb
    Country/TerritoryHong Kong
    DescriptionHumanity had a lucky escape with COVID-19 — a more deadly microbe, like a mutated Ebola, Avian influenza, Marburg, or MERS-CoV virus, all potential causes of the next pandemic, could have produced a far higher death toll.

    But given recent advances like messenger RNA (mRNA) vaccines, and the development of nanomaterial-based optical techniques to speedily detect SARS-CoV-2 at an early stage by PolyU’s Professor Mo YANG, Associate Head and Professor of Biomedical Engineering, and Dr Siu Hong Dexter WONG, Research Assistant Professor of Biomedical Engineering, the world is better prepared to tackle future infectious threats.

    Testing times
    Yang and Wong’s work on advanced biosensors, completed over a year during the COVID-19 pandemic, applies nanomaterials to nucleic acid detection, and promises to improve upon the performance of today’s testing gold standard, the polymerase chain reaction (PCR) method.

    “PCR tests for COVID-19 usually require very complex handling processes in terms of the RNA harvesting, which involves laboratory work of four to six hours,” says WONG. “Our solutions’ greatest advantages are they have fewer steps, reducing the wait to around one hour, and lowering the risk of false positive signals. Also, they can detect the level of infection.”

    Testing is a vital tool for managing pandemics as it enables the identification of infected individuals and helps prevent the pathogen’s spread. It provides information for public health officials to determine the outbreak’s extent and make informed decisions on how to prioritize resources.

    Also, quickly identifying individuals who have been in close contact with an infected person and providing them with the appropriate care can limit the severity and spread.

    Conventional nucleic acid detection techniques like PCR often require Förster resonant energy transfer (FRET), which relies on the transfer of energy from a donor (fluorophore) to an acceptor (quencher). However, high background signals can lower the sensitivity of these techniques.

    Yang and Wong’s AIEgen/graphene oxide nanocomposite (AIEgen@GO)-based two-stage “turn-on” nucleic acid biosensor for the rapid detection of SARS-CoV-2 viral sequence deploys graphene oxide nanosheets to reduce background signals, thereby increasing sensitivity. When the AIEgen@GO meets target viral sequences, the AIEgen detaches from GO for the fluorescent recovery and is lighted up to achieve a dual-on mechanism to maximize the detection sensitivity.

    "We want to decrease the background by applying these nanomaterials to raise sensitivity,” says WONG. "The overall improvement of these technologies is better capacity in terms of sensitivity.”

    A key challenge in creating the platform was determining the best ratio between the graphene and the agent, which took several months to overcome. The result is a platform that “can be modified to detect any type of nucleic acid,” adds WONG.

    PersonsSiu Hong Wong, Mo Yang