Precise Variant Screening Of SARS-CoV-2 Via 2D InSe Field-effect Transistor

Currently,emerging SARS-CoV-2 variants of concern represented by Delta reveal hyper transmissibility and pathogenicity.Rapid and accurate SARS-CoV-2 detection and mutation typing are eagerly expected and pivotal to epidemic prevention.Compared with the quantitative reverse transcriptase polymerase chain reaction（RT-q PCR）detection method,field-effect transistor（FET）biosensor owns the merits of ultra-sensitivity and fast detection.However,its ability of critical intra-molecular accurate sensing,especially to mutation information of single nucleotide,still needs to be substantially improved.Herein,using the two-step Al₂O₃ process,we design an ultrasensitive In O_x/InSe sensing interface with trap states in ultrathin-InSe FET through shallow oxygen substitution,in which carriers transport through trapping,hopping and detrapping.The carrier-transport behavior is spatially proximate to the channel sensing interface and is energetically sensitive to precise varies of Fermi energy caused by the nucleic acid’s negative potential.We first test the basic electrical performance and stability of the trap states-enhanced FET（ts FET）,and verify the feasibility of our FET as the biosensor transducer.Moreover,our ts FET biosensor exhibits a wide detection range(10^-14～10^-8M)and the sub-f M limit of detection（LOD）for DNA and RNA,with the detection time of 10～15 min.More importantly,such ts FET can thus detect the dynamic changes of hybridization once nucleic acids have mutations.Target mutant sequences with mismatched types or positions can be recognized and significantly distinguished from complementary or noncomplementary sequences,finally making InSe-based ts FETs enable to identify single-nucleotide variations.The ability to recognize the mismatch type and location of nucleotide variants enabled our sensor to successfully identify core variants of specific Delta variants.The sensing results are highly consistent with the high-resolution melting（HRM）analysis that reflects the thermodynamic stability of the duplex structure,verifying the reliability of sensing signals.Our strategy realizes the all-in-one sensing for virus detection and mutation diagnosis,provides better early screening and warning for SARS-CoV-2 variants or other highly infectious and mutable viruses in the post-epidemic era.