Zhaoli Gao1,Ting Huang1
Department of Biomedical Engineering and Shun Hing Institute of Advanced Engineering, The Chinese University of Hong Kong1
Zhaoli Gao1,Ting Huang1
Department of Biomedical Engineering and Shun Hing Institute of Advanced Engineering, The Chinese University of Hong Kong1
Point-of-care nucleic acid testing with speed, accuracy, and precision is crucial for early detection and timely treatment of diseases. Electronic biosensors that utilize target recycling and hybridization chain reaction (TRHCR) in combination with graphene field-effect transistors (GFETs) show great promise for highly sensitive diagnostics of nucleic acid, reaching the limit of detection down to 100 aM. However, a challenge arises from its linear kinetics, which results in prolonged sensing times for lower concentration oligonucleotides, e.g., approximately 15 hours for 100 aM oligonucleotides. Here, we report a 30-fold reduction in sensing time, from 15 hours to a mere 30 minutes, for detecting 100 aM miRNA, which is achieved by developing an exponential amplification reaction pathway, synergistically compatible with GFETs. This enables the target miRNA to exponentially trigger TRHCR, leading to long-nicked double-stranded polymers that can be detected by GFET through chemical gating. Consequently, our approach facilitates the detection of 22 mer miRNA at concentrations as low as 100 aM in human serum samples, achieving a time frame congruent with point-of-care testing and superior specificity against single-base mismatched interfering oligonucleotides. Our work paves the way towards highly precise, efficient, and label-free nucleic acid testing, thus facilitating early-stage detection of cancer and other diseases at the point of care.