Aromatic Ring–Mediated Nonspecific Signaling Mechanism and Nafion-Dominated Solution in Graphene Field-Effect Transistor–Based Nucleic Acid Biosensors

Graphene field-effect transistors (G-FETs) have attracted widespread attention in disease diagnosis, benefiting from these advantages of high sensitivity, label-free, easy integration, and direct detection of nucleic acids (NAs) in liquid environments. However, the problem of nonspecific signals in G-FETs is not fundamentally solved due to a lack of systematic theoretical research to support the development of effective solutions. Thus, researchers have to rely on speculative mechanisms to minimize nonspecific signals in experiments as much as possible. Herein, the nonspecific signal mechanism caused by eight types of π – π interaction paths mediated by aromatic rings is theoretically determined. Based on theoretical simulation results, the feasibility of blocking nonspecific signal paths through Nafion functionalization methods is experimentally verified. Experiments confirm that Nafion-modified G-FETs (NMG-FETs) have excellent performance in avoiding nonspecific signals compared to traditional G-FETs. Furthermore, the NMG-FET achieves ultra-sensitive detection of Down syndrome–related DNA down to 1 aM and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA down to 5 aM, and shows good specificity in base recognition. This study is expected to promote the theoretical advancement of the nonspecific signal mechanism in G-FET NA detection and offer a practical strategy for improving signal purity and accuracy.