Triblock polyA probe-engineered solution-gated graphene transistor for high-performance amplification-free and label-free DNA detection

Triblock polyA probe enables amplification-free, label-free SGGT sensing; • Interfacial engineering optimizes probe configuration, buffer, polyA length; • LoD for synthetic L. monocytogenes DNA reaches 2.1 × 10 −17  M; • Contaminated milk samples are detected with LoD of 10 3  CFU/mL; • The sensor shows good selectivity against other foodborne pathogens. The strong signal amplification capability of solution-gated graphene transistors (SGGT) provides a promising basis for highly sensitive biosensing. However, further improvement in sensitivity is often hindered by the molecular recognition interface on the functionalized sensing electrode. In this study, an amplification-free and label-free SGGT DNA biosensor was developed by using a triblock polyadenine (polyA) DNA probe. The sensor interface was systematically optimized by capture-probe configuration, buffer composition and polyA length. Using Listeria monocytogenes ( L. monocytogenes ) as a model target, the sensor achieved limits of detection (LoD) of 2.1 × 10 −17  M for synthetic DNA fragments and 10 3  CFU/mL for L . monocytogenes in contaminated milk samples. These results demonstrate the high sensitivity and good target distinguishability in mixed samples of the sensor, addressing key limitations of conventional methods. The established sensor platform offers a new approach for achieving high-sensitivity DNA detection, with potential applications in pathogen monitoring, food safety, and molecular diagnostics. Download: Download high-res image (176KB) Download: Download full-size image