Label-free electrochemical aptasensor for sensitive and selective recognition of N⁶-Methyladenosine: Applicability in...

The specific and accurate detection of ultra-low levels of N⁶-methyladenosine (m⁶A) in biological samples holds great potential in the clinical diagnosis of various cancer types and neurodegenerative diseases. In this study, a cost-effective, label-free electrochemical aptasensor was developed by self-assembling a thiol-modified aptamer onto the surface of a gold electrode (AuE). Target recognition was measured by differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) using [Fe(CN)₆]^3-/^4- redox probe. The biosensor demonstrated superior selectivity for m⁶A determination in diluted artificial human urine samples, effectively distinguishing it from structurally related nucleosides and endogenous electroactive compounds. Under optimized conditions, the 6-mercapto-1-hexanol (MCH)-blocked electrode gave a limit of detection (LOD) in urine of 0.510 pM over a linear range of 3.2 pM - 10 nM by DPV and 0.700 pM over the same range by EIS. For the MCH/Apt/AuE platform, recovery values of 95.70% by DPV and 96.20% by EIS were obtained in 1:25 diluted artificial human urine, with corresponding relative standard deviations (RSD) of 2.65% and 2.50%. These results confirm the satisfactory accuracy and reproducibility of the developed aptasensor in this matrix. Consequently, the proposed aptasensor has the potential to serve as a non-invasive diagnostic platform that enhances patient comfort in the early diagnosis, treatment, and monitoring of cancer and neurodegenerative diseases, offering a strong alternative to invasive biopsy procedures.