A hemin/rGO/MWCNT nanocomposite-based dual signal electrochemical aptasensor for sensitive detection of NSE†

Neuron-specific enolase (NSE), a tumor marker of small cell lung cancer (SCLC), has high application value in the early diagnosis of SCLC. In this study, a dual signal electrochemical aptasensor for NSE was constructed based on hemin/reduced graphene oxide/multi-walled carbon nanotube (H–rGO–MWCNT) nanocomposites. Hemin played a dual role, functioning not only as an in situ electrochemical probe but also exhibiting excellent peroxidase-like properties, effectively catalyzing the electroreduction of H₂O₂. Reduced graphene oxide and multi-walled carbon nanotubes exhibited excellent conductivity. Through their binding with hemin, the nanocomposites achieved a larger specific surface area, providing numerous active sites for capturing the NSE aptamer. In the presence of NSE, the specific adsorption between the antigen and the aptamer formed a stable antigen–aptamer structure, which inhibited the performance of hemin, resulting in the weakening of the electrochemical signals of hemin and H₂O₂. Leveraging these characteristics, the sensitive and cost-effective dual-signal electrochemical aptasensor has been fabricated for the detection of NSE. One signal corresponded to differential pulse voltammetry (DPV) of hemin, while the other signal was derived from chronoamperometry, capturing the catalytic reduction of H₂O₂. The linear ranges for NSE were 1 pg mL⁻¹ to 1 μg mL⁻¹ and 100 pg mL⁻¹ to 100 ng mL⁻¹ with the limit of detection (LOD) of 0.21 pg mL⁻¹ and 11.22 pg mL⁻¹ by DPV and chronoamperometry, respectively. In addition, this aptasensor exhibited good reproducibility, stability and specificity. The recovery of NSE in human blood serum samples was from 89% to 131%. It provided a promising strategy for the detection of NSE in clinical diagnostics.