Molecular behavior of the aptamer HJ24 self-assembled on highly oriented pyrolytic graphite (HOPG)

Abstract

Nucleic acid sensing analysis has been widely applied to the fields of food quality control, environmental monitoring, and medical diagnosis. A key step in developing effective DNA-based electrochemical biosensors is to obtain a biorecognition layer on the biosensor, which can be influenced by many factors. Hence, we constructed a series of HJ24 layers on highly oriented pyrolytic graphite to investigate the relation between the configuration of the adsorbed probe HJ24 and the redox property using atomic force microscopy and voltammetry. We used HJ24 for its diagnostic value as it specifically recognizes the SH2 domain-containing phosphatase, a critical contributor in many important signaling pathways. The results demonstrated that increasing K ions induced G-quartet oxidation peak occurrence/increase ([K+]￡400 mmol/L), and also resulted in the formation of more compact single strand sheets ([K+]￡300 mmol/L). Moreover, transitions of molecule configurations and redox currents of G-quartets were observed at low concentration [K+]=12 mmol/L, which may indicate the appearance of new configurations under this condition. Besides, by analyzing atomic force microscopy (AFM) images, it was found that the different adsorbed configurations are correlated with the HJ24 concentration, the basal configuration, and the linker group on the HJ24 sequence. This information may be useful for understanding the adsorption process of HJ24 as well as for the further development of practical applications for HJ24 films on DNA electrochemical sensors, and may ultimately help improve the diagnosis and treatment of patients with SHP2-related diseases.