Electrochemical thrombin aptasensor based on using magnetic nanoparticles and porous carbon prepared by carbonization of a zinc(II)-2-methylimidazole metal-organic framework

A homogeneous electrochemical aptasensor was obtained by modifying a glassy carbon electrode (GCE) with a porous carbon nanomaterial (Z-1000, about 70 nm, deteced by transmission electron microscopic) that was obtained by carbonization of a zinc(II)-2-methylimidazole metal-organic framework. Z-1000 possesses a large specific surface and outstanding electrochemical properties. A thrombin-binding aptamer (CP) was immobilized on the magnetite nanoparticles MNPs by the condensation reaction and further combined with reporter probe (RP) that is functionalized with electroactive methylene blue (MB). In the presence of thrombin, the CP was specifically recognized with it to form the CP/MNP/Thb complex, and the RP was dissociated from MNPs. The released RP was captured by the modified GCE through pi-stacking interaction between nucleobases and carbon nanostructure. The electrical signal generated by MB can be monitored by differential pulse voltammetry (DPV). Under the optimized conditions, the DPV peak current at around -0.28 V (vs. SCE) increases with thrombin concentration. The sensor has a detection limit of 0.8 fM of thrombin and a linear range that extends from 10 fM to 100 nM. It was successfully applied to the analysis of spiked serum. The recoveries are 98.1-99.4% and RSDs are 3.9%-4.0%. Conceivably, this aptasensor scheme can be easily extended to other proteins and gives inspiration to manufacture sensitive aptasensor.