Electrochemical Aptasensor Based on Multiwalled Carbon Nanotubes and Graphene for Tetracycline Detection

In this paper, an aptasensor was developed based on the multiwalled carbon nanotubes-chitosan (MWCNTs-CS) and CS-prussian blue-graphene (CS-PB-GR) nanoparticles. MWCNTs-CS combined with CS-PB-GR showed good performance in the aspect of increasing the sensitivity and stability of the electrode. The tetracycline (TET) specific 5´-amine-labeled single-stranded DNA probe (anti-TET) was immobilized on the {CS-PB-GR}2/MWCNTs-CS/glass carbon electrode (GCE) via glutaraldehyde by covalent. The remarkable electrical conductivity of PB-GR and the good biocompatibility of CS enhanced the anti-TET immobilization and facilitate electron transfer between anti-TET and electrode surface. The stepwise assembly process of the aptasensor was characterized by cyclic voltammetry and scanning electron microscope. Under the optimum operating conditions, the response of differential pulse voltammetry was used for detecting the concentrations of TET. The proposed aptasensor showed detection range from 1 × 10^-10 to 1 × 10^-3 M and limit of detection 0.56 × 10^-11 M. Furthermore, the anti-TET/ glutaraldehyde/{CS-PB-GR}₂/MWCNTs-CS/GCE aptasensor was able to detect TET in milk and recoveries were satisfactory, which indicated that it could be used as a prescanning method in TET determination for the analysis of livestock products.