Detection of malachite green by electrochemical sensor constructed from modified high-affinity aptamer

A high-affinity aptamer was developed using a molecular docking approach, leading to the establishment of an electrochemical aptamer biosensor for the detection of malachite green (MG). The aptamer designated as MG-15 was derived from a rational truncation of MG-36, yielding a dissociation constant (K_d) of 45.4 $\pm$ 17.6 μM. Further enhancements were achieved by completely mutating the binding site of MG-15, resulting in a higher affinity aptamer (MG-15-GGT) with a lower K_d of 2.71 $\pm$ 1.95 μM. This sensor exhibited a limit of detection (LOD) value of 2.74 pM and demonstrated excellent specificity, with recoveries ranging from 87.1 to 111.5%. Consequently, electrochemical biosensors utilizing modified aptamers hold great promise for applications in food safety.