Electrochemical detection of matrix metalloproteinase-7 using an immunoassay on a methylene blue/2D MoS2/graphene oxide electrode

Methylene blue (MB) adsorption onto a two-dimensional molybdenum disulfide (2D MoS2)/graphene oxide (GO) nanocomposite sitting on a screen-printed carbon electrode (SPCE) is used to develop a new sensitive label-free electrochemical immunosensor for the detection of matrix metalloproteinase-7 (MMP-7) cancer biomarkers. The 2D MoS2/GO nanocomposite deposited onto an SPCE provides a large specific surface area, fast electron transfer, and exceptional electrical conductivity. Furthermore, MB adsorbed onto the 2D MoS2/GO nanocomposite architecture can be used for signal amplification in electrochemical immunosensors. Moreover, an immunosensor platform was fabricated by the adsorption of anti-MMP-7 capture antibodies onto the MB/2D MoS2/GO nanocomposite surface via electrostatic interactions for the detection of the MMP-7 immunocomplex. Under optimum conditions, the label-free immunosensor exhibits a decrease in the current response for MB corresponding to the MMP-7 concentration. The sensor affords a linear logarithmic range of 0.010-75 ng mL-1 with a limit of detection (LOD) of 0.007 ng mL-1. The developed electrochemical immunosensor provides high selectivity, good reproducibility, and excellent stability. Furthermore, the proposed immunosensor can be applied for the detection of MMP-7 in human serum samples with good recovery. Thus, this device can be applied for the early clinical diagnosis of pancreatic and colorectal cancers.