The Ag+ coordination metal–organic framework under the synthetic modification strategy to construct an electrochemical sensing platform for ultrasensitive detection of glutathione

As a tripeptide molecule widely present in living organisms, glutathione (GSH) exhibits remarkable antioxidant and detoxification effects, and is involved in important physiological processes such as amino acid transport and cellular metabolism. Electrochemical detection can accurately and sensitively determine the GSH content in biological samples, which provides an important basis for early diagnosis, disease assessment and termination monitoring. In this study, ethylenediamine tetraacetic acid (EDTA) was grafted onto the framework of MOF-808 through the strategy of post-synthetic modification, which effectively increased the number of metal affinity active sites on the material. Furthermore, silver ions were abundantly and firmly chelated on MOF-808-EDTA through coordination, and an electrochemical sensing platform (MOF-808-EDTA-Ag/GCE) was successfully constructed for detecting GSH. Due to the solid-state signal amplification effect of AgCl, the current signal (I Ag ) can be significantly improved, while GSH preferred to competitive binding with Ag on the electrode surface, resulting in the extrusion effect caused by competitive coordination, thus the current signal decreased. The sensor realized the quantification of GSH through the decline level of current response, showing a satisfactory linear range (0.02 nM∼20 μM) and a low detection limit (0.013 nM). At the same time, the sensing platform has also been successfully used to measure the GSH content in human serum and urine, the recovery results (95.9 % ∼ 108.8 %) and relative standard deviation (RSD < 4.05 %) were all within the acceptable range, which exhibited an excellent practical application value.