A self-calibration electrochemical sensor for ultrasensitive detection of glutathione based on metal–organic framework-derived Cu nanoparticles/nitrogen-doped porous carbon composites

Glutathione (GSH) is considered to be one of the main factors in maintaining redox homeostasis in living organisms, and alterations in GSH levels are closely associated with many diseases. In this paper, polyvinylpyrrolidone (PVP)-doped copper metal–organic backbone (N-Cu-MOF) was synthesized and N-Cu-MOF was pyrolyzed to produce nano-copper modified nitrogen porous carbon materials (CuNPs@NPC). The CuNPs@NPC modified electrode showed an increased oxidation current due to the presence of CuCl solid-state electrochemistry signal amplification strategy. With the addition of GSH, CuCl was gradually converted to Cu-GSH as a non-electrically active material, which triggered an "extrusion effect" and resulted in a decreased peak current. Meanwhile, the peak current of the internal reference ratio (acetaminophen, APAP), which was added to the electrolyte solution, was almost unchanged. Using the ratio of the peak current variation (ΔICu/IAPAP) as the output signal, the CuNPs@NPC modified electrode achieved an ultra-sensitive detection of GSH in the range of 0.1 nM–10 μM. The detection limit was as low as 0.067 nM. In the detection of human cervical cancer cell lysate, the sensor has high accuracy and selectivity for GSH, which can bring enlightenment for the early diagnosis of clinical diseases.