CuSeO@f-CNFs: A superoxide nanozyme for the selective nanomolar determination of the key cardiovascular biomarker, Glutathione.

Nanocomposites that mimic the characteristics of enzymes, commonly as nanozymes, can function as an efficient sensing material with high selectivity towards the targeted biological macromolecule. These nanozymes overcome of the challenges that arise when using natural enzymes as sensing material. This study presents a novel nanozyme, Copper Selenite (CuSeO) nanoparticles mounted on f-CNF, to electrochemically determine a potential cardiovascular biomarker, Glutathione (GSH). The choice of this material is due to the well-known ability of GSH to form a complex with copper. When a Cu ion enters a healthy cell, it quickly forms a complex with GSH, which then moves to another storage molecule: either a metalloprotein or a chelator. CNF was functionalized using acid to generate functionalized-CNF to enhance biocompatibility and boost conductivity. This was done to provide many active sites for effective integration of CuSeO in the nanocomposite preparation. The glassy carbon electrode (GCE) surface was enhanced by introducing CuSeO@f-CNF nanocomposite, resulting in a significant increase in the current response for GSH in comparison to prior research. CuSeO@f-CNF/GCE sensor has shown excellent sensing properties, like enhanced stability, selectivity, sensitivity, and reproducibility, for detecting and quantifying GSH. The sensor demonstrated an extensive linear detection range from 62.5 nM to 7785.0 μM, signifying one of the most comprehensive ranges documented to date. It attained a remarkable detection limit (LOD) of 17.6 nM. The sensor's performance was further tested by analyzing genuine biological fluid samples. The nanozyme-modified GCE demonstrated exceptional electrocatalytic efficiency for GSH detection, making it extremely appropriate for real-time monitoring applications.