Differential identification of GSH for acute coronary syndrome using a colorimetric sensor based on nanoflower-like artificial nanozymes

Abstract

The ability to detect glutathione (GSH) concentrations in human blood offered a simple and non-invasive method to monitor changes associated with cardiovascular diseases, cancers and diabetes. We showed the potential of employing catalytically active protein-directed nanoflower-like artificial nanozymes (apo-TF-MnO_x NFs) by bio-mineralization method to produce simple and visible colorimetric sensor for GSH. The experiments proved that apo-TF-MnO_x NFs exhibited peroxidase, catalase- and superoxide dismutase-like activities, but the most notable feature was the excellent peroxidase-like activity, which could efficiently catalyze the oxidation reaction of 3,3',5,5'- tetramethylbenzidine (TMB) in the existence of hydrogen peroxide (H₂O₂) to generate a blue product. Some outcomes also indicated that the apo-TF-MnO_x NFs had stronger peroxidase-like activity, which was proved by the Michaelis-Menten constant (K_m) and maximum initial velocity (V_max). Hence, we used the peroxidase-like activity to develop a GSH colorimetric biosensor. Fortunately, the colorimetric platform exhibited a sensitive response to H₂O₂ and GSH in the range of 5 μМ to 300 μМ and 0.5 μМ to 35 μМ with a limit of detection of 3.29 μM and 0.15 μM (S/N = 3) under optimal conditions. The feasibility of the simple method was confirmed by qualitative detection of H₂O₂ and GSH in blood samples from acute coronary syndrome patients. A key outcome of our study was the ability to realized differential identification of GSH for acute coronary syndrome and healthy human without invasive treatment which was an advantage over other methods. This work not only proposed a new type of nanozymes, but also showed the multiple advantages of the apo-TF-MnO_x NFs for the construction of biosensors. Thus, we believe that apo-TF-MnO_x NFs with strong peroxidase-like activity can be employed as nanozymes and be widely applied in the fields of medicine and biological sensors.

Keywords: Colorimetric sensor; GSH; Nanozymes; Peroxidase.