Peroxidase-like Platinum-based Nanozyme For Colorimetric Sensing Of Biological Antioxidants

With the rapid development of nanotechnology,a variety of nano-catalytic materials have been emerged.Among them,nanozymes have attracted the attention of many researchers due to their advantages of good stability,adjustable catalytic activity,easy to store,and low cost.Especially in the field of biosensing,nanozymes are widely used.Platinum（Pt）nanozymes stand out due to their high stability,controllable morphology and excellent catalytic activity.By using surface modification,element doping and other methods.Pt nanozymes can be imaged in a variety of morphologies to fully expose their active sites and exhibit enhanced Peroxidase POD-like activity.The excellent POD-like enzyme activity of Pt nanozymes can be used to construct highly sensitive colorimetric sensors and realize rapid and highly sensitive detection of biomolecules.In this project,we synthesized three Pt nanozymes using a simple hydrothermal method,and investigated the effects of the doping of different elements（Nickel（Ni）and Ruthenium（Ru））on the morphology and POD-like activity of Pt nanozymes.In this study,Tetramethylbenzidine（TMB）and hydrogen peroxide（H₂O₂）were used as colorimetric detection solutions to explore the effect of different element doping on the activity of POD enzyme of Pt nanoenzymes.Based on the excellent POD-like activity of Pt nanoenzymes,we constructed colorimetric sensors based on different Pt nanoenzymes,Ascorbic acid（AA）and Glutathione（GSH）were used as model molecules,to explore the feasibility of Pt nanoenzyme colorimetric sensing to detect the antioxidant capacity of biological small molecules.Firstly,we constructed the Pt Te Ni-TMB-H₂O₂colorimetric sensor,and the inoxidizability of AA that can inhibit the Pt Te Ni-TMB-H₂O₂color reaction was used to realize rapid and highly sensitive analysis of AA.The colorimetric sensor showed a good linear relationship in the range of AA concentration from 5μM to 500μM,and the detection limit was 2.94μM.with interfering substances（amino acids,metal ions,etc）in the presence of this sensor,a highly selective analysis of AA can be achieved.More importantly,the sensor also achieved consistent results with the commercial total antioxidant capacity detection kit in the detection of AA content in real samples（commercially available beverages and vitamin C tablets）.Secondly,we constructed a Pt Ru Te-TMB-H₂O₂colorimetric sensing system for highly sensitive analysis of GSH.The Pt Ru Te-TMB-H₂O₂colorimetric sensor successfully achieved a good linear analysis of GSH concentration in the range of 10μM to 300μM,and the detection limit was as low to 5.52μM.In addition,due to the prevention of oxidative stress in tumor cells,the intracellular GSH concentration show a significant high expression phenomenon.The detection results of GSH in tumor cells were significantly higher than that in normal cells,The results were comparable to the commercial GSH detection kit.It can be seen that the POD-like activity of Pt nanozymes can be improved to a certain extent through the doping of elements,and the colorimetric sensing strategy based on Pt nanozymes has strong feasibility and reliability in the analysis and detection of the antioxidant capacity of biological small molecules.Although this paper only explored the effect of Ni and Ru doping on the POD enzyme activity of Pt nanoenzymes,we will continue to follow up this aspect and further explore the sensing application of Pt nanoenzymes in the future work.