Preparation And Peroxidase Properties Of Graphdiyne-based Nanocomposites

Peroxidase is a kind of important substance that maintains normal physiological activities of living organisms.However,most natural enzymes are proteins with high price.Under conditions of high temperature,strong acid or strong alkali,their structure is unstable and easy to be inactivated.It is difficult to prepare and extract.Based on the understanding of the structure and catalytic mechanism of natural enzymes,it is of great significance to synthesize mimic enzymes with low price and active center to replace the use of natural enzymes.Based on graphdiyne,a promising two-dimensional carbon material,this paper mainly studied three different supported peroxidase-like nanozymes which were synthesized by facile methods:graphdiyne-supported pallium-iron nanosheets(Pd Fe/GDY),graphdiyne-supported hemin nanocomposite(Hemin-GDY)and nitrogen doped graphdiyne quantum dots decorated Au Ag nanocages(N-GDQDs/Au Ag NCs)nanozymes,and then explored their catalytic properties through some different applications such as biosensor,antibacterial and degradation of organic pollutants.The main contents are as follows:1.Pd Fe/GDY nanosheet was prepared by a facile hydrothermal process,and the peroxidase-like activity of Pd Fe/GDY was evaluated by TMB-H₂O₂ as the model.The catalytic mechanism of Pd Fe/GDY nanozyme was studied by Michaelis-Menten equation,electron paramagnetic resonance(EPR)and density functional theory(DFT).The difference of catalytic activity between Pd Fe and Pd Fe/GDY was explained from thermodynamics point of view.Based on the peroxidase-like activity of Pd Fe/GDY,a visual sensor for glutathione(GSH)in biological samples was constructed.The feasibility and mechanism of Pd Fe/GDY as an antibacterial agent in wound healing were further explored.2.Hemin-GDY and Hemin-GR nanocomposits were prepared by ultrasonic method,and the catalytic activity of the two nanozymes were investigated by using TMB-H₂O₂ as the model.The enzyme-catalyzed reaction cycle path was proposed,and the reasons for the different peroxidase-like activity of the two materials were investigated from the perspectives of thermodynamics,kinetics and energy level structure.Based on the peroxidase-like activity of the two nanocomposites,two kinds of sensors for detecting dopamine were constructed and the performance differences of the two sensors were explored.The application performance of two nanozymes in the degradation of organic pollutants were also investigated by using methylene blue(MB)as a model.3.N-GDQDs/Au Ag nanocages(NCs)were synthesized through chemical reduction method and sacrificial templates method.Using TMB-H₂O₂ as the model and with or without 808 nm near-infrared irradiation as the variable,the performance of photo-enhanced peroxidase-like activity of N-GDQDs/Au Ag NCs was evaluated.The mechanism of photo-enhanced catalytic activity was explored.An in vitro bactericidal model was established to explore the feasibility and mechanism of N-GDQDs/Au Ag NCs as an antibacterial agent to inhibit bacterial growth.