Preparation Of Pd-based Nanozymes And Their Application In Bioanalysis

The stable structure and physicochemical properties of nanozymes make them superior to natural enzymes with high stability,easy expansion and low cost.In addition,the catalytic activity of nanozymes can be adjusted according to the actual needs.However,the low utilization of nanozyme atoms,unclear catalytic active sites and poor catalytic activity greatly limit its practical application.Therefore,in order to improve the catalytic activity of Pd-based nanozymes,three Pd-based nanozymes with high enzyme-like activity were synthesized from the perspective of bimetallic synergistic effect,specific surface area and surface lattice stress based on palladium-based nano-materials.The characterization test and performance analysis were carried out,and it was successfully applied in biosensor colorimetric analysis.The main research contents are as follows:（1）.Pd-Pt icosahedra as highly active peroxidase-like mimics in bioanalysis:firstly,from the perspectives of bimetallic synergistic effect,we have successfully synthesized Pd-Pt icosahedron with transverse size of about 30 nm by one-step wet chemistry.Enzyme catalytic reaction shows that Pd-Pt icosahedra H₂O₂ V_max was 2.219×10^-7 M s^-1,TMB V_max was 1.713×10^-7 M s^-1.Compared with the single Pd icosahedra,Pd-Pt icosahedra has higher peroxidase-like activity in catalytic oxidation of 3,3’5,5’-tetramethylbenzidine（TMB）.On this basis,we successfully applied Pd-Pt icosahedra nanozymes in bioanalysis and successively detected H₂O₂,glucose,glutathione,alkaline phosphatase（ALP）,acid phosphatase（ACP）and other biomolecules.However,although the bimetallic synergistic effect of the Pd-Pt icosahedra improves the catalytic activity of the nanozymes,the three-dimensional structure still has low atomic utilization.Therefore,methods are still needed to improve the atomic utilization of Pd-based nanozymes.（2）.Pd metallene as highly active oxidase-like mimics in bioanalysis:aiming at the problem of low utilization of Pd-Pt icosahedra atoms,an ultra-thin,porous and highly curved two-dimensional ultra-thin nanosheet structure,Pd metallene,was synthesized by a simple one-step wet chemical method.Pd metallene exhibited excellent oxidase-like activity with a V_max of 1.66×10^-7 M s^-1.Performance analysis showed that Pd metallene catalysis of TMB V_max was 1.66×10^-7 M s^-1,exhibiting excellent oxidase-like activity.On this basis,Pd metallene nanozymes have been successfully used in several bioanalysis,including total antioxidant capacity（TAC）of beverages and vitamin C tablets and ALP activity.This work not only provides a new type of nanozymes,but also provides an effective strategy for maximizing the utilization of nanozymes atoms.（3）.N-inserted Pd N9.64 metallene with enhanced oxidase-like activity in bioanalysis:on the basis of the ultrathin two-dimensional nanostructures of Pd metallene,the crystal expansion of Pd metallene was induced by the intercalation of Nitrogen atoms by hydrothermal synthesis method,which resulted in the increase of crystal stress on the surface of Pd metallene.The enzyme catalyzed reaction showed that the oxidase-like activity of Pd N metallene was enhanced with the increase of Nitrogen content,and the catalytic activity of Pd N_9.64 metallene was the strongest.The V_max of TMB oxidation catalyzed by Pd N_9.64metallene was 2.86×10^-7 M s^-1,which was much higher than that catalyzed by Pd metallene.Based on the high oxidase-like activity of Pd N_9.64 metallene nanozymes,ACP activity was successfully detected.The results show that the increase of surface lattice stress can effectively enhance the catalytic activity of the material.