Design Of Palladium-Based Nanozyme With High Activity And Its Application In Biological Analysis

In recent years,a large number of literatures have confirmed that nanomaterials can mimic a variety of natural enzymes,which called nanozymes.Nowadays,it has been found that many nanomaterials have the properties of natural enzymes,and have been widely used in many fields,such as biosensors,immunoassay,cancer treatment,environmental protection and so on.Although nanozymes have many advantages of simple preparation,low cost,adjustable catalytic activity,high stability,their low catalytic activity and selectivity and difficult recovery limit their application in clinical medicine,environment and other fields.Based on the above questions,this study aimed to improve the catalytic activity of peroxidase mimic.The application of Pd-based nanozyme in biosensor is studied by rational design,characterization and performance testing of Pd-based nanomaterials.This paper focuses on the preparation of nanozymes and their application in biological detection.The following is a brief description:1.A ready-to-use paper-based chemosensor,using mesoporous carbon-dispersed Pd nanoparticles?Pd NPs/meso-C?as a promising peroxidase mimic for the visual determination of H₂O₂ was fabricated.By simply immobilizing the Pd NPs/meso-C mimic and the TMB substrate onto common filter paper,ready-to-use paper-based sensors were further prepared.Combining these test strips with a smartphone and an easy-to-access color-scanning APP together,the integrated platform could be used for the quantitative analysis of H₂O₂ with advantages of simple operation,fast response,low cost,and good selectivity and repeatability.2.A novel naked-eye and fluorescent dual-readout glucose sensing platform based on the bifunctional peroxidase mimicking and ON-OFF fluorescence of Pd nanoparticles-decorated graphitic C₃N₄ nanosheets?PdNPs/g-C₃N₄?was reported.The PdNPs/g-C₃N₄ hybrid not only exhibited a strong peroxidase-like ability to catalyze the colorless o-phenylenediamine?OPD?into its yellow product OPDox in the presence of H₂O₂,but also acted as a turn-off fluorescent sensor for the assembly of the generated OPDox on g-C₃N₄.When coupled with glucose oxidase?GOx?,the platform was able to detect the target as low as 0.4?M in linear ranges of 1¹,000?M with fluorometer.The developed platform integrates the equipment-free merit of naked-eye observation with the excellent performance of fluorometric analysis well,providing a new andpowerful tool for accurate detection of glucose in diabetes management and other applications.3.A new and facile strategy for the high-performance colorimetric detection of Ag⁺based on the tunable peroxidase-like activity of Pd nanoparticles?NPs?mediated by histidine?His?was proposed.After modification with His,the formed His-Pd nanozyme exhibits significantly improved mimetic activity due to its physicochemical characteristics including interactions between Pd and His,and better hydrophilicity,and such that an enhanced TMB color reaction is observed.When Ag⁺is added into the system,it can despoil the His modifier from the His-Pd surface via the specific interaction between Ag⁺and His,thus resulting in the bald Pd again with weak activity.And highly sensitive determination of Ag⁺in the linear scope of 30³00 nM was achieved with a detection limit down to 4.7 nM.Besides,the colorimetric sensor could provide excellent selectivity for Ag⁺sensing.4.Pd nanoparticles modified with dodecylbenzenesulfonic acid were prepared by aqueous phase reduction method.The catalytic activity of naked palladium is very low at pH 7.The results show that Pd nanomaterials modified with benzenesulfonic acid exhibit good peroxidase activity in neutral physiological environment.Because of the similar working pH with glucose oxidase,a one-step colorimetric method was developed for glucose detection in human serum under physiological conditions?pH7.4?.The results show that the method can be used to detect glucose in human serum at physiological pH.This method has merit of simple processing steps,high selectivity and accuracy.