Analytical Methods Based On Platinum Nanoparticle With Peroxidase-Like Activity

In recent years,the study of nano mimetic enzyme?nanoenzyme?has aroused great interest.Compared with the native enzyme,these enzymes analogues based on nanomaterial has the advantages of low cost,convenient mass production,the adaptability to the environment,high stability,long storage time,regulable activity,large surface area,and can self assemble.It is important to further exploration of catalytic mechanism of the nanoenzymes.To design and develope more new types of nanoenzyme and expand their applications in life science,environmental science and other fields,the effect of surface modification on the functions of nanomaterials and their molecular recognition ability should be in-depth investiagted.In this paper,peroxidase-like activity of citric acid modified platinum nanoparticles and BSA-platinum nanoparticles are studied.Properties of different surface modified platinum nanoparticles are explored.Based on these two types of nanoenzymes,analytical methods for mercury ion,choline,acetylcholine,and acetylcholinesterase are design.The paper will be divided into three chapters:Chapter 1:Citrate-capped platinum nanoparticle as a smart probe for ultrasensitive mercury sensingIn this chapter,we have demonstrated that citrate-capped platinum nanoparticles can be used as a smart probe for facile mercury sensing.The peroxidase-like catalytic ability of citratecapped PtNPs can be inhibited by the in situ reduction of Hg²⁺.The high specificity of Hg-Pt interaction provides the excellent selectivity for Hg²⁺detection.The sensitivity of this probe to Hg²⁺is significant with a limit of detection?LOD?as low as 8.5 pM.In addition,the feasibility of the probe for the rapid analysis of Hg²⁺in tap water has been demonstrated with satisfactory results.These features make this probe a potentially powerful tool for the quantitative determination of mercury ions in water or other environmental samples.Chapter 2:Determination of choline and acetylcholine based on the peroxidese-like activity of bovine serum albumin-platinum nanoparticlesPlatinum nanoparticles in the scaffold of bovine serumal bumin through biomineralization are found to possess excellent peroxidase-like activity that can catalyze N-ethyl-N-?3-sulfopropyl?-3-methylaniline sodium salt?TOPS?coupled with4-amino-antipyrine?4-AAP?by the action of hydrogen peroxide to give an obvious purple product.Based on this phenomenon,acetylcholinesterase and choline oxidase are used to catalyze Ach and choline to form the active product H₂O₂ and the as-produced H₂O₂ is detected optically.Owning to the protection effect of the protein shell,BSA–PtNPs turn out to be very stable and preserve the catalytic activity in the presence of protein and even in the real plasma samples.This protein antifouling property makes the BSA–PtNPs suitable for a wide range of applications in sensors for biological samples.Choline in infant formula and Ach in plasma have been successfully detected.Chapter 3:Determination of hydrogen peroxide and acetylcholinesterase by BSA-PtNPs-TOOS-MBTH-H₂O₂ systemIn this chapter,a new type of Trinder's reagent?TOOS-MBTH?is used as clorimetric substrate to form blue purple products in the precence of hydrogen peroxide and bovine serum albumin-platinum nanoparticles.By optimizing the conditions of the chromogenic system,the detection of hydrogen peroxide has achieved.The linear range is 0.2?M⁰.03 mM,and the detection limit is 128 nM.By coupling this colorimetric system with acetylcholinesterase and choline oxidase enzyme catalysis system,the detection of the acetylcholinesterase activity can be realized.The linear detection range is 0.05-0.4 U/mL.The detection limit is 0.0048U/mL.This method has good specificity and high sensitivity,and provides a new route for the detection of cholinesterase in plasma samples.