Preparation And Visual Detection Of Porphyrin Composite Nano-materials And Two-dimensional MoS₂ Nano-analog Enzymes

Nanomaterials have small size,similar to the length of electronic coherence,and excellent properties in magnetic,optical,electrical and thermal conductivity.As one of nanomaterials,artificial enzymes inherit the advantages of natural enzymes and compensate for the high cost and poor stability of natural enzymes.Therefore,the design of an efficient,stable and low-cost artificial enzyme has become a research hotspot.Fluorescent molecular probes have the advantages of high sensitivity,low cost,simple operation and fast response,and the research and development of chemical sensors with practical value,high sensitivity and good selectivity have become the focus of research in recent years.Currently,many different types of fluorescent nanomaterials and porphyrins fluorescent probes have been prepared by researchers,but few reports have been reported on the fluorescence probes of water-soluble porphyrins modified nanomaterials.In this paper,two kinds of porphyrin composite nano-materials and one kind of two-dimensional MoS₂ nano-materials were designed and prepared,and their properties were studied.The main research contents are as follows:（1）In the first part,the peroxide analog enzyme activity of TPPFe（Ⅲ）-GNR@Au₂S/AuAgS nanocomposites induced by local surface plasmon resonance（LSPR）was enhanced for visualized analysis.Water-soluble 5,10,15,20-tetraphosphite（4-phosphite）iron（Ⅲ）porphyrin（TPPFe（Ⅲ））was successfully synthesized by phosphite modification.The water-soluble TPPFe（Ⅲ）and core-shell gold nanorods（GNR@Au₂S/AuAgS）were finally successfully prepared into the target nanocomposite material TPPFe（Ⅲ）-GNR@Au2S/AuAgS through covalent bond（phosphamide bond）,and the peroxide mimetic enzyme activity was significantly enhanced compared with TPPFe（Ⅲ）.The synergistic effect of thermal electrons excited by LSPR and photoelectron of TPPFe（Ⅲ）can significantly enhance the peroxidase analog enzyme activity of TPPFe（Ⅲ）-GNR@Au2S/AuAgS.This mechanism has been further confirmed that the efficiency of thermal electron injection can be improved by removing holes with electronic donors such as ethanol.Based on the unique properties of TPPFe（Ⅲ）-GNR@Au₂S/AuAgS,a rapid visualized method for the detection of H₂O₂,cholesterol and glucose was established.The visualized analysis is applied to the determination of human serum samples with high accuracy.（2）In the second part,a water-soluble 5,10,15,20-tetraphenyl（4-phosphite）porphyrin（TPP）was successfully prepared by phosphite modification strategy.Then,a TPP-AuNCs composite nano-material was prepared by modifying TPP onto the surface of gold nanocluster（AuNCs）by activating the phosphite group of the water-soluble porphyrin TPP.Based on the fluorescence quenching phenomenon of Fe³⁺to the fluorescence emission peak of TPP-AuNCs at 664nm,a method was established to detect the content of Fe³⁺in the solution.There was a good linear relationship in the concentration range of 9.9×10^-71.02×10^-5mol/L,R²=0.9810,and the detection limit was 9.9×10^-7mol/L.In addition,based on the fluorescence quenching phenomenon of Hg²⁺against the fluorescence emission peak of TPP-AuNCs at573nm,Fe³⁺was successfully shielded by adding masking agent EDTA,thus realizing the selective detection of TPP-AuNCs against Hg²⁺.The concentration range of 5.5×10^-71.29×10^-5mol/L presented a certain linear relationship,R²=0.9816,and the detection limit was 3.4×10^-7mol/L.（3）In the third part,a kind of two-dimensional MoS₂ nanomaterial functionalized by polyvinylpyrrolidone（PVP）was successfully synthesized by hydrothermal method.The nanomaterials have the advantages of good water dispersion,low cost and good biocompatibility,as well as the properties similar to natural horseradish peroxidase（HRP）.The two-dimensional MoS₂ nanomaterial can catalyze the blue reaction of H₂O₂ oxidation of TMB.The kinetics and catalytic mechanism of two-dimensional MoS₂ nanomaterials were studied,and the typical Michaelis-Menten curves were obtained.Based on the mechanism that cholesterol can produce H₂O₂ under the action of cholesterol oxidase,the visualized analysis and detection of cholesterol were carried out and applied to the detection of free cholesterol content in human serum.