Construction Of Novel Optical Sensors And Their Applications For Drug Screening And Pollutant Detection In Traditional Chinese Medicinal Herbs

In recent years,nanozymes have broad application prospects in high-throughput colorimetric drug screening,disease treatment and biomedicine due to their high catalytic activity,good stability and excellent biocompatibility.Based on the advantages of nanozymes,this paper designed and synthesized aerogel nanozymes with porous structure by using metal ion-induced rapid self-assembly strategy of carbon dots,and coupled them withα-glucosidase and glucose oxidase to construct a colorimetric drug screening platform based on multi-enzyme cascade reaction,which provides a means for rapid mining of active components with hypoglycemic function.Fluorescence sensitization technology is widely used in the rapid detection of weak fluorescent substances because of its high sensitivity,fast detection speed and simple operation.In this paper,Hg（II）andβ-cyclodextrin were used to sensitize the two weak fluorescent substances of aflatoxin B₁ and G₁,and the fluorescence spectra of different aflatoxins（aflatoxin B₁,B₂,G₁ and G₂）were analyzed by chemometrics,so as to realize the rapid quantitative detection of four aflatoxins in Chinese medicinal materials.Based on the successful construction of the above optical sensor,it is expected that the optical sensor has broad application prospects in drug screening and quality evaluation of Chinese herbal medicine pollutants.The main contents of this paper are as follows:Chapter 1:This chapter mainly introduces the research background and importance of drug screening and quality evaluation of traditional Chinese medicine,and expounds the classification and construction methods of optical sensors,as well as the application of optical sensors in environmental,food and Chinese herbal medicine pollution detection,drug screening and biomedicine.Then,combined with the current research on drug screening and pollutant detection of Chinese medicinal materials,the problems that need to be solved are proposed,and the significance of the research object and the experimental design scheme and innovation points of this paper are given.Chapter 2:Using adenine as nitrogen source and sodium citrate as carbon source,carbon dots with rich amino and carboxyl groups on the surface were synthesized by one-step hydrothermal synthesis method.Then,Cu（II）ions were added to the treated carbon dot solution to quickly form a hydrogel,and then freeze-dried to form a carbon dot-copper aerogel nanozyme.A multi-enzyme cascade colorimetric screening platform was designed by coupling nanozymes withα-glucosidase and glucose oxidase,and was used to screenα-glucosidase inhibitors for diabetes drugs and the detection of hydrogen peroxide,glucose andα-glucosidase.The results showed that the detection limits of hydrogen peroxide,glucose andα-glucosidase activity were0.22μM,0.19μM and 0.24 m U/m L,respectively.In addition,the morphology and structure of the synthesized Cu-CD_Aaerogel nanozymes were characterized by some apparatus.Fourier transform infrared spectroscopy,specific surface area tester,electron paramagnetic spectroscopy,and fluorescence spectroscopy.The catalytic mechanism of nanozymes was studied.The results showed that the high-efficiency nanozyme activity was derived from the generation of hydroxyl radicals and the rapid electron transfer between carbon dots and copper.The specificity and anti-interference experiments of enzymes and biomolecules proved that the constructed colorimetric sensing platform not only had high sensitivity but also good selectivity.It is expected to be popularized for other antiviral drug screening platforms.Chapter 3:Based on the significant fluorescence enhancement of aflatoxin B₁and G₁ by Hg（II）andβ-cyclodextrin,a fluorescence sensor for simultaneous detection of four aflatoxins（aflatoxin B₁,B₂,G₁ and G₂）in Chinese herbal medicines was developed.Hg（II）andβ-cyclodextrin synergistically enhanced the fluorescence of aflatoxins so that the minimum detection limits of the four aflatoxins could reach 0.01ng/m L.The simultaneous detection of four aflatoxins can be achieved by using chemometrics to analyze their fluorescence spectra.Subsequently,based on fluorescence sensitization and chemometrics methods,simultaneous detection of four aflatoxins in Chinese herbal medicines can be achieved.The main innovations of this paper are as follows:（1）High-efficiency aerogel nanozymes were designed and synthesized,and combined with multi-stage enzyme-linked reactions to construct a molecular-level colorimetric drug screening platform,which realized high-throughput,high-selectivity and high-sensitivity colorimetric screening ofα-glucosidase inhibitors.（2）The simultaneous detection of four aflatoxins in Chinese herbal medicines was realized by fluorescence sensitization technology and chemometrics methods,which provided the possibility for the rapid analysis of pollutants in Chinese herbal medicines.