Application Of Polyethyleneimine Functionalized Sulfur Quantum Dots For Molecular Recognition Of Tetracyclines

Sulfur quantum dots have attracted more and more attention in the field of quantum dots and even light-emitting materials.More and more researchers have turned their attention to the study of sulfur quantum dots.Because of its simple synthesis method,excellent optical properties and antibacterial properties of raw material sulfur,sulfur quantum dots have satisfactory applications in fluorescence sensing,food packaging film,drug delivery and photochemistry.Considering that the surface modifier can improve the performance of sulfur quantum dots,polyethyleneimine was selected as the passivator and modifier to synthesize polyethyleneimine functionalized sulfur quantum dots（PEI-SQDs）.While giving water solubility to sulfur quantum dots,it changes the surface potential of sulfur quantum dots and expands its possible application prospects.Because of its good optical properties,PEI-SQDs was used as a fluorescence probe to construct a fluorescence sensing platform to realize the multi-channel analysis and detection of tetracycline antibiotics.Then polyvinyl alcohol and hydroxypropyl-β-cyclodextrin were used as modifiers to synthesize sulfur quantum dots which are different from those emitted by PEI-SQDs.The sulfur quantum dots are composed of three independent sensing units to form a fluorescence sensor array belonging to sulfur quantum dots,and the array detection of tetracycline antibiotics is realized.The specific work is as follows:Chapter 1:Summary the research progress of green element quantum dots,introduces the synthesis methods and applications of sulfur quantum dots,briefly describes the fluorescent sensor array,and puts forward the research content.Chapter 2:The residue of tetracycline from food and environment poses a potential threat to public health.Developing a more convenient portable optical detection system has become more demanding than the fluorescence detection.This study describes a sensing system of sulfur quantum dots for the detection of tetracycline in the concentrations from 0.20 to 100μM,and the limit of detection was 0.24μM（3σ/k）.A new optical sensing device was also designed with smartphone as a detector for sensing the color change from blue to yellow-green upon the addition of tetracycline.In the presence of Eu³⁺,the detectable color change is extended to red.The sensing device has been applied to the real detection of lake water and milk,with the standard recovery from 93.1%to109%.This dual-channel fluorescent and colorimetric detection system first ensures the great accuracy,also demonstrates great chromatic aberrations upon the tetracycline concentration chang-es.The application of this method has provided a great convenience for the practical detection.Chapter 3:On the basis of the study in chapter 2,polyvinyl alcohol（PVA-SQDs）and hydroxypropyl-β-cyclodextrin（Hβ-SQDs）were synthesized by using polyvinyl alcohol（PVA）and hydroxypropyl-β-cyclodextrin as surface modifiers and passivators.Three kinds of sulfur quantum dots have different fluorescence emission.Using three kinds of quantum dots as sensing units,using the data processing methods of principal component analysis and systematic cluster analysis,a sulfur quantum dot nano-fluorescence sensor array was constructed for molecular recognition and detection of tetracycline antibiotics.The nano-fluorescence sensor array can also distinguish the binary mixture of tetracycline antibiotics,which also shows a good detection effect in the actual samples.Sulfur quantum dot fluorescence sensor array shows a good application prospect for the simultaneous detection of substances with similar structures.Chapter 4:Summary and prospect of the research content.