Construction And Sensing Mechanism Study Of β-Lactam Antibiotic Detection System Based On Functionalized Phosphorescent Quantum Dots

The impact of the large amount of antibiotics on food safety and the ecological environment is a problem that people are generally concerned about.The rapid and convenient detection of antibiotics in environmental samples,food samples,and pharmaceutical products is the primary prerequisite for controlling biological and environmental risks caused by antibiotic residues.On the basis of systematically summarizing the existing antibiotic detection method technologies and drawing on recent domestic and foreign literature reports,this paper is based on the phosphorescent properties of manganese-doped zinc sulfide quantum dots,with the goal of improving the selectivity and sensitivity of the detection process,and use surface modification as a strategy,three functional phosphorescent quantum dots modified with trimercaptopropionic acid（MPA）,bovine serum protein（BSA）,and polyethyleneimine（PEI）were synthesized,and attempted to construct the detection systems of threeβ-lactam antibiotics（FProzil,carbenicillin and ampicillin）which wree suitable for the spectrum,and the main mechanism of their detection was analyzed.The main results are as follows:（1）MPA-coated Mn-doped ZnS quantum dots（MPA-Mn/ZnS QDs）were synthesized by the water phase method,and their morphology and optical properties were characterized.Based on reaction between a large number of carboxyl groups on the surface of MPA-Mn/ZnS QDs and the amino group on the cefprozil（FP）molecule,Phosphorescence of MPA-Mn/ZnS QDs is dynamically quenched by photo-induced electron transfer（PET）which.According to the corresponding relationship between the concentration of FProzil(C_FP)and the room temperature phosphorescence quenching amount（△RTP）of MPA-Mn/ZnS QDs,a room temperature phosphorescence detection system for C_FP was constructed.The detection range of this method for C_FP is 2-16μmol/L,and the detection limit is 0.67μmol/L.It has good anti-interference performance for common ions and substances in human urine,and can be used for the detection of cefprozil in human urine.（2）Taking the optimal coupling ratio of MPA-Mn/ZnS QDs and bovine serum protein（BSA）,BSA was modified on the surface of MPA-Mn/ZnS QDs by a one-step cross-linking method,and a bovine serum protein functionalized Mn-doped ZnS quantum dots（QDs-BSA）was synthesized.Based on the static quenching and internal filter effect of QDs-BSA room temperature phosphorescence（RTP）by carbenicillin（Car）,a simple and sensitive Car phosphorescence detection system was constructed in a neutral environment at p H=7.4.The detection range of carbenicillin is 0-84μmol/L,and the detection limit is 0.26μmol/L.It can be used to detect Car in human urine.（3）Using polyethyleneimine as a ligand,polyethyleneimine-coated phosphorescent quantum dots（PEI-Mn/ZnS QDs）were synthesized,and their physical morphology and spectral characteristics（optical properties）were characterized in detail.Based on the selective recognition of ampicillin（Amp）by PEI-Mn/ZnS QDs surface ligand,an Amp detection system was constructed,with a detection range of 0.04～180μmol/L and a detection limit of0.013μmol/L.Molecular docking showed that the specific recognition modes of Amp and PEI-Mn/ZnS QDs are electrostatic interaction and hydrogen bonding.This method has a wide detection range and low detection limit,and can be used to detect human urine and milk samples.In summary,the morphology and photochemical characteristics of manganese-doped zinc sulfide quantum dots were studied.Based on their superior phosphorescence properties,the detection of FProzil,carbenicillin,and ampicillin was achieved by modifying the surface with different functional molecules,And their sensing mechanism were studied separately.This article provides new methods and theoretical basis for the detection ofβ-lactam antibiotics.However,there are still some deficiencies in the experiment,which need to be further improved.