Detection Of Tetracycline Residues In Animal-derived Foods Based On Molecularly Imprinted Polymer-Carbon Dot Composite

Tetracyclines(TCs)are a class of bacteriostatic drugs.These drugs are not only cheaper than other drugs with similar effects,but also have the effect of inhibiting and resisting bacteria.Because of the above-mentioned excellent characteristics,the demand for tetracycline antibiotics in aquaculture and veterinary medicine industries is very large,but while using its excellent antibacterial effect,tetracycline antibiotics also bring many harams to humans and the ecological environment.The direct effect on humans is physiological toxicity,long-term effects include sensitization and drug resistance,leading to the emergence of drug-resistant bacteria.In this paper,a combination of fluorescence sensor and molecularly imprinted polymer was developed to establish a method for the detection of trace tetracycline in aqueous medium,which not only simplifies the sample preparation process,but also the detection method is fast and sensitive.In this study,carbon dots(CDs)with high fluorescence quantum yield were synthesized by one-step hydrothermal method,and then CDs were immobilized in the imprinted layer of TC molecularly imprinted polymer by bulk polymerization,and finally a fluorescent molecular imprint composite material was obtained.In the experiment,the optimal conditions for detecting TC were determined by optimizing the synthesis conditions and test conditions of CDs@MIP.Then,the morphology,thermodynamics and optical properties of the obtained CDs@MIP were studied using the corresponding instruments.In addition,the identification and detection ability of prepared CDs@MIP in aqueous medium was analyzed by adsorption kinetics experiment,selective recognition experiment and quantitative detection experiment.Finally,the detection method of tetracycline in aqueous medium was established.The results showed that tetracycline quenched the fluorescence of the composite.In addition,the adsorption of tetracycline by CDs@MIP reached equilibrium within 3.5 hours,and it could resist the interference of tetracycline analogues,achieve the purpose of selectively identifying tetracycline,as well.Under the optimal detection conditions,when the tetracycline concentration is 5-100 ?g L-1,the fluorescence intensity change of the material shows a good linear relationship with the concentration.The minimum detection limit of the method is 0.018 ?g L-1.The actual sample selected for the experiment was three kinds of food:milk,egg,pork.The actual sample was spiked and recovered,and the test was verified by the national standard method.The results measured by the two methods were collated for comparative analysis.The recoveries of TC in milk,eggs and pork obtained by the method established in this study were 85.1%-98.7%(RSD<4.3%),78.6%-96.1%(RSD<4.6%),83.9%-97.1%(RSD<5.0%),respectively.This result demonstrates that the established fluorescence sensing method can be applied to the actual sample.The spiked experiments of the above three samples by high performance liquid chromatography showed that the recoveries of TC spiked were 80.7%-97.4%(RSD<4.7%)and 77.5%-95.8%(RSD<5.0%),respectively.81.1%-92.0%(RSD<4.5%).The results obtained by the two methods are consistent,which indicates that the fluorescence sensing detection method of the carbon dot molecularly imprinted composite material are reliable in the actual sample detection.Therefore,the method is feasible and has a certain credibility.