Molecularly Imprinted Ratiometric Fluorescence Sensor For The Detection Of Enrofloxacin In Marine Crude Drugs

In recent ten years,drug residues in the ocean have become a research hotspot.Quinolones（QNs）antibiotics,represented by Enrofloxacin（ENR）,have been widely used in Marine crude drug aquaculture for their advantages of broad antibacterial spectrum,good curative effect,small toxicity and side effects,simple synthesis and low cost.However,the abuse of antibiotics has increasingly threatened the development of Marine raw drug aquaculture industry.Due to the small residual concentration of QNs antibiotics and high toxicity,it is easy to pollute the soil or water source through biological feces and urine,or accumulate step by step through the food chain,and eventually endanger human health.Therefore,it is an urgent problem to detect and analyze the concentration of antibiotic residues in the environment.In this study,a dual-emis sion ratio fluorescence sensor based on MIPs by joint applying molecular imprinting and ratio fluorescence detection technology and can be used fo r highly selective recognition and sensitive visual detection of low ENR antibiotics in complex Marine Crude Drugs.The research contents are as follows:1.Construction of dual-emission nanosensors based on molecular imprinting post-modification strategy and visual identification of enrofloxacin.Using sol-gel polymerization and surface imprinting technique,the polymer was synthesized by one-pot method with ENR as template molecule,Si O₂nanoparticles as support material,3-aminopropyl triethoxysilane（APTES）as functional monomer,ethyl orthosilicate（TEOS）as crosslinking agent and ammonia（NH₃·H₂O）as catalyst.After the template molecule is removed,a dual-emission MI-RFL（Molecularly imprinted ratio fluorescence）sensor is constructed using red cadmium telluride quantum dots（Cd Te QDs）modified with 3-mercaptopropionic acid（MPA）as the fluorescence source.To realize fast,efficient and sensitive visual target recognition.With the increase of ENR concentration,the fluorescence of r-QDs gradually decreased,and the inherent blue fluorescence of ENR was enhanced,resulting in a"red-purple-blue"fluorescence discoloration phenomenon.The concentration of ENR from 0 to 4 ppm has a good linear relationship with the sensor response(I₄₄₅/I₆₁₉)/(I₄₄₅/I₆₁₉)₀（R²=0.9951）,and the detection limit（LOD）is 0.039 ppm.The dual fluorescence emission sensor was used for the determination of ENR in practical crude drug samples（hippocampus,laminae,and cockles）,and the recoveries of75.70%～96.3%were obtained.2.Construction of dual-emission nanosensors based on molecular imprinting surface imprinting strategy and visual identification of Enrofloxacin.Based on the imprinted surface imprinting strategy and embedding method,using ENR as template molecule,Si O₂nanoparticles as support material,APTES as functional monomer,TEOS as crosslinking agent,NH₃·H₂O as catalyst,surface imprinting was used to embed MPA-modified red Cd Te QDs into Si O₂,and a single MIPs was synthesized.Then mixed in a certain proportion,a dual-emission MI-RFL sensor is constructed.With the increase of ENR concentration,the blue fluorescence of ENR itself increases and the red emission peak quenching occurs.The excellent visualization ability helps to accurately read the ENR content by the naked eye through the portable ultraviolet lamp.There was a good linear relationship between peak intensity ratio and ENR concentration from 0 to 4ppm（R²=0.9925）,and LOD was 0.015 ppm.In addition,the sensor was successfully applied to the determination of ENR in real crude drug samples（hippocampus,laminae,clams）,and the recovery rate reached 82.7%～101.7%.