| Norfloxacin,pefloxacin and gatifloxacin are three typical synthetic fluoroquinolone antibiotics.Due to their unique properties including broad-spectrum antibacterial ability,excellent antibacterial activity,low toxicity,less side effects,low price,they have been widely used in clinical medicine and animal husbandry.However,fluoroquinolone antibiotics are not completely metabolized in human and animals,resulting in its charged residues to be constanly accumulated into the environment.Moreover,fluoroquinolone antibiotic residues can be further migrated into to humans or animals through the food chain.The abuse of fluoroquinolone residues likey causes adverse effect on human health such as nausea,vomiting,abdominal pain,headaches,rashes,and even neurological disorders.Abuse of antibiotics not only leads to excessive antibiotic residues in food and the environment,but also results induce antibiotic-resistance genes in bacteria.Therefore,the development of efficient analytical techniques is ultmost important for sensitive detection of fluoroquinolone antibiotics in animal-derived food,natural environment and medical environment.Therefore,in this project,three highly selective and sensitive electrochemical sensor were constructed for ultrasensitive detection of norfloxacin,pefloxacin and gatifloxacin based on molecular imprinting polymers and black phosphorus(BP)nanocomposites.The main research contents are as follows:(1)Molecularly imprinted polypyrrole film-coated poly(3,4-ethylenedioxythiophene):polystyrene sulfonate-functionalized black phosphorus nanosheets(BPNS-PEDOT:PSS)for use in the selective and robust detection of norfloxacinBPNS-PEDOT: PSS were prepared by ultrasonic-assisted exfoliation of BP crystals.The the molecularly imprinted polymer(MIP)film was electropolymerized on the surface of the BPNS-PEDOT:PSS modified glass carbon electrode(BPNS-PEDOT:PSS/GCE).Then,the norfloxacin template molecules were effectively eluted by the combination of electro-oxidation with the mixed solvent elution.The surface morphologies,microstructures,and chemical compostions of BPNS,BPNS-PEDOT:PSS and MIP/BPNS-PEDOT:PSS were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM)and Raman spectroscopy.The MIP/BPNS-PEDOT:PSS/GCE displayed excellent analytical perproties toward norfloxacin detection,with a wide linear range(0.001-10 μM)and quite low limit of detection(LOD,0.25 n M).The MIP/BPNS-PEDOT:PSS/GCE also showed good repeatability,reproducibility,and stability.The MIP/BPNS-PEDOT:PSS/GCE sucessfully realized the accurate detection of norfloxacin from pharmaceutical formulations and milk samples with good recoveries(98.0-100.1%).(2)Ultrasensitive,label-free voltammetric determination of pefloxacin based on molecularly imprinted polymers and Au nanoparticle-functionalized black phosphorus nanosheets nanocompositeBPNS were prepared by ultrasonic-assisted liquid phase exfoliation,and Au nanoparticles(Au NPs)were then in situ grown on BPNS to form BPNS-Au NPs nanocomposite.Then the pefloxacin imprinted polymer films were electropolymerized on the BPNS-Au NPs/GCE in the presence of pefloxacin and pyrrole as templates and functional monomers,respectively.Afterwards,the template molecules were effciently removed by electro-oxidation followed by mixture solvent elution,thus the MIP/BPNS-Au NPs/GCE was successfully fabricated.The surface morphologies,microstructures,and chemical compostions of BPNS,BPNS-Au NPs and MIP/BPNS-Au NPs/GCE were investigated by SEM,TEM,Raman spectroscopy,and X-ray photoelectron spectroscopy(XPS),etc.The analytical parameters were optimized,including electro-polymerization cycles,elution conditions,incubation time,and buffer p H.Under the optimal detection conditions,the MIP/BPNS-Au NPs/GCE achieved a wide linear response range(0.005-10 μM)with a low LOD(1.25 n M).The MIP/BPNS-Au NPs/GCE was successfully applied for reliable detection of pefloxacin in pharmaceutical formulations,milk samples,and serum samples with satisfactory recovery.(3)Higly selective and sensitive voltammetric detection of gatifloxacin based on molecularly imprinted polymers and silver nanoparticles-decorated black phosphorus nanosheetsSilver nanoparticles(Ag NPs)stabilized BPNSs(BPNS-Ag NPs)were used as an efficient sensing material for fabricating molecularly imprinted electrochemical sensor for gatifloxacin detection.Then gatifloxacin molecularly imprinted films were electropolymerized on the surface of the BPNS-Ag NPs/GCE in the presence of gatifloxacin and pyrrole as template molecule and functional monomer,respectively.The gatifloxacin molecules were effectively removed using the combination stragety of electrochemical oxidation and solvent elution.The morphologies,microstructures and chemical composition of BPNSs,BPNS-Ag NPs and MIP/BPNS-Ag NPs were measured by SEM,TEM,Raman spectroscopy and XPS.The analytical parameters including loading amount of BPNS-Ag NPs,electropolymerization cycles,elution method,incubation time and p H were optimized.Under the optimal conditions,the oxidation peak current of the MIP/BPNS-Ag NPs/GCE is linearly related with gatifloxacin concentration ranging from 0.001 to 1μM,and from 1 to 50 μM,with a low LOD of 0.6 n M.The proposed sensor showed good selectivity,repeatability,reproducibility,and stability,and was successfully applied to determine gatifloxacin from pharmaceutical formulations,milk samples and serum samples. |
