| With the development of nanotechnology,graphene nanomaterials with single structure and single properties has not been suitable for the development of science and technology,meaning seeking and designing hybrid nanomaterials with more excellent properties would be the trend of grapheme nanomaterials development.Graphene hybrid nanomaterials not only own the basic properties of single nanomaterials,but also exhibit composite synergistic multifunctional effects.Graphene-based hybrid nanomaterials have been received a great much attention due to its prominent properties and potential applications in many fields.At present,most of the graphene nanocomposites were synthesized by chemical reaction.This thesis mainly prepared three kinds of graphene-based electrochemical sensors by the electrochemical method.The electrochemical performance of graphene nanocomposites was investigated through the detection of gatifloxacin,moxifloxacin and ofloxacin.The specific research work is as follows: 1.Electrochemical sensor based on electro-polymerization of ?-cyclodextrin and reduced-graphene oxide on glassy carbon electrode for determination of gatifloxacinIn this work,aiming to explore the unrevealed sensor potential,a new method of one-pot electro-polymerization of ?-CD and rGO has been employed to prepare the ?-CD/rGO modified electrode for the determination of gatifloxacin.The inner cavities of ?-CD could increase the surface of the electrode and accumulate the analytes at the electrode,and the rGO could remarkably enhance the conductivity.When the ?-CD was electro-polymerized on the electrode by cyclic voltammetry and the rGO was simultaneously immobilized on the electrode,the response current for gatifloxacin was greatly enhanced.Under optimum conditions,the differential pulse voltammogram?DPV?exhibited the oxidation peak currents were linearly proportional to gatifloxacin concentrations in the range from 0.05 to 150 ?mol·L-1.This electrochemical sensor had a low detection limit of 0.02?mol·L-1?S/N = 3?.Moreover,this proposed sensor exhibited good reproducibility,long-term stability and fast current response.To further study the practical applicability of the proposed sensor,the modified electrode was successfully applied to detect gatifloxacin in tablets and human urine samples.2.A novel sensor based on bifunctional monomers molecularly imprinted film at reduced-graphene oxide modified glassy carbon electrode for detecting trace of moxifloxacinHerein,we designed a rapid,selective and sensitive sensor based on MIP for the determination of moxifloxacin.The rGO as a supporting material,moxifloxacin as template molecule,o-phenylenediamine and L-lysine as the functional monomers have been used to construct the MIP film on the surface of modified electrode by electropolymerization.Firstly,a suspension of rGO was deposited on the GCE surface.Subsequently,a molecularly imprinted film was prepared by electropolymerization,via cyclic voltammetry of o-phenylenediamine and L-lysine as the functional monomers in the presence of MFLX as the template molecule.After the removal of the embedded template moxifloxacin by extraction with an 50% ethanol?V/V = 1:1?solution,the MIP/rGO/GCE sensor was finally obtained.The adsorbed moxifloxacin is detected by electrochemical signal of [Fe?CN?6]3-/4-due to the binding of moxifloxacin blocking electron transfer of [Fe?CN?6]3-/4- at the electrode surface.The electrochemical signal intensity is related to the concentration of moxifloxacin.Under the optimal experimental conditions,the imprinted sensor had good linear current responses to moxifloxacin concentrations in the ranges from 1.0 × 10-9 to 1.0 × 10-8 mol·L-1 and 1.0 × 10-8 to 5.0 × 10-5 mol·L-1,with a detection limit of 5.12 × 10-10 mol·L-1?S/N=3?.The fabricated sensor possessed a good selectivity and stability,providing a promising tool for moxifloxacin determination.3.Electrochemical sensor based on a novel Pt–Au bimetallic nanoclusters decorated on reduced graphene oxide for sensitive detection of ofloxacinA promising electrochemical sensor,Pt–Au nanoclusters decorated on the surface of reduced graphene oxide?rGO/Pt–Au?,was facilely prepared by one-pot electrochemical reduction.The electrochemical synthesis of rGO/Pt–Au is carried out via two steps,namely,GO being first assembled on the electrodes by drop-casting and then being immersed in a Pt–Au precursor solution to perform one-step coelectrochemical reduction.For the optimized experimental and instrumental conditions,two linear calibration curves were observed,from 0.08 to 10 ?mol·L-1 and 10 to 100 ?mol·L-1 ofloxacin.A detection limit of 0.05 ?mol·L-1 ofloxacin was observed at pH 5.7 for the GCE/rGO/Pt–Au.The fabricated electrode showed good reproducibility,stability and selectivity.The proposed sensor was successfully applied to determine ofloxacin in tablets and human urine samples and the results were satisfactory. |
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