| Electrochemical sensor has important application in the field of chemistry,food industry,environmental monitoring,clinical medicine and new drug screening due to its simple operation,low cost and easy to be miniaturized.In the development of biosensors,nanomaterials-based on the characteristics of electrochemical signal amplification have great potential in improving sensitivity and selectivity of electrochemical sensors.They are also attractive due to their large specific surface area,good conductivity,special catalytic properties and excellent biocompatibility.In this paper,a novel electrochemical biosensor based on gold-doped nano-titanium dioxide has been developed,and applied for the detection of H2O2 and two kinds of drugs.The main results are as following:(1)The fabrication on 3DOM GTD/ITO modified electrode and detection for H2O2A novel three-dimensionally ordered macroporous(3 DOM)gold-doped nano-titanium dioxide(GTD)modified electrode(3DOM GTD)was fabricated by the colloidal crystal template technique.It has a clear and ordered porous stucture,meanwhile,shows good biocompatibility and electrical conductivity,and could be used as a good carrier of biosensor,The direct electron transfer of Cyt c immobilized on this electrode and electrocatalysis to H2O2 have been investigated.The results indicated that the electrode had good electrocatalytic activity to the reduction of H2O2,the reduction peak current of Cyt c immobilized on the electrode showed a good linear correlation with concentration of H2O2 in the range of 3.0×10-7mol/L～1.7×10-5mol/L,and the limit of detection is 3.6×10-8mol/L(S/N=3).It could be used to determine the concentration of H2O2 in solution.(2)The electrochemical study on interaction between Oflx and BSAWe prepared the BSA/3DOM GTD/ITO electrode by adsorption method,the electrochemical reaction of Oflx in the modified electrode was two electronic irreversible oxidation process.Spectroscopy and electrochemical method were used to study the interaction between Oflx and BSA,suggesting that a complex of Oflx-BSA was formed.The Oflx-BSA complex shows a strong affinity with a binding constant of 9.44 × 104 L/mol obtained by UV-Vis spectrum experiment.The oxidation peak current showed a good linear relationship to Oflx in the range of 1.0×10-6mol/L～1.0×10-3mol/L with a detection limit of 7.5×10-8mol/L(S/N=3)on this modified electrode.This electrode can be used to determine the content of Oflx in drugs,and recovery rate of Oflx in ofloxacin eye drops was determined,with satisfactory results(3)The spectroscopic and electrochemical study on binding between Gflx and BSAThe interaction between Gflx and BSA was studied by spectroscopic and electrochemical method.The binding constants of Gflx and BSA at different pH were determined,and the maximum value of 1.65×106L/mol was obtained under the condition of pH 5.01 The electrochemical reaction of Gflx on the electrode is an irreversible oxidation of two electrons and two protons involved.The oxidation peak current of Gflx and its concentration has a good linear relationship in the range of 3×10-7mol/L～1.0×10-3mol/L on the modified electrode with a detection limit of 8.5×10-8mol/L(S/N=3).Under the optimized experimental conditions,this method can be used to determine the content of Gflx in capsules. |
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