Hydrogen Peroxide Biosensor Based On GNPs-chitosan And Multi-walled Nanotube

ObjectiveThe determination of H₂O₂ is of great significance in clinical laboratory diagnosis,biological analysis, environmental testing and other fields. Biosensor detection method was used for detection of H₂O₂ for the high sensitivity, good linearity, fast and stable response signal.MWNTs is a superior electron transport medium,which with metals and semiconductors, good conductivity, large surface area and good electrocatalytic properties, has been used to promote the electrical activity of biological substances sensor electron transfer; GNPs which has large surface area, good biological compatibility and conductivity are widely used in biological fixation of protein the in biosensors. MWNTs will be modified electrode surface in this experiment, GNPs will be dispersed by CHIT for fixation of HRP. The characteristics of MWNTs and GNPs can amplify electrical signals, widen the linear range of detection of H₂O₂ and reduce the detection limit, thus developed a new type of H₂O₂ biosensor.Methods(1)10 mg carboxylation of MWNTs was dispersed in 10 ml 0.2 mg/mL of sodium dodecyl sulfonate (SDS) solution, and then put the solution in ultrasonic environment for 10 min, made 1.0 mg/mL of MWNTs dispersion. In addition, the gold nanoparticles and chitosan was made mixing solution by volume ratio of 1:1. Glassy carbon electrode (GCE) polished with suspended Al₂O₃ paste into a mirror, put the GCE in anhydrous ethanol and double distilled water in the ultrasonic 10 min, washed with double distilled water, and then the GCE performance experiment were carried out in conventional three-electrode cell containing KCL and [Fe(CN)₆]^3-/ [Fe(CN)₆]^4-solution.(2)MWNTs SDS dispersion was self-assembled at the GCE to construct a negative charge interface, and Thi as a cationic electron mediator was adsorption by electrostatic , GNPs-CHIT was self-assembled by the covalent bond, horseradish peroxidase (HRP) was adsorpted by electrostatic,and then the hydrogen peroxide (H₂O₂) biosensor was maked.(3)Recoverytest was carried out to evaluate the performance of the hydrogen peroxide biosensor based on GNPs-chitosan/ multi-walled carbon nanotube modified glassy carbon electrode.ResultsMWNTs was self-assembled at the GCE surface, and then Thi and GNPs-CHIT composite film mixed solution was self-assembled on the electrode through electrostatic adsorption and covalent bonding, and finally GNPs was adsorpted the HRP to form a H₂O₂ biosensor with good performance. The biosensor showed a wide linear response rang(8.2×10^-6-1.1×10^-3 mol/L) of the H₂O₂ concentration within the detection limit of 5.8×10^-7 mol/L, ,the response time which reached to the 95% steady state is about 15 s.The electrode has good stability and reproducibility. electrodes was scaned in cyclic voltammetry for 50 laps in 0.1 mol/L of HAc-NaAc(pH = 6.0) buffer, the current response signal maintained 92.1 % of the initial signal. Put the sensor in 4℃refrigerator for two weeks, the change in response value does not exceed 6.3% of the original signal for the same concentration of H₂O₂. Four electrodes were preparated at the same time to determine the concentration of H₂O₂ at 0.1 mmol/L were measured, the relative standard deviation of the response current was 3.3%.H₂O₂ electrochemical biosensor prepared by this method has higher stability, low detection limit, fast detection speed, this biosensor showed satisfactory results for the detection of H₂O₂.ConclusionFirst MWNTs was self-assembled on glassy carbon electrode, and then Thi and GNPs-CHIT composite film mixed solution were self-assembled on GCE through electrostatic adsorption and covalent bonding, and finally HRP was adsorbed by GNPs monolayer to form a good biosensor. The enzyme fixation method is simple, which has high stability, low detection limit, The electrode can be repeatedly used.Furthermore the biosensor has practical value.