Electrochemical Sensing Based On Gold Nanoparticles Modified Screen Printed Electrode

Screen printed electrode(SPE)is a kind of disposable electrodes with low space demands and low costs.It is easilly to avoid cross-contamination while using SPE instead of other reusable electrodes.The working electrode of SPE is a mixture of carbon material and polymer,possessing a rough surface,which can be chemical modified.In this work,we modified the SPE by electrodeposition and self-assembly methods,the properties and applications of whose was studied by electrochemistry and other means.The main contents are as follows:(1)A disposable electrochemical sensor for the detection of H2O2 based on the gold nanoparticles(Au NPs)modified SPE was studied.The sensor was fabricated by immobilizing horse radish peroxidase(HRP)labeled bovine serum albumin(BSA)on Au NPs which were in situ electrodeposited on SPE by cyclic voltammetry.The sensor showed a wide range between 10 and 500 μmol/L with the detection limit down to 2.1 μmol/L under optimized conditions.It exhibited a well stability and specificity.(2)A disposable electrochemical sensor for the detection of alpha-fetoprotein(AFP)based on the gold nanoparticles(Au NPs)modified SPE was studied.To prepare the sensor,capture anti-AFP antibodies were introduced to the surface of electrodes.Then,AFP antigens were captured onto the sensor via immunoreactions,followed by the further capture of HRP-labeled BSA signal probes.The signal current was negative correlated with the concentration of AFP.(3)A disposable electrochemical immunosensor for the sensitive detection of AFP based on the dual-amplification effects of Au NPs by using SPE was reported.To construct the sensor,capture anti-AFP antibodies were firstly immobilized on the surface of SPE modified with AuNPs.Then,AFP antigens were captured onto the sensor via immunoreactions,followed by the further capture and immobilization of HRP-labeled Au NPs immunoprobes,which formed a sandwiched immunosensing structure.Finally,the resulting immunocomplex catalyzed the reduction of H2O2 using hydroquinone as an electron mediator to produce reduction currents.Differential pulse voltammetry and scanning electron microscopy were used to characterize the construction process and analytical performance of the sensor.The reduction peak current was linear with the concentration of AFP in the range of 2.5-30 ng/mL under optimized conditions,along with a low detection limit of 0.16 ng/mL.The proposed immunosensor provided a high sensitive,low-cost,simple and practical method for AFP detection.