The Application Of Attapulgite Clay Modified Electrode In The Electrochemical Sensors

The attapulgite clay that possesses natural stability, adsorption and ion exchange capacity, has broad applications in oil drilling, water treatment, buffer release fertilizer, pharmaceutical additive, chemical sensor and other fields. Therefore, research on attapulgite clay is one of the hotspots.In this paper, using attapulgite as matrix, the glassy carbon electrodes modified with the methylene blue dye, horseradish peroxidase and silver nanoparticles were prepared, and their electrochemical property was studied by cyclic voltammetry.The main contents as follows:(1) Preparation and electrocatalytic property of attapulgite/methylene blue composite filmThe composite film consisted of natural attapulgite (ATP) with poly(methylene blue) (PMB) was constructed on glassy carbon (GC) electrode by cyclic voltammetry. The experiment results show that the electrode as-prepared exhibited an effective electrocatalytical activity towards the oxidation of ascorbic acid (AA) and well-defined oxidation peaks were observed in 0.1 M phosphate buffer solutions (PBS, pH 7.0) via cyclic voltammetry. Linear calibration plot was obtained over the range of 1.0×10-5 to 5.0×10-2 M with the detection limit of 1.0μM for ascorbic acid. The main interferent in biological samples could be excluded. In addition, UV-Vis spectra were applied to explore the formation mechanism of the nanocomposite film of PMB-ATP.(2) Preparation and electrocatalytic property of attapulgite biosensor modified with horseradish peroxidaseA novel hydrogen peroxide (H2O2) biosensor was developed by immobilizing horseradish peroxidase (HRP) on the ATP that could provide a biocompatible microenvironment for enzyme molecules and increase the coverage of HRP molecules on the electrode surface. Importantly, the ATP can act as a charge carrier that facilitated the electron transfer between HRP and the electrode. The construction of the biosensor was characterized by atomic force microscopy (AFM) and its electrochemical property wasstudied by cyclic voltammetry. Linear calibration plot of the enzyme electrode was obtained over the range of 5μM to 0.3 mM with the detection limit of 5μM for H2O2.(3) Preparation and property of hydrogen peroxide sensor based on attapulgite/Ag nanoparticlesA novel strategy to fabricate hydrogen peroxide (H2O2) sensor was developed by electrodepositing Ag nanoparticles (NPs) on the surface of ATP. The results of electrochemical experiments show that the sensor as-constructed had a favorable catalytic activity to the reduction of H2O2. The catalytic activity for the sensor may reslut from small Ag NPs that were homogenously distributed on the surface of ATP. The sensor achieved 95% of the steady-state current within 2 s. Linear calibration plot of the electrode was obtained over the range of 10μM to 20 mM with the detection limit of 2.45μM for H2O2.