Study On Ag@C Core-shell Nanocomposite Biosensors

In the last decades, electrochemical techniques have been the most attractive methods. Finding the suitable materials to enhance the direct electron transfer between the electrode and redox protein is one of chief challenges in direct electrochemistry field. Nanomaterials with core-shell structure are one of the significant systems for the enhanced properties from core to shell components and their synergy, which are promising for potential applications in the biochemical field. In this dissertation, the Ag@C core-shell structured nanoparticles were synthesized using one-pot hydrothermal method and built to construct sensitive electrochemical sensors, the tryptophan (Trp) sensor and the H2O2biosensor. We detailed investigated the electrochemical properties of these biosensors and the mechanism was also discussed. The main work could be summarized as follows:Firstly, the Ag@C core-shell structured nanoparticles were synthesized using one-pot hydrothermal method and characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), and Fourier transform-infrared spectroscopy (FTIR). The experimental results prove that Ag@C nanocomposites are spherical particles with core-shell structured as well as many functional groups present after hydrothermal treatment.Secondly, the electrochemical behaviors of Trp on Ag@C/GC electrode were investigated. Under the optimum experimental conditions, the oxidation peak current was linearly dependent on the Trp concentration in the range of1.0×10-7-1.0×10-4M with a detection limit of4.0×10-8M (S/N=3). The electrochemical sensor proposed herein is easy to prepare, and exhibit good reproducibility also with long-term stability. Furthermore, it was successfully employed to determine Trp in pharmaceutical samples.Lastly, the prepared Ag@C nanomaterials with core-shell structure were employed to immobilize HRP for the construction of Ag@C/HRP/ITO biosensors. Ag@C/HRP/ITO biosensor without special film-forming agent has good response of H2O2. The biosensor has a good response sensitivity and low detection limit, the linear range is1.0×10-7to1.0×10-4M (R=0.998), detection limit is0.2μM, response time is less than3s, while Km equals to37.5μM. We can know from the experimental results that Ag@C/HRP/ITO biosensors speed up electron transfer between HRP and the electrode directly, which reveal Ag@C nanoparticles have good biocompatible and broaden application prospects in the field of enzyme immobilization. In addition, this biosensor showed a wide detection range, low detection limit, good stability and anti-jamming in the detection of H2O2. In summary, this new biosensor can be easily constructed, provided a new method for the detection of H2O2, and Ag@C nano-materials are also expected to be used for the immobilization of other enzyme.