Preparation Of Horseradish Peroxidase Biosensor By Hydrotalcite-chitosan Composite

The performance of biosensors depends on their components,among which the enzyme,i.e.,the layer between the recognition layer of biomolecule and transducer,plays a crucial role in defining the stability,sensitivity and shelf-life of a biosensor.Hydrotalcite have become as attractive materials for electrochemical application,principally owing to its metal active ingredient or its property to immobilize enzyme and macromolecules.while the wide application in electrochemistry is limited because of its not good filming property and small adhesive.Chitosan,as a good biofilm material,has attracted much attention due to its biocompatibility,permeability and adhesion.The composite can play an important role in the fields of electrochemistry,catalysis,new energy and so on,which were prepared by hydrotalcite and chitosan.In this paper,we prepared the hydrotalcite-chitosan composite(LDH-CHT)to immobilize the horseradish peroxidase(HRP),and a high-performance horseradish peroxidase biosensor modified by LDH-CHT/HRP was successfully prepared.The biosonser exhibited a good catalytic performance for H2O2.which including the following aspects.ZnAl-LDHs were prepared by urea method.The results showed that ZnAl-LDH with3 molar ratio of Zn/Al had a high crystallinity,interlayer regularity and permanent charge density,which resulting in its high electrochemical performance.The electrochemical reaction process of hydrotalcite-modified electrode(LDH/GCE)was a quasi-reversible reaction,which was controlled together by the diffusion step and the electrochemical reaction.And it can be found that LDH could provide a good electrochemical interface on biosensing.A new type of hydrotalcite-chitosan composite(LDH-CHTs)was successfully prepared.The results showed that LDH-CHTs still have typical hydrotalcite crystal structure.The proper addition of chitosan can increased the specific surface area,the number of the largest channels and the permanent charge density of the LDH-CHTs composite,which was the best in the dosage of chitosan with 2.0 g/L.And the electrochemical property of LDH-CHT was higher than that of pure LDH.The combination of chitosan and hydrotalcite can improve the stability of the surface layer and electrochemical reaction on the modified electrode.Thus LDH-CHT can further improve the electrochemical performance and provide the possibility to prepare a appropriate interface biosensor.HRP was immobilized by LDH-CHT composite and enzymatically modified electrode with LDH-CHT/HRP(LDH-CHT/HRP/GCE)were prepared.A highly stable hydrogen peroxide biosensor based on LDH-CHT/HRP/GCE was successfully obtained.The biosonser exhibited a good catalytic performance for H2O2 and had high sensitivity,high selectivity,good stability and reproducibility.And this biosensor exhibited excellent amperometric response towards H2O2 in the linear concentration range from 2.0×10-5to6.1×10-3 mol/L,low detection limit of 2.04×10-6 mol/L(S/N=3)and a low Michaelis constant(Km)of 6.889.