title: Core-shell structured Ag@C for direct electrochemistry and hydrogen peroxide biosensor applications.
abstract: Ag@C core-shell nano-composites have been prepared by a simple one-step hydrothermal method and are further explored for protein immobilization and bio-sensing. The electrochemical behavior of immobilized horseradish peroxidase (HRP) on Ag@C modified indium-tin-oxide (ITO) electrode and its application as H₂O₂ sensor are investigated. Electrochemical and UV-vis spectroscopic measurements demonstrated that Ag@C nano-composites provide excellent matrixes for the adsorption of HRP and the entrapped HRP retains its bioactivities. It is found that on the HRP-Ag@C/ITO electrode, HRP exhibited a fast electron transfer process and good electrocatalytic reduction toward H₂O₂. Under optimum experimental conditions the biosensor linearly responds to H₂O₂ concentration in the range of 5.0×10⁻⁷-1.4×10⁻⁴ M with a detection limit of 2.0×10⁻⁷ M (S/N=3). The apparent Michaelis-Menten constant (K(app)(M)) of the biosensor is calculated to be 3.75×10⁻⁵ M, suggesting high enzymatic activity and affinity toward H₂O₂. In addition, the HRP-Ag@C/ITO bio-electrode shows good reproducibility and long-term stability. Thus, the core-shell structured Ag@C is an attractive material for application in the fabrication of biosensors due to its direct electrochemistry and functionalized surface for efficient immobilization of bio-molecules.
authors.affiliation: College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, Jiangsu 215123, PR China.
authors.forename: Shuxian
authors.initials: S
authors.lastname: Mao
authors.forename: Yumei
authors.initials: Y
authors.lastname: Long
authors.forename: Weifeng
authors.initials: W
authors.lastname: Li
authors.forename: Yifeng
authors.initials: Y
authors.lastname: Tu
authors.forename: Anping
authors.initials: A
authors.lastname: Deng
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D002384:Catalysis; D055664:Electrochemical Techniques / Q000379:methods; D004800:Enzymes, Immobilized / Q000378:metabolism; D006735:Horseradish Peroxidase / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000032:analysis* / Q000378:metabolism; D053761:Nanocomposites / Q000737:chemistry* / Q000648:ultrastructure; D015203:Reproducibility of Results; D012834:Silver / Q000737:chemistry*; D017971:Tin Compounds / Q000737:chemistry
chemical_list: D004800:Enzymes, Immobilized; D017971:Tin Compounds; D012834:Silver; C109984:indium tin oxide; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase