| The synthesis of novel nanomaterials and the construction of nanomaterial based nano-interface for the development of electrochemical sensors have attracted considerable attentions during the past two decades due to the unique properties of nanomaterials and the good performance of nanomaterial based electrochemical biosensors. In this paper, several electrochemical biosensors were developed based on nanocomposites, including TiO2/graphene nanoribbon composite (GNR), magnetic mesoporous silica and Fe3O4nanoparticle core/shell microspheres, and magnetic graphitized carbon nanosheet, and used for the electrochemical detection of cysteine, phenol, and glucose respectively. The detailed contents are listed as follows:(1). The preparation of TiO2/Graphene nanoribbon(TiO2/GNR) nanocomposite and their applications in the selective and sensitive detection of cysteine.TiO2/GNR nanocomposite was synthesized by ultrasonically mixing the GNR and TiO2nanotube and used for the development of electrochemical sensor for cysteine detection. The GNR could homogeneously distribute on both the inner and outer surface of TiO2nanotube and form an accessible TiO2/GNR nanostructure, which was verified by the SEM images. After the nanocomposite was introduced on the surface of glassy carbon electrode, the TiO2/GNR nanocomposite modified electrode showed high electrochemically catalytic ability towards the anodic oxidation of cysteine, on which the overpotential for cysteine anodic oxidation has been reduced to+75mV. Under the optimal conditions, the as-prepared nanocomposite modified electrode showed a high sensitivity (7.384μAmM-1), and a low limit of detection (0.09μM, S/N=3). In addition, the sensor also showed a wide linear range from1.0μM to0.485mM, which could satisfy the demand of in vivo analysis real samples.(2). Magnetic loading of tyrosinase-Fe3O4/mesoporous silica core/shell microspheres for high sensitive electrochemical biosensing.A new protocol is proposed for magnetic loading and sensitive electrochemical detection of phenol via the tyrosinase cross-linked mesoporous magnetic core/shell microspheres. The mesoporous magnetic microspheres, characterized by transmission electron microscopy, N2adsorption/desorption isotherms, and magnetic curve displays high capacity for enzyme immobilization and strong magnetism to adhere to the magnetic electrode surface without any additional adhesive reagent. The biosensor exhibits a wide linear response to phenol ranging from1.0nM to1.0μM, a high sensitivity of78μAmM-1, a low detection limit of1nM, and a fast response rate (less than5s). The proposed method is simple, rapid, inexpensive and convenient in electrode renewal, which is recommended as a promising experimental platform for wider applications in biosensing.(3). Magnetic loading of glucose oxidase-magenetic graphitized carbon nanosheet for high sensitive electrochemical biosensing of glucose.A magnetic glucose biosensor was developed by magnetically loading the glucose oxidase cross-linked magnetic graphitized carbon (GOD-MGC) nanosheet on magnetic electrode surface.. Electrochemical impedance showed the carbon nanosheet had good conductivity, which was even comparable to the carbon nanotube. Due the good electrochemical conductivity and the strong magnetic property of MGC which would adsorb on the magnetic electrode surface without the addition of any additional adhesive reagent, the as-prepared GOD-MGC modified electrode exhibited a high sensitivity of94.63nAmM-1towards the detection of glucose, a linear response ranging from0.01to1.05mM and from1.35to4.85mM, and an acceptable limit of detection of10μM. The proposed method is simple, rapid, inexpensive and convenient in electrode renewal, which is recommended as a promising experimental platform for wider applications in biosensing. |
