Adsorption of horseradish peroxidase onto titanate nanowires

BACKGROUNDHorseradish peroxidase (HRP) is a peroxidase-type enzyme containing heme as prosthetic group. It is a versatile enzyme that has been used for detection of H2O2. New supports for immobilization based on nanomaterials have demonstrated ideal characteristics for maintaining enzyme stability, offering many advantages over conventional immobilization supports. Titanate nanostructures show attractive properties for this application. RESULTSHRP (EC 1.11.1.7) was immobilized onto titanate nanowires (TNW) by both non-specific and covalent coupling through amine groups. TNW were synthesized by a hydrothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), N-2 physisorption (77K), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR). The coverage of TNW containing HRP adsorbed by covalent coupling was 1.56 mgHRP m(-2) and residual enzymatic activity around 40%. Desorption tests were conducted under different conditions to evaluate the stability of the coupling, showing no significant loss of the enzyme. CONCLUSIONSImmobilization of the enzyme HRP was successfully achieved by covalent coupling to TNW. The enzyme is firmly attached to TNW surface, remaining active for more than 160 days. Altogether, these results indicate that TNW is an excellent matrix for immobilization of HRP and a very promising platform for constructing biosensors. (c) 2014 Society of Chemical Industry