Adsorption of horseradish peroxidase onto titanate nanowires

BACKGROUND Horseradish peroxidase ( HRP ) is a peroxidase‐type enzyme containing heme as prosthetic group. It is a versatile enzyme that has been used for detection of H 2 O 2 . 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 . RESULTS HRP ( 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 (77 K), 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 . CONCLUSIONS Immobilization 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. © 2014 Society of Chemical Industry