Highly ordered transparent mesoporous TiO2 thin films: an attractive matrix for efficient immobilization and spectroelectrochemical characterization of cytochrome c

Abstract

We demonstrate remarkably fast incorporation and high loading of cytochrome c within thin films of periodically ordered nanocrystalline TiO(2) deposited on transparent electrodes. The immobilized cytochrome c is not denaturated and it can be reversibly reduced without mediator over the time scale of a few seconds as evidenced by spectroelectrochemistry.

Interplay Between Charge Accumulation and Oxygen Reduction Catalysis in Nanostructured TiO2 Electrodes Functionalized with a Molecular Catalyst

“…The irreversibility of this electrochemical reduction process is confirmed from the very slow absorbance decay during the backward CVA 432 scan. Such an irreversible interfacial electron transfer is characteristic of what has been previously reported for other porphyrins physisorbed in mesoporous TiO 2 films [23,52] . This behavior results from the formal potential of Mn−P ( E °’ Mn−P ) being located in a potential region where TiO 2 is insulating (see Figure 1).…”

“…Such an irreversible interfacial electron transfer is characteristic of what has been previously reported for other porphyrins physisorbed in mesoporous TiO 2 films. [23,52] This behavior results from the formal potential of MnÀ P (E°' MnÀ P ) being located in a potential region where TiO 2 is insulating (see Figure 1). The electrochemical reduction of the porphyrin can thus only be achieved once the applied potential approaches the conductive zone of TiO 2 during the forward scan.…”

Unraveling the charge transfer/electron transport in mesoporous semiconductive TiO2 films by voltabsorptometry

“…44 The TiO 2 -film-coated ITO glass substrate was used as the working electrode, whereas a platinum wire and Ag/AgCl electrode in 3 M KCl were used as counter and reference electrodes, respectively (i.e., +0.21 V vs. NHE at 25 1C). Both instruments were synchronized through an input trigger signal generated from the potentiostat, allowing thus to simultaneously recorded the change of optical absorbance during a potential step chronoamperometric or CV scan.…”

“…38,39 It allowed us to entirely deconvolute the different modes of electron transport in TiO 2 as a function of the applied potential (and so as a function of film conductivity). 41,43,44 Experimental Chemicals and materials All chemicals were provided by Sigma-Aldrich except TiCl 4 (Fluka) and 5,10,15,20-tetrakis(1-methyl-4-pyridyl)porphyrin-Fe(III) pentachloride (Cayman Chemical). Instead of using conventional films of randomly sintered TiO 2 nanoparticles, suffering thus from a relatively ill-defined structure and porosity, we have chosen to work with highly-ordered mesoporous TiO 2 films prepared from evaporation-induced self-assembly (EISA).…”

Bimodal mesoporous titanium dioxide anatase films templated by a block polymer and an ionic liquid: influence of the porosity on the permeability

“…Titanium dioxide (TiO 2 ) is a cheap and abundant material presenting unique electronic and optical properties 1 for applications in photocatalysis, 2 photovoltaics, 3 energy storage, 4 and sensing. 5 Nanoporous TiO 2 has been under intensive development for the last decade, 1,2,3b-d,f,4a,b,d the objective being to increase the surface area of the material, because interfacial electron transfer is usually the key phenomenon for the aforementioned applications. The Evaporation-Induced-Self-Assembly (EISA) method allows formation of mesoporous metal oxide lms, e.g.…”