Assembly and Charge Transfer in Hybrid TiO₂ Architectures Using Biotin−Avidin as a Connector

Abstract

Exploiting the presence of undercoordinated surface Ti atoms at the tips of TiO2 nanorods and the dopamine selectivity for these Ti surface states, biotin was conjugated to TiO2 nanocrystallites using dopamine as a bridging linker. Using abiotin−avidin complex as a connector the “tip-to-tip” assembly of 400 nm elongated TiO2 rods was obtained. The photoexcitation of avidin−TiO2 hybrids resulted in the transfer of holes from nanocrystallites to protein and consequent oxidation of avidin, most probably at tyrosine 33.

Spatially Confined Defects Induce Chemical Functionality of Anisotropic TiO2 Rods

“…A similar defect healing effect is also known to occur in spherical nanoparticles of TiO 2 upon complexing with dopamine [1]. By selectively modifying the tip surfaces of these nanoparticles with biotin, we are able to induce the tip-to-tip serial assembly of these biohybrid nanocomposites by conjugation with avidin [2]. This reactivity observed at the nanorod ends is reminiscent of the selectivity found with organic and biological self-organizing systems.…”

Reactive Polymers: A Versatile Toolbox for the Immobilization of Functional Molecules on TiO2 Nanoparticles

“…[3] Moreover, the surface characteristics of nanomaterials influence the broad range of properties and the performance of a large variety of devices. For instance, the charge-transport process across the interface between a semiconductor metal oxide and an organic dye [4] or a biomolecule [5] forms the basis for improving the performance of many optoelectronic devices, photovoltaic cells, [6] and light-emitting diodes (LEDs). [7] Oligonucleotides can also be linked to the surfaces of nanoparticles, which may become a new tool for gene therapy.…”

“…[18] The multifunctional polymeric ligand combines three features: 1) a robust anchor group based on dopamine which is capable of binding to many metal oxides (e.g. TiO 2 , Fe 2 O 3 ), [19] 2) a functional molecule (e.g. fluorescent dye, catalyst, biomolecule), and 3) a group that provides solubility of the nanoparticle in different solvents and thereby allows various applications of the inorganic nanomaterial (e.g.…”

“…[20a] The fact that active ester polymers react fast and quantitatively with amines to form the corresponding polyacrylamides opens the possibility to obtain multifunctional polymeric materials. [19] Active ester polymers based on pentafluorophenylacrylates exhibit some outstanding features compared to the commonly used poly(N-hydroxysuccinimideacrylates), such as better solubility and higher reactivity, as described elsewhere.…”

Synthesis of α-Bi4V2O11 and its Sonocatalytic Activity for the Degradation of Rhodamine B

“…The photocatalytic elimination of pollutants in water and air have attracted much interest around the world ever since Fujishima and Honda announced a TiO2 photochemical electrode for splitting water in 1972 (Fujishima and Honda, 1972). TiO2 and ZnO have been widely used as a photocatalyst for the degradation of environmental contaminants (Wang et al, 2006;Kumar et al, 2012;Kumar et al , 2014), because of its chemical stability, high photocatalytic activity, non-toxicity and low cost (Dimitrijevic et al, 2005). It is known that the photocatalytic performance in the presence of nanosized TiO2 powder is very effective (Augugliaro et al, 1988).…”