Photoconductivity studies on nanoporous TiO2/dopamine films prepared by sol–gel method

Valverde-Aguilar, Guadalupe; Prado-Prone, Gina; Vergara-Aragón, P.; García-Macedo, Jorge A.; Santiago, Patrícia; Rendón, L.

doi:10.1007/s00339-013-8187-0

Cited by 16 publications

(16 citation statements)

References 31 publications

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“…Such strategies include TiO 2 doping (Abdullah, Khan, Ong, & Yaakob, 2017), formation of disordered surface layers (Yan, Liu, Ding, et al, 2015), surface modification with quantum dots (Li et al, 2015), plasmonic noble metal NPs (Kumar & Rao, 2017) and organic ligands (Verma, Ghosh, Das, & Ghosh, 2011). The modification of TiO 2 NPs with various organic ligands is a promising photocurrent amplification strategy (Valverde‐Aguilar et al, 2014; Verma et al, 2011; Wang, Xu, & Chen, 2009) due to its relative ease of implementation and effective photoenhancement.…”

Section: Introductionmentioning

confidence: 99%

Surface modification of TiO₂ for photoelectrochemical DNA biosensors

et al. 2020

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A photoelectrochemical (PEC) DNA biosensor is developed using surface‐modified TiO2 nanoparticles (NPs) as a sensitive transducer. Different catecholates and gallates are used as sensitizers for TiO2 NPs. The molecules are adsorbed on TiO2 via the catecholate type bonding mechanism to enhance light absorption in the visible range. The adsorbed molecules act as charge transfer mediators and enhance photocurrent. Despite the similar bonding mechanism of the molecules, the TiO2 NPs exhibit significant differences in photocurrent. The modified TiO2 films showed photocurrent increase in the order: 3,4‐dihydroxy‐L‐phenylalanine < 2,3,4‐trihydroxybenzoic acid < 3,4‐dihydroxybenzoic acid < 2,3,4‐trihydroxybenzaldehyde < 3,4‐dihydroxyphenylacetic acid < 3,4‐dihydroxybenzaldehyde < caffeic acid. Testing results provide an insight into the influence of the structure and properties of the organic molecules on their adsorption and photocurrents of modified TiO2 films. The TiO2 NPs modified with caffeic acid are used for the fabrication of PEC DNA biosensor by forming photoelectrodes and immobilizing probe single‐stranded DNA on their surface. The caffeic acid‐modified TiO2‐based photoelectrodes offer the required signal magnitude to distinguish between complementary and non‐complementary DNA sequences in the 100 nM–1 pM DNA concentration range and with a limit of detection of 1.38 pM, paving the way towards PEC DNA sensing.

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Section: Introductionmentioning

confidence: 99%

Surface modification of TiO₂ for photoelectrochemical DNA biosensors

et al. 2020

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“…In addition, we have previously found that 15C5 also reduces the rate of DA oxidation. 23 For DA-loaded lattices, dopamine hydrochloride (Sigma-Aldrich) was dissolved (0.3 w/v %) in 10 mL of a TiO 2 working solution (TiO 2 lattice); this mixture was stirred for 4 h at room temperature in a light-protected jar. The final solution of DA-loaded TiO 2 lattices (TiO 2 /DA complex) acquired a yellowish tint (Supporting Information, Figure S1A,B), a color that indicates that the DA’s enediol functional group networked with TiO 2 surface through a ligand-to-metal charge-transfer interactions.…”

Section: Methodsmentioning

confidence: 99%

Dopamine Released from TiO₂ Semicrystalline Lattice Implants Attenuates Motor Symptoms in Rats Treated with 6-Hydroxydopamine

et al. 2019

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The motor dysfunction featured by patients aggrieved by Parkinson’s disease (PD) results from the reduction of dopamine (DA) availability in the caudate nucleus (CN). Restituting CN DA levels is therefore essential to ameliorate PD motor deficits. In this regard, nanotechnology may offer solutions to restore CN DA availability. DA, however, can be rapidly oxidized into toxic compounds if made available in situ, unprotected. Then, we tested whether a semicrystalline TiO 2 lattice, implanted into the CN of 6-hydroxydopamine (6-OHDA)-lesioned, hemiparkinsonian rats, was able to release DA during a time window sufficient to attenuate motor symptoms while protecting it from the ongoing oxidation. Accordingly, implanted semicrystalline TiO 2 lattices released incremental amounts of DA into the CN of lesioned rats. Motor symptoms were already attenuated by the 1st month and significantly reduced 2 months after implantation. These effects were specific since TiO 2 lattices alone did not modify motor symptoms in lesioned rats. DA-unloaded or -loaded TiO 2 lattices did not produce obvious symptoms of systemic or neurological toxicity nor significantly increased CN lipid peroxidation in implanted, lesioned rats at the time of sacrifice. Our results thus support that loaded TiO 2 lattices are capable of releasing DA while protecting it from the ongoing oxidation when implanted into the brain. Their implantation does not cause noticeable systemic or local toxicity. On the contrary, they attenuated motor symptoms in hemiparkinsonian rats.

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“…FTIR spectroscopy has been used to detect bidentate or monodentate binding between catechol‐type ligands and metal oxides. [ 22,33,62,87,88 ] In the FTIR spectra of catechol‐modified metal oxides, the development of C–O stretch and a decrease in –OH band intensity of the bonded catechol ligand is typically observed, which indicates deprotonation of the phenolic –OH groups, thereby providing support for the formation of bidentate‐type bonding. [ 66–68,89 ] TGA is another technique used to investigate the surface adsorption of catechol ligands onto metal oxides, particularly looking at the changes in the stability of metal oxide–catechol ligand complexes over a wide range of temperatures.…”

Section: Characterization Of Metal Oxide/catechol Systemsmentioning

confidence: 99%

“…This results in improved photoabsorption in the visible range and increased photocurrent density. [ 33,35,39,64,75,87,92 ] Other spectroscopic techniques used for the characterization of metal oxide/catechol systems include NMR spectroscopy for determining whether catechol‐type ligands link other molecules, [ 93 ] Raman spectroscopy for quantifying the amount of catechol ligand bonded to metal oxide nanostructure surface, [ 68,79 ] and photoemission spectroscopy for experimentally obtaining the occupied and unoccupied states of the adsorbed catechol ligands. [ 41 ] TGA studies allow for the calculation of the maximum grafting density of ligands, adsorption coefficient, and negative‐free binding energies of the surface functionalization of metal oxide nanostructures.…”

Section: Characterization Of Metal Oxide/catechol Systemsmentioning

confidence: 99%

Surface Functionalization of Metal Oxide Semiconductors with Catechol Ligands for Enhancing Their Photoactivity

et al. 2021

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Metal oxide nanostructures are increasingly important materials for various emerging photocatalytic, photovoltaic and photoelectrochemical (PEC) applications. They are commonly used as photoelectrode materials due to their unique functional properties such as wide bandgap, reactive electronic transitions, and high stability. To increase the effectiveness of semiconductor metal oxides photoelectrodes, researchers seek to use various photoabsorption amplification and colloidal stability enhancement strategies. An effective method for achieving this is the surface functionalization of metal oxide semiconductors with catechol‐type ligands. Catechol‐type ligands are a family of organic molecules that adsorb very strongly onto metal oxides by forming complexes with metal atoms through adjacent phenolic —OH groups. Once adsorbed, catechol‐type ligands facilitate improved particle dispersion by inhibiting agglomeration and enhance photoexcitation in metal oxide semiconductors by improving visible light absorption. Herein, the surface complexation of catechol‐type ligand onto metal oxide semiconductor surfaces and their photoabsorption enhancement mechanisms is described. In addition, recent advances and trends in this area are described by presenting recent advancements made in applications of catechol‐modified metal oxide systems in photocatalysis, PEC biosensing, and solar cells.

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Photoconductivity studies on nanoporous TiO2/dopamine films prepared by sol–gel method

Cited by 16 publications

References 31 publications

Surface modification of TiO₂ for photoelectrochemical DNA biosensors

Surface modification of TiO₂ for photoelectrochemical DNA biosensors

Dopamine Released from TiO₂ Semicrystalline Lattice Implants Attenuates Motor Symptoms in Rats Treated with 6-Hydroxydopamine

Surface Functionalization of Metal Oxide Semiconductors with Catechol Ligands for Enhancing Their Photoactivity

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Photoconductivity studies on nanoporous TiO2/dopamine films prepared by sol–gel method

Cited by 16 publications

References 31 publications

Surface modification of TiO2 for photoelectrochemical DNA biosensors

Surface modification of TiO2 for photoelectrochemical DNA biosensors

Dopamine Released from TiO2 Semicrystalline Lattice Implants Attenuates Motor Symptoms in Rats Treated with 6-Hydroxydopamine

Surface Functionalization of Metal Oxide Semiconductors with Catechol Ligands for Enhancing Their Photoactivity

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Surface modification of TiO₂ for photoelectrochemical DNA biosensors

Surface modification of TiO₂ for photoelectrochemical DNA biosensors

Dopamine Released from TiO₂ Semicrystalline Lattice Implants Attenuates Motor Symptoms in Rats Treated with 6-Hydroxydopamine