title: Surface charge-transfer complex formation of catechol on titanium(IV) oxide and the application to bio-sensing.
abstract: Adsorption properties of 2-hydroxyphenol (catechol) on TiO2 particles has been studied at 298K. The adsorption proceeds from the aqueous solution with the Langmuir type behavior. Diffuse reflectance infrared spectra of the catechol-adsorbed TiO2 suggested that catechol is adsorbed on TiO2 solution via the chelation to the surface Ti ions. The adsorption induces a strong absorption in the whole visible region, of which intensity increases with an increase in the adsorption amount. Photoelectrochemical experiments and molecular orbital calculations indicate that the absorption stems from the charge-transfer (CT) transition from the HOMO of catechol to the conduction band of TiO2. Time courses for the adsorption of catechol on mesoporous TiO2 nanocrystalline film-coated glass was traced by measuring the change in the absorbance of the CT band, and analyzed on the basis of the Langmuir model. This study would present a new simple technique for sensing of important biomolecules bearing the catechol moiety.
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, 3-4-1, Kowakae, Higashi-Osaka, Osaka 577-8502, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Murata
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, 3-4-1, Kowakae, Higashi-Osaka, Osaka 577-8502, Japan.
authors.forename: Hiroshige
authors.initials: H
authors.lastname: Hori
authors.affiliation: Faculty of Pharmacy, Kinki University, 3-4-1, Kowakae, Higashi-Osaka, Osaka 577-8502, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Taga
authors.affiliation: Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, 3-4-1, Kowakae, Higashi-Osaka, Osaka 577-8502, Japan. Electronic address: h-tada@apch.kidai.ac.jp.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Tada
mesh_terms: D000327:Adsorption; D015374:Biosensing Techniques / Q000379:methods*; D002396:Catechols / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature; D014025:Titanium / Q000737:chemistry*
chemical_list: D002396:Catechols; C009495:titanium dioxide; D014025:Titanium; C034221:catechol
keywords: Bio-sensing; Catechol; Charge-transfer absorption; Surface complex; TiO(2)