New Hybrid Properties of TiO2 Nanoparticles Surface Modified With Catecholate Type Ligands

Surface modification of nanocrystalline TiO2 particles (45 Å) with bidentate benzene derivatives (catechol, pyrogallol, and gallic acid) was found to alter optical properties of nanoparticles. The formation of the inner-sphere charge–transfer complexes results in a red shift of the semiconductor absorption compared to unmodified nanocrystallites. The binding structures were investigated by using FTIR spectroscopy. The investigated ligands have the optimal geometry for chelating surface Ti atoms, resulting in ring coordination complexes (catecholate type of binuclear bidentate binding–bridging) thus restoring in six-coordinated octahedral geometry of surface Ti atoms. From the Benesi–Hildebrand plot, the stability constants at pH 2 of the order 103 M−1 have been determined

Biology of human hair: Know your hair to control it

Hair can be engineered at different levels—its structure and surface—through modification of its constituent molecules, in particular proteins, but also the hair follicle (HF) can be genetically altered, in particular with the advent of siRNA-based applications. General aspects of hair biology are reviewed, as well as the most recent contributions to understanding hair pigmentation and the regulation of hair development. Focus will also be placed on the techniques developed specifically for delivering compounds of varying chemical nature to the HF, indicating methods for genetic/biochemical modulation of HF components for the treatment of hair diseases. Finally, hair fiber structure and chemical characteristics will be discussed as targets for keratin surface functionalization

Electrochemical investigation of some aromatic redox mediators immobilised on titanium phosphate

Some phenazines, phenoxazines, and phenothiazines as well as riboflavin were immobilised on amorphous titanium phosphate (TP) by adsorption from aqueous solutions. The immobilised organic redox compounds revealed a reasonable electron transfer rate and with a formal potential (E degrees') at pH 7.0 more positive than that observed for their corresponding aqueous soluble counterparts. This shift in the E degrees' was partly assigned to the acidity of TP. The E degrees' of the immobilised redox compound remained virtually constant with a variation of the solution pH between 1 and 8 and was attributed to the protection effect of the matrix. Attenuated total reflectance infrared spectroscopy (ATRIS) of methylene blue and riboflavin adsorbed onto TP deposited on ZnSe-prism was also used to shed further light on the interaction between these aromatic redox compounds and TP, as ATRIS is sensitive to the mode of adsorption of molecules on surfaces. Four of the immobilised compounds (Nile blue, methylene blue, toluidine blue O, methylene violet) were shown to be efficient as electron transfer mediators to electrocatalytically oxidise NADH in aqueous solution at pH 7.0. The kinetic parameters such as apparent Michaelis-Menten constant were obtained for these four immobilised mediators.191152