Di-branched triphenylamine dye sensitized TiO nanocomposites with good photo-stability for sensitive photoelectrochemical detection of organophosphate pesticides.
Journal:
Analytica chimica acta
Published Date:
Dec 12, 2017
Abstract
Herein, a di-branched di-anchoring dye, T(TA), with triphenylamine as electron donor, thiophene as electron transfer π-bridge, and acrylic acid as both acceptor and anchoring groups, was synthesized and coupled with TiO nanoparticles for the highly sensitive photoelectrochemical (PEC) assay of organophosphate pesticides (OPs). The T(TA) exhibited good anchoring stability to TiO nanoparticles in neutral buffer solutions. Under 2 h continual irradiation, the T(TA)-TiO nanocomposites respectively kept 99.7% and 85.9% of their initial photocurrents in neutral Tris-HCl and phosphate buffer solutions. Neither degradation nor desorption of T(TA) from TiO nanoparticles was observed during the continual irradiation in the Tris-HCl solutions. The stability was not only superior to its analogues either possessing one branch, with cyanoacrylic acid as anchoring groups, or without thiophene in the π-bridge, but also better than the Ru(II) complex N719 and the porphyrin dye sensitized TiO nanocomposites. The nanocomposites also showed highly photocatalytic ability towards the oxidation of ascorbic acid and thiocholine (TCh). Since the latter is the enzymatic hydrolysis product of acetylcholinesterase (AChE) and the activity of AChE can be inhibited by OPs, the T(TA)-TiO/FTO was further used for PEC assay of OPs. Using parathion as a model analyte, the PEC method showed a wide linear range from 2 × 10-4 × 10 g mL and an extremely low limit of detection of 5.6 × 10 g mL. Regarding these good analytical performances, this study may provide some guidance and pave the way for the applications of dye-TiO nanocomposites in a lot of PEC devices required to be performed in aqueous solutions.
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