Photoelectrochemical sensing of tannic acid based on the use of TiO2 sensitized with 5-methylphenazinium methosulfate and carboxy-functionalized CdTe quantum dots
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The article describes a method for determination of tannic acid in extracts of medicinal plants. Tannic acid (TA) is an antioxidant and has anticancer and antimicrobial properties. Titanium dioxide nanoparticles (TiO2) were co-sensitized with 5-methylphenazinium methosulfate (PMS) and carboxy-functionalized cadmium telluride quantum dots (CdTe QDs), and immobilized on a fluorine-doped tin oxide electrode. The surface morphology and electrochemical properties of the modified electrode were investigated by scanning electron microscopy and amperometry, respectively. A composite consisting of TiO2, PMS and CdTe QDs in a nafion film has a response to TA under LED light higher than that observed for each separate component. Under optimized experimental conditions and at an applied voltage of +0.4 V vs Ag/AgCl, the photoelectrochemical sensor has a linear response in the 0.2 to 200 μmol L−1 TA concentration range and a detection limit of 60 nmol L−1. The sensor was successfully applied to the determination of TA in spiked extracts from three medicinal plants, with recovery values between 98.3 and 103.9 %.
KeywordsPhotoelectrochemistry LED light Nanoparticles Quantum dots Phenazine Medicinal plants
The authors are grateful to FAPEMA (PRONEM-00155/16; UNIVERSAL-00927/16; UNIVERSAL-01194/17), CNPq (303525/2016-9; 421139/2016-1; 305680/2015-3;426337/2016-6), and Instituto Nacional de Ciência e Tecnologia em Bioanalítica (465389/2014-7) for financial support. The authors are grateful to the Microscopy Center/UFMG by the SEM images.
Compliance with ethical standards
The author(s) declare that they have no competing interests.
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