Photocatalytic activity of AgInS2 quantum dots upon visible light irradiation for melatonin determination through its reactive oxygen species scavenging effect

• Type: Article in International Scientific Journal
• Date: 2020

Authors

Ribeiro, DSM (Author) Other; Castro, RC (Author) Other; Jose X Soares (Author) FFUP; Joao L M Santos (Author) FFUP

Journal

Title: Microchemical Journal

Vol. 155

ISSN: 0026-265X

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 13 Citations

Scopus - 15 Citations

Other information

Authenticus ID: P-00R-Q9C

DOI: 10.1016/j.microc.2020.104728

Abstract (EN): In this work, the ability of thiomalic acid (TMA)-capped AgInS2 quantum dots to generate reactive oxygen species (ROS) upon irradiation with visible light was investigated, which led to the subsequent development of a luminol-based chemiluminometric method for the monitoring of melatonin (MLT) in commercial dietary supplements. The developed approach was based on the antioxidant properties of melatonin conferred by the electron-rich aromatic indole ring which functions as an electron-donor moiety making it a potent direct scavenger of ROS. This capacity to scavenge free radicals was explored as a quantification process relying on MLT quenching effect on the CL emission of the luminol probe produced upon oxidation by ROS in alkaline medium. The short-lived chemiluminescent species resulting from this reactional scheme were detected by means of a multi-pumping flow system (MPFS) coupled to a photo-irradiation unit in order to allow an efficient control of the irradiation process, to improve the mixture between solutions and to reduce reagents' consumption. Upon optimization, the obtained results showed a linear relationship between the ratio of CL signal, in the absence (blank) and presence of the analyte (CL0/CL), and melatonin concentration for values of up to 100 mg L-1. The limit of detection was about 0.44 mg L-1.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 9