title: Application of iridium(III) complex in label-free and non-enzymatic electrochemical detection of hydrogen peroxide based on a novel "on-off-on" switch platform.
abstract: We herein report a label-free and non-enzymatic electrochemical sensor for the highly sensitive detection of hydrogen peroxide (H2O2) based on a novel "on-off-on" switch system. In our design, MB was used as an electron mediator to accelerate the electron transfer while AuNPs was used to amplify the electrochemical signal due to its excellent biocompatibility and good conductivity. The "switch-off" state was achieved by introducing the guanine-rich capture probe (CP) and an iridium complex onto the electrode surface to form a hydrophobic layer, which then hinders electron transfer. Upon addition of H2O2, fenton reaction occurs and produces OH• in the presence of Fe(2+). The OH• cleaves the CP into DNA fragments, thus resulting in the release of CP and iridium complex from the sensing interface, recovering the electrochemical signal to generate a "switch-on" state. Based on this novel switch system, a detection limit as low as 3.2 pM can be achieved for H2O2 detection. Moreover, satisfactory results were obtained by using this method for the detection of H2O2 in sterilized milk. To the best of our knowledge, this is the first G-quadruplex-based electrochemical sensor using an iridium(III) complex.
authors.affiliation: Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
authors.forename: Xiangmin
authors.initials: X
authors.lastname: Miao
authors.affiliation: State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China.
authors.forename: Chung-Hang
authors.initials: CH
authors.lastname: Leung
authors.affiliation: Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
authors.forename: Dik-Lung
authors.initials: DL
authors.lastname: Ma