title: Development of an Iridium(III) Complex as a G-Quadruplex Probe and Its Application for the G-Quadruplex-Based Luminescent Detection of Picomolar Insulin.
abstract: In this study, an unreported Ir(III) complex 1 was identified by screening as a versatile G-quadruplex probe. It exhibited highly selective response for different G-quadruplex DNA over double strand, single strand and triplex DNA. Compared with the organic G-quadruplex probe thioflavin T, complex 1 displays a longer lifetime, a larger Stokes shift, comparable G-quadruplex/ssDNA enhancement ratios, and higher G-quadruplex/triplex DNA enhancement ratios. In consideration of the encouraging G-quadruplex probe performance of complex 1, we employed 1 to develop a G-quadruplex-based detection system for the detection of insulin as a "proof-of-principle" concept. We also demonstrate an optimization process that enhanced the sensitivity of this sensing assay. Compared to previously reported methods, our "mix-and-detect" detection methodology is easy operated, quick, and cost-effective. A detection limit as low as 80 pM for insulin can be achieved by this sensing approach, with a linear relationship between luminescence intensity and insulin concentration established from 80 pM to 20 nM. Moreover, this assay could work effectively in diluted human serum.
authors.affiliation: Department of Chemistry, Hong Kong Baptist University , Kowloon Tong, Hong Kong, China.
authors.forename: Modi
authors.initials: M
authors.lastname: Wang
authors.affiliation: Department of Chemistry, Hong Kong Baptist University , Kowloon Tong, Hong Kong, China.
authors.forename: Wanhe
authors.initials: W
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau , Macao, China.
authors.forename: Tian-Shu
authors.initials: TS
authors.lastname: Kang
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.|Partner State Key Laboratory of Environmental and Biological Analysis, Hong Kong Baptist University , Hong Kong, China.
authors.forename: Dik-Lung
authors.initials: DL
authors.lastname: Ma
mesh_terms: D005456:Fluorescent Dyes / Q000737:chemistry*; D054856:G-Quadruplexes; D006801:Humans; D007328:Insulin / Q000097:blood*; D007495:Iridium / Q000737:chemistry*; D049449:Luminescence; D008163:Luminescent Measurements; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*
chemical_list: D005456:Fluorescent Dyes; D007328:Insulin; D009942:Organometallic Compounds; D007495:Iridium