A G-quadruplex-selective luminescent iridium(III) complex and its application by long lifetime.
The G-quadruplex motif has been widely used for the construction of analytical detection platforms due to its rich structural polymorphism and flexibility. Luminescent assays are often limited due to the interference from endogenous fluorophores in biological samples.



To address this challenge, a novel long lifetime iridium(III) complex 1 was synthesized and used to construct a G-quadruplex-based assay for detecting prostate specific antigen (PSA) in aqueous solution. PSA is a common biomarker in serum and used as a model for demonstration in this work.



The PSA assay has achieved a detection limit of 40.8pg·mL-1, and shows high selectivity towards PSA over other proteins. Additionally, the assay could function in diluted human serum by using time-resolved luminescent spectroscopy, with good linearity from 1 to 10ng·mL-1of PSA, which is adequate to detect the PSA levels for physiological (<4ng·mL-1) and clinical (4-10ng·mL-1) applications.



The assay was successfully constructed. As revealed from time-resolved method, the long lifetime property of iridium(III) complex 1 plays an important role in distinguishing phosphorescence signals from short-life auto-fluorescence of human serum.



Luminescent transition metal complexes offer several advantages over other widely used organic fluorophores, such as long phosphorescence lifetime, large Stokes shift and modular syntheses. In addition, the assay could work effectively in diluted human serum using time-resolved luminescent spectroscopy, it therefore could be potentially developed to monitor PSA in biological samples. This article is part of a Special Issue entitled "G-quadruplex" Guest Editor: Dr. Concetta Giancola and Dr. Daniela Montesarchio.
Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
Sheng
S
Lin
Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China; College of Chemistry and Pharmaceutical Sciences, Qingdao Agricultural University, Qingdao, China.
Lihua
L
Lu
Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
Jin-Biao
JB
Liu
Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China.
Chenfu
C
Liu
State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China.
Tian-Shu
TS
Kang
State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China.
Chao
C
Yang
State Key Laboratory of Quality Research in Chinese Medicine, Institute of Chinese Medical Sciences, University of Macau, Macao, China. Electronic address: duncanleung@umac.mo.
Chung-Hang
CH
Leung
Department of Chemistry, Hong Kong Baptist University, Kowloon Tong, Hong Kong, China. Electronic address: edmondma@hkbu.edu.hk.
Dik-Lung
DL
Ma
D001665:Binding Sites; D004247:DNA / Q000737:chemistry / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism*; D054856:G-Quadruplexes; D006151:Guanosine / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007495:Iridium / Q000737:chemistry / Q000378:metabolism*; D007610:Kallikreins / Q000097:blood* / Q000737:chemistry; D008024:Ligands; D057230:Limit of Detection; D008163:Luminescent Measurements; D009942:Organometallic Compounds / Q000737:chemistry / Q000378:metabolism*; D011237:Predictive Value of Tests; D017430:Prostate-Specific Antigen / Q000097:blood* / Q000737:chemistry; D015203:Reproducibility of Results; D013050:Spectrometry, Fluorescence; D013329:Structure-Activity Relationship; D013997:Time Factors
D005456:Fluorescent Dyes; D008024:Ligands; D009942:Organometallic Compounds; D006151:Guanosine; D007495:Iridium; D004247:DNA; C549870:KLK3 protein, human; D007610:Kallikreins; D017430:Prostate-Specific Antigen
G-quadruplex; Iridium(III) complex; Luminescence; PSA; Phosphorescence