Background: 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.
Methods: 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.
Results: The PSA assay has achieved a detection limit of 40.8 pg·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 10 ng·mL−1 of PSA, which is adequate to detect the PSA levels for physiological (< 4 ng·mL−1) and clinical (4–10 ng·mL−1) applications.
Conclusions: 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.
General significance: 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.
Scopus Subject Areas
- Molecular Biology
- Iridium(III) complex