G-quadruplex-selective iridium(III) complex as a novel electrochemiluminescence probe for switch-on assay of double-stranded DNA

• Published in: Analytical and bioanalytical chemistry 2022-05, Vol.414 (13), p.3755-3763
• Main Authors: Wu, Shujie, Wang, Songen, Li, Zongbing, Wu, Chun, Ma, Dik-Lung, Miao, Xiangmin
• Format: Article
• Language: English
• Subjects: Analysis; Analytical Chemistry; Assaying; Biochemistry; Biosensing Techniques - methods; Biosensors; Characterization and Evaluation of Materials; Chemical synthesis; Chemistry; Chemistry and Materials Science; Coordination compounds; Deoxyribonucleic acid; DNA; DNA - chemistry; DNA sequencing; Electrochemiluminescence; Electrodes; Food Science; G-Quadruplexes; Gene sequencing; Genetic testing; Iridium; Iridium - chemistry; Iridium compounds; Laboratory Medicine; Luminescence; Luminescent Measurements - methods; Methods; Monitoring/Environmental Analysis; Nucleotide sequence; Nucleotide sequencing; Paper in Forefront; Potassium; Properties; Quantum dots; Selectivity; Structure
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-022-04018-2

In this work, we synthesized an iridium(III) complex and studied its selective ability to interact with a specific G-quadruplex DNA sequence (GTGGGTAGGGCGGGTTGG). Results showed that the iridium(III) complex exhibits high selectivity for the G-quadruplex DNA and could be used as an efficient electrochemiluminescence (ECL) probe in a switch-on assay format for the detection of double-stranded DNA (dsDNA). To construct the assay, a hairpin-structured capture probe (CP) which was modified by thiol at its 3′ end and contained the G-quadruplex sequence at its 5′ end was firstly immobilized on a gold electrode. Upon the specific recognition of the dsDNA sequence with the corresponding CP, the hairpin structure of the CP was opened to free G-quadruplex sequence, forming the G-quadruplex structure with the assistance of K + . Then, the iridium(III) complex was able to specifically interact with the G-quadruplex to produce an obvious ECL signal that was proportional to the dsDNA concentration. Notably, this iridium(III) complex/G-quadruplex-based strategy was universal and was not limited to the analysis of DNA using specific sequences, thus opening a new avenue for the application of the G-quadruplex-selective iridium(III) complex in the field of ECL.