Development of Fluorescent Aptasensors Based on G-Quadruplex Quenching Ability for Ochratoxin A and Potassium Ions Detection

• Published in: Biosensors (Basel) 2022-06, Vol.12 (6), p.423
• Main Authors: Yang, Cheng, Chu, Xiaolin, Zeng, Li, Rhouati, Amina, Abbas, Fathimath, Cui, Shengnan, Lin, Daiqin
• Format: Article
• Language: English
• Subjects: Biosensors; Chloride; Design and construction; DNA sequencing; Electron transfer; Experiments; Fluorescein; Fluorescence; fluorescence aptasensor; G-quadruplex; Ions; label-free; Ligands; Measurement; Methods; Mycotoxins; Nucleic acid aptamers; Nucleotide sequencing; Ochratoxin A; photo-induced electron transfer; Potassium; Quenching; Selectivity
• ISSN: 2079-6374; 2079-6374
• DOI: 10.3390/bios12060423

G-quadruplexes have received significant attention in aptasensing due to their structural polymorphisms and unique binding properties. In this work, we exploited the fluorescence-quenching properties of G-quadruplex to develop a simple, fast, and sensitive platform for fluorescence detection of ochratoxin A (OTA) and potassium ions (K+) with a label-free fluorophore and quencher strategy. The quenching ability of G-quadruplex was confirmed during the recognition process after the formation of the G-quadruplex structure and the quenching of the labeled fluorescein fluorophore (FAM). The fluorescence-quenching mechanism was studied by introducing specific ligands of G-quadruplex to enhance the quenching effect, to show that this phenomenon is due to photo-induced electron transfer. The proposed fluorescence sensor based on G-quadruplex quenching showed excellent selectivity with a low detection limit of 0.19 nM and 0.24 µM for OTA and K+, respectively. Moreover, we demonstrated that our detection method enables accurate concentration determination of real samples with the prospect of practical application. Therefore, G-quadruplexes can be excellent candidates as quenchers, and the strategy implemented in the study can be extended to an aptasensor with G-quadruplex.