title: A signal-on fluorescent aptasensor based on Tb3+ and structure-switching aptamer for label-free detection of Ochratoxin A in wheat.
abstract: On the basis of Tb(3+), structure-switching aptamer and magnetic beads (MBs), a signal-on fluorescent aptasensor was developed for the label-free determination of OTA in wheat. Initially, the specific sequence of the anti-OTA aptamer labeled with a biotin group, was attached to streptavidin-modified MBs. Two single-stranded signal probes were added and naturally hybridized with anti-OTA aptamer to form the duplex structure in the solution. Due to the fact that single-stranded oligonucleotides can greatly enhance the emission of Tb(3+) in solution but duplexes do not, through magnetic separation, the supernatant liquid of the above solution contained no single-stranded DNA and cannot increase the emission of Tb(3+). While upon OTA addition, it will bind with aptamer to form OTA-aptamer G-quadruplex while releasing two single-stranded signal probes. Through magnetic separation, the released single-stranded signal probes left in the supernatant liquid can dramatically increase the fluorescent intensity of Tb(3+). By employing the above strategy, this aptasensor can detect as low as 20 pg/mL OTA with high specificity. To the best of our knowledge, the proposed aptasensor is the first attempt to use the fluorescent characteristics of Tb(3+) for OTA detection, which may represent a promising path toward routine quality control of food safety.
authors.affiliation: The Ministry of Education Key Laboratory of Biopesticide and Chemical Biology, and College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, Fujian 350002, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhang
authors.forename: Xi
authors.initials: X
authors.lastname: Zhang
authors.forename: Guidi
authors.initials: G
authors.lastname: Yang
authors.forename: Jinghua
authors.initials: J
authors.lastname: Chen
authors.forename: Shihua
authors.initials: S
authors.lastname: Wang
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry* / Q000235:genetics; D015374:Biosensing Techniques / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005504:Food Analysis / Q000295:instrumentation*; D005506:Food Contamination / Q000032:analysis*; D018189:Immunomagnetic Separation / Q000295:instrumentation; D009793:Ochratoxins / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000295:instrumentation*; D013194:Staining and Labeling; D013725:Terbium / Q000737:chemistry; D014908:Triticum / Q000737:chemistry*
chemical_list: D052157:Aptamers, Nucleotide; D009793:Ochratoxins; D013725:Terbium; C025589:ochratoxin A