Aptamer-based competitive electrochemical biosensor for brevetoxin-2.
Brevetoxins (BTXs) are very potent marine neurotoxins that increased in geographical distribution in the past decade causing the illness clinically described as neurological shellfish poisoning (NSP). The ethical problems as well as the technical difficulties associated with the currently employed analysis methods for marine toxins are encouraging the research for suitable alternatives to be applied in a regulatory monitoring regime. Here, we report an electrochemical biosensor platform for BTX-2 detection utilising aptamer as specific receptor. Using in vitro selection, high affinity DNA aptamers to BTX-2 were successfully selected for the first time from a large pool of random sequences. The binding of BTX-2 to aptamer pools/clones was monitored using fluorescence and electrochemical impedance spectroscopy (EIS). The aptamer BT10 exhibited the highest binding affinity to BTX-2, with a dissociation constant of 42nM. The effects of the incubation time, pH and metal ions concentrations on the aptamer-toxin binding were studied. The aptamer BT10 was used to construct a label-free competitive impedimetric biosensor for BTX-2 achieving a detection limit of 106pg/ml. We observed a high degree of cross reactivity of the selected aptamer to the two similar congeners, BTX-2 and -3, whereas no cross reactivity to other marine toxins was obtained. Moreover, the aptasensor was applied for the detection of BTX-2 in spiked shellfish extract showing a very high recovery percentage. We believe that the proposed aptasensor will facilitate the routine detection of BTX-2 in food samples.
Institut National de la Recherche Scientifique, Centre - Énergie, Matériaux et Télécommunications, 1650, Boul. Lionel Boulet, Varennes, Que., Canada J3X 1S2; Dept. de Chimie et Biochimie, Université du Quebec à Montreal, Montreal, Que., Canada H3C 3P8. Electronic address: shimaaeissa@yahoo.com.
Shimaa
S
Eissa
Dept. de Chimie et Biochimie, Université du Quebec à Montreal, Montreal, Que., Canada H3C 3P8.
Mohamed
M
Siaj
Center of Biomedical Engineering, Cranfield University, Cranfield, Bedfordshire MK43 0AL, UK; Department of Chemistry, Alfaisal University, Riyadh 11533, Saudi Arabia. Electronic address: m.zourob@cranfield.ac.uk.
Mohammed
M
Zourob
D000818:Animals; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation*; D058266:Dielectric Spectroscopy / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005504:Food Analysis / Q000295:instrumentation*; D005506:Food Contamination / Q000032:analysis; D008387:Marine Toxins / Q000032:analysis* / Q000737:chemistry; D035964:Oxocins / Q000032:analysis* / Q000737:chemistry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012758:Shellfish / Q000032:analysis*; D000095702:Polyether Toxins
D052157:Aptamers, Nucleotide; D008387:Marine Toxins; D035964:Oxocins; C546611:brevetoxin 2; D000095702:Polyether Toxins
Aptasensor; DNA aptamer; Electrochemical Impedance spectroscopy; In vitro selection