Publications (108) View all
-
Article: Electrochemical grafting of long spacer arms of hexamethyldiamine on a screen printed carbon electrode surface: application in target induced ochratoxin A electrochemical aptasensor.
[show abstract] [hide abstract]
ABSTRACT: A novel strategy based on direct electrochemistry of amino group on screen printed carbon electrode surface (SPCE) was purposed. The purposed method was employed for the label free detection of ochratoxin A (OTA). A long spacer arm of hexamethyldiamine was immobilized on SPCE via electrochemical oxidation of its terminal amino-group. The activated carboxy-aptamer was covalently linked to other amino terminal group of immobilized hexamethyldiamine. The designed immobilized macromolecules resulted in the formation of long clusters on SPCE surface, while aptamer acted as gate to block the entrance of these clusters. The aptamer gates were closed due to change in conformation of aptamer upon target analyte binding, decreasing the electrochemical signal. The decrease in electrochemical signal was used for the detection of target molecule.The Analyst 03/2013; · 4.23 Impact Factor -
Article: Improvement of the efficiency and simplification of ELISA tests for rapid and ultrasensitive detection of okadaic acid in shellfish
[show abstract] [hide abstract]
ABSTRACT: Okadaic acid (OA) is a marine toxin ingested by shellfish. The consumption of contaminated seafood causes diarrheic shellfish poisoning, responsible for gastrointestinal troubles in humans. The development of fast, reliable and sensitive methods for OA analysis is an evident necessity in order to guarantee the seafood safety and to protect human health. In this work, competitive indirect immunoassays were developed for the toxin detection. Indirect and direct labeling were used and compared. With indirect labeling, the unlabeled anti-OA antibody binds to the toxin and a labeled secondary antibody is used for the signal generation. Alternatively, using the direct labeling, the label is attached via a covalent bond to the anti-OA antibody. In this work, peroxidase was conjugated to the anti-OA antibody through a periodate activation. The peroxidaseeantibody conjugate is used for both toxin recognition and signal generation. In the last case, ELISA test is simplified and the colorimetric competitive indirect immunoassay based on direct labeling is more sensitive to OA than the test based on indirect labeling. In optimized conditions, the IC50 value and detection limit were respectively 0.066 mg L�1 and 0.0061 mg L�1. Then, the colorimetric immunoassay based on direct labeling was validated with certified reference mussel samples, demonstrating the efficiency of the approach.Food Control 03/2013; 30(1):144-149. · 2.66 Impact Factor -
Article: Development of a colorimetric inhibition assay for microcystin-LR detection: comparison of the sensitivity of different protein phosphatases.
[show abstract] [hide abstract]
ABSTRACT: A colorimetric protein phosphatase (PP) inhibition test for the detection of microcystin-LR (MC-LR) has been developed. Three PP2As, one recombinant and two natural versions, as well as one PP1 produced by molecular engineering, were tested. First, assays were performed using the enzymes in solution to compare their sensitivity to MC-LR. The PP2A purchased from ZEU Immunotec and PP1 appeared more sensitive to the toxin than the other enzymes. With PP2A from ZEU Immunotec, the colorimetric test showed a detection limit of 0.0039 μg L(-1) and an IC(50) value of 0.21 μg L(-1). With PP1, the assay gave a detection limit of 0.05 μg L(-1) and an IC(50) value of 0.56 μg L(-1). Therefore, this assay allowed the detection of lower microcystin-LR (MC-LR) concentrations than the maximum level (1 μg L(-1)) recommended by the World Health Organisation (WHO). The main drawback of this PP-based approach in solution is poor enzyme stabilisation. To overcome this problem, enzymes were entrapped within either a photopolymer or an agarose gel. PP2A from ZEU Immunotec and PP1 were immobilised at the bottom of microwells. The agarose-based tests performed better than the photopolymer-based assay for all of the enzymes. Therefore, the agarose gel is a good candidate to replace the photopolymer, which is generally used in PP-immobilising membranes. The assays based on enzyme-entrapping agarose gels showed detection limits equal to 0.17 μg L(-1) and 0.29 μg L(-1) with immobilised PP2A from ZEU and PP1, respectively. In view of these performances, these tests can potentially be used for monitoring water quality.Talanta 02/2013; 85(5):2498-503. · 3.79 Impact Factor -
Article: Detection of the marine toxin okadaic acid: Assessing seafood safety.
[show abstract] [hide abstract]
ABSTRACT: Diarrheic Shellfish Poisoning (DSP) is a gastrointestinal illness caused by consumption of shellfish contaminated with DSP toxins such as okadaic acid (OA) and dinophysistoxins (DTX). The occurrences of OA in bivalves induce not only public health problems but also economic damages to shellfish farming. Consequently, the development of fast, reliable and sensitive detection methods is an evident necessity. The mouse bioassay has been the reference and most commonly used analysis method. However, this technique suffers from low accuracy, specificity and ethical problems due to the animal experimentation. Thus, the development of alternative and efficient detection systems is required. Several biological, chemical, and immunological methods have been developed to evaluate the presence of DSP toxins in seafood. This review gives an overview of different analytical methods and new trends for the detection of OA. Over the past decade, considerable attention has been given to the development of biosensors for the efficient detection of marine toxin. Recent advances in the field of aptamers and nanomaterial offer exciting new opportunities to develop improved and more reliable devices allowing the detection of OA.Talanta 02/2013; 105C:306-316. · 3.79 Impact Factor -
Article: Design of PEG-aptamer two piece macromolecules as convenient and integrated sensing platform: Application to the label free detection of small size molecules.
[show abstract] [hide abstract]
ABSTRACT: A novel strategy for the fabrication of electrochemical label free aptasensor for small size molecules is purposed, and the strategy has been demonstrated by the development of an aptasensor for ochratoxin (A). A long spacer chain of polyethylene glycol (PEG) was immobilized on screen printed carbon electrode (SPCE) via electrochemical oxidation of its terminal amino-group. The amino-aptamer was covalently linked to carboxy end of immobilized PEG to form two piece macromolecules. The designed immobilized macromolecules resulted in the formation of long tunnels on SPCE surface, while aptamer acted as gate of the tunnels. The aptamer gates were closed due to change in conformation of aptamer upon target analyte binding, decreasing the electrochemical signal. The decrease in electrochemical signal was used for the detection of target molecule.Biosensors & bioelectronics 02/2013; 45C:168-173. · 5.43 Impact Factor
