TY - JOUR
T1 - Immunoassay for folic acid detection in vitamin-fortified milk based on electrochemical magneto sensors
AU - Lermo, A.
AU - Fabiano, S.
AU - Hernández, S.
AU - Galve, R.
AU - Marco, M. P.
AU - Alegret, S.
AU - Pividori, M. I.
PY - 2009/3/15
Y1 - 2009/3/15
N2 - An immunoassay-based strategy for folic acid in vitamin-fortified milk with electrochemical detection using magneto sensors is described for the first time. Among direct and indirect competitive formats, best performance was achieved with an indirect competitive immunoassay. The immunological reaction for folic acid (FA) detection was performed, for the first time on the magnetic bead as solid support by the covalent immobilization of a protein conjugate BSA-FA on tosyl-activated magnetic bead. Further competition for the specific antibody between FA in the food sample and FA immobilized on the magnetic bead was achieved, followed by the reaction with a secondary antibody conjugated with HRP (AntiIgG-HRP). Then, the modified magnetic beads were easily captured by a magneto sensor made of graphite-epoxy composite (m-GEC) which was also used as the transducer for the electrochemical detection. The performance of the immunoassay-based strategy with electrochemical detection using magneto sensors was successfully evaluated using spiked-milk samples and compared with a novel magneto-ELISA based on optical detection. The detection limit was found to be of the order of μg l-1 (13.1 nmol l-1, 5.8 μg l-1) for skimmed milk. Commercial vitamin-fortified milk samples were also evaluated obtaining good accuracy in the results. This novel strategy offers great promise for rapid, simple, cost-effective and on-site analysis of biological and food samples. © 2008 Elsevier B.V. All rights reserved.
AB - An immunoassay-based strategy for folic acid in vitamin-fortified milk with electrochemical detection using magneto sensors is described for the first time. Among direct and indirect competitive formats, best performance was achieved with an indirect competitive immunoassay. The immunological reaction for folic acid (FA) detection was performed, for the first time on the magnetic bead as solid support by the covalent immobilization of a protein conjugate BSA-FA on tosyl-activated magnetic bead. Further competition for the specific antibody between FA in the food sample and FA immobilized on the magnetic bead was achieved, followed by the reaction with a secondary antibody conjugated with HRP (AntiIgG-HRP). Then, the modified magnetic beads were easily captured by a magneto sensor made of graphite-epoxy composite (m-GEC) which was also used as the transducer for the electrochemical detection. The performance of the immunoassay-based strategy with electrochemical detection using magneto sensors was successfully evaluated using spiked-milk samples and compared with a novel magneto-ELISA based on optical detection. The detection limit was found to be of the order of μg l-1 (13.1 nmol l-1, 5.8 μg l-1) for skimmed milk. Commercial vitamin-fortified milk samples were also evaluated obtaining good accuracy in the results. This novel strategy offers great promise for rapid, simple, cost-effective and on-site analysis of biological and food samples. © 2008 Elsevier B.V. All rights reserved.
KW - Electrochemical immunosensor
KW - Folic acid
KW - Fortified milk
KW - Indirect competitive immunoassay
KW - Magnetic beads
U2 - 10.1016/j.bios.2008.10.020
DO - 10.1016/j.bios.2008.10.020
M3 - Article
SN - 0956-5663
VL - 24
SP - 2057
EP - 2063
JO - Biosensors and Bioelectronics
JF - Biosensors and Bioelectronics
IS - 7
ER -