Citation:
Alice X. J. Tang, Miloslav Pravda, George G. Guilbault, Sergey Piletsky and Anthony P. F. Turner, Immunosensor for okadaic acid using quartz crystal microbalance, Analytica Chimica Acta, Volume 471, Issue 1, 23 October 2002, Pages 33-40
Abstract:
An immunosensor for the determination of okadaic acid (OA) using a quartz
crystal microbalance (QCM) was developed and optimised in standard solutions.
Several coupling techniques, protein A, protein G and polyethylenimine (PEI)
with glutaraldehyde (GA) cross-linking, were investigated for the determination
of okadaic acid and a very good result was obtained with PEI coupling. With the
PEI coupling method, the optimisation of incubation time for the activation of
PEI on the crystal surface using GA, the effect of the dilution factor of OA-BSA
conjugate and the amount of antibody on crystal frequency were studied.
Different molar ratios (4:1, 14:1, 30:1) of OA to bovine serum albumin (BSA) for
the conjugation were examined and the results using ELISA and a QCM showed that
a ratio of 14:1 was slightly better than the other two. The strong attachment of
the cross-linked complex to the gold surface resulted in an excellent storage
lifetime of 38 days. However, the detection limit (1.9 µg/ml) and the
sensitivity of the sensor were not satisfactory. Significant improvement of the
performance of the device was obtained by incorporating an antibody-BSA
hydrogel. Initial results showed that the minimum amount of analyte detectable
and the sensitivity of the device were improved by 524 and 80 fold, respectively
