Immunoelectrochemical Biosensors for Detection of Saxitoxin and Brevetoxin

Abstract Prototype immunoelectrochemical sensors for marine biotoxins, brevetoxin and saxitoxin, have been developed using chemical immobilization techniques on a solid support membrane. Briefly, PbTx-3 antigen was conjugated to BSA by succinylation and linked covalently through the lysine moiety of BSA to an immobilon membrane. The membrane was then incubated with antibody to PbTx-3, which had been conjugated to the enzyme glucose oxidase by the glutaraldehyde method. A noncovalent, antibody-antigen reaction occurred and the resulting sensor reacted to challenges of a suitable substrate (β-D-glucose) by detection of H 2 O 2 amperometrically. Maximum signal occurred when Immobilized PbTx-3 or STX electrodes were incubated with antibody-enzyme without competition from free PbTx-3 or STX. Competition reactions between free marine biotoxins and the immobilized biotoxin in the presence of enzyme-labeled antibody will decrease the signal in a manner inversely proportional to the free brevetoxin or saxitoxin concentration.