Rapid Detection of Aflatoxin B1 with Reusable Immunochemical Optrodes

Fiber optic measurement of aflatoxins will be performed suing optrodes specific for aflatoxin. One optrode will consist of aflatoxin linked by adsorption or immobilized by sulfhydryl groups on the tip of a fiber optic bundle. For determination of aflatoxin using immobilized F(ab') antibody, the antibody will first be cleaved and then immobilized to quartz plates or wafers by silinization. Aflatoxin-antibody conjugates, in which aflatoxin has a native fluorescence occurring at 362 nm, will be measured directly against a standard curve using a fluorimeter. Another scheme, in which the aflatoxin antibody is immobilized and then labeled with FITC or chemiluminescent tag (isoluminol), will be quenched due to the presence of free aflatoxin. Alternatively, an aflatoxin-oxime can be labeled with either FITC, through a isothiocyanate linkage, or with isoluminol glutaraldehyde condensation and immobilized on the fiber optic bundle. Aflatoxin antibody will be co-incubated with known (spiked) or unknown samples before measurement. As free aflatoxin concentrations increase, signals increase in a proportional manner. These measurements will be conducted with a Lumac Biocounter and plotted against a known standard curve. Optrode accuracy will be determined against standard in-house ELISA and HPLC methods performed at local USDA or FDA laboratories.