Ochratoxin A immunoassay with surface plasmon resonance registration: Lowering limit of detection by the use of colloidal gold immunoconjugates

An immunoanalytical system was developed for the determination of ochratoxin A with the use of a surface plasmon resonance (SPR) sensor amplified by the anti-species antibody–colloidal gold particle (CGP) conjugate. The use of the binding of immune complexes to the CGP–anti-species antibody conjugate leads to the SPR signal amplification by a factor of more than 10 and results in the 60 pg/mL limit of detection of ochratoxin A with an assay time of 30 min. These characteristics are superior to those obtained both in the conventional enzyme immunoassay with the use of the same reagents and the SPR assay with unmodified antibodies and specific antibodies conjugated to colloidal gold.