Amperometric Bioelectrode For Specific Human IgG Determination: Optimisation Of The Method To Diagnose American Trypanosomiasis

MARÍA E. RIBONE, MARÍA S. BELLUZO, DANIELA PAGANI, MARCIPAR IVÁN S. (DIRECTOR EN COLABORACIÓN) AND CLAUDIA M. LAGIER

ANALYTICAL BIOCHEMISTRY

Año: 2005

0003-2697

Bioelectrodes to detect IgG antibodies occurring in sera of patients suffering from American trypanosomiasis were assembled. The device consisted of a gold electrode modified with a thiol, sensitized with parasite proteins. The assemblage was accomplished by adsorbing IgG antibodies from confirmed infected patients, followed by adsorption of anti-human IgG, labeled with a redox enzyme. The appliance was used as a working electrode in a three-electrode cell containing a soluble charge-transfer mediator, also behaving as enzyme co-substrate. The method is based on the measurement of the catalytic current after addition of the enzyme substrate, occurring when a positive serum is used to build-up the biosensor. The discrimination efficiency between positive and negative sera was 100%, for the samples studied. A 0.9525 correlation coefficient was obtained for results acquired by using this approach and one commercial diagnostic kit. The reproducibility, evaluated by the percentage coefficient of variation, varied between 7 and 20%. The sensitivity was 12.4 ng mL-1 IgG, which is in the same order than that obtained with the commercial kit. Stability of the device was studied for a seven-day period and the results showed no significant change (p=0.218). Leishmaniasic sera showed cross-reactivity, when using total parasite homogenate as antigen.