Screen-printed immunosensor modified with carbon nanotubes in a continuous-flow system for the Botrytis cinerea determination in apple tissues

MARTÍN FERNANDEZ BALDO; GERMÁN ALEJANDRO MESSINA; MARIA I. SANZ; JULIO RABA

TALANTA

ELSEVIER SCIENCE BV

Año: 2009 vol. 79 p. 681 - 686

0039-9140

Botrytis cinerea is a plant-pathogenic fungus that produces the disease known as grey mould in a widevariety of agriculturally important hosts in many countries. This paper describes the development of animmunosensor coupled to carbon-based screen-printed electrodes (SPCE) modified with multi-walledcarbon nanotubes (CNTs), which show a rapid and sensitive determination of B. cinerea in apple tissues(Red-delicious) using a competitive immunoassay method.Both the infected plant tissue sample and the B. cinerea-specific monoclonal antibody are allowedto react immunologically with the B. cinerea purified antigens immobilized on a rotating disk. Then,the bound antibodies are quantified by a horseradish peroxidise (HRP) enzyme labeled second antibodiesspecific to mouse IgG, using 4-tertbutylcatechol (4-TBC) as enzymatic mediators. The HRP, inthe presence of hydrogen peroxide, catalyses the oxidation of 4-TBC to 4-tertbutyl o-benzoquinone. Theelectrochemical reduction back to 4-TBC is detected on SPCE-CNT at −0.15 V. The response current isinversely proportional to the amount of the B. cinerea antigens present in the fruit sample. The timeconsumed per assay was 30 min and the calculated detection limits for electrochemical method and theELISA procedure are 0.02 and 10gmL−1, respectively. Moreover the intra- and inter-assay coefficientsof variation were below 7%. This electrochemical immunosensor promises to be usefully suited to thedetection and quantification of B. cinerea in apparently healthy plant prior to the development of thesymptoms.