Fluorescent immunosensor using AP-SNs and QDs for quantitation of IgG anti-Toxocara canis

IgG anti-T. canis antibodies detection was carried out using a non-competitive immunoassay, in which excretory-secretory antigens from T. canis second-stage larvae (TES) were covalently immobilized on 3-aminopropyl-functionalized silica-nanoparticles (AP-SNs). Antibodies present in serum samples immunologically reacted with TES and then were quantified by using a second antibody labeled with cadmium selenide zinc sulfide quantum dots (CdSe-ZnS QDs). The concentration of IgG anti-T. canis antibodies present in the serum sample was measured by LIF detector, using excitation lambda at 491 nm and emission at 540 nm. The total assay time was 30 min, having made LIF detection in less than 1 min. The detection limit calculated for the proposed methodology was 0.12 ng mL− 1 and the coefficients of intra- and inter-assay variation were less than 6%. The results show the usefulness of the developed immunosensor for the fast determination of IgG antibodies anti-T. canis.