Fluorescent quantum dot-based nanotool for targeted identification and evaluation of the schistosomiasis circulating cathodic antigen in tissue samples.

Schistosomiasis represents a serious public health problem, a disease for which the circulating cathodic antigen (CCA) is a relevant biomarker. Quantum dots (QDs) are advantageous fluorescent nanoparticles that can be used as specific nanoprobes. In this study, a nanotool based on QDs and anti-CCA antibodies was developed, which, in association with fluorescence microscopy, was applied to trace and evaluate the CCA profile in schistosomiasis-infected tissue samples. Kidney and liver tissues from mice at different disease phases were used as models. QDs and the conjugates were characterized by absorption and emission spectroscopies. Microscopy analyses were used to map and assess CCA accumulation in infected tissue slices in respect to non-infected control samples. The fluorescent microplate assay (FMA) and Zeta potential (ζ) analyses indicated an effective conjugation, which was corroborated by the absence of labeling in non-infected tissue slices (which lack CCA) after incubation with the nanoprobe. Infected liver and kidney tissues exhibited notable staining by the QDs-anti-CCA conjugate. The CCA accumulation increased as follows: 30 < 60 = 120 days post-infection, with 30, 60, and 120 days corresponding to the pre-patent, acute, and beginning of chronic disease phases, respectively. Therefore, this innovative approach, combining imaging acquisition with the sensitivity and specificity of the QDs-anti-CCA conjugate, demonstrated efficiency in locating and comparatively evaluating CCA deposition in biological samples, thereby opening new possibilities for schistosomiasis research.