Serological diagnosis of Toxoplasmosis disease using a fluorescent immunosensor with chitosan-ZnO-nanoparticles

VICTORIA MEDAWAR-AGUILAR; CLAUDIO F. JOFRÉ ; MARTÍN A. FERNÁNDEZ-BALDO ; ANDRÉS ALONSO; SERGIO ANGEL; JULIO RABA ; SIRLEY V. PEREIRA ; GERMÁN A. MESSINA

ANALYTICAL BIOCHEMISTRY

ACADEMIC PRESS INC ELSEVIER SCIENCE

Lugar: Amsterdam; Año: 2018

0003-2697

This article describes a microfluidic LIF immunosensor for the quantitative determination of anti-Toxoplasma gondii IgG (anti-T. gondii) specific antibodies. The serological detection of these antibodies plays a key role in the clinical diagnosis of toxoplasmosis. Zinc oxide nanoparticles (ZnO-NPs) obtained by wet chemical procedure were covered with chitosan and then used to conjugate T-gondii antigens into the central microfluidic channel. Serum samples containing anti-T-gondii IgG antibodies were injected into the immunosensor where it reacted immunologically with T. gondii antigens. Bound antibodies are quantified after addition of alkaline phosphatase labeled anti-IgG antibodies which, in the presence of non-fluorescent 4-methylumbelliferyl phosphate (4-MUP) was converted to soluble fluorescent methylumbelliferone which was measured using excitation at 355 nm and emission at 440 nm. The relative fluorescent response of methylumbelliferone is proportional to the concentration of anti-T. gondii IgG antibodies in the range from 0 to 200 U⋅mL-1. The coefficients of variation are less than 4.27 % for within-day assays, and less than 6.76 % for between-day assays. Results acquired by LIF immunosensor agree with those obtained by enzyme-linked immunesorbent assay method, suggesting that the designed sensor represents a promising tool for the quantitative determination of anti-T. gondii IgG antibodies of clinical samples