Аннотация:Because of unique optical properties and easy complexation with biopolymers, gold nanoparticles (GNPs) are actively used as markers in various analytical systems, in particular, as components of conjugates with antibodies in rapid immunochromatographic test systems (ICTSs). However, the choice of the most effective conjugates is often empirical. We compared the possibilities of direct sorption immobilization of antibodies on the surface of GNPs and indirect immobilization through the binding of native-specific antibodies to immobilized antispecies antibodies. The work was performed using the example of ICTS for the detection of microcystin- LR (MC-LR), an extremely dangerous phycotoxin produced by microalgae that contaminates drinking water, fish, and seafood. The formats of ICTS with direct and indirect labeling of specific antibodies were compared. It has been shown that indirect labeling provides a lower limit of detection (LOD) for MC-LR than the direct one (the LODs for visual assessment of the results were 0.2 ng/mL and 1 ng/mL, respectively). The duration of the assay was 20 min. The advantages of ICTSs were shown by comparison with a homogeneous MC-LR immunoassay based on fluorescence polarization detection. It was found that the limit of detection of MC-LR for the last assay is 7.5 ng/mL despite the equilibrium of immune interactions. The data obtained confirm the advantages of using indirect immobilization of antibodies on the surface of GNPs, which preserves the functional properties of bound molecules.
