Complexes of Gold Nanoparticles with Antibodies in Immunochromatography: Comparison of Direct and Indirect Immobilization of Antibodies for the Detection of Antibiotics

Abstract

Complexes of spherical gold nanoparticles with antibodies, obtained by direct adsorption and indirect (nanoparticle–anti-species antibody–specific antibody) interaction, were studied. The binding processes for nanoparticle-labeled antibodies in immunochromatographic analysis (ICA) and competitive detection of low molecular weight analytes are considered. Based on the developed mathematical model, the advantages of indirect labeling of antibodies are shown; the parameters determining the gain in the detection limit between two kinds of systems are characterized. The obtained complexes of gold nanoparticles with antibodies were used for the development of ICA for antibiotics. The reached detection limit of ampicillin ICA is 100 ng/mL for direct labeling and 16 ng/mL for indirect; in the case of tetracycline, these values are equal to 4.2 and 1.3 ng/mL, respectively.