Characteristics of Liposome Immunosorbent Assay (LISA) Using Liposomes Encapsulating Coenzyme β-NAD⁺

Abstract

Liposomes encapsulating coenzyme β-NAD⁺ were used for liposome immunosorbent assay (LISA) of antibodies and antigens in place of labeled antibodies in ELISA. Conjugated redox reactions involving β-NAD⁺ can accumulate a colored material and attained high signals in detection of the released marker. The sensitivities of sandwich LISA were compared with those of direct LISA, as well as with ELISA. The immunointeraction of antibody coupled on the surface of liposomes with antigen was studied. The liposomes encapsulating β-NAD⁺ could be used in LISA for measurement of antigens and antibodies, and sandwich LISA showed the higher sensitivity than direct LISA. Liposomes coupling many molecules showed higher affinities (avidity) to antigen than a single molecule of antibody.