Polyelectrolyte multilayers-modified membrane filter for rapid immunoassay: protein condensation by centrifugal permeation

Abstract

We demonstrated that positive polyelectrolyte multilayers (PEMs) have great potential for conventional enzyme-linked immunosorbent assay (ELISA) systems because of the induction protein enrichment on their surface. In this study, we developed a novel simple molecular detection system using a PEMs-modified cellulose acetate (CA) membrane filter (PEMs-CA), which achieved rapid detection without compromising sensitivity as compared with conventional ELISA systems. This rapid detection was carried out by the centrifugal permeation of the antigen solution, thus allowing the local condensation of the antigen molecule in the proximity of the primary antibody-enriched PEMs-CA membrane, which overcame molecular diffusion as the time-limiting factor as compared with conventional ELISA systems. Hence, on the permeation system, the incubation time required for the antigen–antibody reaction corresponded to just the permeation time, which was 1/20 shorten than the conventional ELISA system under optimized conditions for the centrifugal forces. Moreover, the calibration curve of PEMs-CA had wide range of concentration from 0.02 to 5 μg ml−1 and larger change in signal as compared with the bare CA membrane. We concluded that this centrifugal permeation system should be further developed for rapid, precise and simple systems in various immunosensors using PEMs-modified membrane filters. Polyelectrolyte multilayers-modified membrane filter, leading to achieve rapid immunoassay as compared with the conventional enzyme-linked immunosorbent assay (ELISA) system. The antigen–antibody reaction was carried out by the centrifugal permeation of antigen solution allowing the local condensation of the antigen molecules in the proximity of the primary antibody. Hence, the incubation time for the antigen–antibody reaction was just permeation time, 3 min, which overcomes the molecular diffusion as rate-limiting factor compared with conventional ELISA method.