Noncompetitive immunoassays using protein G affinity capillary chromatography and capillary electrophoresis with laser-induced fluorescence detection

A new and simple approach to perform immunoassay using protein G affinity c apillary chromatography and laser-induced fluorescence detection was descri bed. A noncompetitive assay for monoclonal anti-bovine serum albumin (BSA) was used to test the performance of the system. Fluorescein isothiocyanate labeled BSA was used as a tracer to determine anti-BSA in pM level. Capilla ries with inner diameter of 150 mu m were packed with recombinant protein G -bound perfusive support. The packed capillary was used to capture the immu nocomplexes, which were subsequently desorbed by 100 mM glycine (pH 9.0). O pen tube capillary electrophoresis-based immunoassay (CEIA) for anti-BSA wa s also performed. Using standard samples, calibration curves for anti-BSA w as established in both assays. Compared with CEIA, this system improved the concentration sensitivity for about 100-fold due to the pre-concentration of immunocomplex in the protein G column, while the mass sensitivity was si milar in the two methods. (C) 1999 Elsevier Science B.V. All rights reserve d.