A dot-blot test using gold colloid cluster technology as a miniaturizable alternative to ELISA and hapten inhibition tests

Abstract

A novel miniaturizable method to quantify antigens is described in form of a cluster linked immunosorbent assay (CLISA), using inexpensive nitrocellulose (NC) membranes as a support for dot-blotting the antigens. Antibodies for detection are labeled with gold-colloid clusters (GCC). After blocking of the membrane with non reacting protein and application of the GCC-labeled antibodies the signal is detectable by visual colorimetry and can be compared to a color scale prepared from a dilution series of known sample concentrations. The color reaction product is stable for a very long time and does not fade. The sensitivity of the method is comparable to that of ELISA if not better and furthermore needs only small amounts of antibody for detection or for GCC-labeling. This method is an alternative to the use of expensive enzyme-conjugated antibodies for a number of applications, such as tracking of antibodies during purification or hapten inhibition tests.