Polycarbonate membranes: a novel surface for solid-phase determinations with utility in field format serological assays

A simple method for the serodiagnosis of human hydatid disease based on a protein A/colloidal dye conjugate

We have developed a dot immunobinding assay (CM) for the serodiagnosis of the human hydatidosis. The assay employs Samaron blue colloidal dye particles conjugated to hydatid antigen (HA) or protein A, both of which serve as visualizing agents. The test is simple and can be completed in 1 h. It requires few reagents, a nitrocellulose membrane (NC) strip onto which the HA has been bound, and the colored conjugates. It is sensitive and specific for the detection of anti-HA antibodies and generally agrees closely with the data from the enzyme-linked immunosorbent assay (ELISA).

Quantitation of solid-phase immunoassays using a fibre-optic reflectance spectrophotometer

A reflectance measuring instrument (fibre-optic spectrometer linked to a personal computer) which will quantitate the results of immunoassays that result in the deposition of a coloured chromophore on a membrane or other similar solid phase (SP) is described and the reflectance spectra of some chromophores which are commonly produced or used in SP immunoassays are presented. The instrument has been used in conjunction with silver-enhanced SP-immunogold capture assays to determine the concentrations in serum of IgG and of IgM rheumatoid factor (RF) and the results have been compared with those obtained by rate nephelometry and latex agglutination assays, respectively. It is concluded that fibre-optic reflectance photometry is an accurate and useful means of quantitating SP immunoassays in which coloured chromophores are produced and that the results obtained from such immunoassays are comparable to those given by established procedures.

Antigen detection immunoassay using dipsticks and colloidal dyes

A dipstick colloidal dye immunoassay (DIA) for multiple antigen detection is described. The test combines the concepts of double antibody (Ab) sandwich ELISA, dot blotting, and colloidal particle-linked Abs to produce a dipstick test for multiple antigen (Ag) detection. Dipsticks prepared from Ab coated nitrocellulose membrane mounted on acetate strips served as the assay capture matrix. Abs absorbed to colored dye particles from a family of commercially available textile dyes (Dye/Ab reagent) served as Ag detecting reagents. DIA and enzyme labelled dot blot assays showed similar Ag detection limits down to a sensitivity of 10 ng/ml. In a pilot study, an assay designed to detect species-specific IgG for use in mosquito bloodmeal identification demonstrated the feasibility of the technique. Experiments comparing bloodmeal analysis of mosquitoes using DIA and ELISA methods showed 100% agreement. This DIA method provides an inexpensive, simple, robust test for multiple Ag detection without instrumentation suitable for a wide variety of field applications.