Differences in usability of rabbit IgG and chicken IgY after clean-up and impact on gold labelling properties.

For the application of antibodies in rapid test systems such as Lateral Flow Devices (LFD) antibodies have to be coupled to coloured particles for immediate readability of the test system. In this work colloidal gold was selected for conjugation to the antibodies. Polyclonal rabbit antibodies were chosen for the development of Lateral Flow Devices for the detection of bovine alpha-casein. For antibody comparison chicken egg yolk IgY and sheep IgG were additionally used. Rabbit and chicken antibodies were purified from rabbit sera and egg yolk using affinity chromatography and alternatively ammonium sulphate precipitation, Sheep IgG was commercially obtained. In the course of colloidal gold sol titration experiments differences not only between antibody species but also between differently purified rabbit IgG were observed. While affinity purified rabbit IgG was not able to stabilise colloidal gold particles, antibodies obtained by ammonium sulphate precipitation resulted in a stable gold conjugate suitable for application in Lateral Flow Assays. This work compares and discusses the impact of antibody pre-treatment on further conjugation capacity.