Preparing a highly specific inert immunomolecular-magnetic beads for rapid detection and separation of S. aureus and...

The rapid detection and separation of Staphylococcus aureus and group G Streptococcus was based on the affinity chromatography interactions between Fc fragment of human IgG and protein A/G (located on the cell wall of S. aureus and group G Streptococcus). In this case, immobilization of antibodies had to take place in a different and complementary way than in the case of conventional immunosensors. In this study, three different kinds of immunomolecular-magnetic beads (IMB) were prepared for rapid detection and separation of S. aureus and group G Streptococcus (GGS). The Fc regions of the immobilized antibodies were fully accessible to adsorb protein A or protein G. On the contrary, conventional immunosensors had to have fully accessible Fab regions to facilitate the antigen-antibody recognition. It was suggested that the worse method of immobilization of the antibodies for conventional use would yield the better results for this specific use. In this study, we also perfectly solved the nonspecific adsorptions and interaction problems, which were the most serious critical problems for all kinds of sensors. It was achieved by blocking the excess surface groups of aldehyde IMB and the Fab region of the immobilized antibodies with aldehyde-dextran.