Alpaca Anti-Mouse IgG2b Fc monoclonal Antibody, clone WII1386

Optical biosensors based on photonic crystal surface waves (PC SWs) offer a possibility to study binding interactions with living cells, overcoming the limitation of rather small evanescent field penetration depth into a sample medium that is characteristic for typical optical biosensors. Besides this, simultaneous excitation of s-and p-polarized surface waves with different penetration depths is realized here, permitting unambiguous separation of surface and volume contributions to the measured signal. PC-based biosensors do not require a bulk signal correction, compared to widely used surface plasmon resonance-based devices. We developed a chitosan-based protocol of PC chip functionalization for bacterial attachment and performed experiments on antibody binding to living bacteria measured in real time by the PCSW-based biosensor. Data analysis reveals specific binding and gives the value of the dissociation constant for monoclonal antibodies (IgG2b) against bacterial lipopolysaccharides equal to K-D = 6.2 +/- 3.4 nM. To our knowledge, this is a first demonstration of antibody-binding kinetics to living bacteria by a label-free optical biosensor.

Purpose: Mouse IgG subclasses containing IgG1, IgG2a, IgG2b and IgG3 have been defined and described both physiochemically and immunologically. Methods: Sepharose beads conjugated with protein A affinity chromatography was used for purification of mouse IgG2b. Sodium citrate buffer (0.1 M, pH: 3.5) was used for separation of mouse IgG2b. Verification of the purified fractions was monitored by SDS-PAGE (polyacrylamide gel electrophoresis) in reducing condition. Immunized rabbit serum was collected and precipitated at the final concentration of 50% ammonium sulfate. After dialysis against tris-phosphate buffer (pH: 8.1) ion exchange chromatography column was used for purification of rabbit anti-mouse IgG2b. The periodate method was performed for conjugation with some variations. After conjugation, direct ELISA was used to determine the titer of HRP conjugated rabbit IgG against mouse IgG2b. Results: The titer of rabbit anti-mouse IgG2b that determined by ELISA was 32000. The purity of rabbit anti-mouse IgG2b was about 95%. The optimum dilution of prepared HRP conjugated IgG was 1: 10000. This study showed that ion-exchange chromatography and affinity chromatography could be appropriate techniques for purification of mouse IgG and IgG subclasses respectively. Conclusion: This study showed that affinity chromatography could be an appropriate method for purification of IgG2b antibodies.