QDs-labeled microspheres for the adsorption of rabbit immunoglobulin G and fluoroimmunoassay

This paper presents a study on the adsorption of rabbit immunoglobulin G onto CdTe quantum dots (QDs)/polystyrene microspheres. The adsorption appears to be sensitive to pH conditions and ionic strength. Maximum adsorption for protein was obtained near the isoelectric point. Adsorption isotherm analysis demonstrated that the electrostatic interaction plays an important role in the adsorption of protein. The thickness of adsorbed layer calculated from the maximal adsorption amounts (qm) is 6.5 nm, which indicates that the rabbit IgG molecules exist between the side-on and end-on mode in the monolayer. The bio-functional rabbit IgG/fluorescent microspheres were further used for the detection of antibody in fluoroimmunoassays. This approach allowed detection of goat anti-rabbit IgG in the range of 1–100 ng/mL.