Investigation of red blood cell antigens with highly fluorescent and stable semiconductor quantum dots

We report a new methodology for red blood cell antigen expression determination by a simple labeling procedure employing luminescent semiconductor quantum dots. Highly luminescent and stable core shell cadmium sulfide/cadmium hydroxide colloidal par- ticles are obtained, with a predominant size of 9n m. The core-shell quantum dots are functionalized with glutaraldehyde and conjugated to a monoclonal anti-A antibody to target antigen-A in red blood cell membranes. Erythrocyte samples of blood groups A + , A2 , and O + are used for this purpose. Confocal microscopy images show that after 30 min of conjugation time, type A + and A 2 erythrocytes present bright emission, whereas the O + group cells show no emission. Fluo- rescence intensity maps show different antigen expressions for the distinct erythrocyte types. The results obtained strongly suggest that this simple labeling procedure may be employed as an efficient tool to investigate quantitatively the distribution and expression of antigens in red blood cell membranes. © 2005 Society of Photo-Optical Instrumentation Engi-