Characterization of the functional binding properties of antibody conjugated quantum dots

Antibody conjugated quantum dots are an emerging technology for high-resolution labeling of biological systems. In this work we determined the number of functional antibodies (i.e., antibodies that are sterically available for functional binding to target proteins) conjugated to semiconductor quantum dots. This is critical for the interpretation of biological data labeled with these methods. We found that the number of available functional antibodies varied significantly for different conjugation methods and are lower than previously estimated. These results may suggest potential strategies for improving quantum dot labeling of biological preparations.