Interaction of Estrogen-functionalized Quantum Dots with Anti-estrogen Antibodies via Capillary Electrophoresis

The functionalization of quantum dots (QD) to a 17β-estradiol (E2) derivative and their subsequent immunochemical interaction with an anti-E2 antibody (Ab) were characterized using capillary electrophoresis (CE) with laser-induced fluorescence (LIF) detection. The E2-functionalized QDs (QD-E2) were prepared by coupling aminefunctionalized QDs (QD-NH2) to a carboxylic acid E2 derivative (E2-COOH) using EDC/sulfo-NHS as crosslinker. CE characterization of the conjugate QD-E2 showed a slightly longer migration time, indicating the loss of a significant positive charge from the QD surface. Immunochemical reaction between QD-E2 and Ab was monitored by CE-LIF to detect the formation of an immunochemical interaction peak (QD-E2*Ab). Observation of non-linear QD-E2 peak reduction with increasing amount of Ab added suggests binding ratios of greater than 1:1 due to multiple E2 binding sites on the QD surface.