Quantitative characterization of specific targeting of tumor cells by antibody-functionalized particles

Receptor-ligand binding has been one of the more popular approaches to specifically targeting tumor cells. In this work, targeting efficiency was quantitatively characterized using silica particles functionalized with EpCAM antibodies and EpCAM-expressing BT-20 breast cancer cells. The effects of incubation time and particle concentration on the number of functionalized particles bound to target cells were experimentally investigated. The number of bound particles was found to increase with particle concentration, but not necessarily with incubation time. While particle desorption and cellular loss of binding affinity in time seem to be negligible, cell-particle-cell interaction was identified as the limiting mechanism for the number of particles bound to target cells. The current findings suggest that separation of a bound particle from a cell may be detrimental to cellular binding affinity.