Multiplex binding assay assemblies are disclosed. The assemblies generally include at least one assay bar that includes a top side, a bottom side, and at least one well accessible from the top side of the assay bar. Each well includes a side surface, a bottom surface, an open top end, and at least one secondary container, with each secondary container including a capillary tube that (i) begins at a location within an interior volume of the well and (ii) ends at a location beneath the bottom surface of the assay bar. The assemblies further include a dispenser bar that is adapted to be positioned adjacent to the top side of the assay bar, which includes one or more reservoirs that are configured to provide one or more reagents to the at least one secondary container located in each well of the assay bar.