counterstain

Direct Blue 1 (Pontamine sky blue), a counterstain for background autofluorescence in immunofluorescence histochemistry, structurally resembles glutamate and operates as a potent, competitive VGLUT inhibitor, not impacting plasma membrane transporters. This compound stands out as the inaugural small molecule PrP ligand to inhibit Aβ binding.

Nuclear Fast Red is an anthraquinone dye that serves as a red nuclear counterstain when aluminum ions are present in excess, thereby aiding in histological visualization of nuclear components. Nuclear Fast Red additionally functions as a histochemical and colorimetric reagent for calcium detection,Nuclear Fast Red further acts as a highly sensitive “off/on” fluorescent probe for the detection of guanine, making it a multifunctional research reagent.

BODIPY TR methyl ester serves as a lipophilic GFP counterstain, easily permeating cell membranes to accumulate in endomembranous organelles, while exhibiting minimal localization in plasma membranes. It is a highly effective red fluorescent vital dye (Ex=568 nm, Em=625 nm) that can reveal the location and shape of cell nuclei, the morphology of cells in embryonic tissues, and the boundaries of organ-forming tissues within an entire embryo [1].

YOYO-3, a cell-impermeant dye with far-red fluorescence, is utilized as a nuclear counterstain and dead cell indicator, generating bright fluorescence upon binding to DNA.