Trypan Purple™ is similar to Trypan Blue in cell permeability. It is not permeable to live cells. Compared to Trypan Blue, Trypan Purple™ is less toxic to cells, in particular, having minimal effect on cell surface receptors such as G-protein coupled receptors (GPCRs). Another advantage is that the cells can be clearly observed under microscope when Trypan Purple™ is used while Trypan Blue makes it quite difficult to see cells under microscope. Our Trypan Purple™ can also be used to prevent florescent dyes (such as FDA, rhodamine 123, JC-1, TMRE, TMRM, Indo-1 AM, Fura-2 AM, calcein AM, Fluo-3 AM, Fluo-4 AM, Quest Fluo-8™ AM and Rhod-4™ AM) from leaking out of cells. It might inhibit the activities of drug-efflux pumps since it contains a probenecid-like moiety as shown below. Compared to probenecid, it is neutral, highly soluble in water, and convenient to use. Its cellular mechanism is still under investigation. Our Trypan Purple™ is highly purified, and can be used up to 0.75 mM with minimal cell cytotoxicity. Our recommended concentration is 0.5 mM.