Alexa Fluor 568 Hydrazide is a low molecular weight, cell membrane-impermeant, and an aldehyde-fixable molecule that can be used as a cell tracer. This red-fluorescent polar dye is a ready-to-use solution that is dissolved in a 200 mM KCl solution and filter steralized. It is designed to be loaded into cells by microinjection or infusion from patch pipette.