Fluo-3, pentaammonium is membrane-impermeant, but can be loaded into cells via microinjection or scrape loading.    Kd: 450 nM  &lamba;Ex/&lamba;Em (low or high [Ca2 ]) = 506nm/526nm  ε (506 nm) = 86,000 M-1cm-1  Orange red solid soluble in DMSO and water (pH >6)  Store at 4°C and protect from light, especially when in solution  C36H25Cl2N7O13  MW: 854.7  [134907-84-9]