The cell-impermeant bis-fura-2 is a derivative of the ratiometric, UV light—excitable calcium indicator, fura-2. Comprised of two fura-2 dyes linked to one BAPTA chelator, this indicator has a slightly lower affinity for Ca2+ and is useful for intracellular loading by microinjection, infusion from patch pipette or uptake induced by our Influx pinocytic cell-loading reagent (Cat. no. I-14402).