Fluo-4, AM, cell permeant - FAQs

View additional product information for Fluo-4, AM, cell permeant - FAQs (F14201)

4 product FAQs found

Can I fix my cells after loading with Fluo-4 AM dye for the detection of calcium?

No. Since Fluo-4 AM isn't covalently bound to any cellular components and fixation compromises the membrane, the dye would not be retained by the cell.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

I am doing calcium flux imaging with your Fura-2 calibration kit, but am seeing a large variability in ratio in different places around the slide. I am correcting for uniform illumination, using the product as directed, and sealing the coverslip with nail polish.

The nail polish may be the problem. The Kd value (calcium sensitivity) changes depending upon the dye's environment. Nail polish has solvents that can leech under the coverslip and cause variability. We recommend either going without a sealing or sealing with melted paraffin painted on the coverslip edges with a cotton-tipped applicator (paraffin is hydrophobic and has no solvents).

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

I need to label cells with Fluo-4, AM, for a calcium flux assay. How long after labeling will the dye be retained?

After loading dye into the cells, intracellular esterases remove the 'AM' moiety from the dye. When the 'AM' group is removed, the dye is able to bind calcium and fluoresce. Since the dye is not covalently bound to any cellular components, it may be actively effluxed from the cell. The rate of efflux is dependent upon the inherent properties of the cell, culture conditions and other factors. The dye may be retained for hours, days or even weeks or lost in a matter of minutes. The use of Probenecid (Cat. No. P36400) limits loss by active efflux.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.

Why don't I see a significant change in signal for my live-cell fluorescent indicator dye?

Regardless of the type of live-cell indicator dye (e.g., calcium indicators, pH indicator, metal ion indicators), make sure there is no serum during the loading step, which can prematurely cleave dyes with AM esters and bind dyes non-specifically. Always optimize the dye concentration and staining time with a positive control before you run your test samples, to give the best signal-to-background. Always run a positive control with a buffer containing free ions of known concentration and an ionophore to open pores to those ions (for instance, for calcium indicators like Fluo-4 AM, this would include a buffer with added calcium combined with calcimycin, or for pH indicators, buffers of different pHs combined with nigericin). Reactive oxygen indicators, such as CellROX Green or H2DCFDA would require a cellular reactive oxygen species (ROS) stimulant as a positive control, such as menadione. Finally, make sure your imaging system has a sensitive detector. Plate readers, for instance, have much lower detector efficiency over background, compared to microscopy or flow cytometry.

Find additional tips, troubleshooting help, and resources within our Cell Analysis Support Center.