Shop All Ion Indicators & Ionophores

Calcium Calibration Buffer Kit #1, zero and 10 mM CaEGTA (Invitrogen™)

The Calcium Calibration Buffer Kits are designed to help determine the dissociation constant (Kd) of fluorescent Ca2+ indicators using a fluorometer or quantitative imaging system. The Kd of an indicator can be calculated from a plot generated by scanning the excitation or emission of the indicator in the presence of eleven different Ca2+ concentrations. Calcium Calibration Kit #1 contains 50 mL of 10 mM K2EGTA and 50 mL of 10 mM CaEGTA. Both solutions contain 100 mM KCl and 30 mM MOPS, pH 7.2 and are prepared in deionized water. These stock solutions can be blended to make buffers having free Ca2+ ranging from 0 µM to 39 µM.

Calcium Green™-1, Hexapotassium Salt, cell impermeant (Invitrogen™)

The cell-impermeant dye, Calcium Green-1, is a visible light—excitable Ca2+ indicator. Although Calcium Green-1 is structurally similar to fluo-3, it is more fluorescent at low calcium concentrations, facilitating the determination of baseline Ca2+ levels and increasing the visibility of resting cells.

Magnesium Green™, AM, cell permeant - Special Packaging (Invitrogen™)

The cell-permeant Magnesium Green™, AM exhibits a higher affinity for Mg2+ (Kd ~1.0 mM) than mag-fura-2 (Kd ~1.9 mM) or mag-indo-1 (Kd ~2.7 mM). Upon binding Mg2+, Magnesium Green exhibits and increase in fluorescence emission intensity without a shift in wavelength with absorption/emission maxima ~506/531 nm.

SNARF™-1 Carboxylic Acid, Acetate, Succinimidyl Ester - Special Packaging (Invitrogen™)

To permit simultaneous long-term tracing of mixed-cell populations using different fluorescent colors, we have developed a probe whose applications should be similar to those of CFDA SE (commonly called CFSE). Cells labeled with our SNARF-1 carboxylic acid, acetate, succinimidyl ester have orange-red fluorescence that can be easily distinguished from that of cells loaded with green-fluorescent tracers such as CFDA SE.

Newport Green™ DCF, Dipotassium Salt, cell impermeant (Invitrogen™)

The Newport Green™ DCF indicator has moderate zinc-binding affinity (Kd for Zn2+ ~1 µM) but is essentially insensitive to Ca2+ (Kd for Ca2+ >100 µM), making this a valuable probe for detecting Zn2+ influx into neurons through voltage- or glutamate-gated channels. When used alongside dyes with dual Ca2+ / Zn2+ sensitivity such as fura-2 and mag-fura-2, Newport Green™ DCF provides confirmation that changes in Zn2+ levels, and not Ca2+ or Mg2+, are being detected. The response of Newport Green™ DCF to transition metals, including Zn, Mn, Fe, Co, Cu(I), Cu(II), Ni and Cd, has been characterized.

Newport Green™ PDX has a higher Zn2+ dissociation constant (Kd for Zn2+ ~30 µM) and a larger Zn2+-free to Zn2+-saturated fluorescence intensity increase than the Newport Green™ DCF indicators.

Fluorescent Zinc Indicators Specifications:
• Label (Ex/Em): Newport Green™ DCF (~505/535 nm)
• Kd (Zn2+) (in buffer):~1 µM
• Lyophilized product may be dissolved in distilled water or aqueous buffer for use
• Product is typically loaded into cells using microinjection or diffusion from patch pipette


Find Fluorescent Indicators for Zinc and Other Metal Ions
We offer a number of fluorescent indicators to determine polyvalent cation concentrations inside cells, to follow metal ion transport through ion channels, to make measurements in environmental samples, and more. Review Fluorescent Indicators for Zn2+ and Other Metal Ions—Section 19.7 in the Molecular Probes® Handbook for more information on these products.

For Research Use Only. Not for human or animal therapeutic or diagnostic use.

Calcium Green™-1, AM, cell permeant (Invitrogen™)

Labeled calcium indicators are molecules that exhibit an increase in fluorescence upon binding Ca2+. They have uses in many calcium signaling investigations, including measuring intracellular Ca2+, following Ca2+ influx and release, and multiphoton excitation imaging of Ca2+ in living tissues. Cells may be loaded with the AM ester forms of these calcium indicators by adding the dissolved indicator directly to dishes containing cultured cells. The fluorescence signal from these cells is generally measured using fluorescence microscopy, fluorescence microplate assays, or flow cytometry.

Calcium Indicator (AM Ester) Specifications:
• Label (Ex/Em): Calcium Green™ -1 (506/531 nm)
• Fluorescence intensity increase upon binding Ca2+ : ~14 fold
• Exhibit fluorescence increase upon binding Ca2+ with little shift in wavelength


Spectral Characteristics of Molecular Probes® Calcium Indicators
These probes are excited by visible light, and because the energy required for excitation is low, the potential for cellular photodamage is reduced. Commonly used laser-based instruments (i.e., confocal laser scanning microscopes) are able to efficiently excite these indicators, and their emissions are in regions of the spectrum where cellular autofluorescence and scattering backgrounds are often less of a problem.

More Choices for Fluorescent Calcium Indicators
We offer a large selection of Molecular Probes® calcium indicators for use in various experimental scenarios, for example dextran versions for reduced leakage and compartmentalization and BAPTA conjugates for detecting high-amplitude calcium transients. For more information, review Fluorescent Ca2+ Indicators Excited with Visible Light—Section 19.3 in the Molecular Probes® Handbook.

For UV-excitable Ca2+ indicators, protein-based Ca2+ indicators, conjugates of Ca2+ indicators, and for fluorescence-based indicators of other metal ions (i.e., Mg2+, Zn2+) review Indicators for Ca2+, Mg2+, Zn2+ and Other Metal Ions—Chapter 19 in the Molecular Probes® Handbook.

For Research Use Only. Not intended for animal or human therapeutic or diagnostic use.

5-(and-6)-Carboxy SNARF™-1, Acetoxymethyl Ester, Acetate (Invitrogen™)

Carboxy SNARF®-1, acetoxymethyl ester, acetate is a cell-permeant pH indicator that has a pKa of ~7.5 after de-esterification; thus, it is useful for measuring pH changes between pH 7 and pH 8. Carboxy-SNARF®-1 exhibits a significant pH-dependent emission shift from yellow-orange to deep red fluorescence under acidic and basic conditions, respectively. This pH dependence allows the ratio of the fluorescence intensities from the dye at two emission wavelengths - typically 580 nm and 640 nm - to be used for quantitative determinations of pH.

Oregon Green™ 488 BAPTA-2, Octapotassium Salt, cell impermeant (Invitrogen™)

The cell-impermeant visible light—excitable, high affinity Ca2+ indicator, Oregon Green® 488 BAPTA-2, octapotassium salt has a Kd for Ca2+ ~580 nM in the absence of Mg2+ and absorption/emission maxima ~494/523 nm.

Fura Red™, AM, cell permeant (Invitrogen™)

Fura Red, AM is a visible light—excitable fura-2 analog that offers unique possibilities for ratiometric measurement of Ca2+ in single cells by microphotometry, imaging or flow cytometry when used with single excitation, green-fluorescent calcium indicators. This acetoxymethyl (AM) ester form is useful for noninvasive intracellular loading and is also available in 1 mg amounts (F-3020).

Calcium Green™-1 dextran, Potassium Salt, 10,000 MW, Anionic (Invitrogen™)

Labeled calcium indicators are molecules that exhibit an increase in fluorescence upon binding Ca2+. They have uses in many calcium signaling investigations, including measuring intracellular Ca2+, following Ca2+ influx and release, and multiphoton excitation imaging of Ca2+ in living tissues. Cells may be physically loaded with the cell-impermeant salt forms of these dextran-conjugated indicators using patch pipette, microinjection, or our Influx pinocyte-loading reagent. The fluorescence signal from these cells is measured using fluorescence microscopy. The dextran forms of our calcium indicators show a dramatic reduction in both leakage and compartmentalization compared to the AM ester forms.

Calcium Indicator (Cell-Impermeant Salts, Dextran Conjugates) Specifications:
• Label (Ex/Em): Calcium Green™ -1 (506/531 nm)
• Fluorescence intensity increase upon binding Ca2+: ~14 fold
• Dextran size: 10,000 MW
• Exhibit fluorescence increase upon binding Ca2+ with little shift in wavelength


Spectral Characteristics of Molecular Probes® Calcium Indicators
These probes are excited by visible light, and because the energy required for excitation is low, the potential for cellular photodamage is reduced. Commonly used laser-based instruments (i.e., confocal laser scanning microscopes) are able to efficiently excite these indicators, and their emissions are in regions of the spectrum where cellular autofluorescence and scattering backgrounds are often less of a problem.

More Choices for Fluorescent Calcium Indicators
We offer a large selection of Molecular Probes® calcium indicators for use in various experimental scenarios, for example dextran versions for reduced leakage and compartmentalization and BAPTA conjugates for detecting high-amplitude calcium transients. For more information, review Fluorescent Ca2+ Indicators Excited with Visible Light—Section 19.3 in the Molecular Probes® Handbook.

For UV-excitable Ca2+ indicators, protein-based Ca2+ indicators, conjugates of Ca2+ indicators, and for fluorescence-based indicators of other metal ions (i.e., Mg2+, Zn2+) review Indicators for Ca2+, Mg2+, Zn2+ and Other Metal Ions—Chapter 19 in the Molecular Probes® Handbook.

For Research Use Only. Not intended for animal or human therapeutic or diagnostic use.

Sodium Green™, Tetra (Tetramethylammonium) Salt, cell impermeant (Invitrogen™)

This cell-impermeant form of Sodium Green™, tetra(tetramethylammonium) salt is a visible light-excitable Na+ indicator.

Mag-Fura-2, Tetrapotassium Salt, cell impermeant (Invitrogen™)

Mag-fura-2, tetrapotassium salt is an intracellular magnesium indicator that is ratiometric and UV light-excitable. This water-soluble salt form is useful for intracellular loading by microinjection, infusion from patch pipette or uptake induced by our Influx pinocytic cell-loading reagent (I14402).

A-23187 Free Acid (Calcimycin) (Invitrogen™)

The Ca2+ ionophore A-23187 is commonly used for in situ calibrations of fluorescent Ca2+ indicators, to equilibrate intracellular and extracellular Ca2+ concentrations and to permit Mn2+ to enter the cell to quench intracellular dye fluorescence. Although the intrinsic fluorescence of A-23197 is too high for use with UV-excitable calcium indicators like fura-2, indo-1 and quin-2 it is suitable for use with the visible light-excitable indicators, including fluo-4, fluo-3, Calcium Green and rhod-2. A-23187 can also be used to equilibrate extracelular and intrcellular Mg2+ concentrations, making it useful for calibrating Mg2+ indicators.

Newport Green™ DCF Diacetate, cell permeant (Invitrogen™)

The Newport Green™ DCF indicator has moderate zinc-binding affinity (Kd for Zn2+ ~1 µM) but is essentially insensitive to Ca2+ (Kd for Ca2+ >100 µM), making this a valuable probe for detecting Zn2+ influx into neurons through voltage- or glutamate-gated channels. When used alongside dyes with dual Ca2+ / Zn2+ sensitivity such as fura-2 and mag-fura-2, Newport Green™ DCF provides confirmation that changes in Zn2+ levels, and not Ca2+ or Mg2+, are being detected. The response of Newport Green™ DCF to transition metals, including Zn, Mn, Fe, Co, Cu(I), Cu(II), Ni and Cd, has been characterized.

Newport Green™ PDX has a higher Zn2+ dissociation constant (Kd for Zn2+ ~30 µM) and a larger Zn2+-free to Zn2+-saturated fluorescence intensity increase than the Newport Green™ DCF indicators.

Fluorescent Zinc Indicators Specifications:
• Label (Ex/Em): Newport Green™ DCF (~505/535 nm)
• Kd (Zn2+) (in buffer): ~1 µM
• Lyophilized product may be dissolved in DMSO for use
• Product is typically loaded into cells by adding the dissolved indicator to medium containing cells


Find Fluorescent Indicators for Zinc and Other Metal Ions
We offer a number of fluorescent indicators to determine polyvalent cation concentrations inside cells, to follow metal ion transport through ion channels, to make measurements in environmental samples, and more. Review Fluorescent Indicators for Zn2+ and Other Metal Ions—Section 19.7 in the Molecular Probes® Handbook for more information on these products.

For Research Use Only. Not for human or animal therapeutic or diagnostic use.

Indo-1, Pentapotassium Salt, cell impermeant (Invitrogen™)

This cell-impermeant indo-1 pentapotassium salt is a UV light-excitable, ratiometric Ca2+ indicator. The emission maximum of indo-1 shifts from ~475 nm in Ca2+-free medium to ~400 nm when the dye is saturated with Ca2+. The dye is also available in the cell-permeant AM ester form—in our special packaging (I1223), in 1 mg amounts (I1203) and in 1 mM solution (I1226).