Calcium Ion Probe

BAPTA-AM is a calcium chelator that is cell-permeable and selective, blocking hERG, hKv1.3, and hKv1.5 channels (IC50=1.3/1.45/1.23 μM). BAPTA-AM has a 105-fold higher affinity for Ca2+ than for Mg2+, and can be used for the role of calcium in cell signaling.

Fura-2 AM is a membrane-permeable Ca²⁺ (calcium ion) indicator that is converted to Fura-2 by esterase within cells. Its fluorescence emission wavelength is around 510 nm, with excitation maxima at 340 nm under high calcium concentrations and 380 nm under low calcium concentrations. Calcium ion concentrations can be calculated using the fluorescence intensity ratio.

OG 488, SE (Oregon green 488 succinimidyl ester) is a green fluorescent dye that is pH insensitive in the physiological pH range (pH=6-8) and can be used to monitor the proliferation of living cells or microorganisms.

Fluo-4 AM is a cell-permeable calcium ion (Ca²⁺) fluorescent indicator/chemical probe suitable for fluorescence imaging, flow cytometry, and plate screening, with an excitation wavelength of approximately 488 nm and an emission wavelength of 512–520 nm.

Calmagite is an indicator that can be used to detect magnesium and calcium in various samples.

Alizarin Complexone (Alizarin-3-methyliminodiacetic acid) is an inhibitor of Rous-associated virus 2 reverse transcriptase. Alizarin Complexone can be used as a calcium-tracer and a chelating agent for biological studies.

BAPTA, tetrapotassium salt is a Ca2+ chelator.

Fura-2 potassium salt is a commonly used UV-excitable fluorescent probe for intracellular calcium ion imaging.

Fura-FF pentapotassium salt is a low affinity calcium fluorescent dye (Ex/Em: 365/514 nm, no calcium; 339/507 nm, high calcium).

Quin-2AM is a fluorescent Ca2+ chelator with a high affinity for calcium.

Fura-2 is a ratiometric fluorescent calcium indicator that can be used to detect calcium in cells. It is a pentacarboxylate that displays excitation maxima of 340 and 380 nm at high and low calcium concentrations, respectively, when the emission is fixed at 510 nm, enabling determination of ratiometric measurements of calcium influx in live cells.

BTC AM is a cell-permeable acetoxy-methyl ester of BTC . As BTC AM enters cells, it is hydrolyzed by intracellular esterases to produce BTC. BTC is a low affinity calcium indicator (Kd = 7-26 μM) that displays excitation emission spectra of 401 529 nm, respectively. It exhibits a shift in the excitation maximum from approximately 480 to 401 nm upon calcium binding, enabling determination of ratiometric calcium measurements. BTC is suitable for detecting elevated calcium levels associated with activation of smooth muscle, neurons, and intracellular calcium stores.

Rhod-FF AM is a cell-permeant acetoxymethyl ester of the fluorescent calcium indicator rhod-FF . As rhod-FF AM enters cells, it is hydrolyzed by intracellular esterases to produce rhod-FF. Rhod-FF is a difluorinated analog of the cell-impermeant calcium indicator rhod-2. It has a very low affinity for calcium (Kd = 320 μM). Low affinity calcium indicators are particularly useful for studying compartments with high concentrations of calcium, such as endoplasmic reticulum, where high affinity dyes will be insensitive to luminal fluctuations. Rhod-FF has excitation emission maxima of approximately 552 and 580 nm, respectively.

Fluo-3 (ammonium salt) is a fluorescent calcium indicator commonly used in flow cytometry and cell-based experiments to detect changes in intracellular calcium levels. [1] Its absorption maximum at 506 nm makes it compatible with excitation at 488 nm by argon-ion laser sources. Fluo-3 provides intense fluorescence upon binding calcium, detected at a maximum emission at 526 nm which can be monitored by FL1 (green, 525 nm band pass) sensors in flow cytometry.

Calcium Green BAPTA-2 AM serves as a fluorescent indicator for calcium ions.

Calcium measurement is critical for numerous biological investigations. Fluorescent probes that show spectral responses upon binding calcium have enabled researchers to investigate changes in intracellular free calcium concentrations by using fluorescence microscopy, flow cytometry, fluorescence spectroscopy and fluorescence microplate readers. Fluo-3 and Fluo-4 are most commonly used among the visible light-excitable calcium indicators. Fluo-4, pentaammonium salt is an analog of fluo-3 with the two chlorine substituents replaced by fluorines, which results in increased fluorescence excitation at 488 nm and consequently higher fluorescence signal levels.

PAO-Nap is a chemically modified version of PAO, in which a naphthalimide fluorophore is attached to the compound using a linker called aminocaproic acid. This modified compound, PAO-Nap, exhibits a selective targeting of thioredoxin reductase, leading to the induction of apoptosis in HL-60 cells through oxidative stress mechanisms[1].

Indo-1 (sodium salt) is a ratiometric fluorescent calcium indicator. It is ideal for analyses using flow cytometry, as it uses a single excitation source, typically 349-364 nm light from an argon-ion laser. The emission maximum shifts from 475-485 nm without calcium to 400-410 nm when Indo-1 (sodium salt) binds calcium. Indo-1 (sodium salt) is prone to photobleaching, which limits its usefulness in methods involving microscopy.

Rhod-FF is a difluorinated analog of the cell-impermeant calcium indicator rhod-2. It has a very low affinity for calcium (Kd = 320 μM). Low affinity calcium indicators are particularly useful for studying compartments with high concentrations of calcium, such as endoplasmic reticulum, where high affinity dyes will be insensitive to luminal fluctuations. Rhod-FF has excitation emission maxima of approximately 552 and 580 nm, respectively.

Arsenazo III is a dye used to detect micromolar concentrations of ionized Ca2+ and for determining thorium, zirconium, uranium, and rare earth elements [1] [2].

Calcium Green-5N AM is an innovative fluorescent probe that increases in fluorescence intensity upon binding with Ca 2+, allowing it to monitor free Ca 2+ in neurons [1] [2] [3].

Tetrapotassium BTC is a calcium indicator with low affinity (Kd approximately 7-26 µM) that offers favorable characteristics for cellular calcium imaging, such as extended excitation wavelengths (400 485 nm), minimal sensitivity to Mg2+, and precise ratiometric measurement [1].

Coelenterazine hcp is a synthetic bioluminescent luciferin that displays an emission maximum of 445 nm.1It has been used as a calcium indicator and substrate to quantifyRenillaluciferase activity.1,2,3 1.Sabnis, R.W.Handbook of biological dyes and stains: Synthesis and industrial applications(2010) 2.Shimomura, O., Kishi, Y., and Inouye, S.The relative rate of aequorin regeneration from apoaequorin and coelenterazine analoguesBiochemistry Journal296(Pt 3)549-551(1993) 3.Pichler, A., Prior, J.L., and Piwnica-Worms, D.Imaging reversal of multidrug resistance in living mice with bioluminescence: MDR1 P-glycoprotein transports coelenterazineProc. Natl. Acad. Sci. USA.101(6)1702-1707(2004)

Calcium measurement is critical for numerous biological investigations. Fluorescent probes that show spectral responses upon binding calcium have enabled researchers to investigate changes in intracellular free calcium concentrations by using fluorescence microscopy, flow cytometry, fluorescence spectroscopy and fluorescence microplate readers. Fluo-3 and Fluo-4 are most commonly used among the visible light-excitable calcium indicators. Fluo-4, pentasodium salt is an analog of fluo-3 with the two chlorine substituents replaced by fluorines, which results in increased fluorescence excitation at 488 nm and consequently higher fluorescence signal levels.