Innovative Tools for Molecular and Cell Biology

Innovative Tools for Molecular and Cell Biology


CalFluor™ Series

Next Generation Calcium Indicators



  • CalFluor™ is a series of fluorescent probes to detect calcium ions. This series is based on two types of fluorophores: red-fluorescent CaTM and near-infrared CaSiR. CaTM and near-infrared CaSiR are suited for multi-color imaging with other green-fluorescent dyes/proteins as well as for in vivo imaging.
  • Acetoxymethylester (AM) derivatives of each dye are suitable for cell imaging. These AM ester derivatives can permeate the cell membrane. Subsequently, they are hydrolyzed by intracellular esterases. In this confirmation they remain within the cells.

CaTM-3™-AM: Red Fluorescent Ca2+ Probe


HeLa cells were loaded with 3 µM of CaTM-3 dissolved in HBSS at 37 °C for 30 minutes. Without addition of detergent such as Pluronic F-127, the probe uniformly distributes within the cells. Left fluorescence image of 610-680 nm wavelength was obtained with 590 nm excitation. Right, DIC image.


  • Red-fluorescent probe suitable for multicolor imaging with, for instance, GFP
  • Sensitive detection of calcium ions
  • Improved intracellular distribution enables more accurate visualization of intracellular calcium concentration changes


  • CaTM-3™-AM is a red-fluorescent calcium indicator. Fluorescence intensity reversibly changes depending on Ca2+ concentration. It shows a red fluorescence with maximum emission at 609 nm (excitation maximum at 590 nm) and is suitable for detection of micromolar- to submicromolar-range calcium ions.
  • Cell-permeable CaTM-3™-AM is hydrolyzed by intracellular esterases to become soluble CaTM-3™ which equally distributes in the cytoplasm. This feature enables detection of intracellular calcium concentration changes with superior accuracy compared to other calcium indicators.

  • More information can be found in the corresponding CaTM-3™-AM flyer (PDF).

CaSiR-1™ / CaSiR-1™-AM


CaSiR-1™-AM was added to a mouse brain slice in which a fraction of neurons expressed Venus (a mutant of YFP). CaSiR-1™ is shown as red color and Venus is shown green. Increased fluorescence signals visualized a transient elevation of intracellular Ca2+ concentration associated with Ca2+ sparks in cranial nerves.


  • For in vivo imaging using near-infrared excitation and emission filters
  • Large increase in fluorescence intensity upon Ca2+ binding
  • For live-cell imaging


  • CaSiR-1™ and CaSiR-1™-AM are near-infrared fluorescent calcium probes which have a fluorescence maximum at 664 nm. Multicolor imaging is possible with CaSiR-1™/CaSiR-1™-AM and fluorescent probes/proteins which have a fluorescence maximum in the visible area such as Hoechst, Fluorescein, Rhodamine, GFP, YFP, and RFP. Near-infrared fluorophores have a greater tissue penetration, less overlap with the spectrum of background autofluorescence, and exhibit less phototoxicity to cells and tissues.
  • CaSiR-1™ greatly changes its fluorescence intensity when bound to calcium. For example, fluorescence intensity rises more than 1000-fold when calcium concentration is changed from 0 µM to 39 µM. Little fluorescence is detected when calcium concentration is 0 µM.
  • CaSiR-1™ is suited for microinjection, patchclamp, and electroporation. CaSiR-1™-AM, an acetoxymethylester of CaSiR-1™, can permeate the cell membrane. After permeating the cell membrane, CaSiR-1™-AM is hydrolyzed by esterases, and the generated CaSiR-1™ remains within the cell. The probe is suitable for measuring the fluctuation of intracellular calcium concentrations. For instance, action potentials in neurons can be tracked.


  • For shipping and storage information please click on Order#.
Order# Description Amount Price Data Sheet
GC5021 PDF
GC503 CaTM-2 AM 500 μg 588,00 PDF
GC504 CaTM-2 AM 50 μg×10 643,00 PDF
GC5041 CaTM-2 AM 50 μg×5 355,00 PDF
GC507 CaTM-3 AM 40 nmol × 5 355,00 PDF
GC401 CaSiR-1 1 mg 728,00 PDF
GC402 CaSiR-1 50 μg×20 831,00 PDF
GC4021 CaSiR-1 50 μg×10 457,00 PDF
GC4031 PDF
GC405 CaSiR-1 potassium salt 500 μg 464,00 PDF
  • All prices are in EURO excl. VAT and shipping. Only available in Europe.