Calcein
Calcein, also known as fluorexon or fluorescein complex, is a fluorescent dye characterized by its orange crystal appearance and the ability to emit strong green fluorescence. It has excitation and emission wavelengths of 495 nm and 515 nm, respectively. This dye is known for its self-quenching property at concentrations above 70 mM[1]. Calcein is widely used in various biological and chemical applications due to its unique properties.
Applications
- Indicator of Lipid Vesicle Leakage: Calcein is utilized to study the integrity of lipid vesicles, as it can indicate leakage through its fluorescence properties[1].
- Complexometric Indicator for Titration: Traditionally, calcein has been used as an indicator in the titration of calcium ions with EDTA, as well as for the fluorometric determination of calcium[1].
- Cell Viability Testing: The non-fluorescent acetomethoxy derivative of calcein (calcein AM) is particularly useful in biology for testing cell viability. It can penetrate cellular membranes into live cells, where intracellular esterases remove the acetomethoxy group, trapping the molecule inside and emitting strong green fluorescence. This property makes it valuable for labeling live cells and counting them via flow cytometry[1].
- Cell Tracing and Studies of Endocytosis, Cell Migration, and Gap Junctions: Due to its ability to be retained within live cells, calcein is commonly used for cell tracing and studying various cellular processes[1].
- Detection of Drug Interactions with Multidrug Resistance Proteins: Calcein AM assays are employed to screen for transporter substrates and inhibitors, and to determine in vitro drug resistance of cells, including patient samples[1].
- Marking Freshly Hatched Fish and Labeling of Bones in Live Animals: Its application extends beyond cellular biology into zoology and veterinary science[1].
Safety and Handling
Calcein is classified under GHS as having acute toxicity when inhaled, causing skin and eye irritation, and potentially causing respiratory irritation. It is harmful if swallowed, in contact with skin, or if inhaled. Precautionary measures include avoiding breathing dust/fume/gas/mist/vapors/spray, washing thoroughly after handling, and using only in well-ventilated areas or outdoors[3].
Chemical and Physical Properties
Calcein is a highly negatively charged, water-soluble fluorescein derivative. Its fluorescence is nearly independent of pH in the range between 6.5 and 12, making it versatile for various experimental conditions. It is soluble in DMSO, DMF, or water with pH greater than 6, and it should be stored at 4°C and protected from light[5].
In summary, calcein and its derivatives, especially calcein AM, serve as valuable tools in biological research and diagnostics due to their fluorescent properties, ability to indicate cell viability, and applications in studying various cellular processes. Safety precautions should be observed when handling this compound due to its potential toxicity.
Citations:
[1] https://en.wikipedia.org/wiki/Calcein
[2] https://www.sciencedirect.com/topics/chemistry/calcein
[3] https://cdn.caymanchem.com/cdn/msds/16221m.pdf
[4] https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/calcein
[5] https://biotium.com/product/calcein-high-purity/
[6] https://www.fishersci.com/store/msds?countryCode=US&language=en&partNumber=AAL1025506&productDescription=CALCEIN+SOD+SLT+CA+2-3+NA+5G&vendorId=VN00024248
[7] https://www.sciencedirect.com/topics/nursing-and-health-professions/calcein
[8] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1874234/
[9] https://cdn.caymanchem.com/cdn/msds/14948m.pdf
[10] https://www.medchemexpress.com/Calcein.html
[11] https://hellobio.com/calceinam.html
[12] https://www.carlroth.com/medias/SDB-7688-IE-EN.pdf?context=bWFzdGVyfHNlY3VyaXR5RGF0YXNoZWV0c3wyMjgwMjl8YXBwbGljYXRpb24vcGRmfHNlY3VyaXR5RGF0YXNoZWV0cy9oMTcvaGZlLzkwNzQ1MTUzNDU0MzgucGRmfDZlMGQzMGE1MTAzMzJmOTUwZTI4YjBlZjYwMjEwNWNkMDdmOGY3MTU0YzlhYmQ4MTBkZmEyNTZhMTUzZmMwZTA
[13] https://www.thermofisher.com/order/catalog/product/C1430
[14] https://star-protocols.cell.com/protocols/233
[15] https://www.aatbio.com/resources/faq-frequently-asked-questions/Is-calcein-AM-toxic-to-cells
[16] https://en.wiktionary.org/wiki/calcein
[17] https://www.emdmillipore.com/US/en/product/msds/MDA_CHEM-102315
[18] https://www.aatbio.com/resources/application-notes/calcein
[19] https://www.anaspec.com/assets/2b13a856-6dc8-4703-a590-e5d8ebcd29ae/sds-en-as-89201-calcein-am.pdf
[20] https://pubchem.ncbi.nlm.nih.gov/compound/Calcein