by Chunmei Wei, Haitao Guo, Jinfang Liao, Qinglin Meng, Xing Han, Zhenjun Diwu, Qin Zhao
Calcein AM is one of the most popular fluorescent probes used for labeling and monitoring cellular functions of live cells. However, the limited color selection of Calcein AM and its complete spectral overlap with GFP makes this valuable reagent impossible to be used in the multicolor analysis of live cells.
Calcein Red™,
Calcein Orange™ and
CytoCalcein™ have been developed for multiplexing analysis of cellular functions. The non-fluorescent Calcein Red™, Calcein Orange™ and CytoCalcein™ become strongly fluorescent upon entering live cells. Calcein Red™, Calcein Orange™ and CytoCalcein™ are hydrophobic compounds that easily permeates intact live cells and generates their respective cell-retained fluorophores upon intracellular esterase-induced hydrolysis. The cellular esterase activity is proportional to the number of viable cells, and therefore directly related to the fluorescence intensity of Calcein Red™, Calcein Orange™ and CytoCalcein™. Using Calcein Orange™ and CytoCalcein™ cell proliferation and cell cytotoxicity were monitored in HEK, CPA, and Jurkat cells. The consistent results were obtained with flow cytometry, fluorescence plate reader and florescence microscopy. Calcein Orange™ and CytoCalcein™ have minimal cytotoxicity even after 2 weeks dye-loading in Jurkat cells while all the cells are apoptotic/necrotic after 3 days dye-loading with the same concentration of Calcein AM.
CytoCalcein™, Calcein Orange™ and Calcein Red™ are novel fluorescent probes that can be used with Calcein AM or other green fluorescent dyes for multicolor analysis. They have the following benefits and features: