Synthesis, spectral properties of cell-permeant dimethine cyanine dyes and their application as fluorescent probes in living cell imaging and flow cytometry

A series of dimethine cyanine dyes, used as fluorescent probes, were synthesized under microwave irradiation, and identified by H-1 NMR, IR, elemental analysis and HRMS. The investigation of their spectral properties in phosphate-buffer saline (PBS) showed that the absorption and emission maxima of the dyes were in the region 370-480 nm and 471-569 nm, respectively. The properties of the dyes as fluorescent probes for living cells imaging and flow cytometry were investigated. The results showed that dyes 1, 2, 8 or 9 could penetrate an intact cell membrane, stained the cell nuclear and exhibited bright fluorescence. Little background interference, low cell cytotoxicity and little photobleaching were showed during the imaging tests. The dyes 1, 8 and 9 could be applied in flow cytometry and dye 1/PI, dye 8/PI or dye 9/PI couple could be proposed as double staining agents to measure sperm cell viability. Thus the dyes represented the cell-permeant fluorescent probes. (C) 2013 Elsevier Ltd. All rights reserved.