ABSTRACT
<p><b>OBJECTIVE</b>To prepare a pH fluorescence probe based on styrylcyanine dyes for live cell imaging.</p><p><b>METHODS</b>The Probe 1 was prepared by reaction of 4-pyridinecarboxaldehyde with 1,1,2-trimethylbenz[e]indole. The influence of pH on the fluorescent properties was examined, and the cell viability was examined using cell counting kit-8. The Probe 1 was used as a pH fluorescence probe in living cell.</p><p><b>RESULTS</b>Probe 1 emitted green fluorescence under neutral and basic conditions but orange fluorescence under acid condition. Probe 1 selectively stained the cytoplasmic regions of living cells without significantly affecting the cell viability.</p><p><b>CONCLUSION</b>The pH-sensitive fluorescent probe prepared based on styrylcyanine possesses good ability of cell membrane permeation for live cell fluorescent imaging.</p>