Non-fused Phospholes as Fluorescent Probes for Imaging of Lipid Droplets in Living Cells

Abstract

Molecular tools for fluorescent imaging of specific compartments in cells are essential for understanding the function and activity of cells. Here, we report the synthesis of a series of pyridyl- and thienyl-substituted phospholes and the evaluation of these dyes for fluorescent imaging of cells. The thienyl-substituted phospholes proved to be successful for staining of cultured normal and malignant cells due to their fluorescent properties and low toxicity. Co-staining experiments demonstrated that these probes target lipid droplets, which are, lipid-storage organelles found in the cytosol of nearly all cell types. Our findings confirm that thienyl-substituted phospholes can be utilized as fluorescent tools for vital staining of cells, and we foresee that these fluorescent dyes might be used in studies to unravel the roles that lipid droplets play in cellular physiology and in diseases.

Recent Advances in Fluorescent Probes for Lipid Droplets

“…A series of non-fused pyridyl and thienyl-substituted phospholes was proposed as alternative green LD stains (Phos, as shown in Figure 4 ) [ 41 ]. It was shown that the introduction of thienyl groups to the phosphole caused shifts to the red region both in excitation and emission spectra compared to pyridyl groups.…”

Specific Two-Photon Imaging of Live Cellular and Deep-Tissue Lipid Droplets by Lipophilic AIEgens at Ultralow Concentration

“…Great efforts have been made to develop novel lipid droplets dyes to solve these problems. [12][13][14][15][16][17][18][19][20][21] Because the normal concentration used for lipid droplets staining falls in the range of 5-10 μM or even higher, these dyes show weak emission due to the aggregation-caused quenching (ACQ) effect. 22 Few dyes have been synthesized for lipid droplets imaging and function at nano-molar concentrations.…”

Lipid Droplets in Cancer: From Composition and Role to Imaging and Therapeutics

“…Donor-acceptor fluorophores, able to promote internal charge transfer (ICT), have been applied in FRET and in super-resolution STED microscopy [65][66][67]. In addition, new dyes such as pyridyl-and thienyl-substituted phospholes, fluorescent fluoranthenes, and solvatochromic coumarins were developed in recent years for LD imaging in living cells and in human cervical cancer tissues [68][69][70].…”