User:Jhpbroeke/Styryl dye

Styryl dyes are organic molecules with fluorescent properties and are used in the field of neurobiology as a means of labeling recycling vesicles. Their fluorescent properties depend on the insertion of the hydrocarbon tail into a lipid medium, such as the cell membrane.

Properties
Styryl dyes have a hydrocarbon tail, where the length of the tail determines the dissociation constant for membrane insertion. Short tails (43C) have a high dissociation constant and move fast in and out of lipids, while longer tails have a lower dissociation constant. Styryl dyes such as FM1-43 and FM4-64 are excited by blue/green light (430nm-520nm) while the emission spectrum is shifted to yellow/orange (max. 580nm) for FM1-43, and to the far-red (max. 730nm) for FM4-64.

Use in neuroscience
The dye is usually applied to the cells, causing their entire outer membrane to be labeled. By triggering the synaptic vesicle cycle by stimulating the cell synaptic vesicles are endocytosed, the dye in the membrane is internalized. Following the stimulation, the cells are washed to remove all the non-internalized dye molecules from the membrane. When imaging these cells after washing, the exocytosis can be studied as a measure of fluorescent decrease: when a vesicle fuses with the membrane, the dye is released and disperses, resulting in a decrease in fluorescence

Link to video of a FM1-43 experiment in live neurons: #REDIRECT [].