Membrane Potential & Nerve Terminal Dyes

The DiO/DPA system detects cytoplasmic membrane potential changes using the principle of fluorescence resonance energy transfer (FRET), where DiO is a “stationary” FRET donor while DPA acts as a potentiometric FRET acceptor. The DiO/DPA system has been reported to produce a fluorescence signal change of >56% in HEK-293 cells and >25% in neuronal cultures and brain slices per 100 mV membrane potential change.

Nerve Terminal Staining Kits contain Biotium’s nerve terminal dyes and accessories for washing away or quenching extracellular dye fluorescence.

SynaptoGreen™ C1 has the shortest (one-carbon) lipophilic tail and is the most water soluble of the nerve terminal dye series. Thus it is expected to have the slowest on-rate and the fastest off-rate among the SynaptoGreen™ dyes.

SynaptoGreen™ C18 (equivalent to FM®3-25) is a membrane stain similar to their nerve terminal dyes, except that it has the longest lipophilic tail (C18). Because of its large size, it is used as a control for ion channel permeability of nerve terminal dyes.

SynaptoGreen™ C2 is more water soluble than SynaptoGreen™ C4 and thus has a faster de-staining rate than the latter.

SynaptoGreen™ C3 is similar to SynaptoGreen™ C4 (70020), except that the lipophilic tail is one carbon shorter and also the hydrophilic end is a trimethylammonium group.

A widely used green fluorescent dye for following synaptic activity by staining synaptic vesicles at the synapse or neuromuscular junctions. When used in combination with the red fluorescent dye SynaptoRed™ (70021), synapses or neuromuscular junctions can be imaged independently in two colors.

SynaptoGreen™ C5 is similar to SynaptoGreen™ C4 (70020), except that the lipophilic tail is one carbon longer.

A widely used red fluorescent dye for following synaptic activity by staining synaptic vesicles at the synapse or neuromuscular junctions. When used in combination with the green fluorescent dye SynaptoGreen™ (70020), synapses or neuromuscular junctions can be imaged independently in two colors. SynaptoRed™ has also been used to study endocytosis in Dictyostelia.

SynaptoRed™ C2M is a red fluorescent probe used to follow synaptic vesicles.

SynaptoRed™ C1 is similar to the widely used red fluorescent nerve terminal dye SynaptoRed™ C2 (also called FM®4-64) except that the lipophilic tail of SynaptoRed™ C1 is one carbon shorter than that of the SynaptoRed™ C2.

ADVASEP-7 is a sulfonated β-cyclodextrin derivative that has been reported to reduce background fluorescence when using SynaptoGreen C4 (also called FM1-43, catalog no. 70020) to stain brain slices.

AM1-43 is a fixable, activity-dependent fluorescent nerve terminal probe. AM1-43 functions similarly similarly to SynaptoGreen C4 (catalog # 70020), but with the additional property of being fixable.

AM1-44 is a version of AM1-43 (catalog no. 70024) with improved fixability. The dye can also be used as a general probe for following endocytosis.

AM2-10 is a fixable analog of SynaptoGreen™ C2.

AM3-25 is a lipophilic styryl dye that has an amine group at the hydrophilic head. The amine group reacts with formaldehyde or glutaldehyde to make the dye fixable.