Labelling

FM4-64 is a red fluorescent dye commonly used to study synaptic activity at synapses and neuromuscular junctions by staining synaptic vesicles. It is water-soluble, non-toxic, and initially nonfluorescent in aqueous medium. However, after embedding into the outer leaflet of cell membranes, it becomes highly fluorescent. During neurotransmitter release, it internalizes within recycled synaptic vesicles, staining nerve terminals.

TMR-DN is a probe that combines 5-carboxy tetramethylrhodamine (TMR) with a quencher moiety, dinitroaniline (DN). It enables contact quenching, is non-toxic to cells, and can penetrate cell membranes. The core of the molecule contains an aromatic fragment with a negatively charged carboxylic group, providing bright fluorescence properties while minimizing nonspecific binding to genomic DNA or RNA.

Neuro-DiO is a green fluorescent, lipophilic carbocyanine dye optimized for neuronal tracing, with an excitation maximum at 497 nm and an emission maximum at 514 nm. It shares similarities with DiO, a commonly used tracer, but offers improved solubility in membranes and prevents nonfluorescent aggregate formation. Neuro-DiO labels neurons uniformly through membrane diffusion, with minimal transfer between labeled and unlabeled cells in intact tissue.

6-Carboxy-H2DCFDA is a chemically reduced, acetylated form of fluorescein used as an indicator for reactive oxygen species (ROS) in living cells. Initially non-fluorescent, it becomes green-fluorescent after intracellular esterases remove the acetate groups and ROS oxidize it within the cell. The resulting 6-carboxy-2’,7’-dichlorofluorescein emits bright fluorescence in the green channel (with an absorption maximum at 511 nm and an emission maximum at 533 nm).

H2DCFDA is a cell-permeant indicator used to detect reactive oxygen species (ROS) in living cells. Initially non-fluorescent, it becomes highly fluorescent after intracellular esterases remove its acetate groups and oxidation occurs. The resulting product is 2’,7’-dichlorofluorescein (DCF), which emits bright green fluorescence with an absorption maximum at 511 nm and a fluorescence maximum at 533 nm. It’s commonly employed for ROS assays in living cells and is not suitable for sample fixation.

BAPTA-AM is a cell-permeable derivative of BAPTA, a highly selective calcium chelator. Additionally, BAPTA-AM can serve as a calcium indicator: its absorption maximum shifts upon complexing with calcium (free form: absorption max. at 254 nm, complexed form: absorption max. at 274 nm; emission max. remains constant at 363 nm).

Di-4-ANEPPS is a voltage-sensitive dye from the Amino-Naphthyl-Ethenyl-Pyridinium (ANEP) family. Initially non-fluorescent, it becomes active when bound to cell membranes and responds to electrical potential changes. This fast-acting dye detects transient (millisecond) potential fluctuations in excitable cells like neurons, cardiac cells, and intact brains. Due to rapid cell internalization, it’s ideal for short-term studies.Di-4-ANEPPS can also serve as a plasma membrane and endocytosis marker.

Di-8-ANEPPS is a potentiometric fluorescent dye that noninvasively measures transmembrane voltage. Initially non-fluorescent, it becomes strongly fluorescent when bound to the lipid bilayer of cell membranes (with an excitation/emission max of approximately 467/631 nm). The fluorescence intensity of Di-8-ANEPPS varies proportionally with changes in transmembrane voltage.

RH 237 is a lipophilic cationic dye used as a fluorescent probe in biological research. It belongs to the rhodamine class of compounds, known for their high brightness and photostability in imaging applications. RH 237 primarily enables functional imaging of neurons, including membrane potential, synaptic activity, and ion channel function. In methanol, RH 237 exhibits an excitation peak at 550 nm and an emission peak at 786 nm. Notably, in cell membranes, the dye’s spectra experience blue shifts of approximately 20 nm for excitation and 80 nm for emission.