Fluorescent Dyes in Life Science Research: Classification, Labeling Principles, and Experimental Applications

Fluorescent dyes are among the most widely used signal molecules in life science research. Their core value lies not merely in generating color, but in converting molecular distribution, cellular states, subcellular structures, and dynamic biological processes into detectable, quantifiable, and imageable readouts. For most experimental platforms, the choice of fluorescent dye directly affects signal-to-noise ratio, background level, channel design, temporal resolution, and the interpretive boundaries of the results.

 

Keywords: fluorescent dye; fluorescence labeling; nucleic acid staining; protein labeling; organelle probe; functional probe; neural tracing; live-cell imaging

 

1 Basic Principles of Fluorescent Dyes

1.1 Basis of Fluorescence Signal Generation

(1) Excitation and emission

After absorbing photons at a specific wavelength, a fluorescent dye enters an excited state and subsequently returns to the ground state by emitting photons at a longer wavelength. The fluorescence color observed experimentally essentially corresponds to the major distribution region of its emission spectrum.

(2) Brightness and quantum yield

Whether a dye appears “bright” is generally determined by both its molar extinction coefficient and quantum yield. High-brightness dyes are more suitable for detecting low-abundance targets; however, when background is high, nonspecific adsorption is strong, or photobleaching is pronounced, theoretical brightness does not necessarily translate into effective signal.

(3) Stokes shift

The wavelength difference between the excitation peak and the emission peak determines the degree of separation between excitation light and detected signal. Dyes with larger Stokes shifts are generally more favorable for reducing excitation crosstalk and sample autofluorescence interference.

 

1.2 Common Labeling Modes

(1) Covalent labeling

This is commonly achieved through reactive groups such as NHS esters, isothiocyanates, and maleimides, which form covalent bonds with proteins, peptides, or oligonucleotides. It is suitable for antibody labeling, protein conjugation, and probe construction.

(2) Non-covalent binding

Some dyes enter target structures through intercalation, groove binding, electrostatic adsorption, hydrophobic enrichment, membrane-potential-driven accumulation, or local environmental partitioning. This mode is common among nucleic acid dyes, membrane dyes, and organelle probes.

(3) Environment-responsive and activatable labeling

Some dyes exhibit enhanced fluorescence only under specific pH, ionic, redox, enzymatic cleavage, or membrane potential conditions. These dyes are therefore better suited for functional detection rather than static localization alone.

 

1.3 Key Factors Determining Experimental Performance

(1) Photostability

This determines resistance to photobleaching during long-term imaging, repeated scanning, and time-series experiments.

(2) Water solubility and charge

These properties determine dye solubility, aggregation tendency, membrane permeability, and nonspecific adsorption behavior.

(3) Environmental sensitivity

This determines whether the dye undergoes additional fluctuations in response to changes in pH, viscosity, polarity, or ionic strength.

Table 1. Key Evaluation Parameters of Fluorescent Dyes

 

Parameter	Primary Meaning	Direct Experimental Impact
Excitation peak / emission peak	Optimal excitation and detection wavelength range	Whether the dye matches the instrument light source and filter system
Quantum yield	Efficiency of photon emission after excitation	Single-molecule signal intensity
Molar extinction coefficient	Light absorption capacity	Excitation efficiency
Photostability	Resistance to photobleaching	Performance in long-term imaging
Water solubility / charge	Distribution and adsorption characteristics	Sample compatibility and background level
Environmental sensitivity	Responsiveness to external environmental changes	Whether the dye is suitable for functional detection

 

2 Fluorescent Dyes for Protein and Antibody Labeling

2.1 FITC

(1) Basic characteristics

FITC, or fluorescein isothiocyanate, is one of the most classical dyes for protein labeling. It emits in the green region, has mature conjugation chemistry, and has been used extensively for decades.

(2) Labeling principle

Its isothiocyanate group reacts covalently with amino groups on lysine residues of proteins. It is therefore commonly used for direct labeling of antibodies, albumin, and other purified proteins.

(3) Main advantages

It is relatively inexpensive, well established in labeling protocols, and suitable for routine immunofluorescence and flow cytometry.

(4) Main limitations

It is relatively sensitive to pH, has only moderate photostability, and is prone to photobleaching during prolonged exposure and repeated scanning. In addition, the green channel is more susceptible to tissue autofluorescence.

(5) Main applications

It is widely used in immunofluorescence, flow cytometry, direct antibody labeling, and basic protein conjugation experiments.

 

2.2 TRITC

(1) Basic characteristics

TRITC, or tetramethylrhodamine isothiocyanate, is a rhodamine-based dye that emits in the orange-red region.

(2) Labeling principle

Like FITC, it forms covalent bonds with protein amino groups via its isothiocyanate functional group.

(3) Main advantages

Compared with FITC, it generally exhibits better photostability and often produces lower background in tissue samples.

(4) Main limitations

In multicolor experiments, it may still overlap spectrally with other orange-red dyes, so channel design requires greater caution.

(5) Main applications

It is commonly used in tissue immunofluorescence, secondary antibody labeling, and multicolor colocalization experiments.

 

2.3 TAMRA

(1) Basic characteristics

TAMRA is a commonly used rhodamine dye with relatively high brightness and is frequently used in molecular probes and oligonucleotide labeling.

(2) Labeling principle

It can be conjugated to proteins in activated ester forms and can also serve as a terminal modification group for oligonucleotide probes.

(3) Main advantages

It has good stability and is suitable for constructing fluorescent probes and molecular detection systems.

(4) Main limitations

Under high-density labeling conditions, a certain degree of self-quenching may occur.

(5) Main applications

It is commonly used in real-time PCR probes, oligonucleotide labeling, and protein conjugation.

 

2.4 Cy3

(1) Basic characteristics

Cy3 is a representative cyanine dye with orange-red emission and relatively high brightness, making it suitable for microscopy and molecular detection platforms.

(2) Labeling principle

It is typically used in the form of NHS esters, maleimides, or nucleic acid modifications to achieve covalent labeling of proteins or oligonucleotides.

(3) Main advantages

It has high brightness and relatively good compatibility in multicolor systems, making it suitable for FISH and protein labeling.

(4) Main limitations

It shows relatively obvious spectral overlap with neighboring orange-red channel dyes.

(5) Main applications

It is commonly used in FISH, oligonucleotide probes, protein labeling, and flow cytometric detection.

 

2.5 Cy5

(1) Basic characteristics

Cy5 is a far-red fluorophore and is one of the most frequently used long-wavelength dyes in multicolor systems.

(2) Labeling principle

It is commonly introduced through NHS esters, thiol-reactive groups, or terminal nucleic acid modification for covalent labeling.

(3) Main advantages

The far-red region generally has low background, making Cy5 suitable for complex tissue samples and backend channels in multicolor experiments.

(4) Main limitations

Some instruments have limited sensitivity in the far-red channel, and photobleaching can still occur under prolonged strong illumination.

(5) Main applications

It is widely used in high-throughput hybridization, complex-tissue immunofluorescence, multicolor flow cytometry, and protein probe construction.

 

2.6 Alexa Fluor Series

(1) Basic characteristics

The Alexa Fluor series is not a single dye, but a family of high-performance commercial fluorescent dyes spanning blue, green, red, and far-red channels.

(2) Labeling principle

These dyes are commonly conjugated to antibodies and proteins through NHS esters, maleimides, and related chemistries.

(3) Main advantages

They generally provide high brightness, good photostability, and strong compatibility in multicolor systems, making them among the most widely used labeling systems in immunofluorescence and flow cytometry.

(4) Main limitations

They are relatively expensive, and the performance of individual members must still be evaluated separately according to the specific spectral range.

(5) Main applications

They are widely used in immunofluorescence, flow cytometry, confocal imaging, and high-content screening.

Table 2. Common Fluorescent Dyes for Protein and Antibody Labeling

 

Dye	Main Emission Region	Main Advantages	Main Limitations	Common Applications
FITC	Green	Mature labeling chemistry, widely used	Moderate photostability, relatively high green-channel background	Immunofluorescence, flow cytometry
TRITC	Orange-red	Better photostability	Potential channel crosstalk in multicolor experiments	Tissue staining, secondary antibody labeling
TAMRA	Orange-red	Good probe compatibility	Possible self-quenching at high labeling density	qPCR probes, oligonucleotide labeling
Cy3	Orange-red	High brightness, relatively good multicolor compatibility	Spectral overlap with adjacent channels	FISH, protein labeling
Cy5	Far-red	Low background, suitable for complex samples	Greater instrument requirements	Multicolor imaging, flow cytometry
Alexa Fluor series	Multiple bands	High brightness, good photostability	Relatively high cost	Immunofluorescence, flow cytometry, confocal imaging

 

3 Nucleic Acid Fluorescent Dyes

3.1 DAPI

(1) Basic characteristics

DAPI is one of the most commonly used nuclear DNA dyes. It emits in the blue region and shows strong affinity for double-stranded DNA, especially AT-rich regions.

(2) Labeling principle

It binds primarily to the minor groove of double-stranded DNA.

(3) Main advantages

It provides clear nuclear localization with relatively low background and is suitable for nuclear counterstaining in fixed cells and tissue samples.

(4) Main limitations

It usually requires ultraviolet or near-ultraviolet excitation, which imposes certain demands on instrumentation and phototoxicity control. It is not suitable for prolonged live-cell observation.

(5) Main applications

Fixed-cell nuclear staining, tissue section counterstaining, and cell counting.

 

3.2 Hoechst 33342 and Hoechst 33258

(1) Basic characteristics

The Hoechst dyes belong to the bisbenzimide class, like DAPI, and also bind DNA mainly through minor-groove association.

(2) Labeling principle

Fluorescence is enhanced upon DNA binding. Among them, Hoechst 33342 has better membrane permeability and is therefore more suitable for live-cell nuclear staining.

(3) Main advantages

They can be used in both fixed samples and certain live-cell nuclear staining applications.

(4) Main limitations

They also require ultraviolet or near-ultraviolet excitation and occupy the blue nuclear channel in multicolor experiments.

(5) Main applications

Live-cell nuclear staining, cell cycle observation, and nuclear segmentation in high-content imaging.

 

3.3 PI

(1) Basic characteristics

PI, or propidium iodide, is a classical nucleic acid intercalating dye that binds both DNA and RNA and emits in the red region.

(2) Labeling principle

PI does not readily cross intact live-cell membranes and therefore mainly enters membrane-compromised cells, where it fluoresces strongly upon binding nucleic acids.

(3) Main advantages

It provides clear discrimination between live and dead cells and is extremely common in both flow cytometry and microscopy.

(4) Main limitations

Because it also binds RNA, RNase treatment is usually required before DNA quantification.

(5) Main applications

Live/dead cell detection, cell cycle analysis, and fixed-cell nuclear staining.

 

3.4 Acridine Orange

(1) Basic characteristics

Acridine orange can bind both DNA and RNA and produces different fluorescence outputs depending on the nucleic acid context.

(2) Labeling principle

When bound to double-stranded DNA it tends to emit green fluorescence, whereas binding to single-stranded nucleic acids or RNA results in orange-red fluorescence. It can therefore, to some extent, distinguish different nucleic acid states.

(3) Main advantages

It can be used to simultaneously observe differences in nucleic acid type and cellular state.

(4) Main limitations

The readout is sensitive to staining conditions and nucleic acid environment, making interpretation relatively complex.

(5) Main applications

Live-cell nucleic acid staining, dual-staining systems related to acidic vesicles, and cell state observation.

 

3.5 Ethidium Bromide

(1) Basic characteristics

Ethidium bromide is a classical double-stranded DNA intercalating fluorescent dye that has long been used for nucleic acid gel electrophoresis detection.

(2) Labeling principle

Its fluorescence is enhanced through intercalation between DNA base pairs.

(3) Main advantages

It provides relatively high sensitivity and clear gel imaging performance.

(4) Main limitations

Its safety concerns are prominent, and it has been partially replaced in many laboratories by lower-toxicity alternatives.

(5) Main applications

Traditional DNA gel imaging.

 

3.6 SYBR Green I-Type Dyes

(1) Basic characteristics

These dyes are highly sensitive to double-stranded DNA and show marked fluorescence enhancement upon binding.

(2) Labeling principle

By binding double-stranded DNA, they convert PCR product accumulation into real-time fluorescence signals.

(3) Main advantages

They provide high sensitivity and are suitable for real-time quantitative PCR and nucleic acid detection.

(4) Main limitations

They cannot distinguish specific amplification products from primer dimers, so melt curve analysis remains important.

(5) Main applications

qPCR, nucleic acid quantification, and high-sensitivity nucleic acid detection.

Table 3. Common Nucleic Acid Dyes

 

Dye	Main Target	Main Advantages	Main Limitations	Common Applications
DAPI	DNA	Clear nuclear localization	Requires UV excitation	Fixed-cell nuclear staining
Hoechst 33342	DNA	Suitable for live cells	UV excitation, occupies blue channel	Live-cell nuclear staining
PI	DNA/RNA	Clear live/dead discrimination	RNA interference must be considered	Live/dead detection, cell cycle analysis
Acridine orange	DNA/RNA	Can reflect differences in nucleic acid state	Condition-sensitive, interpretation is complex	Live-cell nucleic acid observation
Ethidium bromide	DNA	Classical gel detection dye	Inadequate safety profile	Traditional gel imaging
SYBR Green I-type dyes	Double-stranded DNA	High sensitivity	Cannot distinguish nonspecific amplification	qPCR

 

4 Organelle and Structural Fluorescent Dyes

4.1 Mitochondrial Dyes

(1) Rhodamine 123

This is a cationic fluorescent dye that accumulates in mitochondria in a membrane-potential-dependent manner. It is suitable for preliminary observation of mitochondrial localization and state, but its fluorescence does not solely reflect mitochondrial abundance and is also closely associated with membrane potential.

(2) TMRE and TMRM

These are membrane-potential-sensitive mitochondrial probes and are more suitable for monitoring changes in mitochondrial membrane potential in live cells. Compared with simple localization, they are more function-oriented readouts.

(3) MitoTracker series

This is a family of commercial mitochondrial dyes that includes membrane-potential-dependent types and fixation-retainable types, making them suitable for different live-cell imaging and post-fixation imaging requirements.

 

4.2 Lysosomal Dyes

(1) LysoTracker series

These dyes primarily accumulate in lysosomes through acidic-environment-dependent enrichment and are suitable for observing lysosomal distribution in live cells.

(2) LysoSensor series

In addition to localization, these dyes have more pronounced pH responsiveness and are therefore more suitable for monitoring lysosomal acidification status.

 

4.3 Plasma Membrane and Lipid Structural Dyes

(1) DiI, DiA, DiO, and DiD

These lipophilic membrane dyes achieve membrane tracing by inserting into the lipid bilayer. They cover green, orange-red, and far-red channels and are suitable for cell tracking, membrane fusion studies, and neural fiber labeling.

(2) Nile Red

This dye is sensitive to hydrophobic environments and is suitable for observing lipid droplets and neutral lipids.

(3) BODIPY series

This class includes BODIPY 493/503, BODIPY 500/510 C1,C12, and BODIPY 581/591 C11, which are respectively suitable for lipid droplet imaging, fatty acid metabolism analysis, and lipid peroxidation detection.

 

4.4 Endoplasmic Reticulum and Golgi Probes

(1) ER-Tracker series

These probes are suitable for endoplasmic reticulum localization and live-cell observation.

(2) Golgi-Tracker series

These probes are suitable for Golgi localization and intracellular membrane system studies.

Table 4. Common Organelle and Structural Dyes

 

Dye	Main Target	Main Features	Common Applications
Rhodamine 123	Mitochondria	Membrane-potential-dependent accumulation	Mitochondrial localization
TMRE/TMRM	Mitochondrial membrane potential	More function-oriented detection	Membrane potential analysis
MitoTracker series	Mitochondria	Mature localization system	Live-cell imaging
LysoTracker series	Lysosomes	Acidic-environment-dependent accumulation	Lysosomal localization
LysoSensor series	Lysosomes	Pronounced pH responsiveness	Acidification state analysis
DiI/DiA/DiO/DiD	Plasma membrane	Strong lipophilicity, suitable for tracing	Membrane labeling, cell tracking
Nile Red	Lipid droplets	Hydrophobic-environment responsive	Lipid metabolism research
BODIPY series	Lipid droplets / fatty acids / lipid peroxidation	Narrow spectra, broad applicability	Lipid biology research
ER-Tracker series	Endoplasmic reticulum	Suitable for live-cell imaging	Endoplasmic reticulum localization
Golgi-Tracker series	Golgi apparatus	Clear channel separation	Golgi imaging

 

5 Functional Indicator Fluorescent Dyes

5.1 Calcium Probes

(1) Fluo-3, Fluo-4, Fluo-8, and Fluo-20

These probes are mainly used for intracellular Ca²⁺ dynamics detection. Fluo-4 and Fluo-8 are currently more widely used because of their relatively high sensitivity and suitability for both microscopy and flow cytometry.

(2) Fura-2

This is a ratiometric calcium probe and is more suitable for applications requiring higher quantitative accuracy.

(3) Demethyl Rhod-2 AM

This probe is more suitable for fluorescence detection of intracellular Ca²⁺, especially in certain subcellular compartments.

 

5.2 pH Probes

(1) BCECF AM

This is a classical intracellular pH probe suitable for monitoring changes in intracellular acid-base status.

 

5.3 Oxidative Stress and Reactive Molecule Probes

(1) DHE

This probe is mainly used for superoxide anion and ROS-related detection.

(2) DAF-2

This is a nitric oxide fluorescent probe suitable for studies of NO-related signaling.

(3) SOSG

This probe is suitable for singlet oxygen detection.

(4) ZnAF-1

This probe is suitable for Zn²⁺ detection.

 

5.4 Membrane Potential and Cell Viability Probes

(1) JC-1 and JC-10

These dyes are mainly used for mitochondrial membrane potential analysis and are commonly applied in apoptosis and mitochondrial function studies.

(2) Calcein AM

After entering live cells, it is cleaved by intracellular esterases to generate green fluorescence, making it suitable for live-cell labeling and live/dead dual staining.

(3) RH237, DiOC5(3), and Di-4-ANEPPDHQ

These are mainly used for studies of membrane potential and membrane property changes.

Table 5. Common Functional Probes

 

Dye	Target	Main Advantages	Common Applications
Fluo-3/4/8/20	Ca²⁺	High sensitivity	Calcium flux detection
Fura-2	Ca²⁺	Ratiometric measurement, relatively good quantitative performance	Calcium homeostasis analysis
BCECF AM	pH	Suitable for intracellular pH monitoring	Acid-base homeostasis research
DHE	ROS / superoxide anion	Widely used	Oxidative stress analysis
DAF-2	NO	Relatively strong specificity	Nitric oxide signaling research
SOSG	Singlet oxygen	Suitable for photodynamic studies	Reactive oxygen species detection
ZnAF-1	Zn²⁺	Suitable for zinc ion fluorescence analysis	Metal ion detection
JC-1/JC-10	Mitochondrial membrane potential	Intuitive readout	Apoptosis and mitochondrial function
Calcein AM	Live cells	Clear live-cell identification	Live/dead dual staining
RH237/DiOC5(3)/Di-4-ANEPPDHQ	Membrane potential	Suitable for membrane-state analysis	Electrophysiology and membrane function research

 

6 Neural Tracers and Specialized Fluorescent Dyes

6.1 FluoroGold

(1) Basic characteristics

FluoroGold is a classical specialized fluorescent tracer primarily used for retrograde neural tracing.

(2) Tracing principle

FluoroGold can be taken up by nerve terminals and transported retrogradely along axons, ultimately accumulating in neuronal cell bodies, thereby enabling localization of projection neurons and visualization of neural pathways.

(3) Main advantages

It provides clear signal and is suitable for microscopic observation, particularly in studies of neural circuits, projection relationships, and post-injury connectivity analysis.

(4) Main limitations

Its application scenarios are relatively specialized, being mainly restricted to neuroanatomy and neural pathway research, and it is not suitable as a general-purpose dye for routine immunofluorescence or nucleic acid staining.

 

6.2 Neuronal Probes

(1) NM4-64

This probe is suitable for neuron-related fluorescent labeling and membrane structure observation.

(2) NerveGreen C4 and NerveRed C2

These probes are suitable for green or red fluorescent tracing of neurons and are used for neuronal localization and structural imaging.

Table 6. Common Neural Tracers and Specialized Fluorescent Dyes

 

Dye	Main Use	Main Features	Common Applications
FluoroGold	Retrograde neural tracing	Suitable for projection neuron localization	Neural pathway research
NM4-64	Neuronal imaging	Suitable for neural structure observation	Neuronal tracing
NerveGreen C4	Green neuronal tracing	Green channel	Neuronal localization
NerveRed C2	Red neuronal tracing	Red channel	Neuronal imaging

 

7 Product Table of Fluorescent Dyes and Fluorescent Probes

 

Product Category	Catalog No.	Product Name	CAS No.	Grade and Purity	Applicable Research Direction / Use
Protein/antibody labeling dye	F272903	5-FITC(isomer I)	3326-32-7	Ex:498nm, Em:517nm, ≥95%(HPLC)	Suitable for green fluorescent labeling of antibodies, proteins, and peptides
Protein/antibody labeling dye	F104848	Fluorescein isothiocyanate isomer I (FITC)	3326-32-7	≥90%	Suitable for routine protein labeling in immunofluorescence and flow cytometry
Protein/antibody labeling dye	T131320	6-TRITC, R-isomer [Tetramethylrhodamine-6-isothiocyanate]	80724-20-5	≥80%	Suitable for orange-red channel protein and antibody labeling
Cytoskeletal labeling probe	P287444	Phalloidin-TRITC	915013-10-4	≥97%	Suitable for fluorescence staining of microfilament/actin cytoskeleton
Protein/click-labeling dye	T596602	TAMRA azide, 5-isomer	825651-66-9	≥95%	Suitable for click-chemistry labeling and fluorescent probe construction
Protein/nucleic acid labeling dye	C1499685	CY3	146368-13-0	Moligand™, 10 mM in Water	Suitable for oligonucleotide probes, protein labeling, and FISH
Protein/nucleic acid labeling dye	C266403	Cy5	--	≥95%	Suitable for far-red protein labeling, multicolor imaging, and flow cytometry
Nucleic acid dye	D106471	4',6-Diamidino-2-phenylindole Dihydrochloride	28718-90-3	≥98%	Suitable for nuclear staining of fixed cells and tissue sections
Nucleic acid dye	O1501802	oechst 33342 Staining Solution	23491-52-3	BioReagent, ready-to-use, Biological Stain, for fluorescence analysis, Biological dye grade, for microscopy, for cell culture, Suitable for Immunofluorescence(IF), 1.0 mg/ml in H₂O	Suitable for live-cell nuclear staining and microscopic imaging
Nucleic acid dye	H266330	Hoechst 33258 UltraPure	23491-45-4	≥99%(HPLC)	Suitable for DNA nuclear staining and high-purity nucleic acid imaging
Nucleic acid dye	P266304	Propidium iodide（PI）	25535-16-4	≥98%(HPLC)	Suitable for live/dead cell detection and cell cycle analysis
Nucleic acid dye	A304298	Acridine Orange hydrochloride	65-61-2	≥99%	Suitable for dual DNA/RNA staining and cell state analysis
Nucleic acid dye	E119045	Ethidium bromide(EB)	1239-45-8	Suitable for molecular biology, ≥95%(HPLC), powder	Suitable for nucleic acid gel electrophoresis imaging
Nucleic acid/cell nucleus probe	D266292	DRAQ5 Fluorescent Probe	--	--	Suitable for nuclear staining of live or fixed cells and deep-red channel detection
Mitochondrial dye	R299309	Rhodamine 123	62669-70-9	≥98%	Suitable for mitochondrial localization and membrane-potential-related observation
Mitochondrial functional probe	T131055	TMRE [Tetramethylrhodamine, ethyl ester, perchlorate]	115532-52-0	for fluorescence analysis, ≥90%(HPCE)	Suitable for mitochondrial membrane potential detection
Mitochondrial functional probe	T275831	Tetramethylrhodamine	115532-49-5	≥98%	Suitable for dynamic monitoring of mitochondrial membrane potential in live cells
Mitochondrial probe	M1455700	MitoTracker Deep Red FM	873315-86-7	≥99%	Suitable for far-red mitochondrial tracing
Mitochondrial probe	M1455293	MitoTracker Orange CMTMRos	199116-50-2	--	Suitable for mitochondrial localization and live-cell imaging
Lysosomal probe	L647096	LysoTracker Red	231946-72-8	≥97%	Suitable for red fluorescent imaging of lysosomes
Lysosomal probe	L1455226	LysoTracker Yellow HCK 123	1064123-31-4	≥98%	Suitable for yellow fluorescent tracing of lysosomes
Lysosomal functional probe	L1455145	LysoSensor PDMPO	--	≥98%	Suitable for lysosomal acidification status and pH analysis
Endoplasmic reticulum probe	E745769	ER-Tracker Green	--	--	Suitable for endoplasmic reticulum localization and live-cell imaging
Golgi probe	G746379	Golgi-Tracker Green	133867-53-5	≥97%	Suitable for green fluorescent imaging of the Golgi apparatus
Golgi probe	G746380	Golgi-Tracker Red	571186-05-5	≥97%	Suitable for red fluorescent imaging of the Golgi apparatus
Plasma membrane tracing dye	C598347	Cell tracker cm DiI (cell membrane orange red fluorescent probe)	180854-97-1	--	Suitable for plasma membrane labeling and cell tracking
Plasma membrane tracing dye	D598344	DIA (cell membrane green fluorescent probe)	114041-00-8	--	Suitable for green-channel plasma membrane labeling
Plasma membrane tracing dye	D598343	Dio plus (cell membrane green fluorescent probe upgrade)	--	--	Suitable for green plasma membrane tracing
Plasma membrane tracing dye	D598346	Did (cell membrane red fluorescent probe)	362596-00-7	--	Suitable for far-red plasma membrane and cell tracking experiments
Lipid/lipid droplet dye	N121291	Nile Red	7385-67-3	BioReagent, for fluorescence analysis, ≥95%(HPLC)	Suitable for lipid droplets, neutral lipids, and lipid metabolism research
Lipid/lipid droplet dye	B1455702	BODIPY 493/503 methyl bromide	216434-81-0	≥98%	Suitable for high-resolution fluorescent imaging of lipid droplets
Lipid/fatty acid probe	B744202	BODIPY 500/510 C1, C12 (Fatty Acid Green Fluorescence Probe)	--	--	Suitable for fatty acid uptake and lipid metabolism research
Lipid peroxidation probe	B647088	BODIPY 581/591 C11	217075-36-0	≥99%	Suitable for lipid peroxidation detection
Reactive BODIPY dye	B1452502	BODIPY 530/550 NHS ester	216961-93-2	--	Suitable for fluorescent conjugation of proteins and peptides
Reactive BODIPY dye	B1452007	BODIPY 650/665 NHS ester	1818267-45-6	--	Suitable for far-red protein conjugation and labeling
pH probe	B744102	BCECF AM (pH Fluorescent probe，5mM )	--	BioReagent, for fluorescence analysis, 5mM	Suitable for intracellular pH monitoring
Calcium probe	F746068	Fluo-4 AM	273221-67-3	BioReagent, ≥90%(HPLC), 2mM	Suitable for intracellular Ca²⁺ dynamics detection
Calcium probe	F141112	Calcium Fluorescent Probe Fluo-8, AM	1345980-40-6	BioReagent,≥95%(HPLC)	Suitable for high-sensitivity Ca²⁺ detection
Calcium probe	F1509262	Calcium Fluorescent Probe Fura-2 AM	108964-32-5	BioReagent,≥98%(HPLC)	Suitable for ratiometric quantitative Ca²⁺ analysis
Calcium probe	D1450047	Demethyl Rhod-2 AM	129787-64-0	--	Suitable for intracellular Ca²⁺ detection and live-cell functional analysis
Membrane potential probe	J125134	JC-1	3520-43-2	≥95%	Suitable for mitochondrial membrane potential and apoptosis analysis
Membrane potential probe	J141206	JC-10	--	≥95%	Suitable for mitochondrial membrane potential detection
Membrane potential probe	D598334	Di-4-ANEPPDHQ membrane potential fluorescent probe	--	--	Suitable for membrane potential and membrane order analysis
Membrane potential probe	D598333	Dioc5 (3) membrane potential fluorescent probe	--	--	Suitable for plasma membrane potential detection
Membrane potential probe	R598332	Rh237 membrane potential fluorescent probe	--	--	Suitable for membrane potential and electrophysiology-related studies
ROS probe	R353922	ROS fluorescent probe DHE	38483-26-0	--	Suitable for superoxide anion and oxidative stress research
NO probe	D131457	DAF-2	205391-01-1	≥95%(HPLC)	Suitable for nitric oxide detection
Zn²⁺ probe	I276200	5-Iso-ZnAF-1	321859-09-0	≥95%	Suitable for Zn²⁺ fluorescence detection
Singlet oxygen probe	S750650	Singlet Oxygen Sensor Green Reagent	--	--	Suitable for singlet oxygen detection and photodynamic research
Mitochondrial lipid peroxidation probe	M275561	MitoPerOx (cis- and trans- mixture)	1392820-50-6	≥95%	Suitable for mitochondrial lipid peroxidation research
Live-cell dye	C273362	Calcein-AM	148504-34-1	≥90%(HPLC)	Suitable for live-cell labeling and live/dead dual staining
Amyloid-β probe	C276131	CRANAD-2	1193447-34-5	≥95%	Suitable for amyloid-β imaging and neurodegenerative disease research
Neural tracing dye	F1511492	FluoroGold	223769-64-0	BioReagent,sterile,for microscopy,Biological Stain,for fluorescence analysis	Suitable for retrograde neural tracing and projection neuron localization
Neuronal probe	N598338	Nm4-64 neuron fluorescent probe	--	--	Suitable for tracing neuronal membranes and neural structures
Neuronal probe	N598339	Neurogreentm C4 neuron fluorescent probe	--	--	Suitable for green fluorescent imaging of neurons
Neuronal probe	N598337	Neuroredtm C2 neuron fluorescent probe	--	--	Suitable for red fluorescent imaging of neurons
Bacterial/microbial probe	A1456408	Bacteria Red Probe (AIE)	--	BioReagent, for microscopy, Biological Stain, ≥98%(HPLC), 10mM in DMSO	Suitable for bacterial imaging and microbial fluorescence staining
Microbial staining probe	A1456427	Gram Fluorescent Staining Probe‌ (AIE)	--	BioReagent, 10mM	Suitable for Gram fluorescence staining and bacterial classification observation
AIE plasma membrane probe	A1456411	Membrane Red Probe (AIE)	--	BioReagent, for microscopy, Biological Stain, ≥98%(HPLC), 10mM in DMSO	Suitable for red fluorescent imaging of the plasma membrane
AIE organelle probe	A1456409	Lysosome Red Probe (AIE)	--	BioReagent, for microscopy, Biological Stain, ≥98%(HPLC), 10mM in DMSO	Suitable for lysosome imaging
AIE organelle probe	A1456401	Mitochondrion Red Probe (AIE)	--	BioReagent, for microscopy, Biological Stain, ≥98%(HPLC), 50mM in DMSO	Suitable for mitochondrial imaging
AIE lipid droplet probe	L1456031	Lipid droplets Red Probe (Aggregation-induced emission, AIE)	--	BioReagent, for microscopy, Biological Stain, ≥98%(HPLC), 200μM	Suitable for lipid droplet imaging and lipid metabolism research

 

8 Application Logic Across Major Experimental Platforms

8.1 Immunofluorescence and Tissue Imaging

Immunofluorescence places greater emphasis on spectral separation, tissue background, and resistance to photobleaching. FITC, TRITC, Cy3, Cy5, and the Alexa Fluor series are commonly used in fixed cells, whereas tissue sections are generally better matched to red or far-red channels with lower background.

 

8.2 Flow Cytometry

Flow cytometry emphasizes brightness, compensation, and laser compatibility. Low-expression antigens should preferably be assigned to brighter dyes, whereas highly expressed antigens can be assigned to more conventional channels. Functional assays often combine PI, Fluo-4, DHE, and JC-1.

 

8.3 Live-Cell Imaging

Live-cell experiments should prioritize membrane permeability, phototoxicity, and long-term stability. Hoechst 33342, TMRE, TMRM, LysoTracker, Fluo-4, and Calcein AM are commonly used in this context.

 

8.4 Nucleic Acid Detection and Molecular Biology

DAPI and Hoechst are commonly used for nuclear staining; gel imaging can be performed with ethidium bromide or other nucleic acid dyes; real-time PCR and hybridization probes more commonly employ SYBR Green I-type dyes and fluorescent oligonucleotide probe systems.

 

8.5 Neural Tracing Experiments

Neuroanatomical and projection analyses are better suited to FluoroGold, DiI, DiO, DiD, and specialized neuronal probes. In these experiments, the core issue is not the number of channels available, but whether the tracing path is clear, localization is stable, and the experimental time window is appropriate.

 

The value of fluorescent dyes in life science research lies not in simply providing color, but in converting biological information at the levels of proteins, nucleic acids, organelles, functional states, and neural connectivity into analyzable signals. In experimental design, the more important question is not which color to choose first, but which category the target belongs to, followed by selection of a specific dye that matches the instrument, sample type, and analytical platform. Only when classification, labeling principles, representative dyes, and application scenarios are aligned can fluorescence-based experiments yield results with real interpretive power.

 

For more related articles, please see below:

[1] Selection of fluorescent dyes for multicolor flow-through experiments

[2] Application and Channel Selection of Super Fluor Fluorescent Dyes in Multicolor Antibody Labeling

[3] Introduction to the AF Series Fluorescent Dyes: Overview, Applications, and Selection Guide