Principles, Applicable Scenarios, and Result Interpretation of Common Lipid Staining Methods

Lipid staining is used to visualize neutral lipid droplets, membranous lipids, cholesterol, myelin lipids, and lipid-deposition-related structures in tissue, cell, or microbial samples. Different staining methods vary greatly in target recognition, sample pretreatment, and microscopic readout. Method selection should first clarify whether the research target is lipid droplet content, membrane lipid structure, cholesterol distribution, or observation of myelin and lipid-related lesions.

Keywords: lipid staining; Oil Red O; Sudan Black B; Sudan III; Sudan IV; Nile Red; BODIPY; filipin; osmium tetroxide; neutral lipid droplets; cholesterol; myelin; lipid deposition; histochemical staining

1 Basic Logic of Lipid Staining

1.1 Detection Targets of Lipid Staining

(1) Neutral lipids

Neutral lipids mainly include triglycerides, cholesteryl esters, and storage lipids within lipid droplets. Oil Red O, Sudan dyes, Nile Red, and BODIPY lipid droplet probes are commonly used to visualize neutral lipid droplets. These methods are widely used in studies of fatty liver, adipocyte differentiation, foam cell formation, and cellular lipid accumulation.

(2) Membranous lipids

Cell membranes, organelle membranes, and myelin contain abundant phospholipids, sphingolipids, and cholesterol. Membrane lipid staining does not simply reflect total lipid content; it is also related to membrane structural integrity, lipid organization, and sample fixation conditions.

(3) Cholesterol and its distribution

Cholesterol detection should distinguish free cholesterol from cholesteryl esters. Filipin is more suitable for visualizing free cholesterol and is commonly used in studies of cholesterol transport, lysosomal storage, and membrane cholesterol distribution. Oil Red O and BODIPY probes are more commonly used to observe neutral lipid droplets formed with the participation of cholesteryl esters.

(4) Myelin and lipid lesions

Nervous tissue myelin is rich in lipids. Sudan Black B, Luxol Fast Blue, and osmium tetroxide-related methods can be used to observe myelin structures or lipid components. These staining methods emphasize structural localization and should not be simply used as lipid droplet quantification methods.

1.2 Key Influence of Sample Pretreatment

(1) Limitations of paraffin sections

During routine paraffin embedding, dehydration, clearing, and organic solvent treatment dissolve large amounts of lipids, especially neutral lipids. Therefore, Oil Red O and Sudan staining for lipid droplet observation usually prioritize frozen sections, cell coverslips, or fixed cell samples.

(2) Advantages of frozen sections

Frozen sections can better preserve neutral lipids and lipid droplet structures. They are suitable for studies of fatty liver, atherosclerotic plaques, adipose tissue, tumor lipid metabolism, and lipid deposition. Their limitation is that tissue morphology is less refined than paraffin sections, and section thickness or freezing artifacts may affect interpretation.

(3) Fixation conditions

Lipid staining commonly uses paraformaldehyde, formaldehyde, or relatively mild fixation systems. Strong organic solvents, prolonged dehydration, or excessive permeabilization may cause lipid droplet loss or lipid redistribution. Fluorescent lipid probes especially require strict control of fixation, washing, and light-protection conditions.

Table 1. Detection Targets of Common Lipid Staining Methods

Staining Method	Main Target	Applicable Samples	Main Readout	Typical Applications
Oil Red O staining	Neutral lipids, lipid droplets	Frozen sections, cell coverslips	Red or orange-red lipid droplets	Fatty liver, adipocyte differentiation, foam cells
Sudan Black B staining	Neutral lipids, phospholipids, myelin lipids	Frozen sections, blood cells, nervous tissue	Black or blue-black lipid deposition	Myelin, lipid granules, granulocyte cytochemical staining
Sudan III/IV staining	Neutral lipids	Frozen sections, adipose tissue	Orange-red to red lipid signal	Routine fat staining, histochemical observation
Nile Red staining	Hydrophobic lipids, lipid droplets	Live cells, fixed cells, microorganisms	Lipid-related fluorescence	Lipid droplet dynamics, lipid accumulation screening
BODIPY lipid droplet staining	Neutral lipid droplets, fatty acid or cholesterol analogs	Live cells, fixed cells	Fluorescent lipid droplets or lipid transport signal	Quantitative imaging, flow cytometry, lipid metabolism tracing
Osmium tetroxide staining	Unsaturated lipids, membranous lipids	Tissue blocks, resin samples, electron microscopy samples	Black deposits or enhanced electron density	Electron microscopy, myelin and membrane structure observation
Filipin staining	Free cholesterol	Cells, tissue sections	Blue-violet fluorescence	Cholesterol transport, lysosomal cholesterol accumulation

2 Oil Red O Staining

2.1 Staining Principle

Oil Red O is a fat-soluble azo dye that dissolves into neutral lipid environments, staining triglycerides, cholesteryl esters, and lipid droplets red or orange-red. This method does not recognize lipids through covalent binding, but is based on dye partitioning and enrichment in the lipid phase. It is therefore more suitable for visualizing neutral lipid deposition.

2.2 Applicable Scenarios

(1) Tissue lipid deposition

Oil Red O is commonly used to observe lipid deposition in frozen tissue sections, such as hepatic steatosis, lipid cores in atherosclerotic plaques, adipose tissue morphology, and renal lipid deposition.

(2) Cellular lipid droplet detection

In 3T3-L1 adipocyte differentiation, macrophage foam cell formation, hepatocyte lipid accumulation, and tumor cell lipid metabolism studies, Oil Red O can visualize the number, area, and distribution of intracellular lipid droplets.

(3) Semi-quantitative analysis

After staining, lipid droplet area, positive area percentage, or integrated optical density can be analyzed through microscopy images. In cell experiments, the dye can also be eluted with solvents such as isopropanol for absorbance measurement. However, this readout reflects overall dye loading and cannot replace lipidomics-based quantification.

2.3 Technical Points

(1) Sample type

Frozen sections are preferred for tissue samples, and section thickness should be kept consistent. Cell samples should avoid excessive delipidation and strong organic solvent treatment.

(2) Staining solution filtration

Oil Red O working solution easily precipitates dye particles and should be filtered before use. Unfiltered staining solution may cause background particles and false-positive deposits.

(3) Counterstaining control

Hematoxylin is commonly used for nuclear counterstaining to help locate lipid droplets and tissue structures. Overly intense counterstaining can interfere with lipid droplet boundary recognition, especially during image quantification, so conditions should remain consistent.

3 Sudan Staining

3.1 Sudan Black B Staining

(1) Staining characteristics

Sudan Black B can stain neutral lipids, phospholipids, and some lipoprotein structures, usually producing black or blue-black staining. Compared with Oil Red O, Sudan Black B covers a broader range of lipid categories but has relatively lower specificity.

(2) Application directions

Sudan Black B can be used for lipid deposition, myelin lipid visualization, blood cell cytochemical staining, and observation of certain intracellular granules. In hematology, Sudan Black B has been used as an auxiliary method to distinguish myeloid cells from lymphoid cells. In nervous tissue, it can help observe myelin-related lipid structures.

(3) Precautions

Sudan Black B has relatively dark background staining and may stain lipofuscin, protein-bound lipids, or other nonspecific hydrophobic structures. When used for lipid droplet quantification, negative controls should be included and imaging conditions should be standardized.

3.2 Sudan III and Sudan IV Staining

(1) Staining targets

Sudan III and Sudan IV are fat-soluble dyes that visualize neutral lipids, usually producing orange-red to red staining. Their histochemical use is similar to Oil Red O, although Oil Red O is more widely used in modern cellular and tissue lipid droplet research.

(2) Applicable scope

Sudan III/IV can be used for adipose tissue, lipid deposition tissues, and routine histochemical observation. If more stable image quantification and higher contrast are required, Oil Red O is usually more suitable.

(3) Interpretation boundaries

Sudan staining mainly reflects the enrichment of fat-soluble dyes in hydrophobic phases. It cannot directly distinguish triglycerides, cholesteryl esters, or other neutral lipid types.

Table 2. Comparison of Oil Red O and Sudan Staining

Comparison Dimension	Oil Red O	Sudan Black B	Sudan III/IV
Main staining targets	Neutral lipids, lipid droplets	Neutral lipids, phospholipids, myelin lipids	Neutral lipids
Color appearance	Red or orange-red	Black or blue-black	Orange-red to red
Common samples	Frozen sections, cell coverslips	Frozen sections, blood cells, nervous tissue	Frozen sections, adipose tissue
Quantification suitability	Commonly used for image semi-quantification	Higher background; quantification requires caution	Relatively less used for quantification
Main advantages	Mature operation, intuitive lipid droplet display	Broader lipid coverage	Simple operation, suitable for routine observation
Main limitations	Not suitable for paraffin-delipidated samples	More obvious nonspecific background	Limited resolution and specificity

4 Nile Red Staining

4.1 Staining Principle

Nile Red is a hydrophobic fluorescent dye. Its fluorescence is weak in aqueous environments but increases significantly after entering hydrophobic lipid environments. Its emission wavelength is influenced by the polarity of the lipid microenvironment, making it suitable for observing intracellular lipid droplets and hydrophobic lipid compartments.

4.2 Application Characteristics

(1) Rapid lipid droplet detection

Nile Red is suitable for rapid observation of cellular lipid droplets, especially in cultured cells, microbial lipid accumulation, and high-throughput screening. It has strong fluorescence signals and short staining times, making it suitable for microscopy imaging and plate-reader detection.

(2) Live-cell compatibility

Nile Red can be used for live-cell staining, but dye concentration, incubation time, and cell type can affect background and cytotoxicity. Live-cell experiments should include unstained controls, solvent controls, and lipid droplet induction positive controls.

(3) Sensitivity to lipid environment

Nile Red signal is not only related to lipid droplet quantity, but also affected by lipid composition, polarity, and dye concentration. Therefore, Nile Red is suitable for relative comparison and should not be used as the sole basis for precise quantification of a specific lipid class.

4.3 Technical Points

Nile Red staining requires control of light exposure, solvent proportion, and imaging parameters. Under different microscopy channels, Nile Red can display signals from different lipid environments. Excitation and emission settings should be fixed during experiments. For high-throughput screening, signals should be normalized by cell number, protein content, or nuclear staining.

5 BODIPY Lipid Probes

5.1 Staining Principle

BODIPY probes are boron-dipyrromethene fluorescent dyes with high brightness, good photostability, and broad structural modifiability. Different BODIPY derivatives can be used for neutral lipid droplet labeling, fatty acid uptake tracing, cholesterol transport analysis, phospholipid membrane structure observation, and lipid peroxidation research.

5.2 Application Directions

(1) Neutral lipid droplet imaging

BODIPY 493/503, BODIPY 505/515, and related probes are commonly used to label intracellular neutral lipid droplets. They have low background and clear lipid droplet outlines, making them suitable for analysis of lipid droplet number, size, area, and fluorescence intensity.

(2) Fatty acid uptake and transport

BODIPY FL C12, BODIPY FL C16, BODIPY 500/510 C1,C12, and BODIPY-palmitate can be used as fatty acid analogs to study fatty acid uptake, transport, lipid droplet formation, and lipotoxicity.

(3) Lipid peroxidation detection

BODIPY 581/591 C11 is sensitive to lipid peroxidation and is commonly used in studies of ferroptosis, membrane lipid oxidation, and oxidative-stress-related lipid injury. This probe reflects oxidative state changes and is not equivalent to ordinary lipid droplet staining.

(4) Cholesterol and cholesteryl ester tracing

BODIPY-cholesterol, BODIPY FL cholesterol, and BODIPY 480/508-cholesteryl linoleate can be used for cholesterol uptake, intracellular transport, cholesteryl ester storage, and lipid droplet-related cholesteryl ester metabolism research.

5.3 Technical Points

BODIPY staining signals are affected by cellular uptake, probe concentration, incubation time, washing intensity, and imaging channel. Cells with abundant lipid droplets are prone to signal saturation. Image analysis should avoid overexposure and use a unified threshold or automated segmentation strategy. For multi-channel co-staining, spectral overlap and channel bleed-through should be checked in advance.

Table 3. Comparison of Nile Red and BODIPY Lipid Droplet Staining

Comparison Dimension	Nile Red	BODIPY Lipid Droplet Probes
Detection target	Hydrophobic lipids, lipid droplets	Neutral lipid droplets or specific lipid analogs
Fluorescence characteristics	Sensitive to lipid microenvironment	Stable signal, lower background
Live-cell application	Applicable, but conditions require optimization	Applicable, commonly used for lipid droplet imaging
Quantitative analysis	Suitable for relative comparison	More suitable for image and flow cytometry quantification
Compatibility with multiplex staining	Spectral overlap requires attention	Better compatibility, but suitable channels must be selected
Main limitation	Strong background and environmental sensitivity	Cannot directly distinguish all endogenous lipid molecules

6 Osmium Tetroxide Staining

6.1 Staining Principle

Osmium tetroxide can react with double bonds in unsaturated fatty acids, forming black osmium deposits and enhancing the electron density of membrane structures. This method is highly important in electron microscopy sample preparation and can also be used for certain observations of myelin, fat, and membranous structures.

6.2 Application Scenarios

(1) Electron microscopy

Osmium tetroxide is commonly used for postfixation in transmission electron microscopy samples, enhancing the electron density of cell membranes, mitochondrial membranes, endoplasmic reticulum membranes, myelin, and lipid droplet boundaries.

(2) Myelin observation

Myelin in nervous tissue is rich in lipids. Osmium tetroxide can stain myelin as dark structures and is suitable for studies of peripheral nerve injury, demyelinating lesions, and nerve regeneration.

(3) Lipid structure preservation

Osmium tetroxide can partially fix unsaturated lipids and reduce lipid loss during subsequent processing. It is suitable for samples requiring observation of membranous structures and lipid microstructures.

6.3 Safety and Limitations

Osmium tetroxide is highly volatile, toxic, and strongly oxidative. It must be handled under strict ventilation and protective conditions. This method is not suitable for rapid routine cellular lipid droplet screening or large-scale routine microscopy staining.

7 Filipin Cholesterol Staining

7.1 Staining Principle

Filipin can form complexes with free cholesterol and produce blue-violet fluorescence. It is commonly used to visualize free cholesterol accumulation in cell membranes, endosomes, lysosomes, and intracellular compartments. Unlike Oil Red O or BODIPY lipid droplet staining, filipin is more specific for free cholesterol distribution rather than total neutral lipid droplets.

7.2 Application Scenarios

(1) Cholesterol transport research

Filipin is suitable for analyzing cholesterol distribution changes in the plasma membrane, endocytic system, and lysosomes. It can be used in studies of cholesterol transport proteins, lipid storage diseases, and drug intervention models.

(2) Lysosomal cholesterol accumulation

In models related to cholesterol storage disorders such as Niemann-Pick C disease, filipin can reveal abnormal intracellular cholesterol accumulation and is an important staining method for studying cholesterol transport defects.

(3) Membrane cholesterol observation

Filipin can be used to observe free cholesterol distribution in membranes, but its signal is strongly affected by fixation conditions, ultraviolet excitation, photobleaching, and sample thickness.

7.3 Precautions

Filipin is light-sensitive, so staining and imaging should be performed protected from light. Because it requires ultraviolet excitation, it may cause phototoxicity in live cells and is usually more suitable for fixed cells or tissue samples. Interpretation should avoid directly equating filipin signal with total cholesterol or cholesteryl ester content.

8 Strategy for Selecting Lipid Staining Methods

8.1 Selection by Lipid Category

(1) Neutral lipid droplets

If the goal is to observe intracellular lipid droplet accumulation, Oil Red O, BODIPY lipid droplet probes, or Nile Red can be prioritized. Oil Red O is intuitive and reliable in frozen tissue sections, while BODIPY probes are more suitable for quantitative cellular imaging and flow cytometry.

(2) Cholesterol distribution

If the goal is free cholesterol localization, filipin staining should be prioritized. If the study focuses on cholesteryl ester-related lipid droplets, Oil Red O, BODIPY lipid droplet probes, or BODIPY cholesteryl ester probes are more suitable.

(3) Myelin and membrane lipid structures

If the goal is to observe nervous tissue myelin or membranous structures, Sudan Black B, Luxol Fast Blue, and osmium tetroxide-related methods are more valuable. For electron microscopy observation of membrane structures, osmium tetroxide treatment is particularly important.

8.2 Selection by Sample Type

(1) Tissue samples

Frozen sections should be prioritized for lipid droplet and neutral lipid observation. Paraffin sections are suitable for routine morphology but not for preserving neutral lipids in situ. If paraffin samples must be used, it should be clearly stated that they cannot reliably reflect in situ neutral lipid deposition.

(2) Cultured cells

Cellular lipid droplets can be stained with Oil Red O, Nile Red, or BODIPY probes. If the goal is morphological display, Oil Red O is sufficiently intuitive. If quantification, co-localization, or flow cytometry is required, BODIPY probes are more appropriate.

(3) Microbial samples

Lipid accumulation in yeast, algae, and bacteria can be rapidly screened using Nile Red or BODIPY probes. Cell wall permeability, dye entry efficiency, and background fluorescence differences should be considered.

8.3 Selection by Detection Goal

(1) Morphological display

Oil Red O and Sudan staining are suitable for histological display. Their images are intuitive and suitable for describing lipid deposition regions.

(2) Quantitative analysis

BODIPY, Nile Red, and elution-based Oil Red O methods can be used for relative quantification, but normalization by cell number, protein content, nuclear staining, or tissue area is required.

(3) Mechanistic research

If the study focuses on lipid droplet formation, cholesterol transport, lipotoxicity, lipid peroxidation, or organelle interactions, lipid staining should be combined with lipid metabolism enzymes, transport proteins, mitochondrial function, ROS, and lipidomics.

Table 4. Recommended Lipid Staining Methods for Common Experimental Goals

Experimental Goal	Recommended Method	Sample Type	Interpretation Focus
Hepatic lipid droplets in fatty liver	Oil Red O	Frozen liver sections	Red lipid droplet area and distribution
Adipocyte differentiation	Oil Red O, BODIPY lipid droplet probes	Cell coverslips, cultured cells	Lipid droplet number, area, and maturation
Foam cell formation	Oil Red O, BODIPY lipid droplet probes	Macrophages	Intracellular lipid droplet accumulation
High-throughput lipid droplet screening	BODIPY probes, Nile Red	Cultured cells, microorganisms	Fluorescence intensity and cell normalization
Free cholesterol localization	Filipin	Fixed cells, tissue sections	Intracellular cholesterol localization and lysosomal accumulation
Lipid peroxidation	BODIPY 581/591 C11	Live cells, fixed cells	Oxidized fluorescence shift and membrane lipid injury
Myelin lipid observation	Sudan Black B, osmium tetroxide	Nervous tissue	Myelin integrity and lipid structure
Electron microscopy membrane structure observation	Osmium tetroxide	Electron microscopy samples	Membrane electron density and preservation quality

9 Common Problems and Result Control

9.1 Weak Lipid Droplet Signal

Weak lipid droplet signal may be related to low sample lipid content, inappropriate fixation, insufficient dye concentration, short staining time, or lipid extraction during processing. For tissue samples, confirm whether frozen sections are used. For cell samples, include a lipid droplet induction positive control.

9.2 High Background Staining

High background is commonly caused by unfiltered staining solution, insufficient washing, excessive dye concentration, tissue autofluorescence, or nonspecific hydrophobic structures in the sample. Oil Red O and Sudan staining require filtration of working solutions. Fluorescence staining requires unstained controls and single-stain controls.

9.3 Inability to Distinguish Lipid Types

Most fat-soluble dyes cannot precisely define specific lipid molecular species. Oil Red O, Sudan dyes, Nile Red, and BODIPY lipid droplet staining mainly visualize lipid enrichment or lipid droplet structures. If triglycerides, cholesteryl esters, phospholipids, or sphingolipids need to be distinguished, thin-layer chromatography, LC-MS lipidomics, or specific enzymatic assays should be combined.

9.4 Poor Reproducibility in Image Quantification

Lipid staining image quantification is affected by section thickness, cell density, exposure time, threshold settings, and region selection. Section thickness, staining time, imaging parameters, and analysis workflow should be standardized. Field selection should be blinded, or whole-slide scanning analysis should be used.

Table 5. Common Problems in Lipid Staining and Optimization Directions

Problem	Possible Cause	Impact on Results	Optimization Direction
Weak Oil Red O staining	Lipids dissolved, staining solution failed, insufficient staining	Underestimation of lipid deposition	Use frozen sections; prepare and filter working solution freshly
Many staining particles	Dye precipitation or unfiltered solution	False-positive background	Filter before staining and shorten staining solution storage time
High fluorescence background	Excess dye, autofluorescence, insufficient washing	Reduced signal-to-noise ratio	Reduce dye concentration, add controls, and strengthen washing
Unclear lipid droplet boundaries	Overexposure, high cell density, lipid droplet fusion	Increased quantification error	Optimize exposure and control cell density
Poor tissue morphology	Freezing artifacts, overly thick sections	Difficult localization	Optimize freezing conditions and section thickness
Large quantitative variation	Inconsistent threshold and field selection	Unstable group comparison	Fix analysis workflow and use a unified threshold

10 Product Selection Related to Lipid Staining

Table 6. Common Basic Reagents and Materials for Lipid Staining

Product Category	Product Name	CAS No.	Role in the System	Applicable Direction
Neutral lipid dye	Oil Red O	1320-06-5	Fat-soluble dye for neutral lipid droplet visualization	Frozen sections, cellular lipid droplets, lipid deposition observation
Lipid dye	Sudan Black B	4197-25-5	Stains neutral lipids, phospholipids, and myelin lipids	Myelin, lipid deposition, blood cell cytochemical staining
Lipid dye	Sudan III	85-86-9	Visualizes neutral lipids	Adipose tissue, routine observation of lipid deposition
Lipid dye	Sudan IV	85-83-6	Visualizes neutral lipids, red staining	Tissue lipid deposition observation
Fluorescent lipid probe	Nile Red	7385-67-3	Fluorescence increases in hydrophobic environments	Live-cell lipid droplets, microbial lipid accumulation, high-throughput screening
Fluorescent lipid droplet probe	BODIPY 493/503	121207-31-6	Labels neutral lipid droplets with low background	Lipid droplet quantitative imaging, flow cytometry, co-localization experiments
Cholesterol probe	Filipin III	480-49-9	Forms fluorescent complexes with free cholesterol	Cholesterol transport, lysosomal cholesterol accumulation

Table 7. Ready-to-Use Staining Solutions, Fluorescent Probes, and Auxiliary Reagents Related to Lipid Staining

Product Category	Cat. No.	Product Name	Grade / Specification	Role in the System	Applicable Direction
Oil Red O staining	I774829	Modified Oil Red O Staining Kit	BioReagent, Biological Stain, for microscopy	Visualizes neutral lipid and lipid droplet deposition	Frozen tissue sections, fatty liver, atherosclerotic plaques, lipid deposition observation
Oil Red O staining	O774830	Oil Red O Staining Kit (For Cell Culture)	BioReagent, Biological Stain, for microscopy	Optimized for cultured cell lipid droplet staining systems	Adipocyte differentiation, foam cell formation, cellular lipid droplet accumulation analysis
Sudan IV staining	S774205	Sudan IV Staining Solution	BioReagent, for microscopy, Biological Stain, 0.1%	Visualizes neutral lipids and forms red lipid deposition signals	Adipose tissue, tissue lipid deposition, routine lipid histochemistry
Sudan IV staining	T1507851	Sudan IV Alcohol Saturated Solution	BioReagent,for microscopy,Biological Stain	Fat-soluble dye system for neutral lipid visualization	Lipid deposition observation in frozen sections, tissue lipid staining
Sudan III staining	S774204	Sudan III Staining Solution	BioReagent, Biological Stain, for microscopy, 0.1%	Visualizes neutral lipids and forms orange-red lipid staining signals	Adipose tissue, lipid droplets, routine observation of lipid deposition
Sudan III staining	S774836	Sudan Ⅲ Staining Kit	BioReagent, Biological Stain, for microscopy	Provides a standardized Sudan III lipid staining system	Tissue or cell lipid deposition staining, routine histochemical observation
Sudan III staining	S1520411	Sudan III Alcohol Saturated Solution	BioReagent,Biological Stain,for microscopy	Alcohol-saturated dye system for neutral lipid staining	Lipid observation in frozen sections, adipose tissue staining
Sudan Black B staining	S1508362	Sudan Black B Staining Solution	BioReagent,for microscopy,Biological Stain	Stains neutral lipids, phospholipids, myelin lipids, and some lipid granules	Myelin lipids, lipid deposition, blood cell cytochemical staining
Sudan Black B staining	S1508441	Sudan Black B Staining Solution	BioReagent,for microscopy,Biological Stain	Produces black or blue-black lipid staining signals	Nervous tissue myelin observation, lipid deposition, intracellular lipid granule visualization
BODIPY lipid droplet / neutral lipid probe	B1499713	BODIPY 505/515	Moligand™, 10 mM in DMSO	Fluorescently labels hydrophobic lipid compartments for lipid droplet observation	Live or fixed cell lipid droplet imaging, lipid accumulation analysis
BODIPY lipid droplet / neutral lipid probe	D474977	BODIPY 505/515	≥99%(HPLC)	Neutral lipid-related fluorescent probe	Cellular lipid droplet fluorescence imaging, lipid accumulation detection
BODIPY fatty acid probe	B1455506	BODIPY 500/510 C1, C12	≥99%	Fluorescent fatty acid analog for fatty acid uptake and lipid metabolism tracing	Fatty acid uptake, lipid transport, lipid droplet formation research
BODIPY fatty acid probe	B744202	BODIPY 500/510 C1, C12 (Fatty Acid Green Fluorescence Probe)		Green fluorescent fatty acid probe	Fatty acid uptake, fatty acid metabolism, cellular lipid accumulation research
BODIPY fatty acid probe	B1455679	BODIPY 558/568 C12	≥98%	Red-orange spectral fatty acid fluorescent probe	Fatty acid uptake, lipid droplet formation, multi-channel fluorescence co-staining
BODIPY oxidized lipid probe	B647088	BODIPY 581/591 C11	≥99%	Lipid peroxidation-sensitive probe that reflects membrane lipid oxidation status	Lipid peroxidation, ferroptosis, oxidative-stress-related lipid injury research
BODIPY cholesterol probe	B1451905	BODIPY FL Cholesterol		Fluorescent cholesterol analog for cholesterol localization and transport analysis	Cholesterol transport, membrane cholesterol distribution, lysosomal cholesterol accumulation research
BODIPY cholesterol probe	D130271	23-(dipyrrometheneboron difluoride)-24-norcholesterol	≥98%	Fluorescently labeled cholesterol probe	Cholesterol uptake, transport, and intracellular localization research
BODIPY fatty acid / lipid metabolism probe	B1454592	BODIPY FL C12		Long-chain fatty acid fluorescent probe	Fatty acid uptake, lipid transport, lipid droplet formation analysis
BODIPY fatty acid / lipid metabolism probe	B1455213	BODIPY FL C5	≥99%	Short-chain fatty acid fluorescent probe	Fatty acid uptake, lipid metabolism, intracellular transport research
BODIPY fatty acid / lipid metabolism probe	B1450796	BODIPY FL-C16		Long-chain fatty acid fluorescent probe	Palmitate-related lipid metabolism, fatty acid uptake, and lipid droplet formation
BODIPY phospholipid / membrane lipid probe	B1455093	BODIPY FL-DHPE		Fluorescent phospholipid analog for membrane lipid labeling	Cell membrane lipids, lipid bilayers, membrane structure, and lipid transport research
BODIPY fatty acid probe	B1449573	BODIPY-Palmitate		Fluorescent palmitic acid analog	Fatty acid uptake, lipotoxicity models, lipid droplet formation, and lipid metabolism research
Antifade mounting medium	A598329	Antifluorescent quencher		Reduces fluorescence signal decay and preserves fluorescent lipid staining signals	Mounting of BODIPY, Nile Red, filipin, and other fluorescent lipid-stained samples
Antifade mounting medium	P1508975	Polyvinyl Alcohol Anti-Fluorescence Quenching Mounting Medium	Suitable for Immunofluorescence(IF),BioReagent,for microscopy,for fluorescence analysis	Improves storage stability of fluorescent samples	Lipid droplet fluorescence staining and immunofluorescence combined lipid staining sample mounting
Nuclear counterstain	D609734	DAPI	Moligand™, ≥98%	Fluorescent nuclear counterstain for cell localization and normalization	Nuclear counting combined with BODIPY/Nile Red lipid droplet staining
Nuclear counterstain	D1372407	DAPI Staining Solution	BioReagent, for microscopy, sterile-filtered, Suitable for Immunofluorescence(IF), 1.0 mg/mL	Ready-to-use nuclear staining system	Nuclear localization and cell number normalization in lipid droplet image analysis
Nuclear counterstain	D598342	DAPI staining solution (ready to use)		Ready-to-use nuclear staining solution	Nuclear counterstaining after lipid fluorescence staining
Nuclear counterstain	B693333	bisBenzimide H 33258; H 33258	≥99%	Fluorescent nuclear dye	Nuclear localization and cell number normalization combined with lipid droplet fluorescence staining
Nuclear counterstain	H1373484	Hoechst 33258 staining solution	BioReagent, Biological Stain, Biological dye grade, Suitable for Immunofluorescence(IF), for fluorescence analysis, for cell culture, for microscopy, ready-to-use, 1.0 mg/mL in H₂O	Ready-to-use nuclear counterstain	Nuclear staining combined with live-cell or fixed-cell lipid fluorescence staining
Nuclear counterstain	H288601	Hoechst 33342 trihydrochloride	≥98%(HPLC)	Can be used for live-cell nuclear staining	Live-cell lipid droplet imaging, BODIPY lipid droplet staining combined with nuclear localization
Nuclear counterstain	O1501802	oechst 33342 Staining Solution	Suitable for Immunofluorescence(IF), BioReagent, ready-to-use, Biological Stain, for fluorescence analysis, Biological dye grade, for microscopy, for cell culture, 1.0 mg/ml in H₂O	Ready-to-use live-cell/fixed-cell nuclear staining system	Cell nucleus counting and image normalization combined with lipid droplet fluorescence staining
Mounting medium with nuclear stain	A1209180	AntiFade Mounting Medium (with DAPI)	BioReagent, Suitable for Immunofluorescence(IF), Suitable for Immunohistochemistry(IHC)	Provides DAPI nuclear counterstaining during mounting	Mounting and nuclear localization after fluorescent lipid staining with BODIPY, Nile Red, etc.
Mounting medium with nuclear stain	A1511201	Antifade Mounting Medium (Containing Hoechst 33258)	BioReagent,Biological Stain,for microscopy	Provides Hoechst nuclear counterstaining during mounting	Mounting and nuclear localization of lipid fluorescence-stained samples
Mounting medium with nuclear stain	A1209301	AntiFade Mounting Medium (with Hoechst 33342)	BioReagent, Suitable for Immunohistochemistry(IHC), Suitable for Immunofluorescence(IF)	Provides Hoechst 33342 nuclear counterstaining during mounting	Mounting of live-cell or fixed-cell lipid droplet fluorescence samples

The selection of lipid staining methods should be based on lipid category, sample type, and detection objective. For neutral lipid droplet observation, Oil Red O, BODIPY lipid droplet probes, or Nile Red can be prioritized. For free cholesterol localization, filipin should be selected. For myelin and membranous lipid structures, Sudan Black B or osmium tetroxide-related methods are more suitable. For mechanistic research, lipid staining should be combined with lipid quantification, metabolic enzyme detection, and lipidomics analysis to avoid directly equating staining intensity with the content of a specific lipid molecule.