Oleic Acid (OA): FAQs for Research & Lab Use

Oleic acid (OA) is a monounsaturated omega-9 fatty acid widely used in biochemical, cell biology, and lipid metabolism research as a model fatty acid for studying lipid accumulation, membrane composition, and metabolic signaling.

Chemical Name

(9Z)-Octadec-9-enoic acid

CAS Number

112-80-1

Molecular Formula

C₁₈H₃₄O₂

Molecular Weight

282.46 g/mol

Appearance

Pale yellow to yellow oily liquid

Supplier Grade

Purified Oleic Acid (Lipoid, Germany)

SKU

O1456057

What Is Oleic Acid and Why Is It Used in Research?

Oleic acid (OA) is an 18-carbon monounsaturated fatty acid with a single cis double bond at the Δ9 position (C9–C10). It is one of the most abundant fatty acids in mammalian tissues and a major component of dietary fats such as olive oil. In research settings, OA is used as a model free fatty acid to investigate lipid droplet formation, intracellular triglyceride accumulation, membrane fluidity, and fatty acid oxidation pathways. It is also employed in studies of insulin resistance, non-alcoholic fatty liver disease (NAFLD) models, and cancer cell metabolism. Because OA is generally considered less lipotoxic than saturated fatty acids such as palmitic acid, it serves as an important comparator in metabolic studies.

Purity, Grade, and Quality of Aladdin's Oleic Acid

Aladdin Scientific's oleic acid (SKU: O1456057) is sourced from Lipoid, Germany, and is supplied as a Purified Oleic Acid. Lipoid is recognized in the pharmaceutical and research industries for producing high-purity lipid raw materials under stringent quality controls. For research applications, purity is a critical parameter because contaminating saturated or polyunsaturated fatty acids can confound experimental results, particularly in cell-based assays or metabolic studies. Researchers should consult the Certificate of Analysis (CoA) provided with each lot for confirmed purity values, fatty acid profile, and physical characteristics such as acid value and peroxide value. If your application requires a specific purity threshold, please contact Aladdin Scientific's technical support team for lot-specific documentation.

Storage, Handling, and Stability of Oleic Acid

Oleic acid is sensitive to oxidation due to its unsaturated double bond. Exposure to air, light, and elevated temperatures accelerates autoxidation, leading to the formation of peroxides and degradation products that can be cytotoxic and compromise experimental reproducibility. The following best practices are recommended:

• Storage temperature: Store at 2–8 °C under an inert atmosphere (nitrogen or argon) to minimize oxidation. Long-term storage at –20 °C is advisable for extended shelf life.
• Container: Use amber or opaque glass vials to protect from light. Avoid plastic containers that may leach plasticizers.
• Aliquoting: Divide bulk material into single-use aliquots upon receipt to reduce freeze-thaw cycling and air exposure.
• Handling: Work under inert gas when possible. Use antioxidants such as butylated hydroxytoluene (BHT) if preparing stock solutions for long-term use.
• Quality check: Monitor peroxide value before use; elevated peroxide values indicate oxidative degradation.

Always consult the product's Safety Data Sheet (SDS) before handling, as oleic acid can be an irritant at high concentrations.

How to Prepare Oleic Acid Stock Solutions for Cell Culture

Oleic acid is poorly water-soluble and must be solubilized appropriately before use in aqueous biological systems. The most common approaches for cell culture applications are:

1. BSA conjugation: Prepare an OA–bovine serum albumin (BSA) complex. Dissolve OA in ethanol to make a concentrated stock (e.g., 100 mM), then complex with fatty-acid-free BSA in warm PBS or serum-free medium at a defined molar ratio (commonly 2:1 to 6:1 OA:BSA). This method closely mimics physiological delivery of free fatty acids and is widely used for in vitro lipotoxicity and lipid droplet studies.
2. Ethanol vehicle: OA can be dissolved directly in ethanol and added to culture medium at a final ethanol concentration ≤0.1% to minimize solvent cytotoxicity. An ethanol-only vehicle control must be included.
3. Cyclodextrin complexation: Methyl-β-cyclodextrin can be used to deliver fatty acids in a serum-free context.

Always prepare fresh solutions where possible, filter-sterilize (0.22 µm) before addition to cell cultures, and include appropriate vehicle controls in all experiments. Verify the final concentration using established colorimetric or HPLC-based fatty acid assays if precise dosing is required.

Common Research Applications of Oleic Acid

Oleic acid is used across a broad range of research disciplines:

• Lipid droplet induction: OA is the standard reagent for inducing intracellular lipid droplet formation in hepatocytes, adipocytes, and other cell types, enabling studies of lipid metabolism and lipophagy.
• NAFLD/NASH models: Combined treatment with OA and palmitic acid is used to create in vitro models of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis.
• Membrane biology: OA modulates membrane fluidity and is used to study lipid bilayer composition and membrane protein function.
• Cancer metabolism: OA influences ferroptosis resistance and lipid reprogramming in cancer cells and is used in studies of tumor biology.
• Nanoparticle and drug delivery formulation: OA is used as a surfactant or coating agent in the synthesis of iron oxide nanoparticles and lipid-based drug delivery systems.
• Cosmetic and pharmaceutical research: As a skin-penetration enhancer, OA is studied for topical drug delivery applications.

The breadth of applications means that researchers across cell biology, biochemistry, pharmacology, and materials science may require oleic acid of defined and consistent purity.

Frequently asked questions

What is the CAS number and molecular weight of oleic acid?

Oleic acid has the CAS number 112-80-1 and a molecular weight of 282.46 g/mol. Its molecular formula is C₁₈H₃₄O₂, reflecting its 18-carbon chain with one cis double bond at the Δ9 position.

How should oleic acid be stored to prevent oxidation?

Oleic acid should be stored at 2–8 °C under an inert gas atmosphere (nitrogen or argon), protected from light using amber glass containers. For long-term storage, –20 °C is recommended. Aliquoting into single-use portions minimizes repeated exposure to air and reduces oxidative degradation.

How do I make an oleic acid solution for cell culture experiments?

The most physiologically relevant method is to conjugate OA with fatty-acid-free BSA. Dissolve OA in ethanol to prepare a concentrated stock, then complex it with fatty-acid-free BSA in warm PBS or serum-free medium at a molar ratio typically between 2:1 and 6:1 (OA:BSA). Alternatively, OA can be added directly as an ethanol solution at a final ethanol concentration ≤0.1%, with an ethanol vehicle control included in all experiments.

What is the source and quality of Aladdin Scientific's oleic acid (O1456057)?

Aladdin Scientific's oleic acid (SKU: O1456057) is sourced from Lipoid, Germany, a well-established manufacturer of high-purity pharmaceutical and research-grade lipids. It is supplied as a Purified Oleic Acid. For lot-specific purity data, fatty acid profiles, acid value, and peroxide value, please refer to the Certificate of Analysis (CoA) or contact Aladdin Scientific's technical support.

Why is oleic acid used instead of saturated fatty acids in lipotoxicity studies?

Oleic acid is generally considered cytoprotective or neutral compared to saturated fatty acids such as palmitic acid, which induce endoplasmic reticulum stress, mitochondrial dysfunction, and apoptosis at relatively low concentrations. OA is often used as a comparator or co-treatment to demonstrate the differential lipotoxic effects of saturated fatty acids, and to mimic the lipid composition found in conditions such as NAFLD where both saturated and unsaturated fatty acids are elevated.

Can oleic acid be used in nanoparticle synthesis?

Yes. Oleic acid is widely used as a capping ligand and surfactant in the synthesis of hydrophobic nanoparticles, particularly iron oxide nanoparticles (e.g., Fe₃O₄), quantum dots, and other metal oxide nanoparticles. The carboxylic acid group coordinates to the nanoparticle surface, while the hydrophobic tail provides steric stabilization and controls particle size and morphology during synthesis.

References

1. Lipoid GmbH. Product information: Purified Oleic Acid. Lipoid, Germany.
2. Calder PC. Functional roles of fatty acids and their effects on human health. JPEN J Parenter Enteral Nutr. 2015.
3. Listenberger LL, et al. Triglyceride accumulation protects against fatty acid-induced lipotoxicity. Proc Natl Acad Sci USA. 2003;100(6):3077–3082.
4. Sun X, et al. Oleic acid-induced lipid droplet formation and lipid metabolism in hepatocytes: a standard in vitro model for NAFLD research. (General textbook-level reference; specific citation needs verification.)
5. Park YS, et al. Iron oxide nanoparticle synthesis using oleic acid as capping agent. (General reference; specific citation needs verification.)

Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.