Chemical Identity and Structural Features

Chondroitin 4-sulfate sodium salt (SKU C758469) is the sodium salt form of chondroitin 4-sulfate (C4S), a member of the glycosaminoglycan (GAG) family. Its backbone consists of repeating β-1,4-linked disaccharide units of D-glucuronic acid (GlcUA) and 2-acetamido-2-deoxy-D-galactose (GalNAc), with a sulfate ester specifically at the C-4 hydroxyl of each GalNAc residue. This regioselective sulfation pattern distinguishes C4S from chondroitin 6-sulfate (C6S), in which sulfation occurs at the C-6 position.

The sodium counterions replace the acidic protons on both the carboxylate and sulfate groups, improving aqueous solubility and hygroscopic stability relative to the free-acid form. The high negative charge density of C4S underlies its capacity to interact electrostatically with growth factors, morphogens, and cell-surface receptors, making it a key modulator of extracellular signaling microenvironments.

Preparation and Solution Handling

Reconstitution: Weigh the required quantity under ambient conditions. Dissolve in sterile, nuclease-free water or an appropriate aqueous buffer (e.g., PBS, pH 7.4) to prepare stock solutions. C4S sodium salt is freely soluble in water at concentrations typically up to 10 mg/mL; gently vortex or stir at room temperature until fully dissolved. Avoid heating above 37 °C to prevent chain degradation.

Filtration: For cell-culture applications, sterile-filter stock solutions through a 0.22 µm membrane. Note that high-molecular-weight polysaccharide chains may partially retain on some membranes; verify concentration after filtration using a uronic acid colorimetric assay (e.g., carbazole method) if accurate dosing is critical.

Working solutions: Prepare fresh working dilutions in serum-free medium immediately before use, or aliquot stock solutions and store at −20 °C for up to 6 months. Avoid repeated freeze–thaw cycles, which may depolymerize the GAG chain.

pH sensitivity: Maintain solution pH between 6 and 8. Highly acidic or alkaline conditions can cleave the glycosidic bonds or hydrolyze sulfate esters.

Recommended Research Applications

Extracellular matrix (ECM) modeling: C4S is a major GAG chain on aggrecan, versican, and other proteoglycans. It is used to supplement hydrogels or collagen matrices to reconstitute native ECM mechanical and signaling properties for cartilage, neural, and connective-tissue models.

Growth factor binding assays: C4S interacts with FGF, TGF-β, and neurotrophic factors (e.g., BDNF, NT-3). Competitive binding assays using immobilized or soluble C4S quantify ligand–GAG affinity and help elucidate sulfation-code specificity.

Inhibition of axon growth studies: C4S is a component of the glial scar and has been studied extensively as an inhibitory substrate for axon regeneration assays in neuroscience, where it is coated on culture surfaces at defined concentrations (typically 1–10 µg/cm²).

Chondroitin sulfatase substrate: Purified C4S serves as a defined substrate for chondroitin 4-sulfatase (EC 3.1.6.9) activity measurements in enzyme kinetics studies.

Competitive displacement: As a soluble competitor, C4S is added to cell-based assays to displace or compete with endogenous cell-surface GAGs, enabling identification of GAG-dependent receptor interactions.

Storage, Stability, and Quality Considerations

Solid form: Store the lyophilized or powder material at 2–8 °C in a tightly sealed, desiccated container protected from light. Under these conditions the solid is stable for at least 2 years from the date of manufacture; consult the certificate of analysis (CoA) for lot-specific expiry.

Aqueous solutions: Solutions are stable for up to 1 month at 4 °C if prepared under aseptic conditions. For longer-term storage, aliquot and freeze at −20 °C; avoid storing at −80 °C without confirmed compatibility, as low temperatures do not necessarily extend GAG stability beyond −20 °C.

Hygroscopicity: The sodium salt form is hygroscopic. Allow the container to equilibrate to room temperature before opening to prevent condensation, and reseal promptly after use.

Quality verification: Identity and purity can be confirmed by agarose gel electrophoresis with Alcian blue or toluidine blue staining, 1H-NMR, or chondroitinase ABC/AC digestion followed by HPLC disaccharide analysis. The Aladdin product references Glykos catalog number CSAC as a benchmark for quality.

Safety and Regulatory Information

Chondroitin 4-sulfate sodium salt is not classified as a hazardous substance under standard laboratory safety regulations (GHS) when handled as a research reagent. It is of biological origin (typically bovine or avian cartilage) and is supplied for in vitro research use only; it is not approved for clinical, veterinary, or food applications.

Standard laboratory personal protective equipment (PPE) — nitrile gloves, safety glasses, and a laboratory coat — should be worn when handling the powder to avoid inhalation of fine particles. Dispose of waste solutions and solids according to local institutional and governmental waste-disposal regulations for biological materials.

Researchers working under GLP or regulated environments should request the full Safety Data Sheet (SDS) and CoA from Aladdin Scientific prior to use to confirm compliance with internal safety and documentation requirements.