Methacrylated Hyaluronic Acid (MA-HA, also called HAMA, HA-MA, or MeHA) is a chemically modified derivative of hyaluronic acid where methacrylate groups (-O-CO-C(CH₃)=CH₂) are grafted onto the HA polysaccharide backbone through reaction with methacrylic anhydride at the C6 primary hydroxyl of N-acetyl-D-glucosamine residues. These methacrylate groups enable photocrosslinking via free-radical chain polymerization: (1) Dissolve MA-HA powder in aqueous buffer (PBS, culture medium, HEPES) at 1-10% w/v; (2) Add a photoinitiator — LAP (lithium phenyl-2,4,6-trimethylbenzoylphosphinate, 0.05-0.5% w/v) for visible light/405 nm (recommended for cell-laden bioprinting — highest cytocompatibility), or Irgacure 2959 (0.05-0.5% w/v) for UV/365 nm (most widely characterized in literature, cost-effective for acellular scaffolds); (3) Expose the solution to light (10-50 mW/cm², 30-300 seconds). The photoinitiator undergoes homolytic cleavage → generates free radicals → initiates polymerization across methacrylate C=C double bonds → forms covalent polymethacrylate crosslinks between adjacent HA chains → stable 3D hydrogel network. The resulting hydrogel stiffness is precisely tunable from ~1 kPa (soft, brain-mimetic) to ~50 kPa (stiff, cartilage-like) by adjusting polymer concentration, DoM, photoinitiator concentration, and light exposure — independent control of mechanical and biochemical properties.

UPOR Biotech supplies research-grade MA-HA in the 100-400 kDa molecular weight range with a degree of methacrylation (DoM) of 20-50%. This range is optimized to balance three critical parameters for biomedical research: (1) Sufficient HA chain length for robust hydrogel mechanical integrity after crosslinking — longer chains (higher MW) produce tougher gels at equivalent crosslink density. (2) Good water solubility at working concentrations of 1-10% w/v — lower MW grades dissolve faster and reach higher concentrations without excessive viscosity. (3) Adequate methacrylate density per chain to achieve rapid, complete gelation — higher DoM produces faster gelation and stiffer gels. Each batch is verified by ¹H-NMR spectroscopy (D₂O, 400 MHz) with characteristic methacrylate peaks: δ 6.0 ppm (vinyl H trans to CH₃), δ 5.6 ppm (vinyl H cis to CH₃), δ 1.8 ppm (methacrylate -CH₃); integration ratio vs HA N-acetyl methyl (δ 2.0 ppm, 3H) quantifies DoM. The ¹H-NMR spectrum is provided in your COA documentation. Custom MW ranges (e.g., 50-100 kDa, 400-800 kDa) and DoM specifications (e.g., 10-20%, 50-80%) are available for larger orders — contact our technical team with your target specifications.

MA-HA is a foundational biomaterial across six major biomedical research domains: (1) 3D Bioprinting Bioinks — the core photocrosslinkable HA for extrusion-based, DLP (digital light processing), and SLA (stereolithography) bioprinting. MA-HA provides the structural hydrogel matrix for cell-laden printed constructs — shear-thinning for smooth extrusion, rapid photocuring for shape fidelity. Use at 3-10% w/v with LAP photoinitiator for >85% post-printing cell viability. (2) Tissue Engineering Scaffolds — biochemically relevant HA hydrogels for cartilage (supports chondrogenesis via CD44-mediated Sox9 activation), skin (dermal fibroblast proliferation and collagen synthesis), and connective tissue regeneration. (3) 3D Cell Culture and Organoids — HA-rich 3D matrices that support spheroid/organoid formation, maintain in-vivo-like cell phenotype, and enable more predictive drug screening and disease modeling vs 2D monolayer culture. (4) Controlled Drug Delivery — tunable mesh size (5-50 nm depending on crosslink density) controls the release rate of encapsulated protein therapeutics, growth factors (VEGF, bFGF, TGF-β), peptides, and small molecules via Fickian diffusion + network degradation. Sustained release over days to weeks. (5) Wound Healing and Surgical Sealants — in-situ photocuring enables liquid application to irregular wound geometries → conformal hydrogel dressing. Research in chronic wound care, surgical adhesion prevention, and hemostatic sealants. (6) Medical Device Coatings — photocure MA-HA onto catheter, implant, or microfluidic surfaces creating lubricious (coefficient of friction <0.1), anti-fouling (reduced protein adsorption and bacterial adhesion) biocompatible coatings.

Three photoinitiator systems are commonly used with MA-HA — selection depends on your specific application requirements for cytocompatibility, gelation speed, and light source availability: (1) LAP (Lithium phenyl-2,4,6-trimethylbenzoylphosphinate) — visible light 405 nm. RECOMMENDED for cell-laden bioprinting. LAP has significantly higher cytocompatibility than Irgacure 2959 (lower free radical cytotoxicity, no UV-induced DNA damage), rapid gelation kinetics (30-120 seconds at 10-50 mW/cm²), and is compatible with standard 405 nm LED sources found on most commercial bioprinters (Cellink, Allevi, RegenHU). Use at 0.05-0.5% w/v. (2) Irgacure 2959 (2-Hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone) — UV 365 nm. The most widely characterized photoinitiator in MA-HA literature (established safety profile for acellular applications). More cost-effective than LAP. Best for acellular scaffolds and non-cell applications where UV exposure is acceptable. Use at 0.05-0.5% w/v. Higher concentrations or longer UV exposure can reduce cell viability — limit to <5 minutes for cell-containing constructs. (3) Ruthenium/Sodium Persulfate (Ru(II)bpy₃²⁺/S₂O₈²⁻, Ru/SPS) — visible light 400-450 nm. Excellent cytocompatibility (no free radical photoinitiator byproducts) but slower gelation kinetics (2-10 minutes). Best for applications where rapid curing is not critical and maximum cytocompatibility is required. Use at 1 mM Ru / 10 mM SPS. For most cell-containing applications, LAP at 405 nm provides the optimal balance of speed, cytocompatibility, and compatibility with standard bioprinting hardware. UPOR Biotech can supply MA-HA bundled with your choice of photoinitiator upon request.

Lyophilized powder: Store at -20°C to 4°C in a dry, light-protected environment (amber vials or aluminum foil-wrapped containers). The methacrylate groups are light-sensitive — exposure to ambient light over extended periods can cause premature polymerization. Shelf life: minimum 6 months from receipt under recommended conditions; DoM and solubility re-verified at 0/3/6 months. Reconstituted solution: Once dissolved in aqueous buffer (PBS, DMEM, HEPES), store at 2-10°C protected from light and use within 1 month. Avoid repeated freeze-thaw cycles as this can cause polymer aggregation and premature methacrylate hydrolysis. For long-term storage of reconstituted MA-HA: aliquot into single-use volumes, flash-freeze in liquid nitrogen, and store at -80°C (stable up to 6 months). Thaw on ice immediately before use — do not refreeze. Photoinitiator addition: Add photoinitiator to MA-HA solution immediately before use, not during storage — the photoinitiator is light-sensitive and will slowly generate radicals even in ambient light. Important regulatory note: All MA-HA products are labeled Research Use Only (RUO) — not for human diagnostic, therapeutic, or clinical applications. For c-GMP grade or larger quantities suitable for preclinical/clinical translation, contact our technical team to discuss custom manufacturing.