Categories and Applications of Degradable Biomedical Polymer Materials (PGA, PCL, PLA, PPDO, P4HB, PGS, etc.)
Synthetic biodegradable biomedical polymers are widely used in fields such as clinical implant repair, drug delivery, and tissue engineering, thanks to their controllable degradation rates, excellent biocompatibility, and tunable mechanical properties.
Based on differences in molecular structure and performance, mainstream synthetic biodegradable biomedical polymers can be classified into seven categories: aliphatic polyesters, polycarbonates, poly(ether-ester)s, poly(amino acid)s, poly(ortho ester)s, photocurable biodegradable resins, and water-soluble synthetic polymers.
I. Aliphatic Polyesters (Largest industrial scale; core medical materials)
Aliphatic polyesters are currently the most commercially mature and widely used synthetic degradable medical polymers. Through molecular design and copolymerization modification, their mechanical properties and degradation rates can be tuned across a wide range. They exhibit extremely low immunogenicity and are suitable for the vast majority of implantable medical device and drug delivery applications. 1. PGA (Polyglycolic Acid / Polyglycolide) Characteristics: High crystallinity and high initial tensile strength; degrades very rapidly (2–4 weeks); hydrolysis produces large amounts of glycolic acid, causing significant localized acidic inflammation. Applications: Short-term absorbable surgical sutures, staples, and rapid-release drug microspheres; often copolymerized with LA.
2. PLA (Polylactic Acid) PLLA (Poly-L-lactic Acid): High rigidity and strength; degrades in 12–24 months; a mainstay for load-bearing orthopedic applications. PDLLA (Poly-D,L-lactic Acid): Amorphous with better toughness; degrades in 6–12 months; used for injectable fillers and microspheres. PDLA (Poly-D-lactic Acid): Primarily used for stereocomplex modification to enhance heat resistance. Applications: Orthopedic screws/plates, facial thread lifts, vascular stents, 3D-printed bone scaffolds, and long-acting sustained-release formulations.
3. PLGA (Poly(lactic-co-glycolic acid)) Adjustable LA/GA ratio; covers a full degradation window from 2 weeks to 1 year; excellent processability; mature mass production. Applications: Long-acting injectable microspheres, absorbable soft-tissue tacks, porous tissue engineering scaffolds, and medical aesthetic filler carriers.
4. PCL (Poly-ε-caprolactone) Low melting point, excellent toughness, slow degradation (2–3 years), good compatibility, and easy to 3D print. Applications: Nerve conduits, artificial blood vessels, long-acting sustained-release implants, soft-tissue scaffolds, and base materials for medical aesthetics.
5. PPDO (Polydioxanone): The backbone contains ether linkages, offering flexibility far superior to PGA/PLA. It features mild degradation, minimal acidic degradation products, and a low inflammatory response; the degradation period is 6–12 months. Applications: High-end flexible absorbable sutures, hernia repair meshes, soft-tissue repair tacks, and pediatric implants.
6. PHB/PHBV, P4HB (Poly-4-hydroxybutyrate): PHB is highly rigid and brittle; used for small bone implants, vascular patches, and drug carriers. PHBV: Copolymerization improves toughness; used for small bone implants, vascular patches, and drug carriers. P4HB: Highly elastic and flexible, adapting well to soft tissue; FDA-certified for medical use. Applications: Cardiovascular patches, soft-tissue sutures, and soft-tissue repair membranes.
II. Polycarbonates (Neutral degradation, no acidic irritation, specialized for soft tissue)
1. PTMC (Polytrimethylene carbonate): Hydrolysis yields neutral carbonate small molecules, avoiding local acidic irritation; exhibits excellent elasticity. Applications: Vascular stents, cardiac occluders, elastic soft-tissue scaffolds, and sustained-release drug coatings.
2. PTMCL (Trimethylene carbonate-caprolactone copolymer): Combines the neutral degradation characteristics of PTMC with the toughness of PCL; primarily used for vascular and nerve composite scaffolds.
III. Polyether-ester elastomers
1. PGS (Polyglycerol sebacate): A hot-melt elastomer with mechanical properties matching soft tissues such as skin, myocardium, and fascia; capable of room-temperature cross-linking. Applications: Myocardial repair patches, artificial skin, flexible tissue engineering scaffolds, and anti-adhesion membranes.
IV. Polyamino acids (Degradation products are amino acids; biocompatible)
Side chains can be modified with targeting groups; no acidic degradation products; extremely low cytotoxicity. Examples: Polyglutamic acid, polylysine, and polyaspartic acid. Applications: Gene drug delivery vehicles, targeted chemotherapy microspheres, functional surface coatings for tissues, and hemostatic materials.
V. Poly(ortho ester)s (Surface-eroding controlled-release materials)
Poly(ortho ester)s are a class of typical surface-eroding, degradable polymers. Unlike polyesters, which undergo bulk hydrolytic degradation, the degradation of poly(ortho ester)s occurs only at the material surface. The material maintains stable overall dimensions and enables zero-order (constant-rate) drug release, making it a specialized medical material for precision controlled drug release. These materials degrade under mild conditions with minimal acidic byproducts and induce only slight inflammatory responses; degradation rates can be precisely tuned by adjusting monomer structures and formulation ratios. Key applications include local sustained-release anti-tumor implants, long-acting anti-inflammatory drug carriers, and wound dressings with targeted drug release. They are particularly suitable for clinical scenarios requiring stable, constant-rate drug delivery-such as precise local tumor therapy and long-acting post-operative anti-inflammatory and analgesic treatment-effectively reducing systemic drug toxicity and side effects.
VI. Photocurable/crosslinkable degradable resins (3D printing, bone cements)
1. PPF (Poly(propylene fumarate)): UV-curable and formable at room temperature, with mechanical properties matched to bone tissue. Applications: 3D-printed bone fillers, minimally invasive injectable bone cements, and scaffolds for bone defect repair.
2. MA-PCL and methacrylate-modified PLA: Resins specifically designed for photocurable 3D printing, used for personalized tissue engineering scaffolds.
VII. Water-soluble synthetic degradable polymers
1. PVA (Polyvinyl alcohol): Water-soluble; forms hydrogels via ionic or thermal crosslinking and undergoes slow degradation in vivo. Applications: Medical wound hydrogels, absorbable barrier films, drug encapsulation carriers, and ophthalmic dressings.
2. PEG (Polyethylene glycol / Polyethylene oxide): Cleared from the body naturally; often grafted onto polyester surfaces as a hydrophilic modification segment to enhance blood compatibility. Applications: Anti-fouling surface coatings and long-circulating nanodrug carriers.
VIII. Other specialized synthetic biodegradable medical polymers
Poly(butylene adipate) (PBS): Flexible films, substrates for disposable medical consumables, and wound protection films; Polyanhydrides: Rapidly degradable, used for localized chemotherapy drug-eluting implants; Biodegradable polyurethanes (polyester- or polycarbonate-based): Highly elastic artificial blood vessels and materials for artificial cardiac assist devices.
