Polymer | Key Feature | Biomedical Applications |
Poly(β-hydroxybutyrate) (PHB) | Natural polyester produced by bacteria; biodegradable | Tissue engineering, controlled drug release |
Poly(β-hydroxybutyrate-co-valerate) (PHBV) | Copolymer with improved flexibility | Bone tissue scaffolds, sutures |
Poly(ortho esters) (POE) | Hydrolytically degradable | Long-term drug delivery (controlled degradation) |
Polycarbonates (aliphatic types) | Biodegradable with tunable degradation | Soft tissue scaffolds, drug carriers |
Poly(anhydrides) | Surface-eroding, predictable degradation | Vaccine delivery systems, implants |
Poly(ethylene oxide) (PEO) | Hydrophilic, non-toxic | Surface coatings, hydrogels, drug delivery |
Poly(sebacic acid) | Biodegradable and hydrophobic | Biodegradable implants, drug release |
PHB
PHBV
POE
Poly(sebacic acid)
Decade | Key Events |
1950s–1960s | PEG began to be used as an industrial lubricant, plasticizer, and solvent in cosmetics, textiles, and paints. |
1960s | PEG’s biocompatibility was recognized, leading to its first medical and pharmaceutical uses — e.g., in ointments, suppositories, and tablet coatings. |
1970s | The concept of PEGylation was introduced by Frank Davis and colleagues (1977), who discovered that covalently attaching PEG to proteins greatly improved their stability and reduced immune reactions. This innovation marked the beginning of PEG’s biomedical era. |
PEG
Property | Typical Value / Behavior |
Melting point | 4 °C (PEG 200) to 65 °C (PEG 6000) |
Density | ~1.1–1.3 g/cm³ |
pH (aqueous) | Neutral |
Biodegradability | Slowly biodegradable, but highly biocompatible |
Toxicity | Very low (non-irritant, non-carcinogenic) |
PEGylation
Problem (Before PEGylation) | Solution via PEGylation |
Drugs cleared rapidly by kidneys | Increases hydrodynamic size → slows clearance |
Proteins unstable in blood | PEG layer shields from enzymes and degradation |
Immunogenic or antigenic reactions | PEG masks recognition sites |
Low water solubility | PEG increases hydrophilicity |
Poor formulation stability | PEG prevents aggregation and precipitation |
Steric shielding: PEG forms a hydrophilic cloud around the molecule.
Hydrodynamic volume increase: Larger apparent size reduces renal filtration.
Reduced proteolysis: Enzymes can’t access the protein surface easily.
Decreased immune recognition: PEG layer hides antigenic sites.
Enhanced solubility: Hydrophilic PEG attracts water molecules.
Polymer | Responsive To | Biomedical Use |
Poly(N-isopropylacrylamide) (PNIPAM) | Temperature | Thermoresponsive hydrogels for drug delivery |
Poly(acrylic acid) (PAA) | pH | Controlled drug release in response to acidity |
Poly(vinyl alcohol) (PVA) | Crosslinkable, hydrophilic | Artificial organs, contact lenses, hydrogels |
Poly(2-hydroxyethyl methacrylate) (PHEMA) | Hydrophilic | Soft contact lenses, tissue scaffolds |
Poly(dimethylsiloxane)-PEG block copolymers | Amphiphilic | Controlled release membranes, biointerfaces |
PHEMA
PAA
PVA
NIPAM
Category | Emerging Examples | Key Innovations / Applications |
Smart / Stimuli-Responsive Materials | pH-responsive hydrogels, shape-memory polymers, thermo-responsive scaffolds | Controlled drug delivery, dynamic tissue scaffolds, self-healing implants |
Bioactive Polymers | Gelatin methacrylate (GelMA), hyaluronic acid–PEG hybrids, biofunctional polyesters | Tissue regeneration, 3D bioprinting, wound healing |
Nanostructured Biomaterials | Graphene oxide, nanocellulose, bioactive glass nanoparticles | Bone regeneration, biosensors, antibacterial coatings |
Self-Healing Biomaterials | Reversible covalent or supramolecular polymers | Artificial cartilage, soft robotics, wound dressings |
Biohybrid Materials | Living cell–polymer composites, bacteria-assisted materials | Dynamic tissue scaffolds, biosensing, bioactuation |
Bioresorbable Metals | Mg, Zn, Fe alloys with controlled degradation | Orthopedic screws, cardiovascular stents |
Hydrogels (4D Bioprinting) | Smart hydrogels that change shape over time | Soft tissue engineering, controlled drug delivery |
Immunomodulatory Biomaterials | Designed to direct immune cell behavior | Cancer immunotherapy, tissue repair |
Conductive Biomaterials | PEDOT:PSS, polypyrrole, MXene, carbon nanotubes | Neural interfaces, cardiac patches, bioelectronics |
Bioinspired / Biomimetic Materials | Mussel-inspired polydopamine, nacre-like composites, silk-based films | Adhesives, coatings, regenerative scaffolds |
Peptide- and Protein-based Materials | Self-assembling peptide nanofibers, collagen mimetics | Injectable gels, cell scaffolds, biosensors |
New trend in biomaterials
Polydopamine
trihydroxybenzene
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