BEH.462/3. 962J Molecular Principles of Biomaterials Spring 2003 Physical gels: example-Hydrophobic interactions in physical gels Physical gels are formed by noncovalent cross-links Example blocks: Poly(ethylene glycol)(PEG) Hydrophilic B blocks 3} Hydrophobic A blocks Poly(propylene oxide)(PPO) Poly(butylene oxide)(PBO) Key properties of gels for bioengineering applications 1. in situ formability 2. degradability 3. responsⅳ e swelling 4. tissue-like structure/properties In situ formability Gelation of liquid solutions by Irradiation with light Temperature change(e.g. 4.C to 37C) Cross-linking enzymes Presence of divalent salts ON BOARD In situ formation Heat ACrosslinking by enzymes ntroduction of divalent cations(e.g. Ca*, Mg*) Lecture 7-Hydrogels 1 20f15BEH.462/3.962J Molecular Principles of Biomaterials Spring 2003 Physical gels: example- Hydrophobic water interactions in physical gels Physical gels are formed by noncovalent Example blocks: cross-links Poly(ethylene glycol) (PEG) Hydrophilic B blocks Hydrophobic A blocks Poly(propylene oxide) (PPO) Poly(butylene oxide) (PBO) • Key properties of gels for bioengineering applications: 1. in situ formability 2. degradability 3. responsive swelling 4. tissue-like structure/properties • In situ formability ƒ Gelation of liquid solutions by: • Irradiation with light • Temperature change (e.g. 4°C to 37°C) • Cross-linking enzymes • Presence of divalent salts ON BOARD: In situ formation ¥hν ¥Heat ¥Crosslinking by enzymes ¥Introduction of divalent cations (e.g. Ca++, Mg++) Lecture 7 – Hydrogels 1 2 of 15