BEH.462/3. 962J Molecular Principles of Biomaterials Spring 2003 Yasuda et al. Makromol. Chem. 26, 177(1969) Now Eqn 13 gel, oume=e ('few gel "/eed The free volume in a swollen gel is approximately free, 1 since the free volume contribution from polymer is extremely low(2.5%even in solid polymers at 25C) Egn 14 Vree, gel=中ee+2mee I Therefore Ean 15 Vfreegel-91Vfree, 1=(1-02)Vree, 1=(1-1/Q)Vree. 1 o Where Q is the swelling degree Swollen ge vary gel=1/2 Therefore Eqn 16 _ge/ rohumeo-o red md) volume o V/free, 1-1 for most polymers, experimentally Eqn 17 And thus finally Ean o Insulin: MW-5900 g/mole; hydrodynamic radius =16 A Design of glucose-responsive drug delivery microgels for treatment of diabetes -10 Work by Podual and Peppas Immobilized glucose oxidase enzyme within pH-responsive polyelectrolyte gel network along with encapsulated o Network composed of DEAEM, PEGMA, and TEGDMA GOD covalently tethered to networ o Insulin entrapped in network polymerized gels as microspheres Lecture 10-Bioengineering Applications of Hydrogels 9of12  BEH.462/3.962J Molecular Principles of Biomaterials Spring 2003 ƒ Yasuda et al. Makromol. Chem. 26, 177 (1969) ƒ Peppas and Reinhart, J. Membrane Sci. 15, 275 (1983) ƒ Now: *  v* v*  Eqn 13 Pgel,volume = e −   v free,gel − v free,1   * P0,volume ƒ The free volume in a swollen gel is approximately vfree,1 since the free volume contribution from polymer is extremely low (2.5% even in solid polymers at 25°C) Eqn 14 vfree,gel = φ1vfree,1 + φ2vfree,2 ƒ Therefore: Eqn 15 vfree,gel ~ φ1vfree,1 = (1-φ2)vfree,1 = (1-1/Q)vfree,1 o Where Q is the swelling degree = Vswollen gel/Vdry gel = 1/φ2 ƒ Therefore:   −   v* − v*   *  Q )v free,1 v free,1   − v*   1   1  Eqn 16 Pgel,volume = e   (1− 1  = e v free,1  Q−1  ≈ e −  Q−1  * P0,volume o v*/vfree,1 ~ 1 for most polymers, experimentally ƒ Therefore:     −1   ˆ Eqn 17 D ≅  1− r  e(Q−1) ξ ƒ And thus finally:     −1   Eqn 18 Dgel ≅ D0  1− r  e(Q−1) ξ o Insulin: MW – 5900 g/mole; hydrodynamic radius = 16 Å Design of glucose-responsive drug delivery microgels for treatment of diabetes8-10 ƒ Work by Podual and Peppas ƒ Immobilized glucose oxidase enzyme within pH-responsive polyelectrolyte gel network along with encapsulated insulin o Network composed of DEAEM, PEGMA, and TEGDMA o GOD covalently tethered to network o Insulin entrapped in network o Polymerized gels as microspheres Lecture 10 – Bioengineering Applications of Hydrogels 9 of 12