BEH.462/3. 962J Molecular Principles of Biomaterials Spring 2003 mechanism lI: o Poly(methyl vinyl ether-co-maleic anhydride)-> carboxyl group generation CH2 CH ionizes to 2 carboxyl groups o Poly(alkyl cyanoacrylates) -(CH2C-) MechanismⅢ o poly(a-hydroxy, B-hydroxy esters) acid or base catalyzed R CHaR -(CH-C-O-CH-C-0-x(CH2-C-O-CH2-C-O)y OH+ HO-CH-C-OH KrebS cycle e.g. polypeptide hydrolysis t +H N-CH-C-N-CH-C-O polyanhydrides -C-O-C C-O-H H-0-C Lecture 1-Introduction
BEH.462/3.962J Molecular Principles of Biomaterials Spring 2003 Mechanism II: o Poly(methyl vinyl ether-co-maleic anhydride) -> carboxyl group generation8 ionizes to 2 carboxyl groups o Poly(alkyl cyanoacrylates) C≡N C≡N -(CH2-C-)n- H2O -(CH2-C-)n- C=O C=O O OR Mechanism III: o poly(α-hydroxy, β-hydroxy esters) • acid or base catalyzed CH3 O CH3O O O H2O CH3 O O -(CH-C-O-CH-C-O-)x-(CH2-C-O-CH2-C-O)y- HO-CH-C-OH + HO-CH2-C-OH KrebÕs cycle CO2 + H2O o polyamides • e.g. polypeptide hydrolysis O H O H O H O enzymes O H O O H O + H3N-CH-C-N-CH-C-N-CH-C-N-CH-C-O- + H3N-CH-C-N-CH-C-O- + + H3N-CH-C-N-CH-C-OR1 R2 R3 R4 R1 R2 R3 R4 o polyanhydrides O O H2 O= = = O =O -C-O-C -C-O-H H-O-C- _ _ _ _ _ _ _ Lecture 1 – Introduction
BEH.462/3. 962J Molecular Principles of Biomaterials Spring 2003 o poly(ortho esters)(SKIP?) ooO RO H-O Ho、OH Medically-applied polymers are chosen for metabolizable or excretable final degradation products HO -(CH-C-O-CH-C-O-x(CH2-C-0-CH2-C-O)y HO-CH-C-OH HO-C Kreb@ cycle CO2+ H2O Kreb's cycle citric acid cycle (conversion of pyruvate from glycolytic cycle into energy) (D H. Lewis in"Biodegradable polymers as drug delivery systems, 1990 p. 1-41 M. Chasin, ed PCL H2o Citric acid cycle -(CH2)5-C-O-) HO-((CH2)5-C-OH Co2 +H2o 6-hydroxycaproic acid polyhydroxybutyrate: ( C-O-CH(CH3)CH2h、o HO-CH(CH3)-CH2 -C-OH D-3-hydroxybutyrate (normal blood constituent Holmes, Phys. Technol. 16, 32(1985) · What doesnt work? o e.g. poly(ethylene terephthalate)(PET)-used for soda bottles breaks down to aromatic oligomers which form deposits in body therefore more than just a hydrolysis-susceptible bond is needed CRYSTALLINE, T INELASTIC 256·T.67 Lecture 1-Introduction
BEH.462/3.962J Molecular Principles of Biomaterials Spring 2003 o poly(ortho esters) (SKIP?) H2O RÕ n O RÕ O O + O O O RÕ O R HO HO OH OH RÕ O R Medically-applied polymers are chosen for metabolizable or excretable final degradation products: PLGA: CH3 O CH3O O O H2O CH3 O O -(CH-C-O-CH-C-O-)x-(CH2-C-O-CH2-C-O)y- HO-CH-C-OH + HO-CH2-C-OH KrebÕs cycle CO2 + H2O Kreb’s cycle = citric acid cycle (conversion of pyruvate from glycolytic cycle into energy) (D.H. Lewis in “Biodegradable polymers as drug delivery systems,” 1990 p. 1-41 M. Chasin, ed.) PCL: O H2O O Citric acid cycle -((CH2)5-C-O-)n- HO-((CH2)5-C-OH CO2 + H2O 6-hydroxycaproic acid poly(hydroxybutyrate): O H2O O -(-C-O-CH(CH3)-CH2-)n- HO-CH(CH3)-CH2-C-OH D-3-hydroxybutyrate (normal blood constituent) Holmes, Phys. Technol. 16, 32 (1985) • What doesn’t work? o e.g. poly(ethylene terephthalate) (PET) – used for soda bottles breaks down to aromatic oligomers which form deposits in body therefore more than just a hydrolysis-susceptible bond is needed! = = = = Lecture 1 – Introduction