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Disulfide Cross-linked Biocompatible Polymers

Disulfide Cross-linked Biocompatible Polymers. Ben Moore. Natures Answer. Poly(cysteine) is natural and breaks down in the body. More control of the degradation is needed. Current Material.

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Disulfide Cross-linked Biocompatible Polymers

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  1. Disulfide Cross-linked Biocompatible Polymers Ben Moore

  2. Natures Answer Poly(cysteine) is natural and breaks down in the body. More control of the degradation is needed.

  3. Current Material Orthopedic polymers are focused on matching degradation with the rate of bone growth but what if they don’t match? A sulfur containing polymer could be injected into the body, Cross-linked and reduced after bone replacement is complete.

  4. Reduction Dithiotheritol has been used in studies of proteins for reduction and reformation in anaerobic conditions with small amounts. Photolysis of cysteine in the protein lactalbumin in goats is possible with the excitation of tryptophan. Degradation by light means no needles or chemicals.

  5. Oxidation Once in the body oxidation of the the disulfide bonds will make them more rigid with a mild agent like KMnO4 and will reduce the bonds with stronger agents like KHSO4. A good method to stiffen but what about oxidizing other things in the body?

  6. Polymer Design The backbone of the polymer is a condensation of a dicarboxilic acid and a diol. It mimics cysteine without containing nitrogen. Mercapto groups can be incorporated in the monomers or added to the polymer later. The more the mercapto groups the higher the degree of crosslinking and the smaller the pore size.

  7. Dicarboxilic acids 2-3(meso)dimercaptosuccinic acid is used a treatment for heavy metal poisoning. 3-mercapto or even ordinary succinic acid would reduce the amount of crosslinking and could be used in combination with the other acids.

  8. Diols 3-mercapto 1,2propane diol or 1,2propandiol are possibilities Dithiotheritol would form a six member ring, but if in a polymer would that ring still be favorable?

  9. Sulfur Ring Closure (Poly)DMSA/ 3-mercapto 1,2 propane diol if added back to back can form eight member disulfide rings.

  10. Degree of Cross-linking If every other carbon was disulfide bonded the structure would be very strong but not porous. If it was only linked every few hundred carbon atoms it would behave like a rubber band. 1,2 propane diol is an additive to some foods and dimercaptosuccinic acid passes safely through the body. Put together they would be safe and rigid.

  11. Protecting Mercaptos For the diacids protect with NaOH and benzyloxycaronyl chloride removal with NH4OH. For the diols protect with PhCSSMe and MeOH with NaOMe catalyst. Removal with 0.2M NaOH under N2. They might not even need to be protected so if kept under nitrogen when heated minimal crosslinking should occur.

  12. Synthesis + =

  13. After Crosslinking

  14. References • 1.)Wada, R.; Kitabatake, N. J. Agric. Food Chem. 2001; 49(10); 4971-4976. • 2.)Tsarevsky, N. V.; Matyjaszewski, K. Macromolecules. 2002; 35(24); 9009-9014. • 3.)Fukushima, H.; Yoon, S.H.; Watabe, S. J. Agric. Food Chem. 2003; 51(14); 4089-4095. • 4.)Nagai, A.; Miyagawa, T.; Kudo, H.; Endo, T. Macromolecules; 2003; 36(25); 9335-9339. • 5.)Latha, R.; Ganesh, K.; Kishore, K. Macromolecules; 2000; 33(9); 3224-3231. • 6.)Cho, J. S.; Sato, S.; Takeoka, S.; Tsuchida, E. Macromolecules: 2001; 34(9); 2751-2756. • 7.)Harrison, S.; Sdavis, T. P. Evams, R. A.; Rizzardo, E. Macromolecules; 2000; 33(26); 9553-9560 • 8.)http://www.nature.com/cgi-taf/DynaPage.taf?file=/nbt/journal/v20/nl/full/nbt0102-30.html • 9.)http://www.bloodjournla.org/cgi/content/full/92/5/1661 • 10.)http://www.glenres.com/GlenReports/GR16-12.html

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