Phenylalanine and isoleucine containing protein-based polymers as new biomaterials: Synthesis and solid state properties

Abstract

1487-1493Protein-based polymers exhibit elasticity and plasticity in accordance with the nature of the repeating sequence. Analogs of parent plastic sequence AVGVP are synthesized, polymerized and characterized in their solid state. The thermal behaviour of these polymers have been studied by differential scanning calorimetry. Phe-containing and Ile-containing polypentapeptides, poly(XVGVP) where X = F (Phe), I (Ile), exhibits both melting and decomposition transitions in contrast to the decomposition alone for parent poly(AVGVP). And also incorporation of FVGVP or IVGVP into AVGVP in equal molar ratios, described as poly[(AVGVP),(XVGVP)] where X = F, I induces the polymer to exhibit both melting and decomposition and shifted the values relatively to higher temperatures due to their thermal stability. Further, the appearance of clear exothermic crystalline transition at 251ºC, before melting at 328ºC, for poly(IVGVP), contributes towards a typical behaviour of thermoplasticity. Secondary structure in trifluoroethanol for all the polymers shows, well behaved -helix as evident from the circular dichroism studies, in association with a significant amount of random structure contributes to extended stability