Title:
Self-Assembly of Telechelic Tyrosine End-Capped PEO and Poly(alanine) Polymers in Aqueous Solution
Languages of Item:
English
Abstract:
The self-assembly in aqueous solution of three novel telechelic conjugates comprising a central hydrophilic polymer and short (trimeric or pentameric) tyrosine end-caps has been investigated. Two of the conjugates have a central poly(oxyethylene) (polyethylene oxide, PEO) central block with different molar masses. The other conjugate has a central poly(l-alanine) (PAla) sequence in a purely amino-acid based conjugate. All three conjugates self-assemble into β-sheet based fibrillar structures, although the fibrillar morphology revealed by cryogenic-TEM is distinct for the three polymers-in particular the Tyr5-PEO6k-Tyr5 forms a population of short straight fibrils in contrast to the more diffuse fibril aggregates observed for Tyr5-PEO2k-Tyr5 and Tyr3-PAla-Tyr3. Hydrogel formation was not observed for these samples (in contrast to prior work on related systems) up to quite high concentrations, showing that it is possible to prepare solutions of peptide-polymer-peptide conjugates with hydrophobic end-caps without conformational constraints associated with hydrogelation. The Tyr5-PEO6k-Tyr5 shows significant PEO crystallization upon drying in contrast to the Tyr5-PEO2k-Tyr5 conjugate. Our findings point to the remarkable ability of short hydrophobic peptide end groups to modulate the self-assembly properties of polymers in solution in model peptide-capped "associative polymers'. Retention of fluidity at high conjugate concentration may be valuable in potential future applications of these conjugates as bioresponsive or biocompatible materials, for example exploiting the enzyme-responsiveness of the tyrosine end-groups. © 2016 American Chemical Society.
Authors:
Steven Kirkham
Valeria Castelletto
Ian William Hamley
Mehedi Reza
Janne Ruokolainen
Daniel Hermida-Merino
Panayiotis Bilalis
Hermis Iatrou
Journal:
Biomacromolecules
Publisher:
American Chemical Society (ACS)
Keywords:
Amino acids; Biocompatibility; Biological materials; Hydrophobicity; Organic polymers; Peptides; Polyethylene oxides; Self assembly; Solutions, Associative polymers; Conformational constraints; Fibrillar morphology; Fibrillar structures; Future applications; Hydrophilic polymers; Hydrophobic peptides; Polymer-peptide conjugates, Polymers, poly(alanine); poly(oxyethylene) (polyethylene oxide); polymer; tyrosine; unclassified drug; biomaterial; macrogol derivative; peptide; polyalanine; polytyrosine, aqueous solution; Article; circular dichroism; crystallization; flow kinetics; priority journal; proton nuclear magnetic resonance; size exclusion chromatography; synthesis; transmission electron microscopy; X ray crystallography; X ray diffraction; chemical phenomena; chemistry; polymerization, Biocompatible Materials; Hydrophobic and Hydrophilic Interactions; Peptides; Polyethylene Glycols; Polymerization
Main subject category:
Science
Official URL (Publisher):
DOI:
10.1021/acs.biomac.6b00023
