Self-Assembly of Telechelic Tyrosine End-Capped PEO Star Polymers in Aqueous Solution

• Published in: Biomacromolecules 2018-01, Vol.19 (1), p.167-177
• Main Authors: Edwards-Gayle, Charlotte J. C, Greco, Francesca, Hamley, Ian W, Rambo, Robert P, Reza, Mehedi, Ruokolainen, Janne, Skoulas, Dimitrios, Iatrou, Hermis
• Format: Article
• Language: English
• Subjects: Cell Line; Chromatography, Gel; Circular Dichroism; Humans; Hydrogels - chemistry; Magnetic Resonance Spectroscopy; Microscopy, Electron, Transmission; Peptides - chemistry; Polyethylene Glycols - chemistry; Polymerization; Scattering, Small Angle; Solutions; Spectroscopy, Fourier Transform Infrared; Tyrosine - chemistry; Water - chemistry; X-Ray Diffraction
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/acs.biomac.7b01420

We investigate the self-assembly of two telechelic star polymer–peptide conjugates based on poly­(ethylene oxide) (PEO) four-arm star polymers capped with oligotyrosine. The conjugates were prepared via N-carboxy anhydride-mediated ring-opening polymerization from PEO star polymer macroinitiators. Self-assembly occurs above a critical aggregation concentration determined via fluorescence probe assays. Peptide conformation was examined using circular dichroism spectroscopy. The structure of self-assembled aggregates was probed using small-angle X-ray scattering and cryogenic transmission electron microscopy. In contrast to previous studies on linear telechelic PEO–oligotyrosine conjugates that show self-assembly into β-sheet fibrils, the star architecture suppresses fibril formation and micelles are generally observed instead, a small population of fibrils only being observed upon pH adjustment. Hydrogelation is also suppressed by the polymer star architecture. These peptide-functionalized star polymer solutions are cytocompatible at sufficiently low concentration. These systems present tyrosine at high density and may be useful in the development of future enzyme or pH-responsive biomaterials.