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Solid-phase Submonomer Synthesis of Peptoid Polymers and their Self-Assembly into Highly-Ordered Nanosheets
Published on: November 2, 2011
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Highly Ordered Polypeptide with UCST Phase Separation Behavior.
Sotaro Kuroyanagi1, Naohiko Shimada1, Shota Fujii2
1Department of Life Science and Technology , Tokyo Institute of Technology , 4259 B-57 , Nagatsuta, Yokohama 226-8501 , Japan.
Journal of the American Chemical Society
|January 1, 2019
Summary
Stereoregularity significantly impacts thermoresponsive polymer behavior. Homochiral polypeptides exhibit higher phase separation temperatures and distinct aggregation patterns compared to racemic counterparts, offering insights for advanced biomaterials.
Area of Science:
- Polymer Science
- Biomaterials Science
- Materials Chemistry
Background:
- Thermoresponsive polymers are crucial for drug delivery and tissue engineering.
- Upper Critical Solution Temperature (UCST) behavior in polymers is under-investigated.
- Understanding stereoregularity's influence on UCST is key for material design.
Purpose of the Study:
- To investigate the influence of polypeptide stereoregularity on Upper Critical Solution Temperature (UCST) behavior.
- To compare the phase separation and aggregation of homochiral and racemic citrulline-based polypeptides.
- To explore the structural basis and biodegradability of these thermoresponsive polymers.
Main Methods:
- Synthesis and characterization of poly(ornithine-co-citrulline) (POC) variants with varying stereoregularity.
- Measurement of phase separation temperatures (Tps) using thermal analysis.
- Structural analysis via circular dichroism (CD) and small-angle X-ray scattering (SAXS).
Main Results:
- Homochiral poly(l-ornithine-co-l-citrulline) (PlOC) and poly(d-ornithine-co-d-citrulline) (PdOC) exhibited higher Tps than racemic poly(dl-ornithine-co-dl-citrulline) (PdlOC).
- PdlOC showed liquid-to-coacervate phase separation, while PlOC and PdOC formed solid-like aggregates.
- Homochiral POCs adopted alpha-helical structures and assembled into hexagonal lattices, driven by ureido group interactions.
Conclusions:
- Stereoregularity critically dictates UCST behavior, phase separation modes, and structural organization in citrulline-based polypeptides.
- The observed helical folding and hexagonal assembly in homochiral POCs are attributed to pendent ureido group interactions.
- Phase-separated structures influence biodegradability, highlighting the potential of these UCST-type polymers for tunable biomaterial applications.
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