Ian W. Hamley

A Healable Supramolecular Polymer Blend Based on Aromatic π−π Stacking and Hydrogen-Bonding Interactions

An elastomeric, healable, supramolecular polymer blend comprising a chain-folding polyimide and a telechelic polyurethane with pyrenyl end groups is compatibilized by aromatic pi-pi stacking between the pi-electron-deficient diimide groups and the pi-electron-rich pyrenyl units. This interpolymer interaction is the key to forming a tough, healable, elastomeric material. Variable-temperature FTIR analysis of the bulk material also conclusively demonstrates the presence of hydrogen bonding, which complements the pi-pi stacking interactions. Variable-temperature SAXS analysis shows that the healable polymeric blend has a nanophase-separated morphology and that the X-ray contrast between the two types of domain increases with increasing temperature, a feature that is repeatable over several heating and cooling cycles. A fractured sample of this material reproducibly regains more than 95% of the tensile modulus, 91% of the elongation to break, and 77% of the modulus of toughness of the pristine material.

The amyloid beta peptide: a chemist's perspective. Role in Alzheimer's and fibrillization.

IW Hamley Chemical reviews, 2012 ACS Publications ... the γ-secretase complex and its cell surface localization, in the absence of an effect on Notch ... in the development of effective γ-secretase inhibitors is to avoid side-effects caused by ... EP2 receptor.(79) Prostaglandin E 2 is produced during inflammation due to activity by cytosolic ... Cited by 143 Related articles All 4 versions Cite Save

Self-assembly of amphiphilic peptides

The self-assembly of amphiphilic peptides is reviewed. The review covers surfactant-like peptides with amphiphilicity arising from the sequence of natural amino acids, and also peptide amphiphiles (PAs) in which lipid chains are attached to hydrophilic peptide sequences containing charged residues. The influence of the secondary structure on the self-assembled structure and vice versa is discussed. For surfactant-like peptides structures including fibrils, nanotubes, micelles and vesicles have been reported. A particularly common motif for PAs is β-sheet based fibrils, although other structures have been observed. In these structures, the peptide epitope is presented at the surface of the nanostructure, providing remarkable bioactivity. Recent discoveries of potential, and actual, applications of these materials in biomedicine and bionanotechnology are discussed.

Developments in block copolymer science and technology

List of Contributors.Preface.1. Introduction to Block Copolymers (Ian W. Hamley).2. Recent Developments in Synthesis of Model Block Copolymers using Ionic Polymerisation (Kristoffer Almdal).3. Syntheses and Characterizations of Block Copolymers Prepared via Controlled Radical Polymerization Methods (Pan Cai-yuan and Hong Chun-yan).4. Melt Behaviour of Block Copolymers (Shinichi Sakurai, Shigeru Okamoto and Kazuo Sakurai).5. Phase Behavior of Block Copolymer Blends (Richard J. Spontak and Nikunj P. Patel).6. Crystallization within Block Copolymer Mesophases (Yueh-Lin Loo and Richard A. Register).7. Dynamical Microphase Modelling with Mesodyn (JG.E.M. Fraaije, G.J.A. Sevink and A.V. Zvelindovsky).8. Self-consistent Field Theory of Block Copolymers (An-Chang Shi).9. Lithography with Self-assembled Block Copolymer Microdomains (Christopher Harrison, John A. Dagata and Douglas H. Adamson).10. Applications of Block Copolymer Surfactants (Michael W. Edens and Robert H. Whitmarsh).11. The Development of Elastomers Based on Fully Hydrogenated Styrene-Diene Block Copolymers (Calvin P. Esneault, Stephen F. Hahn and Gregory F. Meyers).Index.

Crystallization in Block Copolymers

Crystallization in block copolymers has a profound effect on their structure. This review article focusses on the morphology of semicrystalline block copolymers, and those containing two crystallizable blocks. The effect of crystallization on mechanical properties is briefly considered. The extent of chain folding upon crystallization is discussed, as is the orientation of crystal stems with respect to the microstructure. The effect of selective solvent on solution crystallization is also highlighted. Recent work on crystallization kinetics is summarized and finally the theories for crystallization in block copolymers are outlined.

Self-Assembly and Hydrogelation of an Amyloid Peptide Fragment

The self-assembly of a fragment of the amyloid beta peptide that has been shown to be critical in amyloid fibrillization has been studied in aqueous solution. There are conflicting reports in the literature on the fibrillization of Abeta (16-20), i.e., KLVFF, and our results shed light on this. In dilute solution, self-assembly of NH 2-KLVFF-COOH is strongly influenced by aromatic interactions between phenylalanine units, as revealed by UV spectroscopy and circular dichroism. Fourier transform infrared (FTIR) spectroscopy reveals beta-sheet features in spectra taken for more concentrated solutions and also dried films. X-ray diffraction and cryo-transmission electron microscopy (cryo-TEM) provide further support for beta-sheet amyloid fibril formation. A comparison of cryo-TEM images with those from conventional dried and negatively stained TEM specimens highlights the pronounced effects of sample preparation on the morphology. A comparison of FTIR data for samples in solution and dried samples also highlights the strong effect of drying on the self-assembled structure. In more concentrated phosphate-buffered saline (PBS) solution, gelation of NH 2-KLVFF-COOH is observed. This is believed to be caused by screening of the electrostatic charge on the peptide, which enables beta sheets to aggregate into a fibrillar gel network. The rheology of the hydrogel is probed, and the structure is investigated by light scattering and small-angle X-ray scattering.

Peptide hormones and lipopeptides: from self-assembly to therapeutic applications

This review describes the properties and activities of lipopeptides and peptide hormones and how the lipidation of peptide hormones could potentially produce therapeutic agents combating some of the most prevalent diseases and conditions. The self‐assembly of these types of molecules is outlined, and how this can impact on bioactivity. Peptide hormones specific to the uptake of food and produced in the gastrointestinal tract are discussed in detail. The advantages of lipidated peptide hormones over natural peptide hormones are summarised, in terms of stability and renal clearance, with potential application as therapeutic agents.

Self-assembling amphiphilic peptides‡

The self‐assembly of several classes of amphiphilic peptides is reviewed, and selected applications are discussed. We discuss recent work on the self‐assembly of lipopeptides, surfactant‐like peptides and amyloid peptides derived from the amyloid‐β peptide. The influence of environmental variables such as pH and temperature on aggregate nanostructure is discussed. Enzyme‐induced remodelling due to peptide cleavage and nanostructure control through photocleavage or photo‐cross‐linking are also considered. Lastly, selected applications of amphiphilic peptides in biomedicine and materials science are outlined.

Nanoshells and nanotubes from block copolymers

Recent work exploring the use of block copolymer vesicles and tubules is reviewed. The stability and toughness of block copolymer vesicles are enhanced compared to those formed by low molar mass amphiphiles. Functionality can also readily be introduced through the polymer chemistry or by incorporating additional components (for example pore-forming membrane proteins). This design flexibility leads to numerous potential applications in encapsulation, in targeted drug delivery, templating of inorganic materials and many others.

Measurement of intrinsic properties of amyloid fibrils by the peak force QNM method.

We report the investigation of the mechanical properties of different types of amyloid fibrils by the peak force quantitative nanomechanical (PF-QNM) technique. We demonstrate that this technique correctly measures the Youngs modulus independent of the polymorphic state and the cross-sectional structural details of the fibrils, and we show that values for amyloid fibrils assembled from heptapeptides, α-synuclein, Aβ(1-42), insulin, β-lactoglobulin, lysozyme, ovalbumin, Tau protein and bovine serum albumin all fall in the range of 2-4 GPa.