Browsing by Author "Hamley, I. W."
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- Hybrid membrane biomaterials from self-assembly in polysaccharide and peptide amphiphile mixtures: controllable structural and mechanical properties and antimicrobial activity
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2017) Castelletto, V.; Kaur, A.; Hamley, I. W.; Barnes, R. H.; Karatzas, K. A.; Hermida-Merino, D.; Swioklo, S.; Connon, C. J.; Stasiak, J.; Reza, M.; Ruokolainen, J.Macroscopic capsules, with tunable properties based on hierarchical self-assembly on multiple lengthscales, are prepared from the co-operative self-assembly of polysaccharide and peptide amphiphiles. Different formulations can be used to create flexible membrane sacs in solution, soft capsules or rigid free-standing capsules. Samples are prepared by injecting a solution containing sodium alginate, with or without graphene oxide (GO), into a matrix consisting of a solution containing the peptide amphiphile PA C16-KKFF (K: lysine, F: phenylalanine), with or without CaCl2. Graphene oxide is added to the hybrid materials to modulate the mechanical properties of the capsules. Injection of sodium alginate solution into a pure PA matrix provides a flexible membrane sac in solution, while injection of NaAlg/GO solution into a PA matrix gives a soft capsule. Alternatively, a rigid free-standing capsule is made by injecting a NaAlg/GO solution into a PA + CaCl2 matrix solution. A comprehensive insight into the hierarchical order within the capsules is provided through analysis of X-ray scattering data. A novel “Langmuir-Blodgett” mechanism is proposed to account for the formation of the sacs and capsules as the alginate solution is injected at the interface of the PA solution. The capsules show a unique antibacterial effect specific for the Gram positive bacterium Listeria monocytogenes, which is an important human pathogen. The hybrid nanostructured capsules thus have remarkable bioactivity and due to their tunable structural and functional properties are likely to have a diversity of other future applications. - Self-assembly and anti-amyloid cytotoxicity activity of amyloid beta peptide derivatives
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2017-03-08) Castelletto, V.; Ryumin, P.; Cramer, R.; Hamley, I. W.; Taylor, M.; Allsop, D.; Reza, M.; Ruokolainen, J.; Arnold, T.; Hermida-Merino, D.; Garcia, C. I.; Leal, M. C.; Castaño, E.The self-assembly of two derivatives of KLVFF, a fragment Aβ(16-20) of the amyloid beta (Aβ) peptide, is investigated and recovery of viability of neuroblastoma cells exposed to Aβ (1-42) is observed at sub-stoichiometric peptide concentrations. Fluorescence assays show that NH 2 -KLVFF-CONH 2 undergoes hydrophobic collapse and amyloid formation at the same critical aggregation concentration (cac). In contrast, NH 2 -K(Boc)LVFF-CONH 2 undergoes hydrophobic collapse at a low concentration, followed by amyloid formation at a higher cac. These findings are supported by the β-sheet features observed by FTIR. Electrospray ionization mass spectrometry indicates that NH 2 -K(Boc)LVFF-CONH 2 forms a significant population of oligomeric species above the cac. Cryo-TEM, used together with SAXS to determine fibril dimensions, shows that the length and degree of twisting of peptide fibrils seem to be influenced by the net peptide charge. Grazing incidence X-ray scattering from thin peptide films shows features of β-sheet ordering for both peptides, along with evidence for lamellar ordering of NH 2 -KLVFF-CONH 2. This work provides a comprehensive picture of the aggregation properties of these two KLVFF derivatives and shows their utility, in unaggregated form, in restoring the viability of neuroblastoma cells against Aβ-induced toxicity.