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Amyloid peptide mixtures: self-assembly, hydrogelation, nematic ordering, and catalysts in aldol reactions

DOI: 10.1021/acs.langmuir.0c00198 DOI Help

Authors: Juliane N. B. D. Pelin (University of Reading; Universidade Federal do ABC) , Barbara B. Gerbelli (Universidade Federal do ABC) , Charlotte J. C. Edwards-gayle (University of Reading) , Andrea M. Aguilar (Universidade Federal de São Paulo) , Valeria Castelletto (University of Reading) , Ian W. Hamley (University of Reading) , Wendel A. Alves (Universidade Federal do ABC)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Langmuir

State: Published (Approved)
Published: March 2020
Diamond Proposal Number(s): 18523 , 21470

Open Access Open Access

Abstract: Morphological, spectroscopic, and scattering studies of the self-assembly and aggregation of mixtures of [RF]4 and P[RF]4 peptides (where R = arginine; F = phenylalanine; P = proline), in solution and as hydrogels, were performed to obtain information about polymorphism. CD data confirmed a β-sheet secondary structure in aqueous solution, and TEM images revealed nanofibers with diameters of ∼10 nm and micrometer lengths. SAXS curves were fitted using a mass fractal-component and a long cylinder shell form factor for the liquid samples, and only a long cylinder shell form factor for the gels. Increasing the P[RF]4 content in the systems leads to a reduction in cylinder radius and core scattering density, suggesting an increase in packing of the peptide molecules; however, the opposite effect is observed for the gels, where the scattering density is higher in the shell for the systems containing higher P[RF]4 content. These compounds show potential as catalysts in the asymmetric aldol reactions, with cyclohexanone and p-nitrobenzaldehyde in aqueous media. A moderate conversion (36.9%) and a good stereoselectivity (69:31) were observed for the system containing only [RF]4. With increasing P[RF]4 content, a considerable decrease of the conversion was observed, suggesting differences in the self-assembly and packing factor. Rheological measurements were performed to determine the shear moduli for the soft gels.

Subject Areas: Chemistry

Instruments: B21-High Throughput SAXS