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Molecules 2017, 22(8), 1368;

Phase Behaviour and Miscibility Studies of Collagen/Silk Fibroin Macromolecular System in Dilute Solutions and Solid State

i3S—Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
INEB—Instituto de Engenharia Biomédica, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
FEUP, Faculdade de Engenharia, Departmento de Enginharia Metalurgia e Materiais, Universidade do Porto, 4200-465 Porto, Portugal
School of Chemical Engineering, University of Campinas, 13083-852 Campinas, Brazil
Department of Chemical Engineering, Federal University of São Paulo, 09913-030 Diadema, Brazil
Nicolaus Copernicus University in Toruń, Faculty of Chemistry, Department of Chemistry of Biomaterials and Cosmetics, ul. Gagarina 7, 87-100 Toruń, Poland
IBMC—Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
FP-ENAS/CEBIMED, University Fernando Pessoa Energy, Environment and Health Research Unit/Biomedical Research Center, 200-150 Porto, Portugal
Authors to whom correspondence should be addressed.
Received: 18 July 2017 / Accepted: 16 August 2017 / Published: 18 August 2017
(This article belongs to the Special Issue Natural Polymers and Biopolymers)
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Miscibility is an important issue in biopolymer blends for analysis of the behavior of polymer pairs through the detection of phase separation and improvement of the mechanical and physical properties of the blend. This study presents the formulation of a stable and one-phase mixture of collagen and regenerated silk fibroin (RSF), with the highest miscibility ratio between these two macromolecules, through inducing electrostatic interactions, using salt ions. For this aim, a ternary phase diagram was experimentally built for the mixtures, based on observations of phase behavior of blend solutions with various ratios. The miscibility behavior of the blend solutions in the miscible zones of the phase diagram was confirmed quantitatively by viscosimetric measurements. Assessing the effects of biopolymer mixing ratio and salt ions, before and after dialysis of blend solutions, revealed the importance of ion-specific interactions in the formation of coacervate-based materials containing collagen and RSF blends that can be used in pharmaceutical, drug delivery, and biomedical applications. Moreover, the conformational change of silk fibroin from random coil to beta sheet, in solution and in the final solid films, was detected by circular dichroism (CD) and Fourier transform infrared spectroscopy (FTIR), respectively. Scanning electron microscopy (SEM) exhibited alterations of surface morphology for the biocomposite films with different ratios. Surface contact angle measurement illustrated different hydrophobic properties for the blended film surfaces. Differential scanning calorimetry (DSC) showed that the formation of the beta sheet structure of silk fibroin enhances the thermal stability of the final blend films. Therefore, the novel method presented in this study resulted in the formation of biocomposite films whose physico-chemical properties can be tuned by silk fibroin conformational changes by applying different component mixing ratios. View Full-Text
Keywords: biopolymers; protein-protein interaction; silk fibroin; miscibility; coacervation biopolymers; protein-protein interaction; silk fibroin; miscibility; coacervation

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Ghaeli, I.; de Moraes, M.A.; Beppu, M.M.; Lewandowska, K.; Sionkowska, A.; Ferreira-da-Silva, F.; Ferraz, M.P.; Monteiro, F.J. Phase Behaviour and Miscibility Studies of Collagen/Silk Fibroin Macromolecular System in Dilute Solutions and Solid State. Molecules 2017, 22, 1368.

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