Dataset Information

Biomimetic Fabrication of Genetically-Engineered Collagen Peptide-Assembled Freestanding Films Reinforced by Quantum Dot Joints.

ABSTRACT: Genetically-engineered collagen peptides were assembled into freestanding films when QDs are co-assembled as joints between collagen domains. These peptide based films show excellent mechanical properties with Young's modulus of ~20 GPa, much larger than most of multi-composite polymer films and previously reported freestanding nanoparticle-assembled sheets, and it is even close to the bone tissue in nature. These films show little permanent deformation under small indentation while the mechanical hysteresis becomes remarkable when the load approaches near and beyond the rupture point, which is also characteristic to the bone tissue.

SUBMITTER: Wei Z

PROVIDER: S-EPMC3439209 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature

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Publications

Biomimetic Fabrication of Genetically-Engineered Collagen Peptide-Assembled Freestanding Films Reinforced by Quantum Dot Joints.

Wei Zengyan Z Maeda Yoshiaki Y Matsui Hiroshi H

Soft matter 20120101 26

Genetically-engineered collagen peptides were assembled into freestanding films when QDs are co-assembled as joints between collagen domains. These peptide based films show excellent mechanical properties with Young's modulus of ~20 GPa, much larger than most of multi-composite polymer films and previously reported freestanding nanoparticle-assembled sheets, and it is even close to the bone tissue in nature. These films show little permanent deformation under small indentation while the mechanic ...[more]

PMID: 22982983

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Project description:Wet spinning is an established fibre manufacturing route to realise collagen fibres with preserved triple helix architecture and cell acceptability for applications in biomedical membranes. However, resulting fibres still need to be chemically modified post-spinning to ensure material integrity in physiological media, with inherent risks of alteration of fibre morphology and with limited opportunities to induce fibrillogenesis following collagen fixation in the crosslinked state. To overcome this challenge, we hypothesised that a photoactive type I collagen precursor bearing either single or multiple monomers could be employed to accomplish hierarchically assembled fibres with improved processability, macroscopic properties and nanoscale organisation via sequential wet spinning and UV-curing. In-house-extracted type I rat tail collagen functionalised with both 4-vinylbenzyl chloride (4VBC) and methacrylate residues generated a full hydrogel network following solubilisation in a photoactive aqueous solution and UV exposure, whereby ~85 wt.% of material was retained following 75-day hydrolytic incubation. Wide-angle X-ray diffraction confirmed the presence of typical collagen patterns, whilst an averaged compression modulus and swelling ratio of more than 290 kPa and 1500 wt.% was recorded in the UV-cured hydrogel networks. Photoactive type I collagen precursors were subsequently wet spun into fibres, displaying the typical dichroic features of collagen and regular fibre morphology. Varying tensile modulus (E = 5 ± 1 - 11 ± 4 MPa) and swelling ratio (SR = 1880 ± 200 - 3350 ± 500 wt.%) were measured following post-spinning UV curing and equilibration with phosphate-buffered saline (PBS). Most importantly, 72-h incubation of the wet spun fibres in PBS successfully induced renaturation of collagen-like fibrils, which were fixed following UV-induced network formation. The whole process proved to be well tolerated by cells, as indicated by a spread-like cell morphology following a 48-h culture of L929 mouse fibroblasts on the extracts of UV-cured fibres.

Project description:Joints that connect thermoplastic polymer matrices (TPMs) and metals, which are obtained by comolding, are of growing importance in numerous applications. The overall performance of these constructs is strongly impacted by the TPM-metal interfacial strength, which can be tuned by tailoring the surface chemistry of the metal prior to the comolding process. In the present work, a model TPM-metal system consisting of poly(methyl methacrylate) (PMMA) and titanium is used to prepare comolded joints. The interfacial adhesion is quantified by wire pullout experiments. Pullout tests prior to and following surface modification are performed and analyzed. Unmodified wires show poor interfacial strength, with a work of adhesion (Ga) value of 3.8 J m-2. To enhance interfacial adhesion, a biomimetic polydopamine (PDA) layer is first deposited on titanium followed by a second layer of a poly(methyl methacrylate-co-methacrylic acid) (P(MMA-co-MAA)) copolymer prior to comolding. During processing, the MAA moieties of the copolymer thermally react with PDA, forming amide bonds, while MMA promotes the formation of secondary bonds and molecular interdigitation with the PMMA matrix. Control testing reveals that neither PDA nor the copolymer provides a substantial increase in adhesion. However, when used in combination, a significant increase in adhesion is detected. This observation indicates a pronounced synergistic effect between the two layers that strengthens the PMMA-titanium bonding. Enhanced adhesion is optimized by tuning the MMA-to-MAA ratio of the copolymer, which shows a maximum at a 24% MAA content and a greatly increased Ga value of 155 J m-2; this value corresponds to a 40-fold increase. Further growth in the Ga values at higher MAA contents is hindered by the thermal cross-linking of MAA; MAA contents above 24% restrict the formation of secondary bonds and molecular interdigitation with the PMMA chains. Our results provide new design principles to produce thermoplastic-metal comolded joints with strong interfaces.

Dataset Information

Biomimetic Fabrication of Genetically-Engineered Collagen Peptide-Assembled Freestanding Films Reinforced by Quantum Dot Joints.

Publications

Biomimetic Fabrication of Genetically-Engineered Collagen Peptide-Assembled Freestanding Films Reinforced by Quantum Dot Joints.

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