The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Ali Khademhosseini - One of the best experts on this subject based on the ideXlab platform.
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photocrosslinkable kappa carrageenan hydrogels for tissue engineering applications
Advanced Healthcare Materials, 2013Co-Authors: Silvia M Mihaila, Manuela E Gomes, Ali Khademhosseini, Akhilesh K Gaharwar, Rui L Reis, Alexandra P MarquesAbstract:Kappa carrageenan (κ-CA) is a natural-origin polymer that closely mimics the glycosaminoglycan structure, one of the most important constituents of native tissues extracellular matrix. Previously, it has been shown that κ-CA can crosslink via ionic interactions rendering strong, but brittle hydrogels. In this study, we introduce photocrosslinkable methacrylate moieties on the κ-CA backbone to create Physically and chemically crosslinked hydrogels highlighting their use in the context of tissue engineering. By varying the degree of methacrylation, the effect on hydrogel Crosslinking was investigated in terms of hydration degree, dissolution profiles, morphological, mechanical, and rheological properties. Furthermore, the viability of fibroblast cells cultured inside the photocrosslinked hydrogels was investigated. The combination of chemical and Physical Crosslinking procedures enables the formation of hydrogels with highly versatile Physical and chemical properties, while maintaining the viability of encapsulated cells. To our best knowledge, this is the first study reporting the synthesis of photocrosslinkable κ-CA with controllable compressive moduli, swelling ratios and pore size distributions. Moreover, by micromolding approaches, spatially controlled geometries and cell distribution patterns could be obtained, thus enabling the development of cell-material platforms that can be applied and tailored to a broad range of tissue engineering strategies.
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modified gellan gum hydrogels with tunable Physical and mechanical properties
Biomaterials, 2010Co-Authors: Daniela F Coutinho, Shilpa Sant, Hyeongho Shin, Joao T Oliveira, Manuela E Gomes, Nuno M Neves, Ali KhademhosseiniAbstract:Abstract Gellan Gum (GG) has been recently proposed for tissue engineering applications. GG hydrogels are produced by Physical Crosslinking methods induced by temperature variation or by the presence of divalent cations. However, Physical Crosslinking methods may yield hydrogels that become weaker in physiological conditions due to the exchange of divalent cations by monovalent ones. Hence, this work presents a new class of GG hydrogels crosslinkable by both Physical and chemical mechanisms. Methacrylate groups were incorporated in the GG chain, leading to the production of a methacrylated Gellan Gum (MeGG) hydrogel with highly tunable Physical and mechanical properties. The chemical modification was confirmed by proton nuclear magnetic resonance ( 1 H NMR) and Fourier transform infrared spectroscopy (FTIR-ATR). The mechanical properties of the developed hydrogel networks, with Young’s modulus values between 0.15 and 148 kPa, showed to be tuned by the different Crosslinking mechanisms used. The in vitro swelling kinetics and hydrolytic degradation rate were dependent on the Crosslinking mechanisms used to form the hydrogels. Three-dimensional (3D) encapsulation of NIH-3T3 fibroblast cells in MeGG networks demonstrated in vitro biocompatibility confirmed by high cell survival. Given the highly tunable mechanical and degradation properties of MeGG, it may be applicable for a wide range of tissue engineering approaches.
Piedad Ganan - One of the best experts on this subject based on the ideXlab platform.
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Bioactive 3D-Shaped Wound Dressings Synthesized from Bacterial Cellulose: Effect on Cell Adhesion of Polyvinyl Alcohol Integrated In Situ
Hindawi Limited, 2017Co-Authors: Marlon Osorio, Robin Zuluaga, Orlando J Rojas, Piedad Ganan, Jorge Velásquez-cock, Luz Marina Restrepo, Isabel Ortiz-trujillo, Cristina CastroAbstract:We investigated wound dressing composites comprising fibrils of bacterial cellulose (BC) grown by fermentation in the presence of polyvinyl alcohol (PVA) followed by Physical Crosslinking. The reference biointerface, neat BC, favoured adhesion of fibroblasts owing to size exclusion effects. Furthermore, it resisted migration across the biomaterial. Such effects were minimized in the case of PVA/BC membranes. Therefore, the latter are suggested in cases where cell adhesion is to be avoided, for instance, in the design of interactive wound dressings with facile exudate control. The bioactivity and other properties of the membranes were related to their morphology and structure and considered those of collagen fibres. Bioactive materials were produced by simple 3D templating of BC during growth and proposed for burn and skin ulcer treatment
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highly percolated poly vinyl alcohol and bacterial nanocellulose synthesized in situ by Physical Crosslinking exploiting polymer synergies for biomedical nanocomposites
RSC Advances, 2015Co-Authors: Cristina Castro, Robin Zuluaga, Orlando J Rojas, Ilari Filpponen, Hannes Orelma, M Londono, Santiago Betancourt, Piedad GananAbstract:Bacterial cellulose (BC) grown from a culture medium in the presence of water-soluble poly(vinyl alcohol) (PVA) produced an assemblage that was used as precursor for the synthesis of biocompatible nanocomposites. Physical Crosslinking via cyclic freezing and thawing of the formed hydrogel facilitated retention of PVA matrix upon composite separation and purification. The composites displayed a porous architecture within the PVA matrix and an excellent compressive strength as a result of the synergism between BC and PVA. BC largely improved the thermo-mechanical performance as well as moisture and dimensional stability of the systems while PVA imparted optical transparency and extensibility. Compared to the respective reference sample (BC-free material), elastic modulus increments of 40, 98 and 510% were measured for PVA-based nanocomposites loaded with BC at 10, 20 and 30% levels, respectively. Likewise, the corresponding strength at break were 30, 77 and 104% higher. The results indicate an exceptional reinforcing effect endowed by the three-dimensional network structure that was formed in situ upon BC biosynthesis in the presence of PVA and also suggest a large percolation within the matrix. BC is relatively inexpensive, can produce scaffolds of given shapes and with high strength and acts as an excellent reinforcing element that promotes cell proliferation. Taken these properties together, BC and BC/PVA composites are promising materials in biomedical engineering.
Liming Bian - One of the best experts on this subject based on the ideXlab platform.
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one pot solvent exchange preparation of non swellable thermoplastic stretchable and adhesive supramolecular hydrogels based on dual synergistic Physical Crosslinking
Npg Asia Materials, 2018Co-Authors: Qian Feng, Kongchang Wei, Kunyu Zhang, Boguang Yang, Feng Tian, Guixue Wang, Liming BianAbstract:With their unique properties of self-healing and viscoelasticity, Physically crosslinked supramolecular hydrogels are promising materials for soft robotics, wearable electronics and biomedical applications. However, the weak mechanical properties of supramolecular hydrogels, especially those prepared with natural polymers, limit their wide-spread application, and swelling is one of the key factors that contributes to the weakening of hydrogels. Herein, we utilize a simple one-pot solvent exchange method to prepare non-swellable, thermoplastic and tough supramolecular gelatin hydrogels based on two synergistic Physical Crosslinkings, namely, the self-assembled tri-helix structure of gelatin and the hydrophobic aggregation of gelatin-grafted and free hydrophobic motifs. The obtained hydrogels possess a stable water content above 70% with extended incubation in water. These hydrogels are highly malleable upon heating but are extremely stretchable and tough after cooling to room temperature. Furthermore, the supramolecular gelatin hydrogels exhibit robust adhesion to various material surfaces and minimal cytotoxicity. A method for synthesizing a mechanically robust soft material that can heal itself has been developed by scientists in Hong Kong and China. Self-healing hydrogels are so called because crosslinked polymers can spontaneously form new bonds when old ones break. They are soft and flexible, making them ideal for soft robots and biomedical applications. However, they can swell rapidly when wet, which undermines their mechanical strength. Liming Bian from the Chinese University of Hong Kong and colleagues created a non-swellable, stretchable and tough hydrogel using a simple one-pot technique. They reduced swelling by harnessing two types of Crosslinking: the self-assembled tri-helix Crosslinking of gelatin and the aggregation of hydrophobic groups on the gelatin molecule. The supramolecular gelatin hydrogel is malleable when heated but extremely stretchable and tough once cooled. A simple one-pot solvent exchange method is developed to prepare non-swellable, thermoplastic and tough supramolecular gelatin hydrogels based on two synergistic Physical Crosslinking, namely, the self-assembled tri-helix structure of gelatin and hydrophobic aggregation of gelatin-grafted and free hydrophobic motifs. The obtained hydrogels possess stable water content >70% with extended incubation in water and these hydrogels are highly malleable upon heating but are extremely stretchable and tough after cooling to room temperature. Furthermore, the supramolecular gelatin hydrogels exhibit robust adhesion to various material surfaces and minimal cytotoxicity.
Cristina Castro - One of the best experts on this subject based on the ideXlab platform.
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Bioactive 3D-Shaped Wound Dressings Synthesized from Bacterial Cellulose: Effect on Cell Adhesion of Polyvinyl Alcohol Integrated In Situ
Hindawi Limited, 2017Co-Authors: Marlon Osorio, Robin Zuluaga, Orlando J Rojas, Piedad Ganan, Jorge Velásquez-cock, Luz Marina Restrepo, Isabel Ortiz-trujillo, Cristina CastroAbstract:We investigated wound dressing composites comprising fibrils of bacterial cellulose (BC) grown by fermentation in the presence of polyvinyl alcohol (PVA) followed by Physical Crosslinking. The reference biointerface, neat BC, favoured adhesion of fibroblasts owing to size exclusion effects. Furthermore, it resisted migration across the biomaterial. Such effects were minimized in the case of PVA/BC membranes. Therefore, the latter are suggested in cases where cell adhesion is to be avoided, for instance, in the design of interactive wound dressings with facile exudate control. The bioactivity and other properties of the membranes were related to their morphology and structure and considered those of collagen fibres. Bioactive materials were produced by simple 3D templating of BC during growth and proposed for burn and skin ulcer treatment
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highly percolated poly vinyl alcohol and bacterial nanocellulose synthesized in situ by Physical Crosslinking exploiting polymer synergies for biomedical nanocomposites
RSC Advances, 2015Co-Authors: Cristina Castro, Robin Zuluaga, Orlando J Rojas, Ilari Filpponen, Hannes Orelma, M Londono, Santiago Betancourt, Piedad GananAbstract:Bacterial cellulose (BC) grown from a culture medium in the presence of water-soluble poly(vinyl alcohol) (PVA) produced an assemblage that was used as precursor for the synthesis of biocompatible nanocomposites. Physical Crosslinking via cyclic freezing and thawing of the formed hydrogel facilitated retention of PVA matrix upon composite separation and purification. The composites displayed a porous architecture within the PVA matrix and an excellent compressive strength as a result of the synergism between BC and PVA. BC largely improved the thermo-mechanical performance as well as moisture and dimensional stability of the systems while PVA imparted optical transparency and extensibility. Compared to the respective reference sample (BC-free material), elastic modulus increments of 40, 98 and 510% were measured for PVA-based nanocomposites loaded with BC at 10, 20 and 30% levels, respectively. Likewise, the corresponding strength at break were 30, 77 and 104% higher. The results indicate an exceptional reinforcing effect endowed by the three-dimensional network structure that was formed in situ upon BC biosynthesis in the presence of PVA and also suggest a large percolation within the matrix. BC is relatively inexpensive, can produce scaffolds of given shapes and with high strength and acts as an excellent reinforcing element that promotes cell proliferation. Taken these properties together, BC and BC/PVA composites are promising materials in biomedical engineering.
Marcel Karperien - One of the best experts on this subject based on the ideXlab platform.
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enzyme catalyzed crosslinkable hydrogels emerging strategies for tissue engineering
Biomaterials, 2012Co-Authors: Liliana Moreira Teixeira, Jan Feijen, Clemens Van Blitterswijk, Pieter J Dijkstra, Marcel KarperienAbstract:State-of-the-art bioactive hydrogels can easily and efficiently be formed by enzyme-catalyzed mild- Crosslinking reactions in situ. Yet this cell-friendly and substrate-specific method remains under explored. Hydrogels prepared by using enzyme systems like tyrosinases, transferases and lysyl oxidases show interesting characteristics as dynamic scaffolds and as systems for controlled release. Increased attention is currently paid to hydrogels obtained via Crosslinking of precursors by transferases or peroxidases as catalysts. Enzyme-mediated Crosslinking has proven its efficiency and attention has now shifted to the development of enzymatically crosslinked hydrogels with higher degrees of complexity , mimicking extracellular matrices. Moreover, bottom-up approaches combining biocatalysts and self- assembly are being explored for the development of complex nano-scale architectures. In this review, the use of enzymatic Crosslinking for the preparation of hydrogels as an innovative alternative to other Crosslinking methods, such as the commonly used UV-mediated photo-Crosslinking or Physical cross-linking, will be discussed. Photo-initiator-based Crosslinking may induce cytotoxicity in the formed gels, whereas Physical Crosslinking may lead to gels which do not have sufficient mechanical strength and stability. These limitations can be overcome using enzymes to form covalently crosslinked hydrogels. Herewith, we report the mechanisms involved and current applications, focusing on emerging strategies for tissue engineering and regenerative medicine.