The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
Dong Shi - One of the best experts on this subject based on the ideXlab platform.
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4 hydroxyproline derived sustainable polythioesters controlled ring opening polymerization complete recyclability and facile functionalization
Journal of the American Chemical Society, 2019Co-Authors: Jingsong Yuan, Wei Xiong, Xuhao Zhou, Yi Zhang, Dong ShiAbstract:The sustainable production of chemically recyclable polymers presents a significant opportunity to polymer scientists to tackle the growing environmental and energy problems of current petroleum-based plastics. Despite recent advances, however, there are still pressing needs for an expanded horizon of chemically recyclable polymers. Herein, we introduce a new paradigm of biosourced polythioesters (PTEs) with high polymerizability and complete recyclability under mild and economical conditions. The thiolactone monomers with a high ring strain can be easily prepared in a two-step process from 4-hydroxyproline. Controlled ring-opening polymerizations (ROP) using inexpensive and weak bases afford PTEs with high molar masses ( Mn) up to 259 kg mol-1 and narrow dispersities generally below 1.15. The properties of PTEs can be readily adjusted by copolymerization and/or pre/post-functionalization on the side chains. Selective and complete depolymerizations of the PTEs in dilute solution at ambient to modest temperatures recycle clean monomers. Density functional theory (DFT) calculation of model reactions provides mechanistic insights and highlights the importance of judicious molecular design. Taken together, the unique ROP/depolymerization chemistry of such PTEs may offer a sustainable solution for creating and manufacturing high-value materials such as optical/photochemical plastics, self-immolative polymers, and Degradable Biomaterials under situations where recycle and reuse are indispensable.
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4‑Hydroxyproline-Derived Sustainable Polythioesters: Controlled Ring-Opening Polymerization, Complete Recyclability, and Facile Functionalization
2019Co-Authors: Jingsong Yuan, Wei Xiong, Xuhao Zhou, Yi Zhang, Dong ShiAbstract:The sustainable production of chemically recyclable polymers presents a significant opportunity to polymer scientists to tackle the growing environmental and energy problems of current petroleum-based plastics. Despite recent advances, however, there are still pressing needs for an expanded horizon of chemically recyclable polymers. Herein, we introduce a new paradigm of biosourced polythioesters (PTEs) with high polymerizability and complete recyclability under mild and economical conditions. The thiolactone monomers with a high ring strain can be easily prepared in a two-step process from 4-hydroxyproline. Controlled ring-opening polymerizations (ROP) using inexpensive and weak bases afford PTEs with high molar masses (Mn) up to 259 kg mol–1 and narrow dispersities generally below 1.15. The properties of PTEs can be readily adjusted by copolymerization and/or pre/post-functionalization on the side chains. Selective and complete depolymerizations of the PTEs in dilute solution at ambient to modest temperatures recycle clean monomers. Density functional theory (DFT) calculation of model reactions provides mechanistic insights and highlights the importance of judicious molecular design. Taken together, the unique ROP/depolymerization chemistry of such PTEs may offer a sustainable solution for creating and manufacturing high-value materials such as optical/photochemical plastics, self-immolative polymers, and Degradable Biomaterials under situations where recycle and reuse are indispensable
Jingsong Yuan - One of the best experts on this subject based on the ideXlab platform.
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4 hydroxyproline derived sustainable polythioesters controlled ring opening polymerization complete recyclability and facile functionalization
Journal of the American Chemical Society, 2019Co-Authors: Jingsong Yuan, Wei Xiong, Xuhao Zhou, Yi Zhang, Dong ShiAbstract:The sustainable production of chemically recyclable polymers presents a significant opportunity to polymer scientists to tackle the growing environmental and energy problems of current petroleum-based plastics. Despite recent advances, however, there are still pressing needs for an expanded horizon of chemically recyclable polymers. Herein, we introduce a new paradigm of biosourced polythioesters (PTEs) with high polymerizability and complete recyclability under mild and economical conditions. The thiolactone monomers with a high ring strain can be easily prepared in a two-step process from 4-hydroxyproline. Controlled ring-opening polymerizations (ROP) using inexpensive and weak bases afford PTEs with high molar masses ( Mn) up to 259 kg mol-1 and narrow dispersities generally below 1.15. The properties of PTEs can be readily adjusted by copolymerization and/or pre/post-functionalization on the side chains. Selective and complete depolymerizations of the PTEs in dilute solution at ambient to modest temperatures recycle clean monomers. Density functional theory (DFT) calculation of model reactions provides mechanistic insights and highlights the importance of judicious molecular design. Taken together, the unique ROP/depolymerization chemistry of such PTEs may offer a sustainable solution for creating and manufacturing high-value materials such as optical/photochemical plastics, self-immolative polymers, and Degradable Biomaterials under situations where recycle and reuse are indispensable.
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4‑Hydroxyproline-Derived Sustainable Polythioesters: Controlled Ring-Opening Polymerization, Complete Recyclability, and Facile Functionalization
2019Co-Authors: Jingsong Yuan, Wei Xiong, Xuhao Zhou, Yi Zhang, Dong ShiAbstract:The sustainable production of chemically recyclable polymers presents a significant opportunity to polymer scientists to tackle the growing environmental and energy problems of current petroleum-based plastics. Despite recent advances, however, there are still pressing needs for an expanded horizon of chemically recyclable polymers. Herein, we introduce a new paradigm of biosourced polythioesters (PTEs) with high polymerizability and complete recyclability under mild and economical conditions. The thiolactone monomers with a high ring strain can be easily prepared in a two-step process from 4-hydroxyproline. Controlled ring-opening polymerizations (ROP) using inexpensive and weak bases afford PTEs with high molar masses (Mn) up to 259 kg mol–1 and narrow dispersities generally below 1.15. The properties of PTEs can be readily adjusted by copolymerization and/or pre/post-functionalization on the side chains. Selective and complete depolymerizations of the PTEs in dilute solution at ambient to modest temperatures recycle clean monomers. Density functional theory (DFT) calculation of model reactions provides mechanistic insights and highlights the importance of judicious molecular design. Taken together, the unique ROP/depolymerization chemistry of such PTEs may offer a sustainable solution for creating and manufacturing high-value materials such as optical/photochemical plastics, self-immolative polymers, and Degradable Biomaterials under situations where recycle and reuse are indispensable
Philippe Dubois - One of the best experts on this subject based on the ideXlab platform.
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from controlled ring opening polymerization to bioDegradable aliphatic polyester especially poly β malic acid derivatives
Progress in Polymer Science, 2006Co-Authors: Olivier Coulembier, Philippe Degee, James L Hedrick, Philippe DuboisAbstract:BioDegradable polymers represent a class of extremely useful materials for many biomedical and pharmaceutical applications, as exemplified by drug delivery systems, which in recent years have taken advantage of (bio)Degradable polymeric matrices. However, before being selected for any biomedical application, a bioDegradable polymer requires careful investigation of its interactions and compatibility within the human body. To date, polyesters, both natural and synthetic, constitute the most fully developed class of Degradable Biomaterials. Poly(e-caprolactone) (PCL) and polylactides (PLAs), recognized as biocompatible and bioDegradable polyesters, are very promising for controlled drug delivery devices. Bacterial polyesters and malic acid-based polymers (poly(malic acid), PMLA and derivatives) are poly(β-hydroxyacid)-type polyesters that represent excellent alternatives for temporary therapeutic applications. Although these polyesters can be produced by polycondensation, high molecular weight structures have, until now, been produced almost exclusively by ring-opening polymerization (ROP) of the corresponding cyclic monomers. The ability of aluminum alkoxides (AlRx(OR′)3−x) and tin(II) bis(2-ethylhexanoate) (Sn(Oct)2) to control the ROP of (di)lactones in terms of molecular parameters has opened the way to a wide range of molecular structures and topologies. Beyond the mechanistic and thermodynamic aspects of ROP of (di)lactones using organometallic compounds, this review is focused on new non-organometallic N-heterocyclic carbenes recently reported as catalysts for the controlled ROP of cyclic esters. Interestingly, the use of these simple organic molecules as catalysts or promoters in asymmetric polymer synthesis has provided organocatalytic alternatives to traditional organometallic reagents.
Rui L Reis - One of the best experts on this subject based on the ideXlab platform.
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biomimetic ca p coatings incorporating bisphosphonates produced on starch based Degradable Biomaterials
Journal of Biomedical Materials Research Part B, 2010Co-Authors: João F. Mano, Ana Oliveira, A J Pedro, Saiz C Arroyo, Gema Rodriguez, San J Roman, Rui L ReisAbstract:In this study, sodium clodronate, a well-known therapeutic agent from the family of bisphosphonates (BPs), is incorporated in a biomimetic calcium phosphate (CaP) coating, previously formed on the surface of a starch-based biomaterial by a sodium silicate methodology, as a strategy to develop a site-specific drug delivery system for bone tissue regeneration applications. The effects on the resulting CaP coatings were evaluated in terms of morphology, chemistry, and structure. The dissolution of Ca and P from the coating and the release profiles of sodium clodronate was also assessed. As a preliminary approach, this first study also aimed at evaluating the effects of this BP on the viability of a human osteoblastic cell line since there is still little information available on the interaction between BPs and this type of cells. Sodium clodronate was successfully incorporated, at different doses, in the structure of a biomimetic CaP layer previously formed by a sodium silicate process. This type of BPs had a stimulatory effect on osteoblastic activity, particularly at the specific concentration of 0.32 mg/mL. It is foreseen that these coatings can, for instances, be produced on the surface of Degradable polymers and then used for regulating the equilibrium on osteoblastic/osteoclastic activity, leading to a controlled regenerative effect at the interface between the biomaterial and bone.
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bioDegradable systems in tissue engineering and regenerative medicine
2004Co-Authors: Rui L Reis, Julio Sa RomaAbstract:PROCESSING AND APPLICATIONS OF BIODegradable SYSTEMS BioDegradable Polymers in Medicine M. Suzuki and Y. Ikada Injectable BioDegradable Systems L. F. Boesel and R. L. Reis Injectable Polymeric Scaffolds for Bone Tissue Engineering M.E. Gomes, R.L. Reis, and A.G. Mikos Totally or Partially BioDegradable Self-Polymerizing Composites for Orthopedic Surgery and Dental Applications B. Vazquez, G.A. Abraham, C. Elvira, and J. San Roman Fiber Bonding and Particle Aggregation as Promising Methodologies for the Fabrication of BioDegradable Scaffolds for HardTissue Engineering M.E. Gomes, P.B. Malafaya, and R.L. Reis Design and Fabrication of Scaffolds Via Solid Free Form Fabrication D.W. Hutmacher BioDegradable Composites for Biomedical Applications N. M. Neves, J. F. Mano, and R.L. Reis Development of Bioactive Composites Based on BioDegradable Systems for Bone Replacement Applications B. Leonor, R. A. Sousa, and R.L. Reis Mechanical Characterization of Biomaterials J. F. Mano, N. M. Neves, and R.L. Reis Chitosan-Based Microcomposites - From BioDegradable Microparticles to Self-Curing Hydrogels A. Gallardo, M.R. Aguilar, C. Elvira, C. Peniche, and J. San Roman Processing and Biomedical Applications of Degradable Polymeric Fibers K. Tuzlakoglu and R.L. Reis Understanding the Enzymatic Degradation of BioDegradable Polymers and Strategies to Control Their Degradation Rate H.S. Azevedo and R.L. Reis PRODUCTION OF BIOMIMETIC COATINGS ON THE SURFACE OF Degradable POLYMERS Bonelike Apatite Coatings Nucleated on BioDegradable Polymers as a Way to Induce Bone Mineralization: Current Developments and Future Trends A. L. Oliveira and R.L. Reis Biomimetic Coatings, Proteins, and Biocatalysts: A New Approach to Tailor the Properties of BioDegradable Polymers I.B. Leonor, H.S. Azevedo, C.M. Alves, and R.L. Reis SYSTEMS FOR CONTROLLED RELEASE OF BIOACTIVE AGENTS Strategies for Delivering Bone and Cartilage Regenerating Factors P.B. Malafaya, G.A. Silva, and R.L. Reis Resorbable Polymeric Delivery Systems Based on Physical Absorption/Diffusion versus Chemically Controlled Delivery Systems J. San Roman, A. Gallardo, C. Elvira, B. Vazquez, and G.A. Abraham Enzyme Immobilization in BioDegradable Polymers for Biomedical Applications S. A. Costa, H.S. Azevedo, and R.L. Reis Use of Chemically Modified Chitosan and Other Natural-Origin Polymers in Tissue Engineering and Drug Delivery E. T. Baran and R.L. Reis BIOCOMPATIBILITY AND IMMUNOLOGICAL RESPONSES TO Degradable Biomaterials Cytotoxicity Screening of BioDegradable Polymeric Systems G.A. Silva, A. P. Marques, M.E. Gomes, O. P. Coutinho, and R.L. Reis Natural-Origin Degradable Materials: The Barrier or the Passage through the Immune System? P. Marques, J. A. Hunt, and R.L. Reis Mediation of the Cytokine Network in the Implantation of Orthopedic Devices P. Marques, J. A. Hunt, and R.L. Reis Protein and Cell Interactions with BioDegradable Systems C.M. Alves and R.L. Reis Surface Activation and Modification - A Way for Improving the Biocompatibility of Degradable Biomaterials I. Pashkuleva and R.L. Reis BIODegradable POLYMERS FOR THE ENGINEERING AND REGENERATION OF DIFFERENT TISSUES Bone and Articular Cartilage Tissue Engineering: The Biological Components A.J. Salgado, M.E. Gomes, O. P. Coutinho, and R.L. Reis Tissue Engineering of the Liver Y.M. Elcin Smart BioDegradable Hydrogels with Applications in Drug Delivery and Tissue Engineering C. Elvira, G.A. Abraham, A. Gallardo, and J. San Roman Skin Tissue Engineering Part I - Review D.W. Hutmacher, K. W. Ng, and H. L. Khor Skin Tissue Engineering Part II - The In Vitro Evaluation of Natural and Synthetic 3-D Matrices as Dermal Substrates K. W. Ng, H. L. Khor, and D.W. Hutmacher BioDegradable Polymers for Guided Nerve Regeneration K. Tuzlakoglu and R.L. Reis INDEX
João F. Mano - One of the best experts on this subject based on the ideXlab platform.
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biomimetic ca p coatings incorporating bisphosphonates produced on starch based Degradable Biomaterials
Journal of Biomedical Materials Research Part B, 2010Co-Authors: João F. Mano, Ana Oliveira, A J Pedro, Saiz C Arroyo, Gema Rodriguez, San J Roman, Rui L ReisAbstract:In this study, sodium clodronate, a well-known therapeutic agent from the family of bisphosphonates (BPs), is incorporated in a biomimetic calcium phosphate (CaP) coating, previously formed on the surface of a starch-based biomaterial by a sodium silicate methodology, as a strategy to develop a site-specific drug delivery system for bone tissue regeneration applications. The effects on the resulting CaP coatings were evaluated in terms of morphology, chemistry, and structure. The dissolution of Ca and P from the coating and the release profiles of sodium clodronate was also assessed. As a preliminary approach, this first study also aimed at evaluating the effects of this BP on the viability of a human osteoblastic cell line since there is still little information available on the interaction between BPs and this type of cells. Sodium clodronate was successfully incorporated, at different doses, in the structure of a biomimetic CaP layer previously formed by a sodium silicate process. This type of BPs had a stimulatory effect on osteoblastic activity, particularly at the specific concentration of 0.32 mg/mL. It is foreseen that these coatings can, for instances, be produced on the surface of Degradable polymers and then used for regulating the equilibrium on osteoblastic/osteoclastic activity, leading to a controlled regenerative effect at the interface between the biomaterial and bone.
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Dynamic mechanical properties of hydroxyapatite-reinforced and porous starch-based Degradable Biomaterials.
Journal of materials science. Materials in medicine, 1999Co-Authors: João F. Mano, R. L. Reis, Cláudia M. Vaz, S.c. Mendes, A. M. CunhaAbstract:It has been shown that blends of starch with a poly(ethylene-vinyl-alcohol) copolymer, EVOH, designated as SEVA-C, present an interesting combination of mechanical, degradation and biocompatible properties, specially when filled with hydroxyapatite (HA). Consequently, they may find a range of applications in the Biomaterials field. This work evaluated the influence of HA fillers and of blowing agents (used to produce porous architectures) over the viscoelastic properties of SEVA-C polymers, as seen by dynamic mechanical analysis (DMA), in order to speculate on their performances when withstanding cyclic loading in the body. The composite materials presented a promising performance under dynamic mechanical solicitation conditions. Two relaxations were found being attributed to the starch and EVOH phases. The EVOH relaxation process may be very useful in vivo improving the implants performance under cyclic loading. DMA results also showed that it is possible to produce SEVA-C compact surface/porous core architectures with a mechanical performance similar to that of SEVA-C dense materials. This may allow for the use of these materials as bone replacements or scaffolds that must withstand loads when implanted.