Scaffolds play a crucial role in tissue engineering. Biodegradable polymers with great processing flexibility are the predominant scaffolding materials. Synthetic biodegradable polymers with well-defined structure and...Scaffolds play a crucial role in tissue engineering. Biodegradable polymers with great processing flexibility are the predominant scaffolding materials. Synthetic biodegradable polymers with well-defined structure and without immunological concerns associated with naturally derived polymers are widely used in tissue engineering. The synthetic biodegradable polymers that are widely used in tissue engineering, including polyesters, polyanhydrides, polyphosphazenes, polyurethane, and poly(glycerol sebacate) are summarized in this article. New developments in conducting polymers, photoresponsive polymers, amino-acid-based polymers, enzymatically degradable polymers, and peptide-activated polymers are also discussed. In addition to chemical functionalization, the scaffold designs that mimic the nano and micro features of the extracellular matrix(ECM) are presented as well, and composite and nanocomposite scaffolds are also reviewed.展开更多
Pomegranate rind is abundantly available as a waste material. Pomegranate Rind Extract (PRE) can be applied to cotton fabrics for its natural colours, as a mordanting agent and also for imparting certain functional pr...Pomegranate rind is abundantly available as a waste material. Pomegranate Rind Extract (PRE) can be applied to cotton fabrics for its natural colours, as a mordanting agent and also for imparting certain functional properties such as fire retardancy and antimicrobial properties. This paper reviews the feasibility of Pomegranate Rind Extract to improve the functional properties of cellulosic fabrics. Studies show that varying concentrations and higher temperatures that were used to apply the extract on the fabric, resulted in enhanced functional properties. At a particular concentration, the treated fabric showed a 15 times lower burning rate in comparison with the control fabric. Also, antimicrobial efficacy has been observed against Gram-positive and Gram-negative bacteria. Due to the natural colouring material, it can be used as a natural dye on cotton material. The fire retardancy of pomegranate rind extract was tested on jute material under varying alkalinity. Research has indicated that pomegranate rind extract could be used to dye polyamide as well. The rubbing and wash fastness of the finished fabrics is good. The light fastness was fair, and its antibacterial efficiency against tested bacteria was good.展开更多
With the growth of deep drilling and the complexity of the well profile,the requirements for a more complete and efficient exploitation of productive formations increase,which increases the risk of various complicatio...With the growth of deep drilling and the complexity of the well profile,the requirements for a more complete and efficient exploitation of productive formations increase,which increases the risk of various complications.Currently,reagents based on modified natural polymers(which are naturally occurring compounds)and synthetic polymers(SPs)which are polymeric compounds created industrially,are widely used to prevent emerging complications in the drilling process.However,compared to modified natural polymers,SPs form a family of high-molecular-weight compounds that are fully synthesized by undergoing chemical polymerization reactions.SPs provide substantial flexibility in their design.Moreover,their size and chemical composition can be adjusted to provide properties for nearly all the functional objectives of drilling fluids.They can be classified based on chemical ingredients,type of reaction,and their responses to heating.However,some of SPs,due to their structural characteristics,have a high cost,a poor temperature and salt resistance in drilling fluids,and degradation begins when the temperature reaches 130℃.These drawbacks prevent SP use in some medium and deep wells.Thus,this review addresses the historical development,the characteristics,manufacturing methods,classification,and the applications of SPs in drilling fluids.The contributions of SPs as additives to drilling fluids to enhance rheology,filtrate generation,carrying of cuttings,fluid lubricity,and clay/shale stability are explained in detail.The mechanisms,impacts,and advances achieved when SPs are added to drilling fluids are also described.The typical challenges encountered by SPs when deployed in drilling fluids and their advantages and drawbacks are also discussed.Economic issues also impact the applications of SPs in drilling fluids.Consequently,the cost of the most relevant SPs,and the monomers used in their synthesis,are assessed.Environmental impacts of SPs when deployed in drilling fluids,and their manufacturing processes are identified,to展开更多
基于原子力显微镜(atomic force microscopy,AFM)的单分子力谱技术以其操作简便、适用面广等优势,成为了单分子领域应用最为广泛的技术之一.本文阐述了该技术的基础原理与实验技巧,包括仪器构造、工作原理、探针与基底的选择、样品固定...基于原子力显微镜(atomic force microscopy,AFM)的单分子力谱技术以其操作简便、适用面广等优势,成为了单分子领域应用最为广泛的技术之一.本文阐述了该技术的基础原理与实验技巧,包括仪器构造、工作原理、探针与基底的选择、样品固定、实验操作、单分子信号的获得以及数据处理.介绍了基于AFM的单分子力谱技术在合成高分子及生物大分子表征中的典型应用及前沿进展.AFM单分子力谱技术将有助于建立合成高分子的链结构、链组成与单链弹性以及链间相互作用与其宏观力学性能间的关联,帮助理解生物大分子的结构、相互作用与其生物功能之间的联系.展开更多
Bone defects caused by trauma, infection or bone tumor resection, are highly prevalent. A small number(5%–10%) of these injuries fail to heal due to non-union and require surgical intervention. Currently, the princip...Bone defects caused by trauma, infection or bone tumor resection, are highly prevalent. A small number(5%–10%) of these injuries fail to heal due to non-union and require surgical intervention. Currently, the principal treatment options for these defects are autografts, allografts, xenografts or synthetic grafts. The main problems associated with these therapies include pain,infection and donor site morbidity. Bone tissue engineering is a diverse field that focuses on the regeneration of bone by combining cells, scaffolds, growth factors and dynamic forces. There have been many recent studies utilizing biomineralized polymer matrix composites which mimic the natural structure of bone. The principal focus of this review is on recent advances in the synthesis of various types of biomineralized polymer matrix composite. Examples of the biomineralization of naturallyderived and synthetic polymers widely used for bone engineering are also summarized.展开更多
The application of various materials in biomedical procedures has recently experienced rapid growth.One area that is currently receiving significant attention from the scientific community is the treatment of a number...The application of various materials in biomedical procedures has recently experienced rapid growth.One area that is currently receiving significant attention from the scientific community is the treatment of a number of different types of bone-related diseases and disorders by using biodegradable polymer-ceramic composites.Biomaterials,the most common materials used to repair or replace damaged parts of the human body,can be categorized into three major groups:metals,ceramics,and polymers.Composites can be manufactured by combining two or more materials to achieve enhanced biocompatibility and biomechanical properties for specific applications.Biomaterials must display suitable properties for their applications,about strength,durability,and biological influence.Metals and their alloys such as titanium,stainless steel,and cobalt-based alloys have been widely investigated for implant-device applications because of their excellent mechanical properties.However,these materials may also manifest biological issues such as toxicity,poor tissue adhesion and stress shielding effect due to their high elastic modulus.To mitigate these issues,hydroxyapatite(HA)coatings have been used on metals because their chemical composition is similar to that of bone and teeth.Recently,a wide range of synthetic polymers such as poly(L-lactic acid)and poly(L-lactide-co-glycolide)have been studied for different biomedical applications,owing to their promising biocompatibility and biodegradability.This article gives an overview of synthetic polymer-ceramic composites with a particular emphasis on calcium phosphate group and their potential applications in tissue engineering.It is hoped that synthetic polymer-ceramic composites such as PLLA/HA and PCL/HA will provide advantages such as eliminating the stress shielding effect and the consequent need for revision surgery.展开更多
Recent developments in synthetic bone grafting materials and adjuvant therapeutic agents have opened the door to the regenerative reconstruction of critical-size long bone segmental defects resulting from trauma,osteo...Recent developments in synthetic bone grafting materials and adjuvant therapeutic agents have opened the door to the regenerative reconstruction of critical-size long bone segmental defects resulting from trauma,osteoporotic fractures or tumour resections.Polymeric scaffolds with controlled macroporosities,degradability,useful surgical handling characteristics,and the ability to deliver biotherapeutics to promote new bone ingrowth have been developed for this challenging orthopaedic application.This review highlights major classes of degradable synthetic polymers and their biomineral composites,including conventional and amphiphilic polyesters,polyanhydrides,polycarbonates,and polyethylene glycol-based hydrogels,that have been explored for the regenerative reconstruction of critical-size long bone segmental defects over the past two decades.The pros and cons of these synthetic scaffold materials are presented in the context of enabling or impeding the functional(mechanical and radiographic)repair of a long bone segmental defect,with the long bone regeneration outcomes compared with healthy long bone controls or results achieved with current grafting standards.展开更多
基金the financial support of the US National Institutes of Health(NIDCR DE015384,DE017689,DE022327)DOD(W81XWH-12-2-0008)+1 种基金the National Science Foundation of the United States(DMR-1206575)the National Natural Science Foundation of China(21304073)
文摘Scaffolds play a crucial role in tissue engineering. Biodegradable polymers with great processing flexibility are the predominant scaffolding materials. Synthetic biodegradable polymers with well-defined structure and without immunological concerns associated with naturally derived polymers are widely used in tissue engineering. The synthetic biodegradable polymers that are widely used in tissue engineering, including polyesters, polyanhydrides, polyphosphazenes, polyurethane, and poly(glycerol sebacate) are summarized in this article. New developments in conducting polymers, photoresponsive polymers, amino-acid-based polymers, enzymatically degradable polymers, and peptide-activated polymers are also discussed. In addition to chemical functionalization, the scaffold designs that mimic the nano and micro features of the extracellular matrix(ECM) are presented as well, and composite and nanocomposite scaffolds are also reviewed.
文摘Pomegranate rind is abundantly available as a waste material. Pomegranate Rind Extract (PRE) can be applied to cotton fabrics for its natural colours, as a mordanting agent and also for imparting certain functional properties such as fire retardancy and antimicrobial properties. This paper reviews the feasibility of Pomegranate Rind Extract to improve the functional properties of cellulosic fabrics. Studies show that varying concentrations and higher temperatures that were used to apply the extract on the fabric, resulted in enhanced functional properties. At a particular concentration, the treated fabric showed a 15 times lower burning rate in comparison with the control fabric. Also, antimicrobial efficacy has been observed against Gram-positive and Gram-negative bacteria. Due to the natural colouring material, it can be used as a natural dye on cotton material. The fire retardancy of pomegranate rind extract was tested on jute material under varying alkalinity. Research has indicated that pomegranate rind extract could be used to dye polyamide as well. The rubbing and wash fastness of the finished fabrics is good. The light fastness was fair, and its antibacterial efficiency against tested bacteria was good.
文摘With the growth of deep drilling and the complexity of the well profile,the requirements for a more complete and efficient exploitation of productive formations increase,which increases the risk of various complications.Currently,reagents based on modified natural polymers(which are naturally occurring compounds)and synthetic polymers(SPs)which are polymeric compounds created industrially,are widely used to prevent emerging complications in the drilling process.However,compared to modified natural polymers,SPs form a family of high-molecular-weight compounds that are fully synthesized by undergoing chemical polymerization reactions.SPs provide substantial flexibility in their design.Moreover,their size and chemical composition can be adjusted to provide properties for nearly all the functional objectives of drilling fluids.They can be classified based on chemical ingredients,type of reaction,and their responses to heating.However,some of SPs,due to their structural characteristics,have a high cost,a poor temperature and salt resistance in drilling fluids,and degradation begins when the temperature reaches 130℃.These drawbacks prevent SP use in some medium and deep wells.Thus,this review addresses the historical development,the characteristics,manufacturing methods,classification,and the applications of SPs in drilling fluids.The contributions of SPs as additives to drilling fluids to enhance rheology,filtrate generation,carrying of cuttings,fluid lubricity,and clay/shale stability are explained in detail.The mechanisms,impacts,and advances achieved when SPs are added to drilling fluids are also described.The typical challenges encountered by SPs when deployed in drilling fluids and their advantages and drawbacks are also discussed.Economic issues also impact the applications of SPs in drilling fluids.Consequently,the cost of the most relevant SPs,and the monomers used in their synthesis,are assessed.Environmental impacts of SPs when deployed in drilling fluids,and their manufacturing processes are identified,to
文摘基于原子力显微镜(atomic force microscopy,AFM)的单分子力谱技术以其操作简便、适用面广等优势,成为了单分子领域应用最为广泛的技术之一.本文阐述了该技术的基础原理与实验技巧,包括仪器构造、工作原理、探针与基底的选择、样品固定、实验操作、单分子信号的获得以及数据处理.介绍了基于AFM的单分子力谱技术在合成高分子及生物大分子表征中的典型应用及前沿进展.AFM单分子力谱技术将有助于建立合成高分子的链结构、链组成与单链弹性以及链间相互作用与其宏观力学性能间的关联,帮助理解生物大分子的结构、相互作用与其生物功能之间的联系.
基金supported by the National Key Research and Development Program of China (2017YFC1103500, 2017YFC1103502)the National Natural Science Foundation of China (31525009)+2 种基金Sichuan Innovative Research Team Program for Young Scientists (2016TD0004)Distinguished Young Scholars of Sichuan University (2011SCU04B18)Sichuan Science and Technology Project (2017GZ0429)
文摘Bone defects caused by trauma, infection or bone tumor resection, are highly prevalent. A small number(5%–10%) of these injuries fail to heal due to non-union and require surgical intervention. Currently, the principal treatment options for these defects are autografts, allografts, xenografts or synthetic grafts. The main problems associated with these therapies include pain,infection and donor site morbidity. Bone tissue engineering is a diverse field that focuses on the regeneration of bone by combining cells, scaffolds, growth factors and dynamic forces. There have been many recent studies utilizing biomineralized polymer matrix composites which mimic the natural structure of bone. The principal focus of this review is on recent advances in the synthesis of various types of biomineralized polymer matrix composite. Examples of the biomineralization of naturallyderived and synthetic polymers widely used for bone engineering are also summarized.
基金financial support for this research by the Australian Research Council(ARC)through the Discovery Project(DP170102557)supported by an ARC Future Fellowship(FT160100252).
文摘The application of various materials in biomedical procedures has recently experienced rapid growth.One area that is currently receiving significant attention from the scientific community is the treatment of a number of different types of bone-related diseases and disorders by using biodegradable polymer-ceramic composites.Biomaterials,the most common materials used to repair or replace damaged parts of the human body,can be categorized into three major groups:metals,ceramics,and polymers.Composites can be manufactured by combining two or more materials to achieve enhanced biocompatibility and biomechanical properties for specific applications.Biomaterials must display suitable properties for their applications,about strength,durability,and biological influence.Metals and their alloys such as titanium,stainless steel,and cobalt-based alloys have been widely investigated for implant-device applications because of their excellent mechanical properties.However,these materials may also manifest biological issues such as toxicity,poor tissue adhesion and stress shielding effect due to their high elastic modulus.To mitigate these issues,hydroxyapatite(HA)coatings have been used on metals because their chemical composition is similar to that of bone and teeth.Recently,a wide range of synthetic polymers such as poly(L-lactic acid)and poly(L-lactide-co-glycolide)have been studied for different biomedical applications,owing to their promising biocompatibility and biodegradability.This article gives an overview of synthetic polymer-ceramic composites with a particular emphasis on calcium phosphate group and their potential applications in tissue engineering.It is hoped that synthetic polymer-ceramic composites such as PLLA/HA and PCL/HA will provide advantages such as eliminating the stress shielding effect and the consequent need for revision surgery.
基金This work is supported by an Alex Lemonade Stand Foundation Innovation Grant and a BRIDGE Award from the University of Massachusetts Medical School.
文摘Recent developments in synthetic bone grafting materials and adjuvant therapeutic agents have opened the door to the regenerative reconstruction of critical-size long bone segmental defects resulting from trauma,osteoporotic fractures or tumour resections.Polymeric scaffolds with controlled macroporosities,degradability,useful surgical handling characteristics,and the ability to deliver biotherapeutics to promote new bone ingrowth have been developed for this challenging orthopaedic application.This review highlights major classes of degradable synthetic polymers and their biomineral composites,including conventional and amphiphilic polyesters,polyanhydrides,polycarbonates,and polyethylene glycol-based hydrogels,that have been explored for the regenerative reconstruction of critical-size long bone segmental defects over the past two decades.The pros and cons of these synthetic scaffold materials are presented in the context of enabling or impeding the functional(mechanical and radiographic)repair of a long bone segmental defect,with the long bone regeneration outcomes compared with healthy long bone controls or results achieved with current grafting standards.
