Protein- and peptide-based electrospun nanofibers in medical biomaterials

Electrospun fibers are being studied and developed because they hold considerable promise for realizing some advantages of nanostructured materials. The fibers can be made of biocompatible and biodegradable polymers. Electrospinning has therefore attracted interest in biotechnology and medicine, and there has been rapid growth in this area in recent years. This review presents an introduction to polymer nanofiber electrospinning, focusing on the use of natural proteins and synthetic peptides. We summarize key physical properties of protein-based and peptide-based nanofiber mats, survey biomedical applications of these materials, identify key challenges, and outline future prospects for development of the technology for tissue engineering, drug delivery, wound healing, and biosensors.From the Clinical EditorThis review focuses on polymer nanofiber electrospinning using natural proteins and synthetic peptides. The authors describe key properties and applications of these materials, and outline future prospects for tissue engineering, drug delivery, wound healing, and biosensors based on these nanomats and nanofibers.     

Alginate and alginate composites for biomedical applications

Alginate is an edible heteropolysaccharide that abundantly available in the brown seaweed and the capsule of bacteria such as Azotobacter sp. and Pseudomonas sp. Owing to alginate gel forming capability, it is widely used in food, textile and paper industries; and to a lesser extent in biomedical applications as biomaterial to promote wound healing and tissue regeneration. This is evident from the rising use of alginate-based dressing for heavily exuding wound and their mass availability in the market nowadays. However, alginate also has limitation. When in contact with physiological environment, alginate could gelate into softer structure, consequently limits its potential in the soft tissue regeneration and becomes inappropriate for the usage related to load bearing body parts. To cater this problem, wide range of materials have been added to alginate structure, producing sturdy composite materials. For instance, the incorporation of adhesive peptide and natural polymer or synthetic polymer to alginate moieties creates an improved composite material, which not only possesses better mechanical properties compared to native alginate, but also grants additional healing capability and promote better tissue regeneration. In addition, drug release kinetic and cell viability can be further improved when alginate composite is used as encapsulating agent. In this review, preparation of alginate and alginate composite in various forms (fibre, bead, hydrogel, and 3D-printed matrices) used for biomedical application is described first, followed by the discussion of latest trend related to alginate composite utilization in wound dressing, drug delivery, and tissue engineering applications.     

Electrospinning of polysaccharides for regenerative medicine

Electrospinning techniques enable the production of continuous fibers with dimensions on the scale of nanometers from a wide range of natural and synthetic polymers. The number of recent studies regarding electrospun polysaccharides and their derivatives, which are potentially useful for regenerative medicine, is increasing dramatically. However, difficulties regarding the processibility of the polysaccharides (e.g., poor solubility and high surface tension) have limited their application. In this review, we summarize the characteristics of various polysaccharides such as alginate, cellulose, chitin, chitosan, hyaluronic acid, starch, dextran, and heparin, which are either currently being used or have potential to be used for electrospinning. The recent progress of nanofiber matrices electrospun from polysaccharides and their biomedical applications in tissue engineering, wound dressings, drug delivery, and enzyme immobilization are discussed.     

Pharmaceutically versatile sulfated polysaccharide based bionano platforms

Sulfated polysaccharides are complex polysaccharide molecules with excellent physico-chemical properties and bioactivities. On the basis of origin, they are classified as plant, animal, microbial and chemically synthesized sulfated polysaccharides. They have been widely applied in the fields of material and biological sciences. Biocompatibility and biodegradability of these molecules facilitate their increased use in the nanoparticle synthesis and tissue engineering applications. This review focuses on the structure, function and applications of important types of natural and chemically derived sulfated polysaccharides in the fields of nanotechnology and biomedical sciences. In the first part, we discuss the classification and role of sulfated polysaccharides in various fields. Later, we elaborate the specific bionano applications of commercially important sulfated polysaccharides in ionic gelation, stabilizing, cross-linking, capping and encapsulation of drugs. Finally, we conclude with the future scope and advanced applications of sulfated polysaccharides in various fields of interdisciplinary science.From the Clinical EditorThis comprehensive review focuses on the structure, function, and applications of natural and chemically derived sulfated polysaccharides in the fields of nanotechnology and biomedical sciences.     

光响应生物材料研究进展及应用

目的：对光响应生物材料在药物控制系统及组织工程支架方面的研究及应用进行综述,为推进基础研究成果走向临床转化提供参考。方法：通过文献研究,归纳光响应生物材料的分类及光化学反应机理,讨论其在药物控制系统及组织工程支架领域中的应用,探讨其在临床转化中面临的挑战,并对未来发展方向进行展望。结果与结论：由于光源具有很多优点,使得光响应生物材料在药物控释系统、生物传感器、荧光探针及组织工程支架等生物医药领域得到广泛的关注。尽管近年来光响应生物材料基础理论研究已经取得巨大进展,但是在临床转化中仍存在激发光源和生物相容性等问题。未来新材料研发上如果能有创新,例如制备出对近红外光响应的生物材料或者兼具对多种刺激如光、pH、酶等有响应的生物材料,将会给光响应生物材料在医疗领域应用带来更大希望。     

海洋生物医用材料的临床应用和安全性评价

目的： 对海洋生物医用材料在医疗领域的应用情况和海洋生物材料来源医疗器械的安全性评价趋势进行分析，为推进该材料的临床转化提供参考。方法： 归纳海洋生物医用材料的分类和应用，介绍该材料的安全性评价的程序要点，探讨其安全性评价中面临的挑战。结果与结论： 常用的海洋生物医用材料主要为多糖和蛋白质，在创伤修复和组织工程领域应用广泛。海洋生物医用材料具有生物活性和良好的生物相容性，对此类材料的安全性评价应根据材料特性和预期用途，科学制定评价程序和选择检验方法。     

Growth factor release from tissue engineering scaffolds.

Synthetic scaffold materials are used in tissue engineering for a variety of applications, including physical supports for the creation of functional tissues, protective gels to aid in wound healing and to encapsulate cells for localized hormone-delivery therapies. In order to encourage successful tissue growth, these scaffold materials must incorporate vital growth factors that are released to control their development. A major challenge lies in the requirement for these growth factor delivery mechanisms to mimic the in-vivo release profiles of factors produced during natural tissue morphogenesis or repair. This review highlights some of the major strategies for creating scaffold constructs reported thus far, along with the approaches taken to incorporate growth factors within the materials and the benefits of combining tissue engineering and drug delivery expertise.     

Hydrogels for pharmaceutical and biomedical applications

Hydrogels are crosslinked hydrophilic polymer structures that can imbibe large amounts of water or biological fluids. Hydrogels are one of the upcoming classes of polymer-based systems that embrace numerous biomedical and pharmaceutical applications. This review discusses various parameters of hydrogels such as surface properties, water content and swelling behavior, effect of nature of polymer, ionic content, and thermodynamics, all of which can influence the biomedical usage of hydrogels. Meanwhile, intelligent or environment-sensitive hydrogels and bioadhesive hydrogels continue to be important materials for medical applications; therefore, a part of this review is devoted to some of their important classes. Hydrogels are extensively used for various biomedical applications--tissue engineering, molecular imprinting, wound dressings materials, immunoisolation, drug delivery, etc. Thus, this review aims to throw light on the numerous applications that hydrogels have in the biomedical arena.     

Surface-functionalized electrospun nanofibers for tissue engineering and drug delivery

Electrospun nanofibers with a high surface area to volume ratio have received much attention because of their potential applications for biomedical devices, tissue engineering scaffolds, and drug delivery carriers. In order to develop electrospun nanofibers as useful nanobiomaterials, surfaces of electrospun nanofibers have been chemically functionalized for achieving sustained delivery through physical adsorption of diverse bioactive molecules. Surface modification of nanofibers includes plasma treatment, wet chemical method, surface graft polymerization, and co-electrospinning of surface active agents and polymers. A variety of bioactive molecules including anti-cancer drugs, enzymes, cytokines, and polysaccharides were entrapped within the interior or physically immobilized on the surface for controlled drug delivery. Surfaces of electrospun nanofibers were also chemically modified with immobilizing cell specific bioactive ligands to enhance cell adhesion, proliferation, and differentiation by mimicking morphology and biological functions of extracellular matrix. This review summarizes surface modification strategies of electrospun polymeric nanofibers for controlled drug delivery and tissue engineering.     

Controlled local drug delivery strategies from chitosan hydrogels for wound healing

Introduction: The main target of tissue engineering is the preparation and application of adequate materials for the design and production of scaffolds, that possess properties promoting cell adhesion, proliferation and differentiation. The use of natural polysaccharides, such as chitosan, to prepare hydrogels for wound healing and controlled drug delivery is a research topic of wide and increasing interest.

Areas covered: This review presents the latest results and challenges in the preparation of chitosan and chitosan-based scaffold/hydrogel for wound healing applications. A detailed overview of their behavior in terms of controlled drug delivery, divided by drug categories, and efficacy was provided and critically discussed.

Expert opinion: The need to establish and exploit the advantages of natural biomaterials in combination with active compounds is playing a pivotal role in the regenerative medicine fields. The challenges posed by the many variables affecting tissue repair and regeneration need to be standardized and adhere to recognized guidelines to improve the quality of evidence in the wound healing process. Currently, different methodologies are followed to prepare innovative scaffold formulations and structures. Innovative technologies such as 3D printing or bio-electrospray are promising to create chitosan-based scaffolds with finely controlled structures with customizable shape porosity and thickness. Chitosan scaffolds could be designed in combination with a variety of polysaccharides or active compounds with selected and reproducible spacial distribution, providing active wound dressing with highly tunable controlled drug delivery.     

Cyclodextrin-based supramolecular systems for drug delivery: Recent progress and future perspective

The excellent biocompatibility and unique inclusion capability as well as powerful functionalization capacity of cyclodextrins and their derivatives make them especially attractive for engineering novel functional materials for biomedical applications. There has been increasing interest recently to fabricate supramolecular systems for drug and gene delivery based on cyclodextrin materials. This review focuses on state of the art and recent advances in the construction of cyclodextrin-based assemblies and their applications for controlled drug delivery. First, we introduce cyclodextrin materials utilized for self-assembly. The fabrication technologies of supramolecular systems including nanoplatforms and hydrogels as well as their applications in nanomedicine and pharmaceutical sciences are then highlighted. At the end, the future directions of this field are discussed.     

自组装多肽在生物医药领域的研究进展

自组装多肽通过分子间非共价键作用力自组装成各种高度有序的纳米结构，表现出有别于单个小分子或小分子聚集体的独特性能，具有优良的生物相容性和生物降解性，在生物医药领域具有广泛的应用前景。本综述介绍了自组装多肽的概念、设计原则、分析方法，重点对其在药物递送、生物医学检测、组织工程、疫苗工程等方面的研究进行总结及展望。     

Functional electrospun nanofibrous scaffolds for biomedical applications

Functional nanofibrous scaffolds produced by electrospinning have great potential in many biomedical applications, such as tissue engineering, wound dressing, enzyme immobilization and drug (gene) delivery. For a specific successful application, the chemical, physical and biological properties of electrospun scaffolds should be adjusted to match the environment by using a combination of multi-component compositions and fabrication techniques where electrospinning has often become a pivotal tool. The property of the nanofibrous scaffold can be further improved with innovative development in electrospinning processes, such as two-component electrospinning and in-situ mixing electrospinning. Post modifications of electrospun membranes also provide effective means to render the electrospun scaffolds with controlled anisotropy and porosity. In this article, we review the materials, techniques and post modification methods to functionalize electrospun nanofibrous scaffolds suitable for biomedical applications.     

Biodegradable ‘intelligent’ materials in response to physical stimuli for biomedical applications

Background: Stimuli-responsive materials that undergo dramatic changes in physical–chemical properties in response to mild physical changes in environmental conditions are attracting increasing interest because of their potential application in biomedical fields. Biodegradable materials are highly desired for most biomedical applications in vivo, such as transient implants, drug-delivery carriers, and tissue engineering scaffolds. Biomedical systems that are both biodegradable and stimuli-responsive have therefore been studied intensively and significant progress in this field has been achieved. Objective/methods: This review summarizes the development of biodegradable ‘intelligent’ materials in response to physical stimuli and their potential biomedical applications. A detailed analysis of publications and patents on such materials in recent years is presented. Results/conclusion: Although biodegradable stimuli-responsive materials are highly attractive for biomedical applications, most such materials are currently at a developmental research stage. Additionally, single stimulus-responsive property limits the practical applications of these materials. To achieve more favorable applications for these materials, further efforts are still necessary, especially for developing multi-stimuli-responsive functions of materials and improving the stimuli-responsive properties of such materials in a biological environment. Bearing in mind the great prospect of these biodegradable stimuli-responsive materials, we hope that this review will help in the future development of stimuli-responsive polymers or systems that could be reliably employed in biomedical applications.     

Recent advances in the role of supramolecular hydrogels in drug delivery

Introduction: Supramolecular hydrogels, formed by noncovalent crosslinking of polymeric chains in water, constitute an interesting class of materials that can be developed specifically for drug delivery and biomedical applications. The biocompatibility, stimuli responsiveness to various external factors, and powerful functionalization capacity of these polymeric networks make them attractive candidates for novel advanced dosage form design.

Areas covered: This review summarizes the significance of supramolecular hydrogels in various biomedical and drug delivery applications. The recent advancement of these hydrogels as potential advanced drug delivery systems (for gene, protein, anticancer and other drugs) is discussed. The importance of these hydrogels in biomedical applications, particularly in tissue engineering, biosensing, cell-culture research and wound treatment is briefly described.

Expert opinion: The use of supramolecular hydrogels in drug delivery is still in very early stages. However, the potential of such a system is undeniably important and very promising. A number of recent studies have been conducted, which mainly focus on the use of cyclodextrin-based host–guest complex as well as other supramolecular motifs to form supramolecular hydrogels for delivery of various classes of drugs, therapeutic agents, proteins and genes. However, there are still plenty of opportunities for further development in this area for drug delivery and other biomedical applications.     

海洋来源的可生物降解材料

摘要:近年来,可生物降解材料在生物医学领域的研究取得了突破进展。来源于海洋的可生物降解材料有很好的生物相容性和多样的生物活性,可作为药物的缓控释载体,在组织工程学中可以作为组织替代物和多孔支架,应用十分广泛。本文着重介绍了多糖和蛋白质两大类海洋来源可生物降解材料的物理、化学、生物特性和降解性能,总结了它们在生物医学领域的应用。     

Marine polysaccharides: therapeutic efficacy and biomedical applications

The ocean contains numerous marine organisms, including algae, animals, and plants, from which diverse marine polysaccharides with useful physicochemical and biological properties can be extracted. In particular, fucoidan, carrageenan, alginate, and chitosan have been extensively investigated in pharmaceutical and biomedical fields owing to their desirable characteristics, such as biocompatibility, biodegradability, and bioactivity. Various therapeutic efficacies of marine polysaccharides have been elucidated, including the inhibition of cancer, inflammation, and viral infection. The therapeutic activities of these polysaccharides have been demonstrated in various settings, from in vitro laboratory-scale experiments to clinical trials. In addition, marine polysaccharides have been exploited for tissue engineering, the immobilization of biomolecules, and stent coating. Their ability to detect and respond to external stimuli, such as pH, temperature, and electric fields, has enabled their use in the design of novel drug delivery systems. Thus, along with the promising characteristics of marine polysaccharides, this review will comprehensively detail their various therapeutic, biomedical, and miscellaneous applications.     

基于海洋多糖水凝胶的组织工程材料研究应用进展

海洋天然多糖以其优异的生物相容性、生物可降解性、安全性以及特定的生物活性,成为生物医用材料研究的热点领域之一.近年来,基于海洋来源的糖类生物大分子开发的新型水凝胶在组织工程领域得到了广泛应用.本文综述了基于海藻酸盐、壳聚糖、透明质酸、卡拉胶和岩藻聚糖硫酸酯研发的功能性水凝胶,评述了这些水凝胶的设计思路、制备方法、理化性...     

Biomedical potential of clay nanotube formulations and their toxicity assessment

ABSTRACT

Introduction: Halloysite clay nanotubes (HNTs) are a naturally abundant and biocompatible aluminosilicate material with a structure able to encapsulate 10–20% of drugs. These features are attractive toward the clinical application in controlled drug delivery, tissue engineering and regenerative medicine.

Areas covered: We describe the application of HNTs as a viable method for clinical purposes, particularly developing formulations for prophylaxis, diagnosis and therapeutics, having a special attention to these nanotubes bio-safety. HNTs may be used for pharmaceuticals, biopharmaceuticals, wound healing, bone regeneration, dental repair, hair surface engineering and biomimetic applications.

Expert opinion: HNTs are a versatile, safe and biocompatible nanomaterial used for drug encapsulation for numerous clinical applications. The studies here reviewed confirm the HNTs biocompatibility, describing their low toxicity. Further developments will be made regarding the long-term efficacy of halloysite-based treatments in humans, concentrating mostly on topical applications.     

Poly(lactic acid)-poly(ethylene oxide) block copolymers: new directions in self-assembly and biomedical applications

In this review, we focus on recent developments in biomaterials of poly(lactic acid)-poly(ethylene oxide)-poly(lactic acid) (PLA-PEO-PLA) triblock copolymers. This system has been widely explored for a number of applications in controlled and sustained release of drugs and in tissue engineering devices. New insights into self-assembly of these materials have resulted in new PLA-PEOPLA solutions and gels with novel structural, mechanical, and drug release properties. Recent innovations include hydrogels with nanoscale crystalline domains, solutions and gels based on PLA stereocomplexes, and nanoparticle-copolymer assemblies. We first briefly review synthetic approaches to these materials. We then describe characterization of the solution properties, formation of micelles, drug release characteristics, and investigation of the sol-gel transition. The properties of PLA-PEO-PLA hydrogels are then discussed, including the effect of crystalline domains on the gel microstructure and efforts to tune the elastic modulus and degredation properties of gels through the addition of chemical crosslinks. In the second half of the review, we discuss the wide variety of biomedical applications currently being pursued for PLA-PEO-PLA triblock copolymer systems. Polymer-nanoparticle complexes have been investigated to facilitate the formation of metal nanoclusters used as biosensors, as well as to enhance the elastic modulus of hydrogels. Thin polymer films have also been investigated for use as tissue engineering scaffolds and as drug-eluding coatings for stents and other medical implants. Finally, we discuss future directions for biomedical applications of this system, including new strategies for improving the specificity and cell affinity of PLA-based biomaterials.