Stimuli‐Responsive Supramolecular Hydrogels and Their Applications in Regenerative Medicine

Supramolecular hydrogels are a class of self‐assembled network structures formed via non‐covalent interactions of the hydrogelators. These hydrogels capable of responding to external stimuli are considered to be smart materials due to their ability to undergo sol–gel and/or gel–sol transition upon subtle changes in their surroundings. Such stimuli‐responsive hydrogels are intriguing biomaterials with applications in tissue engineering, delivery of cells and drugs, modulating tissue environment to promote innate tissue repair, and imaging for medical diagnostics among others. This review summarizes the recent developments in stimuli‐responsive supramolecular hydrogels and their potential applications in regenerative medicine. Specifically, various structural aspects of supramolecular hydrogelators involved in self‐assembly, the role of external stimuli in tuning/controlling their phase transitions, and how these functions could be harnessed to advance applications in regenerative medicine are focused on. Finally, the key challenges and future prospects for these versatile materials are briefly described.     

Biodendrimers: new polymeric biomaterials for tissue engineering

Dendrimers composed entirely of building blocks known to be biocompatible or degradable in vivo to natural metabolites were synthesized using a high yield divergent approach. This synthesis is amenable to the design and development of new biomaterials that are of interest for a variety of medical applications, including tissue engineering. In a novel application, photocross-linkable dendrimers are used to seal large corneal lacerations.     

Tunable bifunctional silyl ether cross-linkers for the design of acid-sensitive biomaterials

Responsive polymeric biomaterials can be triggered to degrade using localized environments found in vivo. A limited number of biomaterials provide precise control over the rate of degradation and the release rate of entrapped cargo and yield a material that is intrinsically nontoxic. In this work, we designed nontoxic acid-sensitive biomaterials based on silyl ether chemistry. A host of silyl ether cross-linkers were synthesized and molded into relevant medical devices, including Trojan horse particles, sutures, and stents. The resulting devices were engineered to degrade under acidic conditions known to exist in tumor tissue, inflammatory tissue, and diseased cells. The implementation of silyl ether chemistry gave precise control over the rate of degradation and afforded devices that could degrade over the course of hours, days, weeks, or months, depending upon the steric bulk around the silicon atom. These novel materials could be useful for numerous biomedical applications, including drug delivery, tissue repair, and general surgery.     

生物大分子自组装膜及其应用研究进展

本文主要介绍了酶，蛋白质、DNA等生物大分子自组装膜的研究进展，并对生物大分子膜在生物传感器，分子器件，高效催化材料，医用生物材料等方面的应用前景进行了展望。     

Complicity of degradable polymers in health-care applications

Polymeric biomaterials have revolutionized biomedical technology and related fields as biomaterials for health-care applications. Recent trend in polymeric medical technology has adapted a tendency to substitute degradable polymers instead of non-degradable synthetic polymers for the advancement of various health-care modalities. They have got considerable attention for their potential in various interdisciplinary arenas, which implies tissue engineering scaffolds, sustainable drug release, delivery agents, regenerative medicine, and development of life-saving devices, implants, dental products as well as in food technology. Various types of degradable polymers are been developed to date having stringent features applicable for various aspects in modern science. Thus, being the most renovative field of biomedicine and biomedical technology degradable polymers has gained substantial acceptance and appreciation recent times. This review critically underlines various degradative polymers and their subtypes, potential applications, types of degradation, and their possible effects in the biological system. Assessment of possible toxicological risks behind is an important criterion to be focused before validating any biomaterial safe for biomedical applications. Therefore various toxicological assessment strategies and their impact in biomedicine and technology were also included. In addition, the risk versus benefit assessment is also critically summarized.     

Hydroxyapatite/polyurethane composites as promising biomaterials

The biomaterials are intended to augment or replace the function of tissues or organs in human body. Every year millions of people require soft- or hard-tissue regeneration worldwide. Polymers and their composites are a large class of biomaterials appreciated for tissue regeneration. Polyurethane (PUR) is an organic synthetic multifunctional polymer with established biomedical applications. The hydroxyapatite (HA) is one of the biocompatible ceramic materials similar to natural bone material. The amalgamation of hydroxyapatite with polyurethane enhances the bioactivity of final product along with the combination of individual properties. Here, we review the synthesis, characterization, and applications studies of HA/PUR-based biomaterials. We initiate this review with a brief and representative compilation of the chemical composition and methods of preparation for HA/PUR biomaterials. Then, moving ahead, first, we review the simple HA/PUR biomaterials and use of PUR templates. Second, we review the significance of modified HA and PUR in these biomaterials. Third, we discuss the potential of bio-based PUR and inclusion of third constituent in the HA/PUR biomaterials. Then, we appraise the involvement of trace nutrient in deposition of HA on PUR scaffolds. Finally, we consider the other expedient applications of HA/PUR composites such as drug delivery system and sorbent of pollutants.     

Properties and applications of proteins encapsulated within sol-gel derived materials

The last decade has seen a revolution in the area of sol-gel-derived materials since the demonstration that these materials can be used to encapsulate biological species such as enzymes, antibodies and other proteins in a functional state. The interactions between the biomolecule and the inorganic, organic or hybrid nanocomposite material determines the degree to which the biomolecule retains its native properties, and such interactions can be tuned to provide optimised biomaterials that are suitable for a variety of applications. Typical applications of sol-gel derived biomaterials include selective coatings for optical and electrochemical biosensors, stationary phases for affinity chromatography, immunoadsorbent and solid-phase extraction materials, controlled release agents, solid-phase biosynthesis, and unique matrices for biophysical studies. Through careful selection of precursors and additives, these materials can be designed for specific applications, and can produce useful, robust devices with good analytical parameters of merit. Indeed, current advances in the development of nanocomposite and mesostructured materials suggest that major improvements in bioimmobilisation are on the horizon, and should result in substantial improvements in bioanalytical devices over the next decade.     

Application of polymeric nanofibers in soft tissues regeneration

Nanotechnology has wide applications in many fields, especially in the biological sciences and medicine. Nanomaterials are applied as potential materials for treatment and diagnosis. The development of nanofibers has greatly enhanced the scope for fabricating designs that can potentially be used in medical sciences. The application of polymeric nanofibers in biomaterials sciences and tissue engineering review in fields of skin and eye, neural and cardiovascular tissues, and urological tissues. Copyright © 2016 John Wiley & Sons, Ltd.     

The rheological and structural properties of Fmoc-peptide-based hydrogels: the effect of aromatic molecular architecture on self-assembly and physical characteristics

Biocompatible hydrogels are of high interest as a class of biomaterials for tissue engineering, regenerative medicine, and controlled drug delivery. These materials offer three-dimensional scaffolds to support the growth of cells and development of hierarchical tissue structures. Fmoc-peptides were previously demonstrated as attractive building blocks for biocompatible hydrogels. Here, we further investigate the biophysical properties of Fmoc-peptide-based hydrogels for medical applications. We describe the structural and thermal properties of these Fmoc-peptides, as well as their self-assembly process. Additionally, we study the role of interactions between aromatic moieties in the self-assembly process and on the physical and structural properties of the hydrogels.     

On improving blood compatibility: from bioinspired to synthetic design and fabrication of biointerfacial topography at micro/nano scales

Blood compatibility plays an important role in the successful implantation of biomaterials and biodevices such as artificial blood vessels, pace makers, and stents. Developing better blood compatible biomaterials is of great significance in both material and medical sciences. Traditional methods to improve the blood compatibility include minimization of blood/material interactions, chemical modification of drugs on material surfaces and vascular endothelial cell seeding, which still do not meet the requirements of practical applications. In this article we propose a bioinspired strategy to mimic the multiscale micro/nano structures on the inner surface of natural blood vessels, and review recent progress on the design and fabrication of micro/nano scale topography at biointerfaces to improve blood compatibility.     

Selecting polymers for medical devices based on thermal analytical methods

This biomaterials overview for selecting polymers for medical devices focuses on polymer materials, properties and performance. An improved understanding of thermoplastics and thermoset properties is accomplished by thermal analysis for device applications. The medical applications and requirements as well as the oxidative and mechanical stability of currently used polymers in devices are discussed. The tools used to aid the ranking of the thermoplastics and thermosets are differential scanning calorimetry (DSC), thermogravimetry (TG), thermal mechanical analysis (TMA) and dynamic mechanical analysis (DMA) as well as a number of key ASTM polymer tests. This paper will spotlight the thermal and mechanical characterization of the bio-compatible polymers e.g., olefins, nylon, polyacetals, polyvinyl chloride and polyesters.     

Collagen-based biomaterials for ibuprofen delivery

Drug delivery systems based on collagen sponges have increasingly become interesting materials for different medical applications. In this paper we present the obtaining, characterization and in vitro release of ibuprofen from collagen-based biomaterials in the form of sponges. The structural and morphological characteristics of these materials were investigated by infrared spectroscopy (FT-IR) and water uptake tests. Collagenase degradation, anti-inflammatory drug release and the kinetic mechanism are also discussed. The results obtained suggest that these new systems based on collagen have good potential for sustained release of analgesic and anti-inflammatory agents such as ibuprofen and the combination of collagen and ibuprofen as a sponge is a promising therapeutic method for the treatment of dental problems.     

高分子在生物工程中的应用进展

在生物工程中所用的高分子材料一般统称为高分子生物材料,其涉及的范围很广。医用高分子是其中很重要的一类,另一类就是在生物技术中所用的高分子材料。对于高分子生物材料可根据其材料性质进行分类,也可按使用范围进行分类。如体内应用的材料,半体内应用的材料和体外应用的材料。本文着重介绍了抗凝血材料、药用高分子材料及应用于生物技术中高分子材料的研究进展,并总结分析了这几个研究领域中的发展趋势。     

Application of carbon fibers to biomaterials: a new era of nano-level control of carbon fibers after 30-years of development

Carbon fibers are state-of-the-art materials with properties that include being light weight, high strength, and chemically stable, and are applied in various fields including aeronautical science and space science. Investigation of applications of carbon fibers to biomaterials was started 30 or more years ago, and various products have been developed. Because the latest technological progress has realized nano-level control of carbon fibers, applications to biomaterials have also progressed to the age of nano-size. Carbon fibers with diameters in the nano-scale (carbon nanofibers) dramatically improve the functions of conventional biomaterials and make the development of new composite materials possible. Carbon nanofibers also open possibilities for new applications in regenerative medicine and cancer treatment. The first three-dimensional constructions with carbon nanofibers have been realized, and it has been found that the materials could be used as excellent scaffolding for bone tissue regeneration. In this critical review, we summarize the history of carbon fiber application to the biomaterials and describe future perspectives in the new age of nano-level control of carbon fibers (122 references).     

Customized PEG-derived copolymers for tissue-engineering applications

PEG-containing copolymers play a prominent role as biomaterials for different applications ranging from drug delivery to tissue engineering. These custom-designed materials offer enormous possibilities to change the overall characteristics of biomaterials by improving their biocompatibility and solubility, as well as their ability to crystallize in polymer blends and to resist protein adsorption. This article demonstrates various principles of PEG-based material design that are applied to fine tune the properties of biomaterials for different tissue engineering applications. More specifically, strategies are described to develop PEG copolymers with various block compositions and specific bulk properties, including low melting points and improved surface hydrophilicity. Highly hydrated polymer gel networks for promoting cellular growth or suppressing protein adsorption and cell adhesion are introduced. By incorporating selectively cleavable cross-links, these hydrophilic polymers can also serve as smart hydrogel scaffolds, mimicking the natural extracellular matrix for cell cultivation and tissue growth. Ultimately, these developments lead to the creation of biomimetic materials to immobilize bioactive compounds, allowing precise control of cellular adhesion and tissue growth. [image: see text]     

Preparation of new biomedical materials and their application in clinics

Biomaterials – tissues interaction is important to study in biomaterials science. The information is indispensable to make medical devises and artificial organs and to predict their performance. It is also very useful to consider a hypothesis to design new biomaterials. New materials have brought big progress in the society as we know. There are few biomaterials specially designed to use in biomedical fields. The most important effort must be preparation of biocompatible materials, that must be essential to develop new type high performance devices and artificial organs. Preparation of new dental biomaterials used in bonding of prostheses to dentinal tissues that require fundamental change in modern dentistry and a new methacrylate, MPC, to develop promising several kinds of biomaterials with unusually excellent biocompatibility and functions are going to present. Topics in tissue engineering are also discussed.     

Protein and Polysaccharide-Based Electroactive and Conductive Materials for Biomedical Applications

Electrically responsive biomaterials are an important and emerging technology in the fields of biomedical and material sciences. A great deal of research explores the integral role of electrical conduction in normal and diseased cell biology, and material scientists are focusing an even greater amount of attention on natural and hybrid materials as sources of biomaterials which can mimic the properties of cells. This review establishes a summary of those efforts for the latter group, detailing the current materials, theories, methods, and applications of electrically conductive biomaterials fabricated from protein polymers and polysaccharides. These materials can be used to improve human life through novel drug delivery, tissue regeneration, and biosensing technologies. The immediate goal of this review is to establish fabrication methods for protein and polysaccharide-based materials that are biocompatible and feature modular electrical properties. Ideally, these materials will be inexpensive to make with salable production strategies, in addition to being both renewable and biocompatible.     

生物医用类环糊精/聚合物(准)聚轮烷

环糊精及其衍生物具有“内疏水、外亲水”的特殊分子结构,可与许多客体分子包结形成包合物。利用环糊精与聚合物的包结作用构建稳定、结构可控并具有广泛应用前景的生物医用材料是材料及医学界研究的焦点之一。本文介绍了环糊精基(准)聚轮烷的概念及其组装驱动力,同时围绕由环糊精和聚合物组装形成的(准)聚轮烷在生物医用方面的研究包括药物载体(如超分子凝胶、超分子胶束、超分子纳米囊泡、药物键合(准)聚轮烷、刺激响应型(准)聚轮烷等)、基因载体、多重识别与靶向、形状记忆材料及其它相关领域工作进展作一概述。     

Cold Plasma Systems and Their Application in Surface Treatments for Medicine

In this paper, a review of cold plasma setups and the physical and chemical processes leading to the generation of active species is presented. The emphasis is given to the interaction of cold plasmas with materials used in medical applications, especially medical implants as well as live cells. An overview of the different kinds of plasmas and techniques used for generation of active species, which significantly alter the surface properties of biomaterials is presented. The elemental processes responsible for the observed changes in the physio-chemical properties of surfaces when exposed to plasma are described. Examples of ongoing research in the field are given to illustrate the state-of-the-art at the more conceptual level.     

Biomaterial-induced macrophage polarization for bone regeneration

As the main target cells of immune regulation, macrophages play an important role in the bone regeneration process. Macrophages can be polarized into the M1 and M2 types under the stimulation of different factors. They have proinflammatory and anti-inflammatory effects, respectively, and play key roles in different stages of bone regeneration. The ratio of M1 to M2 macrophages can be regulated by immunomodulatory biomaterials to promote bone repair and regeneration. In this paper, we review the recent literature on the chemical, physical and biological properties of biomaterials and the regulation of macrophage polarization under the influence of other factors. We also cover new methods for preparing immunomodulatory biomaterials for bone regeneration. This paper will provide new design ideas for the development of biomaterials with immunological properties and will support the clinical translation of bone-related medical biomaterials.