聚乳酸在生物医药领域的改性研究进展

聚乳酸类材料是一种用途广泛的生物降解高分子材料,已经成为生物医用材料中最受重视的材料之一。但由于聚乳酸本身的缺陷,限制了其在生物医学工程中的应用。对聚乳酸的改性工作就一直备受关注。本文综述了近几年聚乳酸生物降解材料的物理改性和化学改性研究进展,经改性后聚乳酸的力学性能、降解性能、亲水性能和生物活性得到有效改善,从而更好地满足了生物医用需要。     

医用可生物降解高分子材料

对目前医用可生物降解高分子材料的研究及应用状况分化学合成，天然和生物技术合成三类作了综述。对材料的生物相容性、可生物降解性及物理机械性能进行了分析和比较。并就医用生物降解高分子材料的发展趋势作了预测。     

生物大分子层层组装:从生物分子的固定,界面控释到细胞外基质模拟

随着超分子科学、界面科学方法技术与生物医用材料科学的交叉与渗透,生物大分子层层组装已成为生物医用材料界面设计和制备的重要方法.本论文从采用生物大分子层层组装进行生物活性分子固定、界面控释涂层构建到细胞外基质结构功能模拟3个相互关联的研究视角,结合该领域国内外和本课题组的研究成果,对该领域的研究进展进行了综述,并对生物大分子层层组装作为一种生物医用材料界面设计制备新方法的未来进行了展望.     

新型官能团化聚己内酯的研究进展

聚己内酯(PCL)是一种具有良好药物透过性的可生物降解的脂肪族聚酯,是一类优良的药物载体.由于其结晶性强,亲水性差,生物降解速度慢,限制了其在组织工程等生物医用领域更广泛的临床应用.在PCL主链上引入功能性官能团既可有效地降低其结晶性、改善其亲水性、调控其降解速率,同时又可通过反应性官能团进行进一步的化学改性或生物活性化修饰,已成为生物可降解材料新的研究热点.本文综述了含侧基官能团己内酯单体的合成及其聚合反应,简要介绍了侧基官能团对聚己内酯性能的影响.     

端氨基聚乙二醇-聚已内酯二嵌段共聚物的合成及其微球表面氨基和形态的调控

生物降解高分子作为一种重要的生物材料已经发展到第3代[1],实际应用的复杂性不仅要求高分子材料本身具有合适的降解性能、热性能、力学性能和加工性能等,而且还要求高分子材料具有能够刺激细胞生长、识别特定细胞等生物活性特征.高分子材料的这些生物活性主要是通过高分子材料     

脂肪族聚酯类可生物降解医用高分子材料的研究进展

脂肪族聚脂是一类重要的合成医用高分子材料,具有良好的生物相容性及生物可降解性。本文在介绍了几种研究较为成熟的聚酯类医用材料的基础上,着重综述了它们的设计、合成及其在生物医学领域中应用的研究进展,并展望了可生物降解医用高分子材料的发展趋势。     

可生物降解交联聚合物的研究进展

交联聚合物具有稳定的三维网络结构,可以提高药物缓释载体的尺寸稳定性。本文综述了可生物降解交联聚合物的研究进展,主要介绍了可生物降解交联聚合物的制备方法,包括交联剂交联、辐照交联、光致交联以及过氧化物交联在制备可生物降解交联聚合物中的应用,详细介绍了交联剂的种类及结构对交联效果的影响、交联后聚合物性能的变化等。最后总结了可生物降解交联聚合物在组织工程支架、药物缓释材料、神经再生修复材料以及形状记忆材料等生物医用领域的应用。     

硫酸软骨素类可注射水凝胶体系及其凝胶化机制

硫酸软骨素是一种硫酸化糖胺聚糖类天然多糖,广泛分布于动物组织的细胞外基质和细胞表面,具有促进软骨生长、调控生长因子、加快伤口愈合等多种生物功能。近年来,基于硫酸软骨素良好的生物活性、生物相容性和生物降解性,硫酸软骨素类可注射水凝胶作为一种新型生物材料受到了广泛关注,尤其是在组织工程、药物输送和细胞治疗等生物医用领域的应用已有较多研究。侧重综述了国内外发展的基于硫酸软骨素的可注射水凝胶的凝胶化体系、凝胶化机制和凝胶改性方法。重点介绍了基于物理热诱导的凝胶化,以及通过形成席夫碱反应、点击化学反应、形成酰胺键和光交联等化学交联、以及酶交联等形成三维网络结构的方式,并综述了调控体系凝胶化时间、力学性能和组织黏附性的方法。最后对硫酸软骨素可注射水凝胶作为新型生物材料的发展方向进行了展望。     

聚磷酸酯医用材料

聚磷酸酯是一种生物相容性好、结构较易进行修饰和功能化的生物降解高分子，可以应用于药物缓释材料、组织工程材料、动物体内显影剂等医用领域。本文论述了近年来的聚磷酸酯医用材料的研究进展，尤其是作为药物缓释材料的合成与应用情况。随着合成研究的深入，聚磷酸酯在医用材料方面的应用将更加引人注目。     

侧链含羟基聚(D,L-丙交酯-co-碳酸酯)的合成与表征

聚乳酸(PLA)具有良好的生物相容性及可生物降解性,是适用于组织工程及药物释放系统的聚酯材料,一直是生物医用材料领域中研究的热点之一[1,2].但由于这类聚酯材料是疏水性的,因而存在多肽、蛋白质药物包覆量太低,控释系统制备过程及存放过程中易于失活及药物释放过程难于控制等     

The in-vitro biocompatibility of ureido-pyrimidinone compounds and polymer degradation products

Supramolecular biomaterials based on ureido-pyrimidinone (UPy) moieties are versatile polymer materials as their function can be tailored to the application. These UPy-materials can be designed into polymer coatings, self-healing polymers, hydrogels and elastomers. The biocompatibility of UPy-based materials and their degradation products is a long-term success requirement for many regenerative medicine and biomedical applications. Earlier research has shown that UPy-based materials and polymers display no immediate toxic effects, but in-depth in-vitro studies on potential UPy-polymer degradation products have not been executed. Owing to their resemblance to naturally occurring purines and pyrimidines, UPy-compounds and their degradation products could potentially initiate an immune response or be mutagenic. Accordingly, 11 selected UPy-compounds were synthesized, and their effect on cell viability, wound healing, and their immunogenicity and potential mutagenic potential, were studied. We showed that low molecular weight degradation products of UPy-based biomaterials do not affect cell viability, nor do these interfere with several aspects of endothelial function including proliferation, angiogenic sprouting and cellular migration even in levels exceeding plausibly attainable concentrations. Furthermore, the compounds are neither immunogenic nor mutagenic, showing that UPy-biomaterials exhibit good biocompatibility in vitro, and could in principle be used in humans.     

Self‐Assembled Gels for Biomedical Applications

Natural and synthetic gel‐like materials have featured heavily in the development of biomaterials for wound healing and other tissue‐engineering purposes. More recently, molecular gels have been designed and tailored for the same purpose. When mixed with, or conjugated to therapeutic drugs or bioactive molecules, these materials hold great promise for treating/curing life‐threatening and degenerative diseases, such as cancer, osteoarthritis, and neural injuries. This focus review explores the latest advances in this field and concentrates on self‐assembled gels formed under aqueous conditions (i.e., self‐assembled hydrogels), and critically compares their performance within different biomedical applications, including three‐dimensional cell‐culture studies, drug delivery, and tissue engineering. Although stability and toxicity issues still need to be addressed in more detail, it is clear from the work reviewed here that self‐assembled gels have a bright future as novel biomaterials.     

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]     

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.     

组织工程相关生物材料表面工程的研究进展

生物材料用作人工细胞外基质(ECM ) 在组织工程中占据重要位置。本文在分析细胞2生物材料表面相互作用的基础上, 从生物材料中的水、材料表面的形态、材料表面的特异性识别及生物材料诱发愈合等方面探讨了生物材料的复杂性。生物材料对细胞的影响是一个双向、动态过程, 起着调节细胞增殖和凋亡平衡的作用。基于生物材料对细胞生长的影响, 本文提出了生物材料表面生物仿生化以提高细胞亲和力,糖链团簇、糖脂质及材料表面蛋白质修饰以提高细胞特异性识别, 材料表面的自组装修饰以改善表面形态等观点。     

生物可降解及生物材料的电场纺丝及应用

电场纺丝是制备生物可降解及生物材料纳米纤维非织造布的简单工艺,由于纳米纤维具有较大的比表面积,具有多孔结构,使其在生物医学领域,如：组织工程、药物缓释及医用纱布等领域有潜在的应用前景。本文综述了生物降解材料及生物材料的电场纺丝及其应用。     

Effectiveness of cell adhesive additives in different supramolecular polymers

Supramolecular motifs in elastomeric biomaterials facilitate the modular incorporation of additives with corresponding motifs. The influence of the elastomeric supramolecular base polymer on the presentation of additives has been sparsely examined, limiting the knowledge of transferability of effective functionalization between polymers. Here it was investigated if the polymer backbone and the additive influence biomaterial modification in two different types of hydrogen bonding supramolecular systems, that is, based on ureido-pyrimidinone or bis-urea units. Two different cell-adhesive additives, that is, catechol or cyclic RGD, were incorporated into different elastomeric polymers, that is, polycaprolactone, priplast or polycarbonate. The additive effectiveness was evaluated with three different cell types. AFM measurements showed modest alterations on nano-scale assembly in ureido-pyrimidinone materials modified with additives. On the contrary, additive addition was highly intrusive in bis-urea materials. Detailed cell adhesive studies revealed additive effectiveness varied between base polymers and the supramolecular platform, with bis-urea materials more potently affecting cell behavior. This research highlights that additive transposition might not always be as evident. Therefore, additive effectiveness requires re-evaluation in supramolecular biomaterials when altering the polymer backbone to suit the biomaterial application.     

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.     

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.     

Control of the Structure and Functions of Biomaterials by Light

Vision and other light-triggered biochemical transformations in plants and living organisms represent a sophisticated biological processes in which optical signals are recorded and transduced as (physico)chemical events. Photoswitchable biomaterials are a new class of substances in which optical signals generate discrete “On” and “Off” states of biological functions, resembling logic gates that flip between 0 and 1 states in response to the changes in electric currents in computers. The (photo)chemistry of photochromic materials has been extensively developed in the past four decades. These materials isomerize reversibly upon light absorption, and the discrete photoisomeric states exhibit distinct spectral and chemical features. Integration of photoisomerizable (or photochromic) units into biomaterials allow their secondary functions such as biocatalysis, binding, and electron transfer to be tailored so that they can be switched on or off. This can be accomplished by chemical modification of the biomaterial by photoisomerizable units and by integration of biomaterials in photoisomerizable microenvironments such as monolayers or polymers. The photoswitchable properties of chemically modified biomaterials originate from the light-induced generation or perturbation of the biologically active site, whereas in photoisomerizable matrices they depend upon the regulation of the physical or chemical features of the photoisomerizable assemblies of polymers, monolayers, or membranes. Light-triggered activation of catalytic biomaterials provides a means of amplifying the recorded optical signal by biochemical transformations, and photostimulated biochemical redox switches allow its electrochemical transduction and amplification. The field of photoswitches based on biomaterials has developed extensively in the past few years within the general context of molecular switching devices and micromachinery. The extensive knowledge on the manipulation of biomaterials through genetic engineering and the fabrication of surfaces modified by biologically active materials enables us to prepare biomaterials with improved optical-switching features. Their application in optoelectronic or bioelectronic devices has been transformed from fantasy to reality. The use of photoswitchable biomaterials in information storage and processing devices (biocomputers), sensors, reversible immunosensors, and biological amplifiers of optical signals has already been demonstrated, but still leaves important future challenges.