海藻酸盐医用敷料的研究进展

海藻酸盐(alginate)是一类从褐藻中提取的天然线性多糖,具有无毒、可生物降解、生物相容性高的特点,海藻酸盐的高吸湿性和凝胶性,使其在现代伤口敷料方面得到了广泛应用。海藻酸盐敷料则具有成本低、使用方便、能促进伤口愈合的特点,有海绵形式、纤维形式和水凝胶等形式,作为医用敷料有广阔应用前景。本文对海藻酸医用辅料的主要特点和不同形式的应用进行了综述,并展望了其应用前景。     

胶原/氧化透明质酸复合水凝胶支架的制备与表征

目的制备复合水凝胶并初步考察其在软骨组织工程中的应用。方法用高碘酸钠对透明质酸进行改性,与中性的胶原反应,37℃下形成水凝胶。二甲氨基苯甲醛反应测透明质酸含量并用TNBS法测胶原与氧化透明质酸的交联度。软骨细胞包埋于水凝胶中培养并观察其生长状态。结果氧化透明质酸被有效固定于水凝胶中,胶原的氨基与氧化透明质酸的醛基反应形成西夫碱结构,二者交联度随氧化透明质酸含量的增加而提高。软骨细胞在水凝胶中均匀分布且活性良好,透明质酸的添加对细胞生长有一定促进作用。结论胶原/氧化透明质酸复合水凝胶仿生支架在软骨组织工程中有很大的应用前景。     

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、制备方法和理化性质,及其作为细胞培养与递送支架材料中的应用,并展望了其发展方向和应用潜力。     

海藻酸钠复合水凝胶的制备及其细菌检测应用研究

目的 制备海藻酸钠-金纳米颗粒复合水凝胶并研究其检测细菌的性能,为可视化细菌检测创伤敷料的开发奠定基础。方法 以羧海藻酸钠为原料,掺杂显色底物氯酚红β-D-吡喃半乳糖苷及半乳糖苷酶修饰的金纳米颗粒,通过钙离子引发海藻酸钠交联制备复合水凝胶,研究其对细菌的检测性能。结果 当金纳米颗粒尺寸为5纳米,浓度为100 nM时,水相中传感器对大肠杆菌和金黄色葡萄球菌的检测限可达100 细菌/mL;复合凝胶对金黄色葡萄球菌的检测限可达1000细菌/mL。结论 海藻酸钠-金纳米颗粒复合水凝胶具有生物相容性好细菌检测灵敏度高的优点,有望作为伤口敷料用于检测伤口愈合过程中的细菌感染。     

鱼皮胶原蛋白-壳聚糖复合海藻酸盐水凝胶敷料对烧烫伤创面的促愈合作用

本文以海藻酸钠为原料,复配壳聚糖、鱼皮胶原蛋白,通过Ca2+离子交联制备成海藻酸盐水凝胶敷料。测试了该敷料的物理机械性能及其对大白兔浅Ⅱ度烧烫伤创面的促愈合作用。结果表明：鱼皮胶原蛋白-壳聚糖复合海藻酸盐水凝胶的含水量≥80%,具有良好的吸湿保湿和机械性能,是一种理想的伤口创面敷料;对浅Ⅱ度烧烫伤的愈合周期远远少于医用纱布、市售聚氨酯水凝胶敷料,且能消除伤口炎症,抑制瘢痕的生成,在伤口护理方面有着良好的前景和应用方向。     

蛋白多肽类药物的水凝胶给药系统

蛋白药物由于药效强、特异性高的特点近年来受到广泛的关注.而将蛋白药物引入水凝胶中,利用环境刺激敏感性水凝胶,能够对体内环境微小变化做出响应,从而控制蛋白药物在体内的释放;本文综述了基于蛋白药物合成材料的交联聚合物水凝胶,详述了温度敏感性水凝胶的研究概况以及水凝胶目前存在的问题和未来展望.     

水凝胶材料在颌骨修复中的作用研究进展

颌骨损伤是一种以外伤为主的常见疾病,可影响颜面部美观及导致运动功能障碍,使咀嚼、发音等功能受限。目前的临床治疗措施主要以外科手术为主,但是存在手术创伤大、缺损愈合慢等缺点。水凝胶材料的应用可加快颌骨损伤的愈合,因此有着广阔的临床应用前景。水凝胶不仅可以搭载相关的生长因子及药物,同时还可以起到生物支架的作用,充填因损伤造成的颌骨缺失,从而可以促进颌骨修复。目前颌面部水凝胶可以应用于颞下颌关节软骨修复、颌骨缺损修复及部分颌骨癌症治疗等。本文就水凝胶的类型、促进颌骨修复的原理及在颌骨修复中的研究进展进行综述,以便为临床选择提供参考。     

基于水凝胶的核酸药物负载策略的研究进展

基因治疗在癌症以及遗传疾病的治疗中具有广阔的应用前景,基因治疗的关键在于如何实现将核酸药物精准递送至靶部位。近年来,研究人员致力于将核酸药物负载于水凝胶中,以实现全身或局部的基因递送。水凝胶系统由于其良好的生物相容性、高效的核酸药物负载能力和局部定位控制释放等优势,为核酸药物的递送提供了有效的工具,在实体瘤和再生医学领域具有巨大的潜力。本文综述了近年来水凝胶系统作为核酸药物载体的研究,并重点探讨基于水凝胶的核酸药物负载策略,以期为基于水凝胶的核酸药物递送系统的研究提供参考。     

新型藻酸凝胶创伤敷贴材料的开发

藻酸是从海藻中提取的多糖物质，因其具有高 吸水性，易制成柔软而坚韧的凝胶，自古以 来就作为止血和创伤敷贴材料使用。目前，以藻酸为主成分的凝胶几乎都是以钙等２价金属离子作为交联剂。离子交联藻酸凝胶有凝聚快、操作简便等优点，并具有可逆性，可用大量的１价金属离子或ＥＤＴＡ等螯合剂进行溶解。但在实际应用中发现，这类材料具有较强的细胞毒性，敷贴材料的碎片会长期残存在修复组织中，并且其中所含的钙，可能通过和体液中的钠离子交换而被吸收，继而产生细胞毒性或活化机体分解酶而妨碍治疗。另外，由于其所具有的可逆性，因而…     

交联固化时间对利多卡因水凝胶贴剂的影响

目的 研究交联固化时间对利多卡因水凝胶贴剂的初黏力、持黏力、剥离强度、体外释放度等的影响.方法 以初黏力、持黏力、剥离强度为黏性评价指标,采用桨碟法测定体外释放度,用计算相似因子f2值比较释放度,以水凝胶溶胀率和弹性模量E'分析其内部结构和成型机理.结果 初黏力、持黏力、剥离强度在交联固化前7d迅速降低,之后趋于稳定;利多卡因的体外释放度、水凝胶溶胀率和弹性模量E'随着交联固化时间的增加先增加再趋于稳定.结论 交联固化的初始7d为快速反应期,对初黏力、持黏力、剥离强度体外释放度的影响较大.交联固化7d之后,凝胶交联网络基本形成,水凝胶贴剂的质量相对稳定.     

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.     

Protein release from alginate matrices

There are a variety of both natural and synthetic polymeric systems that have been investigated for the controlled release of proteins. Many of the procedures employed to incorporate proteins into a polymeric matrix can be harsh and often cause denaturation of the active agent. Alginate, a naturally occurring biopolymer extracted from brown algae (kelp), has several unique properties that have enabled it to be used as a matrix for the entrapment and/or delivery of a variety of biological agents. Alginate polymers are a family of linear unbranched polysaccharides which contain varying amounts of 1,4'-linked beta-D-mannuronic acid and alpha-L-guluronic acid residues. The residues may vary widely in composition and sequence and are arranged in a pattern of blocks along the chain. Alginate can be ionically crosslinked by the addition of divalent cations in aqueous solution. The relatively mild gelation process has enabled not only proteins, but cells and DNA to be incorporated into alginate matrices with retention of full biological activity. Furthermore, by selection of the type of alginate and coating agent, the pore size, degradation rate, and ultimately release kinetics can be controlled. Gels of different morphologies can be prepared including large block matrices, large beads (>1 mm in diameter) and microbeads (<0.2 mm in diameter). In situ gelling systems have also been made by the application of alginate to the cornea, or on the surfaces of wounds. Alginate is a bioadhesive polymer which can be advantageous for the site specific delivery to mucosal tissues. All of these properties, in addition to the nonimmunogenicity of alginate, have led to an increased use of this polymer as a protein delivery system. This review will discuss the chemistry of alginate, its gelation mechanisms, and the physical properties of alginate gels. Emphasis will be placed on applications in which biomolecules have been incorporated into and released from alginate systems.     

Composite alginate microspheres as the next-generation egg-box carriers for biomacromolecules delivery

Introduction: Alginate microspheres are versatile tools for the delivery of a wide range of therapeutic biomacromolecules. This naturally occurring biopolymer has many unique properties making it an ideal candidate for tailoring with different composites of polymers leading to the formation of strong complexes for a broad range of applications.

Areas covered: This article overviews various types of composite alginate microspheres, methods of preparation, new technologies available, physico-chemical characteristics, controlled release profiles, applications and the future directions of composite alginate microsphere delivery system for biomacromolecules.

Expert opinion: Composite alginate microsphere systems are the ideal carriers for controlled delivery applications because of their ability to encapsulate a myriad of therapeutic drugs, proteins, enzymes, DNA, antisense oligonucleotides, vaccines, growth factors and chemokines as well as the ease of processing, mechanical properties, biocompatibility, high bioavailability, controlled release rates, stability, suitability for different administration modes, targeted/localized delivery of different agents and large-scale production with cost-effectiveness. This article presents updated information of applying microalginate-based technologies and tools in the biomedical field which will benefit research scientists and clinical physicians or biopharmaceutical industries keen in the development of application-based new therapeutic and diagnostic strategies for various diseases. Furthermore, this technology will play more important roles in biosensors, vaccination, tissue engineering, cancer chemotherapeutics and stem cell research.     

Drug delivery strategies using polysaccharidic gels

Hydrogels are hydrophilic polymeric networks, with chemical or physical crosslinks, that are capable of swell and can retain a large amount of water. Among the numerous types of macromolecules that can be used for hydrogel formation, polysaccharides show very attractive advantages in comparison to synthetic polymers. They are widely present in living organisms, are usually abundant and show a number of peculiar physicochemical properties; furthermore, these macromolecules are, in most cases, non-toxic, biocompatible and can be obtained from renewable sources. For these reasons, polysaccharides seem to be particularly suitable for different applications in the wide field of pharmaceutics. As examples of the studies that have been carried out on this topic, this review will focus on two polysaccharides, alginate and xyloglucan. Alginate has been, and still is, extensively investigated and has numerous industrial applications, whereas xyloglucan was chosen because, although it has been much less studied, it shows interesting properties that should find important practical uses in the near future. The possible advantages of physical gels over those that are chemically crosslinked are also discussed.     

Drug delivery strategies using polysaccharidic gels

Hydrogels are hydrophilic polymeric networks, with chemical or physical crosslinks, that are capable of swell and can retain a large amount of water. Among the numerous types of macromolecules that can be used for hydrogel formation, polysaccharides show very attractive advantages in comparison to synthetic polymers. They are widely present in living organisms, are usually abundant and show a number of peculiar physicochemical properties; furthermore, these macromolecules are, in most cases, non-toxic, biocompatible and can be obtained from renewable sources. For these reasons, polysaccharides seem to be particularly suitable for different applications in the wide field of pharmaceutics. As examples of the studies that have been carried out on this topic, this review will focus on two polysaccharides, alginate and xyloglucan. Alginate has been, and still is, extensively investigated and has numerous industrial applications, whereas xyloglucan was chosen because, although it has been much less studied, it shows interesting properties that should find important practical uses in the near future. The possible advantages of physical gels over those that are chemically crosslinked are also discussed.     

Release characteristics of chitosan treated alginate beads: I. Sustained release of a macromolecular drug from chitosan treated alginate beads

Alginate and chitosan treated alginate beads were prepared and compared as an oral controlled release system for macromolecular drugs. Dextran (M.W. 70,000) was used as a model substance. The beads were prepared by the ionotropic gelation method and the effect of various factors (alginate, chitosan, drug and calcium chloride concentrations, the volume of external and internal phases and drying methods) on bead properties were investigated. The addition of chitosan increased the drug loading capacity of the beads, and larger beads were obtained in the presence of chitosan. On the other hand, addition of chitosan in the gel structure reduced the drug release from beads. The erosion of the beads was suppressed by chitosan treatment. The drying method was important to the properties of the chitosan-alginate beads. It is proposed that chitosan treated alginate beads may be used as a potential controlled release system of such macromolecules.     

Semi-IPN hydrogel based on scleroglucan and alginate: drug delivery behavior and mechanical characterisation

This paper deals with the characterization of the semi-IPN based on a scleroglucan/borax hydrogel with interspersed alginate chains, with regard to both its physicochemical properties and its suitability for modified drug release formulations. In particular, the feasibility of a drug delivery system based on this new polysaccharidic matrix was explored in terms of ability of the network to discriminate the releases of model drugs with different steric hindrance. The investigated mechanical properties of the semi-IPN hydrogel evidenced the relevant effect of alginate on the scleroglucan/borax system: experiments in shear oscillation regime showed that the rheological properties of the polymeric system are more than additive; in fact it has been observed that alginate induces an increase in the hydrogel storage modulus of an order of magnitude. Optical data collected in circular dichroic experiments showed no interactions, at molecular level, between scleroglucan and alginate in solution, irrespective of the presence of borax. The studied semi-IPN is thermo irreversible in the temperature range that was explored.     

Protein release from alginate matrices

There are a variety of both natural and synthetic polymeric systems that have been investigated for the controlled release of proteins. Many of the procedures employed to incorporate proteins into a polymeric matrix can be harsh and often cause denaturation of the active agent. Alginate, a naturally occurring biopolymer extracted from brown algae (kelp), has several unique properties that have enabled it to be used as a matrix for the entrapment and/or delivery of a variety of biological agents. Alginate polymers are a family of linear unbranched polysaccharides which contain varying amounts of 1,4′-linked β-d-mannuronic acid and α-l-guluronic acid residues. The residues may vary widely in composition and sequence and are arranged in a pattern of blocks along the chain. Alginate can be ionically crosslinked by the addition of divalent cations in aqueous solution. The relatively mild gelation process has enabled not only proteins, but cells and DNA to be incorporated into alginate matrices with retention of full biological activity. Furthermore, by selection of the type of alginate and coating agent, the pore size, degradation rate, and ultimately release kinetics can be controlled. Gels of different morphologies can be prepared including large block matrices, large beads (> 1 mm in diameter) and microbeads (< 0.2 mm in diameter). In situ gelling systems have also been made by the application of alginate to the cornea, or on the surfaces of wounds. Alginate is a bioadhesive polymer which can be advantageous for the site specific delivery to mucosal tissues. All of these properties, in addition to the nonimmunogenicity of alginate, have led to an increased use of this polymer as a protein delivery system. This review will discuss the chemistry of alginate, its gelation mechanisms, and the physical properties of alginate gels. Emphasis will be placed on applications in which biomolecules have been incorporated into and released from alginate systems.     

藻酸盐水凝胶的研究进展

藻酸盐是一种无毒、无味的天然多糖高分子,具有一定的生物相容性、生物降解性及低致敏性,被广泛应用于生物医学工程领域。藻酸盐水凝胶是用途广泛且适应性强的生物材料,如用作组织工程的细胞传递载体和支撑基质、药物载体以及体外细胞实验的模型。本文综述藻酸盐的化学性质和结构修饰,及其生物反应。