DNA水凝胶应用于环境样品快速检测的研究进展

DNA作为生物大分子既可以引导生物发育和生命机能活动,也可以被用作构筑纳米生物材料。DNA水凝胶可以制备成兼具DNA生物功能和水凝胶特质,应用于环境样品的分析检测。依据制备DNA水凝胶长链的方法,对比分析了聚合酶链反应、杂交链式反应、滚环扩增技术的制备,物理水凝胶和化学水凝胶的合成过程和改性方法技术特点;并结合环境样品浓度检测的变性响应特点,分析了荧光、比色、电化学法分析检测的技术要点和检测性能,与大型仪器分析方法相比该方法具有检出限低、检出范围广、检测时间快、测样成本偏低等特点,是一种方便快捷、应用前景广泛的方法;最后对其检出性能和经济性进行评估,并对其应用前景进行总结和展望。     

功能核酸DNA水凝胶的制备与组装

功能核酸DNA水凝胶是一种以DNA为构建单元通过化学反应或物理缠结自组装而成的新型柔性材料,其构建单元中包含1种或多种能够形成功能核酸的特定序列。功能核酸是通过碱基修饰和DNA分子之间的相互作用力组合的一类特定核酸结构,包括核酸适配体、DNA核酶、G-四联体(G-quadruplex,G4)和i-motif结构等。传统上,高浓度的长DNA链是制备DNA水凝胶的必要条件,而核酸扩增方法的引入为DNA水凝胶的组装方式提供了新的可能。因此,对常用于制备DNA水凝胶的多种功能核酸以及核酸的提取、合成和扩增手段进行了详细的介绍。在此基础上,综述了通过化学或物理交联方式组装功能核酸DNA水凝胶的制备方法。最后,提出了DNA纳米材料的组装所面临的挑战和潜在的发展方向,以期为开发高效组装的功能核酸DNA水凝胶提供参考。     

刺激响应型DNA水凝胶的性质及其应用 *

DNA水凝胶作为一种生物合成分子,既具有DNA分子的特异性,生物可降解性和分子识别等特性,又具有水凝胶的高亲水性等特征.刺激响应型DNA水凝胶主要是在环境因素的刺激下,利用常规DNA序列经Watson-Crick碱基互补配对形成的DNA分支结构或多种功能核酸的特殊DNA序列形成的i-motif结构;T-A·T三螺旋结构,C-G·C ⁺三螺旋结构及G-四链体结构等对环境的响应行为使水凝胶形成及应用.近年来,刺激响应型DNA水凝胶因其在温度,pH,光,金属离子,生物分子等单刺激因素,以及光热,金属离子,有机物,温度与pH等多刺激因素下的独特应答性质,在生物传感,生物成像,药物递送,生物材料等方面得到了广泛的应用.综述了刺激响应型DNA水凝胶的形成方法,分类及其核酸来源,形成后的表征手段以及在环境刺激下的响应行为与应用,概括了目前刺激响应型DNA水凝胶的研究热点,并就其未来发展趋势做出了预测.     

酶启动和调控自组装超分子水凝胶

超分子间的弱相互作用使自组装超分子水凝胶的结构比较容易改变。用酶启动和调控超分子水凝胶的自组装不仅能在原位上对超分子水凝胶结构进行调整和控制,而且具有很好的生物选择性,有望制造出生物医学上所需要的材料,并能够控制生物体系中一些重要的生物过程。本文对酶启动和调控自组装超分子水凝胶的两类过程进行了总结,并以磷酸酯酶、β-内酰胺酶、嗜热菌蛋白酶、脂肪酶、基质金属蛋白酶和磷酸酯酶/激酶等酶为例,综述了如何设计和使用酶来启动和调控小分子的自组装超分子水凝胶。     

生物水凝胶及其复合材料在骨修复中的应用

由于外伤、疾病或骨吸收引起的大面积骨缺损无法自行修复,往往需要植入人工骨来恢复缺损区的骨形态和功能。由于传统的异体和异种骨存在易被宿主吸收、排斥等问题,且自体骨取材有限,因此,骨组织工程是目前最具前景和可行的骨修复策略。骨组织工程的关键是要有种子细胞、支架材料以及生长因子,生物水凝胶是潜在的组织工程细胞支架材料之一。水凝胶具有良好的生物相容性和可降解性,越来越受到组织工程领域学者的关注。本文对生物水凝胶在骨组织工程中的应用进行了评述。     

功能核酸DNA水凝胶的理化特性及应用进展

自DNA被开发为纳米级的自组装材料以来,凭借其可调节的多功能性、便利的可编程性、精确的分子识别能力、高通用性以及优越的生物相容性和生物降解性连接了生命科学和材料科学两大领域。受益于DNA纳米材料的结构特性,以功能核酸作为构建单元,经交联、自组装形成的功能核酸DNA水凝胶已成为新型材料领域的研究热点。基于此,对功能核酸DNA水凝胶所具有的主要理化特性进行了总结,并进一步综述了近年来功能核酸DNA水凝胶在药物递送与靶向治疗、生物传感、三维组织构建等生物医学、分子检测及环境工程等领域中的应用进展。最后,从生命科学和材料科学的角度总结了在设计与搭建功能核酸DNA水凝胶时应考虑的关键点和方向,以期助力DNA水凝胶在多学科领域的研究与应用。     

刺激响应型DNA水凝胶的性质及其应用

DNA水凝胶作为一种生物合成分子,既具有DNA分子的特异性、生物可降解性和分子识别等特性,又具有水凝胶的高亲水性等特征。刺激响应型DNA水凝胶主要是在环境因素的刺激下,利用常规DNA序列经Watson-Crick碱基互补配对形成的DNA分支结构或多种功能核酸的特殊DNA序列形成的i-motif结构; T-A·T三螺旋结构、C-G·C~+三螺旋结构及G-四链体结构等对环境的响应行为使水凝胶形成及应用。近年来,刺激响应型DNA水凝胶因其在温度、pH、光、金属离子、生物分子等单刺激因素,以及光热、金属离子、有机物、温度与p H等多刺激因素下的独特应答性质,在生物传感、生物成像、药物递送、生物材料等方面得到了广泛的应用。综述了刺激响应型DNA水凝胶的形成方法、分类及其核酸来源,形成后的表征手段以及在环境刺激下的响应行为与应用,概括了目前刺激响应型DNA水凝胶的研究热点,并就其未来发展趋势做出了预测。     

木质素复合水凝胶性能及应用的研究进展北大核心CSCD

木质素是自然界中储量仅次于纤维素的木质纤维素资源,也是唯一的天然芳香族聚合物,其衍生的高值化产品可以应用于多个领域。木质素的高效高值高质生产是木质纤维素生物炼制的关键所在,但木质素大分子结构复杂多变、反应的活性差、官能团冗杂,制备出性能稳定的高分子材料有一定的难度。随着木质素改性的研究越来越深入,木质素复合水凝胶的应用也受到了极大的关注。本文从木质素的基本结构组成与反应特性出发,简要概括了木质素复合水凝胶的制备方法;具体介绍了木质素复合水凝胶的应用现状,包括生物传感器、控制释放材料、环境响应材料、吸附材料、电极材料以及其他材料的应用;综述了木质素复合水凝胶的最新研究与应用进展,并对木质素制备复合水凝胶的发展前景进行了评述。     

基于天然水凝胶的生物材料在骨组织工程中的应用*

天然水凝胶是指原材料来自于天然生物材料的水凝胶。由于这种天然的聚合物含有构成生物体的天然成分,与天然组织具有生物学和化学相似性,而受到特别关注。天然水凝胶由于其与细胞外基质高度的相似性被认为是骨组织工程中优良的仿生基质材料。而针对天然水凝胶机械性能差、成骨诱导性能弱等缺陷,通常需要对天然水凝胶进行改性、引入其他材料或生物活性因子,以此来获得更适用于骨组织工程支架材料。对近年来基于天然水凝胶的生物材料在骨组织工程的应用,与其不同的应用形式(可注射水凝胶、多孔水凝胶支架、3D生物打印水凝胶支架等)进行了概述,以期对这类基于天然水凝胶的生物材料在未来骨组织工程中的应用提供参考。     

γ-聚谷氨酸水凝胶研究与应用进展

主要介绍了一种集吸水性能、保水性能、环境友好性于一身的高分子材料γ-聚谷氨酸水凝胶的研究现状及发展前景,分别从γ-聚谷氨酸水凝胶、γ-聚谷氨酸与其他物质复合水凝胶的合成以及γ-聚谷氨酸类水凝胶的应用三方面进行了综述。     

Enhanced tissue adhesiveness of injectable gelatin hydrogels through dual catalytic activity of horseradish peroxidase

Development of bioadhesives with tunable mechanical strength, high adhesiveness, biocompatibility, and injectability is greatly desirable in all surgeries to replace or complement the sutures and staples. Herein, the dual catalytic activity of horseradish peroxidase is exploited to in situ form the hydroxyphenyl propionic acid‐gelatin/thiolated gelatin (GH/GS) adhesive hydrogels including two alternative crosslinks (phenol‐phenol and disulfide bonds) with fast gelation (few seconds – several minutes) and improved physicochemical properties. Their elastic moduli increase from 6.7 to 10.3 kPa by adding GS polymer that leads to the better stability of GH/GS hydrogels than GH ones. GH/GS adhesive strength is respectively 6.5‐fold and 15.8‐fold higher than GH‐only and fibrin glue that is due to additional disulfide linkages between hydrogels and tissues. Moreover, in vitro cell study with human dermal fibroblast showed the cell‐compatibility of GH/GS hydrogels. Taken together, GH/GS hydrogels can be considered as promising potential adhesive materials for various biomedical applications.     

Injectable, mixed natural-synthetic polymer hydrogels with modular properties

A series of synthetic oligomers (based on the thermosensitive polymer poly(N-isopropylacrylamide) and carbohydrate polymers (including hyaluronic acid, carboxymethyl cellulose, dextran, and methylcellulose) were functionalized with hydrazide or aldehyde functional groups and mixed using a double-barreled syringe to create in situ gelling, hydrazone-cross-linked hydrogels. By mixing different numbers and ratios of different reactive oligomer or polymer precursors, covalently cross-linked hydrogel networks comprised of different polymeric components are produced by simple mixing of reactive components, without the need for any intermediate chemistries (e.g., grafting). In this way, hydrogels with defined swelling, degradation, phase transition, drug binding, and mechanical properties can be produced with properties intermediate to those of the mixture of reactive precursor polymers selected. When this modular mixing approach is used, one property can (in many cases) be selectively modified while keeping other properties constant, providing a highly adaptable method of engineering injectable, rapidly gelling hydrogels for potential in vivo applications.     

Graphene oxide-polyethylenimine nanoconstruct as a gene delivery vector and bioimaging tool

Graphene oxide (GO) has attracted an increasing amount of interest because of its potential applications in biomedical fields such as biological imaging, molecular imaging, drug/gene delivery, and cancer therapy. Moreover, GO could be fabricated by modifying its functional groups to impart specific functional or structural attributes. This study demonstrated the development of a GO-based efficient gene delivery carrier through installation of polyethylenimine, a cationic polymer, which has been widely used as a nonviral gene delivery vector. It was revealed that a hybrid gene carrier fabricated by conjugation of low-molecular weight branched polyethylenimine (BPEI) to GO increased the effective molecular weight of BPEI and consequently improved DNA binding and condensation and transfection efficiency. Furthermore, this hybrid material facilitated sensing and bioimaging because of its tunable and intrinsic electrical and optical properties. Considering the extremely high transfection efficiency comparable to that of high-molecular weight BPEI, high cell viability, and its application as a bioimaging agent, the BPEI-GO hybrid material could be extended to siRNA delivery and photothermal therapy.     

Recombinant protein-co-PEG networks as cell-adhesive and proteolytically degradable hydrogel matrixes. Part II: biofunctional characteristics

We present here the biological performance in supporting tissue regeneration of hybrid hydrogels consisting of genetically engineered protein polymers that carry specific features of the natural extracellular matrix, cross-linked with reactive poly(ethylene glycol) (PEG). Specifically, the protein polymers contain the cell adhesion motif RGD, which mediates integrin receptor binding, and degradation sites for plasmin and matrix-metalloproteinases, both being proteases implicated in natural matrix remodeling. Biochemical assays as well as in vitro cell culture experiments confirmed the ability of these protein-PEG hydrogels to promote specific cellular adhesion and to exhibit degradability by the target enzymes. Cell culture experiments demonstrated that proteolytic sensitivity and suitable mechanical properties were critical for three-dimensional cell migration inside these synthetic matrixes. In vivo, protein-PEG matrixes were tested as a carrier of bone morphogenetic protein (rhBMP-2) to heal critical-sized defects in a rat calvarial defect model. The results underscore the importance of fine-tuning material properties of provisional therapeutic matrixes to induce cellular responses conducive to tissue repair. In particular, a lack of rhBMP or insufficient degradability of the protein-PEG matrix prevented healing of bone defects or remodeling and replacement of the artificial matrix. This work confirms the feasibility of attaining desired biological responses in vivo by engineering material properties through the design of single components at the molecular level. The combination of polymer science and recombinant DNA technology emerges as a powerful tool for the development of novel biomaterials.     

Enzymatic collapse of artificial polymer composite material containing double-stranded DNA

Large amounts of DNA-enriched biomaterials, such as salmon milts and shellfish gonads, are discarded as industrial waste around the world. Therefore, the utilizations of DNA with the specific function are important for the biomaterial science and the curce technology. We could convert the discarded DNA to an enzymatic collapsible material by the addition of DNA to the artificial polymer material, such as nylon. Although these DNA-artificial polymer composite materials were stable in water, these materials indicated the collapsibility at the DNA-hydrolyzed enzyme, such as Micrococcal nuclease, condition. Additionally, these collapsibilities under enzyme condition were controlled by the number of imino groups in the components of the artificial polymer. Furthermore, these composite materials could create the fiber form with a highly ordered molecular orientation by the reaction at the liquid/liquid interface. The DNA-artificial polymer composite materials may have the potential utility as a novel bio-, medical-, and environmental materials with the enzymatic collapsibility and degradability.     

Highly extensible, tough, and elastomeric nanocomposite hydrogels from poly(ethylene glycol) and hydroxyapatite nanoparticles

Unique combinations of hard and soft components found in biological tissues have inspired researchers to design and develop synthetic nanocomposite gels and hydrogels with elastomeric properties. These elastic materials can potentially be used as synthetic mimics for diverse tissue engineering applications. Here we present a set of elastomeric nanocomposite hydrogels made from poly(ethylene glycol) (PEG) and hydroxyapatite nanoparticles (nHAp). The aqueous nanocomposite PEG-nHAp precursor solutions can be injected and then covalently cross-linked via photopolymerization. The resulting PEG-nHAp hydrogels have interconnected pore sizes ranging from 100 to 300 nm. They have higher extensibilities, fracture stresses, compressive strengths, and toughness when compared with conventional PEO hydrogels. The enhanced mechanical properties are a result of polymer nanoparticle interactions that interfere with the permanent cross-linking of PEG during photopolymerization. The effect of nHAp concentration and temperature on hydrogel swelling kinetics was evaluated under physiological conditions. An increase in nHAp concentration decreased the hydrogel saturated swelling degree. The combination of PEG and nHAp nanoparticles significantly improved the physical and chemical hydrogel properties as well as some biological characteristics such as osteoblast cell adhesion. Further development of these elastomeric materials can potentially lead to use as a matrix for drug delivery and tissue repair especially for orthopedic applications.