Institute of Chemistry
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Localized Co-delivery of Doxorubicin, Cisplatin, and Methotrexate by Thermosensitive Hydrogels for Enhanced Osteosarcoma Treatment
No full textLocalized cancer treatments with combination drugs have recently emerged as crucial approaches for effective Inhibition of tumor growth and reoccurrence. In this study, we present a new strategy for the osteosarcoma treatment by localized co-delivery of multiple drugs, including doxorubicin (DOX), cisplatin (CDDP) and methotraxate (MTX), using thermosensitive PLGA PEG PLGA hydrogels. The release profiles of the drugs from the hydrogels were investigated in vitro. It was found that the multidrug coloaded hydrogels exhibited synergistic effects on cytoto]dcity against osteosarcoma Saos-2 and MG-63 cells in vitro. After a single peritumoral injection of the drug-loaded hydrogels into nude mice bearing human osteosarcoma Saos-2 xenografts, the hydrogels coloaded with DOX, CDDP, and MTX displayed the highest tumor suppression efficacy in vivo for up to 16 days, as well as led to enhanced tumor apoptosis and increased regulation of the expressions of apoptosis-related genes. Moreover, the monitoring on the mice body change and the ex vivo histological analysis of the key organs indicated that the localized treatments caused less systemic toxicity and no obvious damage to the normal organs. Therefore, the approach of localized co-delivery of DOX, CDDP, and MTX by the thermosensitive hydrogels may be a promising approach for enhanced osteosarcoma treatment
Fabrication of biomembrane-like films on carbon electrodes using alkanethiol and diazonium salt and their application for direct electrochemistry of myoglobin
No full textAlkanethiols generally form self-assembled monolayers on gold electrodes and the electrochemical reduction of aromatic diazonium salts is a popular method for the covalent modification of carbon. Based on the reaction of alkanethiol with aldehyde groups covalently bound on carbon surface by the electrochemical reduction of aromatic diazonium salts, a new strategy for the modification of carbon electrodes with alkanethiols has been developed. The modification of carbon surface with aldehyde groups is achieved by the electrochemical reduction of aromatic diazonium salts in situ electrogenerated from a nitro precursor, p-nitrophenylaldehyde, in the presence of nitrous acid. By this way, in situ electrogenerated p-aminophenyl aldehyde from p-nitrophenylaldehyde immediately reacts with nitrous acid, effectively minimizing the side reaction of amine groups and aldehyde groups. The as-prepared alkanethiol-modified glassy carbon electrode was further used to make biomembrane-like films by casting didodecyldimethylammonium bromide on its surface. The biomembrane-like films enable the direct electrochemistry of immobilized myoglobin for the detection of hydrogen peroxide. The response is linear over the range of 1-600 mu M with a detection limit of 0.3 mu M. (C) 2014 Elsevier B.V. All rights reserved
Porous carbon nanotubes decorated with nanosized cobalt ferrite as anode materials for high-performance lithium-ion batteries
No full textGenerally, the fast ion/electron transport and structural stability dominate the superiority in lithium-storage applications. In this work, porous carbon nanotubes decorated with nanosized CoFe2O4 particles (p-CNTs@CFO) have been rationally designed and synthesized by the assistance of supercritical carbon dioxide (scCO(2)). When tested as anode materials for lithium-ion batteries, the p-CNTs@CFO composite exhibits outstanding electrochemical behavior with high lithium-storage capacity (1077 mAh g(-1) after 100 cycles) and rate capability (694 mAh g(-1) at 3 A g(-1)). These outstanding electrochemical performances are attributed to the synergistic effect of porous p-CNTs and nanosized CFO. Compared to pristine CNTs, the p-CNTs with substantial pores in the tubes possess largely increased specific surface area and rich oxygen-containing functional groups. The porous structure can not only accommodate the volume change during lithiation/delithiation processes, but also provide bicontinuous electron/ion pathways and large electrode/electrolyte interface, which facilitate the ion diffusion kinetics, improving the rate performance. Moreover, the CFO particles are bonded strongly to the p-CNTs through metal-oxygen bridges, which facilitate the electron fast capture from p-CNTs to CFO, and thus resulting in a high reversible capacity and excellent rate performance. Overall, the porous p-CNTs provide an efficient way for ion diffusion and continuous electron transport as anode materials. (C) 2015 Elsevier B.V. All rights reserved
Enhanced catalytic performance of carbon supported palladium nanoparticles by in-situ synthesis for formic acid electrooxidation
No full textThe development of facile, surfactant-free strategy for the scale-up production Of catalysts with superior performance for energy science is an interesting challenge. Pd/C is synthesized using an in-situ method from PdO/C for formic acid electrooxidation based on the reducibility of formic acid. The morphology, composition and electrocatalytic properties are investigated using transmission electronmicroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, linear scan voltammograms (LSV) and chronoamperometry. The in-situ synthesized Pd nanoparticles show better distribution and smaller average particle size than the normally synthesized Pd/C, which indicates that the well-known Ostwald ripening is most limited in the synthesis process. The electrochemical measurements show that the Pd/C catalyst exhibits enhanced performance towards formic acid electrooxidation. For example, the peak current of the Pd/C catalyst is approximately three times that of the homemade Pd/C catalyst and twice as high as that of the commercial Pd/C catalyst in the LSV test. The in-situ synthesized Pd/C catalyst has potential application for direct formic acid fuel cells, and the in-situ route should be art effective strategy to synthesize high performance catalysts. (C) 2015 Elsevier B.V. All rights reserved
Molecular Mechanisms for Conformational and Rheological Responses of Entangled Polymer Melts to Startup Shear
No full textIn this work, we have carried out Brownian dynamics simulation to describe the detailed characteristics of conformational and rheological responses to startup shear. In addition to the evaluation of the contour length of the primitive chain, the state of chain entanglement and the first normal stress difference as a function of strain, three methods are applied to determine the time-dependent shear stress. Our results show significant stretching of the primitive chain up to many Rouse times, followed by retraction, as the primary origin of stress overshoot for deformation rates lower than the reciprocal of the Rouse time but higher than the reciprocal of the reptation time. The analysis of such results reveals heterogeneous local chain stretching, demonstrating the coupling between stretching and orientation that extends to times considerably longer than the Rouse time. Explicit comparison between the simulation and the theoretical description from the GLaMM theory shows marked differences. For example, the simulation indicates a slower decline in the number of original entanglements than that at equilibrium up to many Rouse times whereas the GLaMM theory predicts a faster decrease. Moreover, contrary to the simulation that depicts a nearly constant slope in the stress strain relationship during startup shear, the GLaMM theory shows an immediate and precipitous strain softening
应用化学交流论坛举办第二期——计算模拟技术及应用
No full text6月1日，应用化学交流论坛第二期成功举办，本期论坛的主题为"计算模拟技术及应用"，邀请所内相关领域七位青年科技工作者做工作报告，近百人参加了此次论坛。 汪尔康院士应邀参加本期论坛，并与中青年科技人员进行交流。汪院士强调现代研究中，计算模拟技术越来越重要，不仅是实验现象的补充与验证，更是对实验工作的指导，计算模拟已近发展成为重要的学科方向，未来科学发展会更加倚重计算模拟。汪院士结合求学经历和60多年的科研经验，勉励大家做学问要持之以恒、坐得住板凳，不要盲目追热，要对认定的研究方向有信心、有耐心、有决心。 稀土资源利用国家重点实验室刘孝娟研究员、王颖副研究员，高分子物理与化学国家重点实验室李占伟副研究员、韩媛媛副研究员、卢宇源副研究员，电分析化学国家重点实验室晏致强副研究员、甘霖锋助理研究员分别以"稀土材料的第一性原理计算"、"石墨烯可控制备及石墨烯氢化的理论研究"、"各向异性胶体粒子聚集结构的设计与调控"、"嵌段共聚物在溶液中自组装行为的Monte Carlo模拟"、"高分子特性粘度的普适性理论"、"蛋白质折叠与识别的计算研究"和"量子化学在实验室上的一些应用"为题作了工作报告。 "应用化学交流论坛"由所学术委员会牵头，由规划与信息处负责组织实施。其设立的目的在于加强所内科研人员相互了解，增进沟通交流，推进所内相近领域方向人员展开合作，促进跨学科跨领域前沿探索，激发中青年人才创新活力。论坛每月组织一期，每期结合国家政策、社会需求及研究所发展方向选定一个可广泛参与的议题，组织相近领域方向中青年科技人员3-5人进行约10分钟/人的口头报告，并展开讨论。每期论坛还将邀请研究员代表与中青年科技人员举行座谈，交流科研心得，答疑解惑
我所首届“应用化学交流论坛”成功举行
No full text5月11日，由学术委员会牵头，规划与信息处组织实施的首届"应用化学交流论坛"成功举行。此次论坛以"生物材料及相关领域"为主题，所内百余位科研人员参加了论坛。 杨小牛副所长出席了论坛，并发表了讲话。杨小牛副所长表示，中青年科技工作者充满朝气，富有活力，是推动未来科技进步的主力。他指出，希望通过举办"应用化学交流论坛"的形式，助力弘扬科学精神，营造尊重人才、鼓励创新的氛围，树立起科技创新要面向国家需求、面向产业发展的意识，促进所内中青年科研人员之间的交流，推动各个学科之间的交叉融合。研究所将持续不断地为青年人创造条件，鼓励青年人自由畅想、大胆探索。 此次论坛邀请到了所学术委员会主任、高分子物理与化学国家重点实验室殷敬华研究员与中青年科技人员进行座谈。殷敬华研究员鼓励青年科研人员要面向国家的需求，紧跟时代的步伐，适应市场的变化，全身心投入到科研事业上来，并结合生物医用材料研发与医疗器械产业发展的具体案例，分享了多年以来的研究心得与体会。 高分子物理与化学国家重点实验室的石强副研究员，中科院生态环境高分子材料重点实验室的陶友华研究员、汤朝晖研究员，先进化学电源实验室的李云琦研究员，稀土资源利用国家重点实验室的马平安副研究员，化学生物学实验室的王晓辉研究员，中科院高分子复合材料工程实验室的于喜飞研究员分别以"血液接触类医用高分子材料"，"氨基酸单体的可控聚合"、"抗肿瘤纳米药物高分子载体材料研究现状"、"分子及纳米尺度相互作用和结构的多学科交叉研究方法"、"稀土纳米发光材料的生物应用浅谈"、"药物化学生物学"、"通用细胞膜粘接剂--药物/基因载体材料"为题做了口头报告。 "应用化学交流论坛"由所学术委员会牵头，由规划与信息处负责组织实施。其设立的目的在于加强所内科研人员相互了解，增进沟通交流，推进所内相近领域方向人员展开合作，促进跨学科跨领域前沿探索，激发中青年人才创新活力。论坛每月组织一期（暂定），每期结合国家政策、社会需求及研究所发展方向选定一个可广泛参与的议题，组织相近领域方向中青年科技人员3-5人进行约10分钟/人的口头报告，并展开讨论。每期论坛还将邀请研究员代表与中青年科技人员举行座谈，交流科研心得，答疑解惑
新型钼系复合析氢电催化剂的制备及性能研究
No full text氢能作为一种公认的高效、清洁、零碳的二次能源, 有望代替传统的化石能源。在众多制氢技术当中，电解水制氢具有操作简单和产品纯度高等优点，受到了高度关注。克服在电极产生的高析氢过电位以降低能耗，开发高活性、高稳定性的析氢电催化剂具有重要意义。目前，铂基材料是最有效的析氢阴极催化剂，但由于铂在地球上储量少，大大制约了其大规模应用。近年来，低成本的过渡金属钼及其化合物展现出了较高的电催化析氢性能和稳定性，有望代替铂基电催化剂。本论文围绕钼系复合材料的制备及其电催化性能开展了一系列研究工作，主要的研究内容如下： 1. 采用常见的镍盐、钼酸盐、硫脲为原料，通过简单的一步水热法，制备了硫化镍掺杂的二硫化钼微球(NMSHMs)。这种复合材料在酸性环境中的电催化活性明显优于单独的硫化镍(NixSy)、二硫化钼(MoS2)及其物理混合物(mNM)。此外，通过控制镍盐的用量探索了镍的含量对二硫化钼微球催化性能的影响。 2. 采用在自然界广泛存在的生物大分子海藻酸钠作为碳源，钼酸铵作为钼源，采用高温煅烧法制备出碳化钼纳米颗粒修饰的石墨化碳片(Mo2C/GCSs)。碳化钼纳米颗粒尺寸在5-23 nm 之间，在碳片上分散性良好。该复合材料在酸性电解质中获得了较好的电催化析氢活性和稳定性，产氢效率接近100%。其中，由于碳化钼与碳之间具有牢固的键合作用，能有效加快电子转移速率，并能提高结强度。此外，碳片支持的纳米结构抑制了碳化钼颗粒的团聚，暴露更多的活性位点，从而获得优异的电催化性能。 3. 我们采用较绿色安全的内氧化还原策略，在上述体系中引入磷酸二氢钠作为磷源，在相同煅烧条件下制备了磷化钼纳米片与碳片的复合材料(MoP/CF)。与体相磷化钼(bulk MoP)相比，该材料在酸性及中性体系中展示了更优秀的电催化产氢性能。为证明在内氧化还原策略的普适性和碳的还原作用，进一步采用多壁碳纳米管作为碳源，在同样煅烧条件下得到了磷化钼纳米颗粒与碳管的复合材料(MoP/CNT)，该材料同样在酸性及中性体系中获得较好的电催化析氢性能。Hydrogen, an efficient, clean, and carbon-free fuel, is being considered as a replacement for today's fossil fuels. Electrolysis of water is a simple way to produce hydrogen of high purity and has thus attracted considerable attention. In order to improve the reaction rate and lower the overpotential, an efficient and stable hydrogen evolution reaction (HER) electrocatalyst is usually required. Pt-based materials are the most efficient HER electrocatalysts, however, they are not sustainable catalysts for large-scale applications due to their scarcity on earth. Recently, it was found that molybdenum (Mo) and its compounds are very promising HER electrocatalysts owing to their low-cost and abundance. In the thesis, we focused on the preparation and characterization of Mo-based HER electrocatalysts. The main points of the thesis are addressed as follows: 1. We demonstrate the preparation of NixSy-doped MoS2 microspheres (NMSHMs) via one-pot hydrothermal treatment of aqueous solutions of Ni(NO3)2?6H2O, Na2MoO4?2H2O and H2NCSNH2. As an electrocatalyst toward HER, the NMSHMs exhibit superior activity over NixSy, MoS2 and their physical mixture (mNM) in acidic solutions. In addition, we further explored and optimize the amount of Ni species in the products. 2. We demonstrate the synthesis of Mo2C nanoparticles decorated graphitic carbon sheets (Mo2C/GCSs) via a biopolymer-derived reaction between (NH4)6Mo7O24?4H2O and sodium alginate at high temperature in Ar atmosphere. These well-dispersed nanoparticles have sizes in the range of 5-23 nm. The Mo2C/GCSs hybrids exhibit high HER activity and stability in acidic solutions, with a near 100% Faradaic efficiency. The strong conjugation between the anchored Mo2C particles and carbon supports enhances fast electron transport. Besides, the unique carbon sheet-supported nanostructure inhibits the aggregation of Mo2C nanoparticles and exposing large amounts of active sites, resulting in high electrocatalytic activity. 3. An internal oxidation and reduction route was utilized to prepare molybdenum phosphide (MoP). We introduced phosphorous precursor (NaH2PO4?2H2O) to the above experiment system and MoP nanosheets supported on carbon flake were obtained via similar calcination conditions. As novel HER electrocatalysts, such hybrids show superior activity as compared to bulk MoP in both acidic and neutral electrolytes. Carbon species play a key role in reducing phosphorous. To prove this, multi-wall carbon nanotubes were utilized in a similar calcination process and MoP/CNT hybrids were finally obtained. The robust hybrids also operate in H2 producing in acidic and neutral conditions
催化转化5-羟甲基糠醛（HMF）制备呋喃衍生物
No full text利用可再生的生物质资源制备精细化学品意义重大。5-羟甲基糠醛（HMF）是糖类在酸催化下的脱水产物，是一种重要的生物质衍生物，受到很大的关注。HMF可以通过氧化、氢化等反应转化成2,5-呋喃二甲醛（DFF）、2,5-二羟甲基呋喃（BHMF）、5-羟甲基-2-呋喃甲酸（HFCA）和2,5-呋喃二甲酸（FDCA）等呋喃衍生物，它们可作为高分子聚合物的单体，也可以用于制备多种精细化学品。目前，开发高效的、环境友好的催化体系用于催化转化HMF制备呋喃衍生物是研究的热点。 使用柠檬酸溶胶凝胶法对CeO2进行Bi的掺杂改性，得到的固溶体存在大量的氧空位缺陷。Ce1-xBixO2-δ（0.08≤x≤0.5）可以有效催化 HMF在碱性水溶液中转化生成BHMF和HFCA，反应20分钟后，HMF转化率达97%。这是首次发现的非贵金属氧化物催化的HMF的Cannizzaro反应且Bi的掺杂具有特异性。Ce1-xBixO2-δ（x≤0.2）上负载Au后，得到的催化剂可以有效催化HMF氧化生成FDCA。使用Au/Ce0.9Bi0.1O2-δ催化剂，65℃下反应2小时，FDCA的收率大于99%。 制备了PVP稳定的Pt溶胶并负载在Ce1-xBixO2-δ上用于催化HMF转化。Pt/Ce0.8Bi0.2O2-δ催化剂表现了优异的催化氧化活性，室温下反应30分钟，FDCA收率高达98%。这是首次发现的铈基载体负载的Pt催化剂高效催化醇的氧化反应。Bi的存在使Ce0.8Bi0.2O2-δ具有优异的低温活性氧的能力，在催化氧化过程中，Pt和Ce0.8Bi0.2O2-δ发挥各自特定的功能，它们的作用很好的结合，实现高效的催化醇和醛的氧化。 不同的Bi系氧化物负载的Pt催化剂都表现出优异的催化HMF氧化的性能，使用Pt/Bi2W3O12催化剂时，室温下反应仅15分钟，HMF完全转化，FDCA的收率高达99%。反应体系中碱的浓度、氧压、反应温度和催化剂的用量对产物分布都有较大影响。 Au/LaMO3（M=Cr，Mn，Fe，Co，Ni）催化剂在高温、高氧压条件下可以催化HMF氧化制备HFCA和FDCA。在室温、大气环境下反应，Au/LaMnO3可以有效催化HMF发生Cannizzaro反应。对LaMnO3进行Zn掺杂后，得到的Au/LaMn0.9Zn0.1O3在室温、大气环境下高效催化HMF的转化，反应仅5分钟，HMF完全转化，产生等量的Cannizzaro反应产物HFCA和BHMF。 以SiO2@Au为模型催化剂，考察了不同处理条件对其催化环己烷选择氧化的活性影响。对SiO2@Au直接烷基化疏水处理造成催化活性的降低，包硅后再疏水处理得到的SiO2@Au@SiO2-s催化剂的催化活性明显提高，150℃下反应3小时，环己烷的转化率达13%，环己醇和环己酮的总选择性近80%。With the continuous consumption of fossil resources, it is of great importance to exploit and utilize renewable biomass resources for preparation of bulk and fine chemicals. 5-Hydroxymethylfurfural (HMF), which can be obtained from dehydration of glucose or fructose under the catalyzing of acid, is a compelling platform chemical for the production of 2,5-diformylfuran (DFF), 2,5-bishydroxymethylfuran (BHMF), 5-hydroxymethyl-2-furancarboxylic acid (HFCA) and 2,5-furandicarboxylic acid (FDCA). These stuffs have been regarded as promising monomers for preparing resins, polymers and fine chemicals. The development of highly efficient, environmental-friendly catalytic system for the preparation of furan-based materials from HMF is a key research field nowadays. Porous Bi-doped ceria was prepared by the citrate method, and there existed large amount of oxygen vacancies in the obtained Ce1?xBixO2?δ solid solution. In the presence of O2, Ce1?xBixO2?δ (0.08 ≤ x ≤ 0.5) efficiently catalyzed the conversion of HMF to HFCA and BHMF in alkaline aqueous solution without degradation of HMF. A 97% conversion of HMF was achieved only after 20 min. The excellent catalytic activity was attributed to the oxygen activation and hydride transfer enhanced by Bi doping and the large amount of oxygen vacancies. After Au nanoparticles (NPs) were supported on Ce1?xBixO2?δ (x ≤ 0.2), the presence of Auδ+ facilitated the activation of the C-H bond in the hydroxymethyl group and then the production of FDCA as an end product, inhibiting the generation of BHMF. When performing the reaction at 65 °C, a >99% yield of FDCA was obtained after 2 h over the Au/Ce0.9Bi0.1O2?δ catalyst. The oxidation of HMF to FDCA was efficiently catalyzed when PVP stabilized Pt NPs were supported onto a Ce0.8Bi0.2O2?δ solid solution. 98% yield of FDCA was achieved within 30 min at room temperature and the catalyst was reused five times without much loss of FDCA selectivity. It is the first report on the oxidation of HMF, an alcohol and an aldehyde, effectively catalyzed by a ceria-based material supported Pt catalyst. The individual properties of the Pt NPs and the ceria-based support were retained and not affected after their combination. The superior oxygen activation ability of the Bi-doped ceria thoroughly changed the performance of the ceria supported Pt catalyst. The specific functions of Pt NPs and Bi-containing ceria were well incorporated during the catalytic oxidation cycle, leading to the generation of the highly efficient Pt/Ce0.8Bi0.2O2?δ catalyst for the oxidation of alcohol group and aldehyde group at room temperature. A series of Bi-contained oxide supported Pt catalyst were prepared and was evaluated for the selective oxidation of HMF to FDCA. All the catalysts showed excellent catalytic activities. When using Pt/Bi2W3O12 catalyst, a 100% conversion of HMF and a 99% yield of FDCA were obtained only after 15 min at room temperature. The effect of the reaction parameters on the product distribution was also investigated, such as amount of base, oxygen pressure, temperature and the usage amount of catalyst. When performing the reaction at high temperature and high oxygen pressure, the prepared Au/LaMO3 (M = Cr, Mn, Fe, Co, Ni) could catalyze the oxidation of HMF to HFCA and FDCA. When it reaction at room temperature and air atmosphere, the Au/LaMnO3 efficiently catalyzed the Cannizzarro reaction of HMF, and the catalytic activity was highly enhanced after doping 10mol% Zn in the Au/LaMnO3. With the presence of Au/LaMn0.9Zn0.1O3, HMF was totally converted only after reaction for 5 min, the Cannizzarro reaction products BHMF and HFCA were obtained equally. Liquid-phase selective oxidation of cyclohexane is a very important reaction in the industry. The effect of the treatment conditions on the catalytic activity towards cyclohexane oxidation was investigated using the model catalyst, SiO2@Au. The hydrophobic treatment reduced the catalyti
可注射酶交联水凝胶的制备及其在软骨组织工程中的应用
No full text软骨组织工程的发展为关节软骨缺损的修复提供了新的思路和方法。利用软骨组织工程修复关节软骨缺损时，需要将体外培养扩增后的种子细胞，如干细胞、软骨细胞等，种植于支架材料中，从而在相关的生长因子作用下实现软骨组织的修复和重建。可注射水凝胶用作软骨组织工程支架时，不仅需要为种子细胞的生长提供支撑作用，还需要具备能够促进种子细胞增殖和分化的功能。其中，可注射酶交联水凝胶由于其形成条件温和、反应速率容易控制、具有良好的生物相容性而受到了广泛关注。酶交联水凝胶采用天然的酶作为催化剂，安全性高，不会引入有机溶剂，具有良好的生物相容性，便于包载药物、细胞和生物活性分子，不会对细胞造成损伤，且能够避免药物及生物活性分子的失活。酶交联水凝胶的反应速率容易控制，可以通过调节酶的催化活性进行有效调控，可控的反应速率能够有效地防止水凝胶的前驱体溶液的扩散。酶交联水凝胶可以进行原位注射，适用于修复形状复杂的组织缺损部位，不仅避免了预塑型支架材料难以与修复部位吻合的缺陷，还避免了植入型支架材料带来的手术创伤及并发炎症等，实现微创治疗。 本论文制备了多种可注射酶交联水凝胶，侧重研究酶交联水凝胶的性能调控及其对软骨细胞的表型、骨髓间充质干细胞的软骨向分化的影响，评价了可注射酶交联水凝胶作为3D细胞载体和软骨组织工程支架的可行性。具体研究内容和主要结论如下： （1）从酶催化苯酚类化合物的聚合出发，设计并合成了一种两端为苯酚基团的亲水性的线形聚合物TA-SA-PEG-SA-TA，对该线形聚合物的成凝胶行为和水凝胶性能进行了考察，通过改变聚合物、HRP的浓度和H2O2与苯酚基团的摩尔比，实现了对水凝胶的成凝胶时间和强度的有效调控。进一步合成了单端为苯酚基团的亲水性的线形聚合物mPEG-SA-TA，深入研究了其在HRP和H2O2的存在下的酶催化反应，结果表明，在HPR和H2O2的存在下，mPEG-SA-TA发生酶催化反应，其末端的苯酚基团能够相互反应形成二聚体或多聚体。我们推断，线形聚合物TA-SA-PEG-SA-TA采用同样的机理制备得到酶交联水凝胶，当H2O2与TA的摩尔比大于0.5时，TA-SA-PEG-SA-TA相互反应生成较多的苯酚多聚体，能够形成足够多的交联点，从而制备得到水凝胶，而当H2O2与TA的摩尔比小于0.5时，TA-SA-PEG-SA-TA上的苯酚基团虽然也能够相互反应生成部分多聚体，但产物中仍存在较多的单体，交联点数量较少，无法形成水凝胶。成功论证了两端为苯酚基团的线形聚合物的酶催化成凝胶机理，拓宽了酶交联水凝胶的材料选择范围。 （2）将酶催化的交联方式引入聚氨基酸领域，制备了一种新型的基于聚谷氨酸-g-酪胺/聚乙二醇的可注射酶交联水凝胶，水凝胶的理化性能，如机械强度、微孔结构、溶胀率等能够通过改变HRP、H2O2的浓度进行有效调节。进一步评价了水凝胶在体内外的生物相容性。细胞实验表明，该水凝胶及其浸提液具有良好的细胞相容性。用作3D细胞载体时，低浓度的H2O2制备的水凝胶具有更大的多孔结构，便于营养物质的渗透和细胞代谢产物的扩散，能够提供较大的空间以供细胞生长，更有利于细胞增殖。将水凝胶的前驱体溶液皮下注射到大鼠背部，水凝胶能够原位形成，14周后完全降解。水凝胶在降解过程中不会引起组织的病变，具有良好的生物相容性。 （3）制备了一种基于聚谷氨酸-g-酪胺的酶交联水凝胶，水凝胶的理化性能，如强度、微孔结构及体外降解性能等能够通过改变聚合物浓度进行有效调控。聚合物材料及水凝胶具有良好的细胞相容性。水凝胶能够在大鼠皮下完全降解，且降解过程中不会引起组织的病变，具有良好的生物相容性。通过改变聚合物浓度构建了不同的水凝胶微环境，选择兔的骨髓间充质干细胞（BMSCs）作为种子细胞，考察不同的水凝胶微环境对BMSCs的3D细胞形貌、增殖以及软骨向分化等的影响。结果表明，低浓度的水凝胶具有更大的多孔结构，便于营养物质的渗透和细胞代谢产物的扩散，能够提供较大的空间，促进BMSCs的铺展及增殖。在诱导培养基中培养4 周后，BMSCs在低浓度的水凝胶中形成结节，能够表达和分泌II型胶原、糖胺聚糖等软骨特异性细胞外基质，促进BMSCs向软骨分化。 （4）从模拟天然软骨细胞外基质中蛋白多糖的结构出发，设计并制备了基于类糖肽的可注射酶交联水凝胶，通过改变聚合物、HRP、H2O2浓度能够有效调控水凝胶的理化性能。聚合物材料及水凝胶具有良好的细胞相容性。水凝胶能够在大鼠皮下完全降解，且降解过程中不会引起组织的病变，具有良好的生物相容性。以类糖肽水凝胶作为仿生软骨组织工程支架材料，选用软骨细胞为种子细胞，评价了该凝胶作为软骨组织工程支架材料的可行性。结果表明，在体外3D培养和裸鼠皮下模型中，类糖肽水凝胶有利于软骨细胞的存活和增殖，促进去分化的软骨细胞在类糖肽水凝胶中3D环境中再分化，表达并分泌软骨特异性细胞外基质，在软骨组织工程中具有一定的应用潜力。Cartilage tissue engineering provides a promising approach for the regeneration of cartilage defects. This approach involves the combination of chondrocytes or progenitor cells, growth factors with three-dimensional scaffolds. Injectable hydrogels may be suitable platforms for supporting the survival, proliferation and differentiation of incorporated chondrocytes or progenitor cells and serve as scaffolds for cartilage tissue engineering, attributed to their physical properties that resemble the native ECM. Recently, increasing attention has been paid to enzymatically crosslinked hydrogels for biomedical applications due to their excellent biocompatibility, fast gelation process and tunable mechanical properties. Enzymatically crosslinked hydrogels can be formed in situ under physiological conditions with the presence of natural enzymes. Meanwhile, cells and bioactive molecules can be homogeneously incorporated in the hydrogels, avoiding the damage to cells and the inactivation of bioactive molecules. The gelation time could be adjusted effectively by varying the concentrations of the enzymes, preventing the diffusion of precursor solutions. The precursor solutions of enzymatically crosslinked hydrogels can be administrated via a minimally invasive procedure, and are able to appropriately ?ll irregular-shaped defects. In this dissertation, we have prepared several injectable enzymatically crosslinked hydrogels with the presence of horse horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) and focused on the regulation of the properties of hydrogels, chondrocyte phenotype and differentiation of bone marrow mesenchymal stem cells (BMSCs). The feasibility of injectable enzymatically crosslinked hydrogels as three dimensional cell carriers and scaffolds for cartilage tissue engineering has been evaluated. The main contents and conclusions of this dissertation are summarized as follows: (1) Motivated by enzyme-catalyzed polymerization of phenol compounds, a hydrophilic linear polymer containing terminal phenol groups, TA-SA-PEG-SA-TA was designed. When the molar ratio of H2O2 to TA was greater than 0.5, the hydrogels based on the linear polymer were rapidly formed under physiological conditions with the presence of HRP and H2O2. The gelation time and storage modulus of the hydrogels were adjusted by changing the concentrations of polymer, HRP and the molar ratio of H2O2 to TA. Another hydrophilic linear polymer containing single terminal phenol group, mPEG-SA-TA, was then synthesized to clarify the enzyme-catalyzed polymerization reaction and gelation mechanism. The results demonstrated that mPEG-SA-TA formed dimers or oligomers with the presence of HRP and H2O2. Therefore, we inferred that the gelation process of TA-SA-PEG-SA-TA occurred in the similar manner. When the molar ratio of H2O2 to TA was great than 0.5, the oxidative coupling reaction of phenol moieties in TA-SA-PEG-SA-TA generated enough oligomers, resulting in the formation of intermolecular crosslinks and the formation of hydrogels. While the molar ratio of H2O2 to TA was less than 0.5, the precursor solutions didn’t undergo sol-gel transition, owing to the formation of less oligomers. (2) A kind of enzyme-mediated injectable hydrogel based on poly(L-glutamic acid) grafted with tyramine and poly(ethyleneglycol) (PLG-g-TA/PEG) was prepared. The hydrogels were rapidly formed under physiological conditions with the presence of HRP and H2O2. The gelation time could be adjusted by varying the concentrations of HRP and H2O2. The physicochemical properties of the hydrogels, including mechanical strength, swelling ratio and porous structure, were dependent on the concentrations of HRP and H2O2. The live-dead staining and cell counting kit-8 revealed that the PLG-g-TA/PEG hydrogels exhibited good cytocompatibility in vitro. The in situ formed hydrogels in the subcutaneous layer of rats persisted for up to 14 weeks and displayed acceptable biocompatibility in vivo. Ther