银纳米粒子在木瓜蛋白酶固定化中的应用

通过超声条件下正硅酸四乙酯与g-氨丙基三乙氧基硅烷的同步水解,一步制备了带氨基的二氧化硅微球,并在其表面沉积了银纳米粒子. 以此负载银的二氧化硅微球作为载体固定木瓜蛋白酶,研究了银纳米粒子负载量对木瓜酶固定化的影响,考察了固定化木瓜蛋白酶的性能. 结果表明,当载体的银负载量为0.68%时,固定木瓜蛋白酶活回收率达到最高,比使用未负载银的载体提高了188%;该固定酶比游离酶具有更好的热稳定性,在重复使用20次后仍保持原有酶活的43%,4℃下储存2个月后酶活基本没有下降.     

溶胶-凝胶法固定化木瓜蛋白酶的活性保护

选择糖和脂质体作为溶胶-凝胶法固定木瓜蛋白酶(Papain)过程中的保护剂. 研究了蔗糖、葡萄糖、海藻糖、木糖、麦芽糖及构成脂质体的正癸烷溶液中胆固醇含量、卵/胆比等因素对固定化酶活性的影响. 结果表明,80 mL 20 mg/mL Papain溶液与15 mg木糖、500 mL正癸烷溶液[溶有1.5%(w)胆固醇,卵磷脂/胆固醇质量比为4.5:1]充分混合后制备的固定化酶活性最高. 在优化条件下制备的固定化酶包封率为42.0%,活力回收率为61.2%. SEM分析表明,固定化酶形态呈球状且大小均匀,内孔分布呈蜂窝状. 破膜剂对固定化酶活性发挥的影响研究表明,TritonX-100的效果最好.     

大分子拥挤下介孔中木瓜蛋白酶的微波辅助固定化

为了增强酶的固定化效果,通过添加大分子试剂,在微波辐射作用下将木瓜蛋白酶固定在介孔泡沫硅的孔道中. 结果表明,在加酶量为400 mg/g时,微波辐射下木瓜蛋白酶与牛血清白蛋白(BSA)共固定化制得的固定化酶催化效果最好. 当BSA含量为加酶量的5%(w)时,固定化酶表观活力高达419.1 U/mg,相对活力和酶活回收率分别为126.0%和119.1%. 影响固定化酶活力的主要因素依次为加酶量、BSA含量、微波功率和固定化pH. 该固定化酶的最适反应pH为7.0,最适反应温度为75℃,热稳定性优于游离酶和未加入BSA的固定化酶,80℃下热处理3 h,剩余活力仍为初始活力的88.2%.     

酶酸连续降解壳聚糖制备低分子量水溶性壳聚糖的研究

采用酶酸连续降解壳聚糖制备低分子量水溶性壳聚糖。首先确定了单因素降解壳聚糖的最佳技术参数：木瓜蛋白酶降解壳聚糖时最优条件为45℃、2h;醋酸降解壳聚糖时最优条件为30℃、4h;盐酸降解壳聚糖最优条件为90℃、8h;然后根据单因素降解壳聚糖最优条件确定了酶酸连续降解壳聚糖新工艺,并优化反应时间为7h。在相同条件下,酶酸连用方法最终降解产物的粘度低于单因素降解产物的粘度,产物表面性状有很大不同,分子量由降解前的33523．14下降到3134．11。     

Salen-Mn催化剂的固载化及在环氧化反应中的应用研究

以HMS(NH2)、HMS-PAMAM(G0)、HMS-PAMAM(G1)、HMS-PAMAM(G2)为载体,采用化学接枝法合成了4种Salen-Mn固相催化剂;用红外光谱、热重分析和滴定分析等手段对其进行了表征,并考察了它们在反式二苯乙烯环氧化反应中的催化活性。结果表明随着HMS-PAMAM代数的增加,催化剂催化活性增强,转化频率降低,催化剂重复使用性能较好。     

Importance of Matrix Cues on Intervertebral Disc Development,Degeneration, and Regeneration

Back pain is one of the leading causes of disability worldwide and is frequently caused by degeneration of the intervertebral discs. The discs’ development, homeostasis, and degeneration are driven by a complex series of biochemical and physical extracellular matrix cues produced by and transmitted to native cells. Thus, understanding the roles of different cues is essential for designing effective cellular and regenerative therapies. Omics technologies have helped identify many new matrix cues; however, comparatively few matrix molecules have thus far been incorporated into tissue engineered models. These include collagen type I and type II, laminins, glycosaminoglycans, and their biomimetic analogues. Modern biofabrication techniques, such as 3D bioprinting, are also enabling the spatial patterning of matrix molecules and growth factors to direct regional effects. These techniques should now be applied to biochemically, physically, and structurally relevant disc models incorporating disc and stem cells to investigate the drivers of healthy cell phenotype and differentiation. Such research will inform the development of efficacious regenerative therapies and improved clinical outcomes.     

硝苯地平骨架控释片的制备及其体外释放性能

研制了硝苯地平口服骨架控释片,考察了片剂处方和主要制备参数对药物释放速率的影响。通过对硝苯地平口服骨架片的制备工艺和处方组成进行优化,确定最优片剂处方为:硝苯地平固体分散体(硝苯地平与羟丙基甲基纤维素质量比为1∶1)60mg,聚环氧乙烷20mg,甘露醇10mg;采用粉末直接压片方法,压制硬度为(85±10)N的硝苯地平控释骨架片。体外释放研究表明,在14h内药物的释放度为89.69%,释放曲线的线性相关度为0.9962,具有良好的零级释放特性。这为研制恒速释放的硝苯地平制剂提供了一种新思路。     

Immobilization of glucose oxidase in alginate-chitosan microcapsules

In order to improve its stability and catalytic rate in flour, the immobilization of glucose oxidase (GOX) was investigated in this work. The enzyme was encapsulated in calcium alginate-chitosan microspheres (CACM) using an emulsification-internal gelation-GOX adsorption-chitosan coating method. The interaction between alginate and chitosan was confirmed by infrared spectroscopy (IR). The resultant CACM in wet state, whose morphology was investigated by scanning electron microscopy (SEM), was spherical with a mean diameter of about 26 μm. The GOX load, encapsulation efficiency and activity of the CACM-GOX were influenced by concentration of chitosan, encapsulation time and encapsulation pH. The highest total enzymatic activity and encapsulation efficiency was achieved when the pH of the adsorption medium was near the isoelectric point (pI) of GOX, approximately pH 4.0. In addition, the molecular weight of chitosan also evidently influenced the encapsulation efficiency. Storage stabilities of GOX samples were investigated continuously over two months and the retained activity of CACM-GOX was 70.4%, markedly higher than the 7.5% of free enzyme. The results reveal the great potential of CACM-GOX as a flour improver.     

催化无基体法制备碳纳米管

用一种新的催化裂解法 ,制备出了直径在 2 0～ 30nm ,长度为 2 0 0 μm的碳纳米管。在此方法中 ,繁琐的催化剂制备工艺被省略 ,催化剂前驱体在载气带动下直接进入反应器。另外还发现两类结构独特的碳纳米管。     

The Use of Poly-L-Lysine to Form Novel Silica Morphologies and the Role of Polypeptides in Biosilicification

Silicification at neutral pH and under ambient conditions in vitro is of great interest due to its relationship with silicification in vivo as well as for the benign conditions of the process. As it is important to know the exact group(s) or a particular site in the macromolecules that are responsible for the silicification under these conditions in vivo, poly-L-lysine (PLL) was chosen for this investigation in vitro. Here we report the use of tetramethoxysilane (TMOS) as a silica precursor and the utilization of poly-L-lysine (PLL) for silicification at neutral pH and under ambient conditions. We describe (1) the use of PLL to precipitate silica, (2) the effect of mixing of macromolecules PLL and poly(allylamine hydrochloride) (PAH) to control morphologies of the product, and (3) the formation of novel silica morphologies.     

氧化竹纤维固定木瓜蛋白酶

通过高碘酸钠-甲醛法对几种竹纤维氧化改性,制备了良好的竹纤维固定化酶载体,并对木瓜蛋白酶进行固定,考察了固定化酶固定条件、最适微环境以及稳定性。结果表明,在4℃、pH=7.5,给酶量为15 g/L条件下固定24 h,改性竹纤维固定化木瓜蛋白酶具有较高催化活性,活力可达805.5 U/g,其最适催化条件为50℃、pH=7.5,较游离酶有更好的耐热性和耐碱性,重复使用6次后活性仍能达到初始活力的76.9%。     

Biofilm Matrix and Its Regulation in Pseudomonas aeruginosa

Biofilms are communities of microorganisms embedded in extracellular polymeric substances (EPS) matrix. Bacteria in biofilms demonstrate distinct features from their free-living planktonic counterparts, such as different physiology and high resistance to immune system and antibiotics that render biofilm a source of chronic and persistent infections. A deeper understanding of biofilms will ultimately provide insights into the development of alternative treatment for biofilm infections. The opportunistic pathogen Pseudomonas aeruginosa, a model bacterium for biofilm research, is notorious for its ability to cause chronic infections by its high level of drug resistance involving the formation of biofilms. In this review, we summarize recent advances in biofilm formation, focusing on the biofilm matrix and its regulation in P. aeruginosa, aiming to provide resources for the understanding and control of bacterial biofilms.     

超氧化物歧化酶的固定化及其酶学性质

目的制备固定化超氧化物歧化酶(SOD),并分析其酶学性质。方法以壳聚糖为载体,戊二醛为交联剂,制备固定化超氧化物歧化酶。以邻苯三酚自氧化法分别测定溶液酶与固定化酶的活力,并计算回收率。对固定化酶的温度和pH稳定性、半衰期、重复使用的回收率及米氏常数(Km)进行测定。结果固定化超氧化物歧化酶活力为333U/g,酶活回收率为86.32%,半衰期为43.8d;固定化酶室温保存5d后,相对酶活力仍保持在80%以上,最适反应温度为45℃,使用一次后回收率为70.12%,重复使用两次后回收率为51.72%;固定化酶与溶液酶在pH6时活性最强,Km分别为0.18mmol/L和0.16mmol/L。结论该固定化酶较溶液酶的稳定性得到提高,便于贮存,在食品、药品、日用品等领域有良好的应用前景。     

Synthesis and Application of Silica-Coated Quantum Dots in Biomedicine

Quantum dots (QDs) are semiconductor nanoparticles with outstanding optoelectronic properties. More specifically, QDs are highly bright and exhibit wide absorption spectra, narrow light bands, and excellent photovoltaic stability, which make them useful in bioscience and medicine, particularly for sensing, optical imaging, cell separation, and diagnosis. In general, QDs are stabilized using a hydrophobic ligand during synthesis, and thus their hydrophobic surfaces must undergo hydrophilic modification if the QDs are to be used in bioapplications. Silica-coating is one of the most effective methods for overcoming the disadvantages of QDs, owing to silica’s physicochemical stability, nontoxicity, and excellent bioavailability. This review highlights recent progress in the design, preparation, and application of silica-coated QDs and presents an overview of the major challenges and prospects of their application.     

含钛介孔SiO2 催化剂的合成及其催化性能

分别以廉价硅酸钠与正硅酸乙酯为硅源,通过复合模板剂制备了介孔二氧化硅,并利用吸附相反应技术合成了TiO2/SiO2复合催化剂。用X射线衍射(XRD)、红外谱图分析(FT-IR)等手段对其结构进行了表征,通过苯酚的羟基化反应考察了催化剂的催化性能。     

判断实对称矩阵正定性的又一种方法

本文给出了判断实对称矩阵正定性的一种方法,它比通常使用的方法更为简单和方便。     

A Novel Nanocomposite Matrix Based on Silylated Chitosan and Multiwall Carban Nanotubes for the Immobilization of Urease

A nanocomposite matrix made up of silylated chitosan and multiwall carbon nanotubes (CHIT–SiO₂–MWCNTs) was fabricated to investigate the immobilization of urease (Urs). Urs enzyme was covalently immobilized with the CHIT–SiO₂–MWCNTs matrix using glutaraldehyde as a linker. The resulting Urs/CHIT–SiO₂–MWCNTs biomatrix was characterized with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and cyclic voltammetry (CV) taking CHIT–SiO₂–MWNTs as a reference. The influence of various parameters on Urs enzyme activity within the matrix was investigated including pH, temperature, and time. The Michaelis–Menten constant and apparent activities for the Urs enzyme were calculated to be 0.51 mM and 89.02 mg/cm², respectively; indicating CHIT–SiO₂–MWCNTs nanocomposite matrix has a high affinity to immobilize Urs enzyme.     

三种树脂基复合材料在不同温度的性能研究

目前在耐高温树脂中能经受长期高温氧化的热固性树脂只有聚酰亚胺，作为耐高温树脂基体及其复合材料，本文研究了CF／聚酰亚胺复合材料在不同温度的力学性能和热性能。作为应用量大面广的树脂基体及其复合材料，本文研究了两种环氧基体及其CF／环氧复合材料和GF／环氧复合材料在不同温度的力学性能。研究结果表明，复合材料的耐热性主要取决于基体。基体耐热性高的，复合材料在高温也保持高强度。     

铝酸锌包覆氢氧化镁的制备及其在软质PVC中的抑烟性能研究

在氢氧化镁存在的悬浮液中,通过硫酸锌与铝酸钠反应生成铝酸锌来制备铝酸锌包覆的氢氧化镁粉体,并考察了其在聚氯乙烯（PVC）中的抑烟作用。结果表明,与未处理的氢氧化镁相比,铝酸锌包覆的氢氧化镁碱性更弱,吸油值更低;锥形量热仪和烟密度测试结果表明,添加20份铝酸锌包覆氢氧化镁的PVC阻燃材料的总烟释放量为10.36 m2/m2,比添加2份铝酸锌和20份氢氧化镁的分别降低了24 %和48 %;其烟密度等级为65,而添加铝酸锌的为76,添加氢氧化镁的为90。     

基于SiO2材料的细胞固定化研究及应用

基于SiO2的材料主要由烷氧基与水溶性方法合成：前者主要以TMOS或TEOS为SiO2前躯体,并用其它有机硅化合物,甘油和海藻酸钙等对其进行进行修饰或复合,后者主要以硅酸钠溶液与胶体SiO2为硅源。这种材料可以包埋微生物,植物细胞,动物细胞,包埋后的生物复合材料则成为生物反应器,生物传感器,生物催化剂,人造生物器官等,它们可用于工业化学合成、信号监测、废水处理和细胞治疗。