低温等离子体引发PTFE膜接枝丙烯酸固定化酶研究

利用Ar等离子体引发PTFE膜接枝丙烯酸(Acrylic Acid),然后进行固定化脲酶,最终得到PTFE-g-pAAc-i-Urease膜.采用XPS和ATR-FTIR等分析手段对固定化酶膜表面进行表征,结果表明在PTFE表面固定上了脲酶.固定化脲酶保持了与溶液脲酶相当的活性,最佳活性温度为60℃,pH值为6.0左右,与溶液酶相比固定化脲酶的环境稳定性有较大的提高.     

聚乙烯醇凝胶固定化脲酶及载体生物相容性的评价

本文以聚乙烯醇（ＰＶＡ）凝胶为载体，用包埋法对脲酶进行了固定化，并与聚丙烯酰胺固定化脲酶进行了对比研究。结果表明，ＰＶＡ凝胶固定化脲酶具有较高的活力收率（７９％）。其急性毒性及溶血试验合格，表明该材料具有良好的生物相容性。     

紫外老化对PET光栅印刷品性能的影响

目的研究聚对苯二甲酸乙二醇酯(PET)原料与不同配比的G905、G910、G918紫外光屏蔽剂片材经UV油墨印刷,紫外老化对PET光栅印刷品颜色色差值△E的影响。方法以PET为原料,经添加紫外光屏蔽剂、PET光栅挤出、UV胶印等工艺成为PET光栅印刷品,对添加不同配比紫外光屏蔽剂的3种PET光栅印刷品进行紫外老化试验,测试PET光栅印刷品颜色L~*、a~*、b~*值和色差值△E的变化。结果在同等条件下,紫外老化216 h,PET光栅印刷品颜色随紫外老化时间的增加色差值△E逐渐变大,色差值△E均在4.0以内,适合大部分PET光栅印刷品的使用要求。结论添加紫外光屏蔽剂有利于提高PET光栅印刷品的抗老化性能,在PET原料内添加紫外光屏蔽剂,是延缓老化速率的有效方法。     

担载不同结构胺基的P(GMA-EDGMA)大孔载体的固定化酶活

设计并制备了一种树枝状超支化胺(DHA-NH2),并用红外光谱(IR)、核磁共振谱(NMR)对其结构和性能进行了研究。利用DHA-NH2、乙二胺、己二胺、二乙烯三胺分别修饰P(GMA-EDGMA)树脂,制备得到4种表面带有不同胺基结构的固定化酶载体,以木瓜蛋白酶为被固定酶模型,研究表面胺基结构与固定化酶活之间的构效关系。结果表明,在胺基含量基本相同的条件下,载体固定化酶活顺序为二乙烯三胺>己二胺>乙二胺>DHA-NH2;活性链段数目、活性链段官能团密度以及活性链段长度共同决定固定化酶的酶活,且增加活性链段数目、增大活性链段官能团密度以及增长活性链段长度均能在一定程度上提高固定化酶活。     

异相聚合物对PET光扩散膜性能的影响研究

通过共混法在PET(聚对苯二甲酸乙二酯)中添加其它聚合物制备PET光扩散膜,采用其他聚合物作为内添加剂进行分析、研究,并通过实验对理论结果进行验证。研究光扩散材料的折射率、光扩散剂粒径、光扩散剂用量、光扩散膜拉伸倍率影响光扩散膜透光率、雾度性能结果。并探讨区别于传统的表面涂布的方法,运用一步法共混挤出工艺方法制备出透光率高、雾度大的光扩散膜材料。     

紫外辐照改性聚丙烯纤维固定化溶菌酶的研究

在聚丙烯纤维紫外光照法接枝甲基丙烯酸甲酯(MMA)的基础上,通过酰胺化反应将改性纤维表面官能团转换为胺基后进行溶菌酶固定化,实现聚丙烯纤维的酶法功能化改性.通过对比不同处理条件下纤维的红外光谱(FT-IR)和扫描电镜(SEM),可以看出MMA已经成功接枝到聚丙烯纤维上,并且将溶菌酶固定在了纤维上.另外,还考察了MMA接枝率对纤维表面胺基密度和固定化溶菌酶酶活的影响.结果表明,纤维上的胺基密度随改性效果的提高而增大,当接枝率为1.69%时,固定化的溶菌酶酶活达到最大值为18U/cm2.     

二氧化钛催化光降解聚对苯二甲酸乙二酯的研究

利用原位聚合法合成PET/TiO2复合材料.通过分析PET/TiO2复合薄膜在紫外光降解过程中的质量和表面形态的变化情况,研究了锐钛矿型二氧化钛对PET光氧化降解性能的影响.结果说明,在试验范围内,在253.9nm的紫外光照射的光降解实验中,锐钛矿型TiO2的含量越高,PET/TiO2复合薄膜的质量损失率就越高;同时,紫外光照射试样288h之后,由SEM照片发现复合材料表面损伤程度也随着TiO2含量的升高而越发严重.这说明,锐钛矿型TiO2对PET的光氧化降解具有催化作用,而且含量越高催化作用就越强.     

涤纶材料表面固定水蛭素及其血液相容性研究

利用紫外辐照仪在聚对苯二甲酸乙二醇酯(涤纶,PET)膜表面接枝聚丙烯酸(PET-AA)长链分子,再通过化学方法进一步固定水蛭素,获得的改性表面的X光电子能谱分析表明水蛭素分子被有效地固定在PET表面.改性表面的水接触角降低,亲水性得到改善.体外血小板粘附实验的结果显示,固定了水蛭素的PET薄膜的血液相容性比未改性的PET膜有明显的改善.     

马来酸酐/苯乙烯电荷转移络合物体系的表面光接枝反应

研究了有氧条件下,以二苯甲酮(BP)为光敏引发剂,马来酸酐(M AH)/苯乙烯(S t)电荷转移络合物(CTC)体系为双单体体系,经紫外光照射,在聚酯(PET)薄膜表面进行的薄液相接枝反应。探讨了光敏引发剂浓度、光照时间以及苯乙烯浓度对接枝效果的影响,通过表面亲水性的测试表征了接枝效果的好坏,SEM照片从直观上表征了接枝后PET薄膜表面形貌的巨大变化,大大改善了原PET膜印刷性差的特点。此外,UV光谱图作为马来酸酐、苯乙烯电荷转移络合物体系的表征,初步探讨了此双单体体系接枝反应的机理。     

系列有机硅改性紫外光-热混杂固化树脂的表面性能EI北大核心CSCD

以有机硅改性丙烯酸环氧单酯为树脂配制了一系列紫外光-热混杂固化体系,用红外光谱(FT-IR)表征了固化过程特征吸收峰的变化;测试了有机硅链段的长短对固化膜表面水接触角、表面能和硅元素分布的影响。结果表明,在相同稀释剂条件下,丙烯酸环氧单酯光-热固化膜的表面水接触角为62.53°,表面能为47.62 mN/m,有机硅改性丙烯酸环氧单酯体系光-热固化膜的表面水接触角最高可达106.75°,相应的表面能为18.62 mN/m。有机硅改性体系中随着有机硅链段的增长,固化膜表面水接触角和表面硅元素含量逐渐增加,表面能则逐渐下降,表面元素分析也显示固化膜表面硅元素含量要比背面的高。     

Biomolecular modification of carbon nanotubes for studies of cell adhesion and migration

We report a strategy for tailoring and patterning carbon nanotubes (CNTs) for biospecific cell studies. We synthesized a new electroactive hydroquinone terminated pyrene molecule to tailor CNTs. These modified CNTs can be oxidized and chemoselectively reacted with oxyamine tethered ligands to generate various ligand tethered CNTs. A cell adhesive Arg-Gly-Asp peptide (RGD) is immobilized to the CNTs and a new microfluidic patterning method is employed to generate multiplex patterned surfaces for biospecific cell adhesion and migration studies. This work demonstrates the integration of a new functionalization strategy to immobilize a variety of ligands to CNTs for a range of potential drug delivery, tissue imaging and cellular behavior studies and a microfluidic patterning strategy for generating complex high-throughput surfaces for biotechnological and cell based assay applications.     

Antibody arrays prepared by cutinase-mediated immobilization on self-assembled monolayers

Antibody arrays hold considerable potential in a variety of applications including proteomics research, drug discovery, and diagnostics. Many of the schemes used to fabricate the arrays fail to immobilize the antibodies at a uniform density or in a single orientation; consequently, the immobilized antibodies recognize their antigens with variable efficiency. This paper describes a strategy to immobilize antibodies in a single orientation, with a controlled density, using the covalent interaction between cutinase and its suicide substrate. Protein fusions between cutinase and five antibodies of three different types (scFv, V(HH), and FN3) were prepared and immobilized upon self-assembled monolayers (SAMs) presenting a phosphonate capture ligand. The immobilized antibodies exhibit high affinity and selectivity for their target antigens, as monitored by surface plasmon resonance and fluorescence scanning. Furthermore, by changing the density of capture ligand on the SAM the density of the immobilized antibody could be controlled. The monolayers, which also present a tri(ethylene glycol) group, are inert to nonspecific adsorption of proteins and allow the detection of a specific antigen in a complex mixture. The demonstration of cutinase-directed antibody immobilization with insert SAMs provides a straightforward and robust method for preparing antibody chips.     

Enhancement of the thermal and storage stability of urease by covalent attachment to phospholipid-bound silica.

Urease was immobilized directly on silanized silica surfaces carrying alkyl moieties with terminal carboxylic groups. The enzyme was also covalently attached to phospholipid-bound silanized silica surfaces through the terminal carboxyl moiety on the sn-2 acyl chain of the lipid. The surfaces were characterized by X-ray photoelectron spectroscopy and ellipsometry. The activity of the immobilized urease was determined by UV spectrophotometry using a urea/bromocresol purple substrate. The enzymic activity decreases exponentially upon storage under dry solid conditions for 1 week or upon heating to 100 degrees C in the case of the silane/enzyme surfaces. On the other hand, the enzyme immobilized on phospholipid-carrying silica surfaces retained its entire original activity under dry storage or heat treatment conditions. Such immobilized urease systems could find extensive applicability in the design of in vivo dialysis equipment or for on-line monitoring of urea.     

Simple surface modification techniques for immobilization of biomolecules on SU-8

SU-8, an epoxy based negative photoresist polymer has found wide range of applications in the field of microfabrication based biosensors. SU-8 surfaces need to be modified in order to immobilize bioreceptors. We studied the possibility of grafting desired functional groups by means of simple chemical treatments under normal laboratory conditions. These chemical treatments involve the use of crosslinkers that are expected to react with epoxy groups or hydroxyl groups generated by acid/alkali treatment. Here, a comparison of the results obtained on surface modification using glycine and 11-mercapto undecanoic acid as crosslinkers is presented. Human Immunoglobin G (HIgG) was covalently immobilized to carboxylic acid on SU-8 surface using carbodiimide/succinimide chemistry. The activity of immobilized HIgG was verified by using fluorescence imaging of FITC tagged goat anti HIgG bound to the surface. Fluorescence imaging was used to determine the chemistry best suited to functionalize SU-8 surface for biosensor applications.     

Preparing catalytic surfaces for sensing applications by immobilizing enzymes via hydrophobin layers

Simple and reliable immobilization techniques that preserve the activity of enzymes are of interest in many technologies based on catalysis. Here, two redox enzymes, glucose oxidase from Aspergillus niger and horseradish peroxidase, were immobilized by physisorption on glassy carbon electrodes coated with Schizophyllum commune hydrophobin. Hydrophobins are small, interfacially active proteins that have the remarkable property of adhering to almost any surface. We showed recently that these proteins can be used to immobilize small, electroactive molecules. The results obtained in this work show a way to easily manufacture stable, enzyme-based catalytic surfaces for applications in biosensing.     

聚丙烯－胰蛋白酶膜的制备与性能

讨论了用空气等离子体活化处理技术制备聚丙烯－胰蛋白酶膜的方法。研究了等离子体处理参数和接枝反应条件对聚丙烯接枝丙烯酸的接枝率和聚丙烯－胰蛋白酶固定化酶膜活力的影响。评价了聚丙烯－胰蛋白酶膜的稳定性。用ＩＲ和ＥＳＣＡ分析了接枝膜和聚丙烯－胰蛋白酶的结构与组成。     

Phospholipid-sepiolite biomimetic interfaces for the immobilization of enzymes

Biomimetic interfaces based on phosphatidylcholine (PC) assembled to the natural silicate sepiolite were prepared for the stable immobilization of the urease and cholesterol oxidase enzymes. This is an important issue in practical advanced applications such as biocatalysis or biosensing. The supported lipid bilayer (BL-PC), prepared from PC adsorption, was used for immobilization of enzymes and the resulting biomimetic systems were compared to several other supported layers including a lipid monolayer (ML-PC), a mixed phosphatidylcholine/octyl-galactoside layer (PC-OGal), a cetyltrimethylammonium monolayer (CTA), and also to the bare sepiolite surface. Interfacial characteristics of these layers were investigated with a focus on layer packing density, hydrophilicity/hydrophobicity, and surface charge, which are being considered as key points for enzyme immobilization and stabilization of their biological activity. Cytoplasmic urease and membrane-bound cholesterol oxidase, which served as model enzymes, were immobilized on the different PC-based hybrid materials to probe their biomimetic character. Enzymatic activity was assessed by cyclic voltammetry and UV-vis spectrophotometry. The resulting enzyme/bio-organoclay hybrids were applied as active phase of a voltammetric urea biosensor and cholesterol bioreactor, respectively. Urease supported on sepiolite/BL-PC proved to maintain its enzymatic activity over several months while immobilized cholesterol oxidase demonstrated high reusability as biocatalyst. The results emphasize the good preservation of bioactivity due to the accommodation of the enzymatic system within the biomimetic lipid interface on sepiolite.     

交联海藻酸钠磁性微球的制备及固定化胰蛋白酶研究

制备了交联海藻酸钠磁性微球,并以磁性微球为载体,戊二醛为交联剂,将胰蛋白酶固定化;利用透射电镜、粒度分析、红外分析对交联海藻酸钠磁性微球进行了表征;探讨给酶量、戊二醛浓度和pH值对固定化酶活性的影响;与自由酶比较,考察了固定酶的酶学性质.结果表明:交联海藻酸钠磁性微球是固定化胰蛋白酶的良好载体,固定化酶最适宜的条件是吸附时间12h,给酶量为100mg/0.1g磁性载体、交联剂戊二醛浓度为5%、溶液pH值为6,同时将酶固定化后,酶的稳定性和催化性能均有所提高.