聚天门冬氨酸阻垢作用的研究

以L－天门冬氨酸为原料采用聚合－水解二步反应合成出具有优异阻垢性能的聚天冬氨酸，考察分析了它对碳酸钙的阻垢作用及相关机理。     

聚天门冬氨酸阻垢作用的研究

以L 天门冬氨酸为原料采用聚合—水解二步反应合成出具有优异阻垢性能的聚天冬氨酸 ,考察分析了它对碳酸钙的阻垢作用及相关机理     

聚天门冬氨酸类阻垢剂的生物降解性评定方法

介绍了一种评价聚天门冬氨酸(PASP)类阻垢剂生物降解性的评定方法——摇床实验法，提出了相应的评价标准，并用该方法对10种聚天门冬氨酸类物质的生物降解性进行了合理评价。     

顺酐为原料合成聚天门冬氨酸及其阻垢性能的测定

研究了以顺酐为主要原料合成聚天门冬氨酸(PASP), 最佳合成条件为顺酐与氨水及催化剂的摩尔比20∶20：1, 240℃条件下常压反应1h。该条件下的聚琥珀酰亚胺(PSI)的产率可以达到90%, 纯度为98.7%, 聚天门冬氨酸钠盐的相对分子质量达到3000。当Ca²⁺,HCO₃^-离子质量浓度为500mg/L(以CaCO₃计),阻垢率为95.3%。     

类蛋白质阻垢剂聚天门冬氨酸的合成研究

以L－天门冬氨酸（L－Asp)为原料，采用分散悬浮聚合法合成出具有优异阻垢性能的聚天门冬氨酸。通过正交试验设计确定了适宜的反应条件，并讨论了催化剂用量、聚合温度、聚合时间、原料粒度等对产品性能及分子量的影响。利用IR、^13CNMR和^1H NMR对聚合物进行了表征。研究表明适量催化剂可保护－NH2基，减少副反应，加快反应速度，同时可提高分子量，能催化剂过量时起封端作用。具有优异阻垢性能的聚天门冬氨酸盐的聚合度约为100。     

微波辐射法合成聚天门冬氨酸的研究

研究了以L-天门冬氨酸为原料，用微波辐射法合成聚天门冬氨酸的最佳条件，采用粘度法测定了聚天门冬氨酸的分子量，其分子量范围8000—10000。     

聚天门冬氨酸高吸水性树脂吸水率测定方法的研究

试验采用常用的吸水量测定方法考察聚天门冬氨酸吸水树脂的吸水性能,得出茶袋法更适合对其性能研究,采用此法测定吸水率的最适条件为：干树脂质量为02?g;在标有刻度的水槽中同时测定若干个样品;凝胶态树脂在吸水1,6,24h后测定吸水率;白色块状（含粉末状）树脂在吸水10,30min,10,22h后测定吸水率。文中还探讨了树脂的外部形态及部结构对其吸水性能的影响,发现白色块状和粉末状树脂的吸水率和吸水速度高于凝胶态树脂,树脂外观结构越疏松吸水速度越快。     

聚乙烯醇固定化细胞生产L—天门冬氨酸的研究

用聚乙烯醇作为主要载体，用共混，复合和加入多种助剂的方法，对固定天门冬氨酸酸的大肠杆菌，研究了固定化细胞的性质及固定化细胞的储存稳定性，探索了固定化细胞间隙和连续发酵生产Ｌ－天门冬氨酸的生产工艺，获得了间隙和连续发酵的生产能力及固定化细胞的半寿期。     

天门冬氨酸对精氨酸激酶的作用研究

应用酶活测定、荧光发射光谱等方法分析了精氨酸激酶在不同浓度天门冬氨酸中活性变化和去折叠动力学。实验结果表明：天门冬氨酸引起精氨酸激酶失活与去折叠,并且过程中没有蛋白质的聚沉;精氨酸激酶的去折叠遵循一级反应动力学的二相过程,包括快相和慢相;失活与天门冬氨酸浓度呈正相关;当去除天门冬氨酸的影响,精氨酸激酶的活力能得到恢复。通过对比实验结果暗示,天门冬氨酸是通过其解离状态的H＋改变了机体pH值而影响精氨酸激酶活性的,并且就天门冬氨酸对精氨酸激酶影响及其意义进行探讨。     

聚乙烯醇固定化细胞生产L－天门冬氨酸的研究

用聚乙烯醇作为主要载体，用共混、复合和加入事种助剂的方法，对固定天门冬氨酸酶的大肠杆菌，研究了固定化细胞的性质及固定化细胞的储存稳定性。探索了固定化细胞间隙和连续发酵生产Ｌ－天门冬氨酸的生产工艺．获得了间隙和连续发酵的生产能力及固定化细胞的半寿期．     

碱性介质中二羟基二过碘酸合镍(IV)配离子氧化天冬氨酸的反应动力学及机理

在碱性介质中于 ２０－３５℃用分光光度法研究了二羟基二过碘酸合镍（ＩＶ）配离子 （ＤＤＮ）氧化天冬氨酸的动力学。结果表明,反应对［Ｎｉ（ＩＶ）］为一级,对天冬氨酸为正分数级。准 一级速率常数（Ｋｏｂｓ）随［ＯＨ－］增加而减小,１／ｋｏｂｓ对［ｉｏ－４］有线性关系,表明二羟基一过碘酸合镍 （ＩＶ）配离子（ＤＭＮ）是氧化剂的活性物种。无盐效应且未检出自由基的存在。据此提出了包括 ＤＰＮ和ＭＰＮ以及天冬氨酸存在前期平衡的反应机理,并求出相应的活化参数。     

聚乳酸-聚乙二醇嵌段共聚物及其交联聚氨酯弹性体的性能研究

通过改变聚乙二醇的用量,将丙交酯与聚乙二醇共聚制成嵌预聚体,用二苯基甲烷二异氰酸酯扩链后再用三羟甲基丙烷交联,制得系列聚氨酯型新颖性体。通过对其性能研究表明,随着ＰＥＧ含量的增加,共聚物的特性粘度降低,玻璃化转变温度降低,拉伸强度先升后降;聚氨酯弹性体的玻璃化转变温度降低,拉伸强度降低,而降解速度去加快。     

利用重组大肠杆菌生产聚-3-羟基丁酸的研究

利用携带能合成聚-3-羟基丁酸的基因的大肠杆菌E. coli XL1-Blue,优化培养基和培养条件后,进行了补料分批培养.结果表明,重组大肠杆菌E. coli XL1-Blue(pKSS105)的最适培养基为R培养基.在最佳条件下,以葡萄糖为唯一碳源培养工程菌60h后,发酵液中菌体干重达183g/ L,P(3HB)的产量为133.8g/ L,P(3HB)含量为73.1%.实验结果为P(3HB)实际应用提供了可能性的基础.     

乙基纤维素共混改性聚乳酸的研究

将聚L-乳酸(PLLA)和乙基纤维素(EC)的三氯甲烷溶液以不同比例混合浇膜制备出的PLLA-EC共混物膜,采用红外光谱(FT-IR)、示差扫描量热法(DSC)和X-射线衍射等方法对共混物膜进行了表征。结果表明:PLLA与EC两种聚合物间存在着氢键作用,两种组分部分相容;PLLA与EC的比例对共混物的结晶性能有极大影响,随着EC含量的增加,共混物中PLLA结晶的熔点降低,结晶度、晶体尺寸和晶体完美度均降低;EC的含量对PLLA-EC共混物在磷酸缓冲溶液中的降解速率也有显著影响,当EC含量高于30%时,PLLA-EC共混物的降解速率会迅速增大。     

聚乙二醇-g-聚天冬氨酸(阿霉素)的制备与毒性

聚天冬氨酸侧链修饰得到聚乙二醇接枝聚天冬氨酸(PEG-g-PAsp),将此载体与抗癌药物阿霉素(ADR)反应,透析后得到PEG-g-PAsp(ADR)胶束.药物ADR作为胶束的核,PEG作为外壳,药物的包封率最高可达29.7%.进行的毒性分析表明形成的纳米粒子与纯药物相比,表现出了更高的抗肿瘤活性.从而证明PEG-g-PAsp可以作为一种非常有潜力的药物载体.     

Enhanced flame-retardant performance of poly (lactic acid) (PLA) composite by using intrinsically phosphorus-containing PLA

The intrinsically phosphorous-containing flame-retardant poly(lactic acid)(P-PLA) was synthesized through the chain extension of L-lactide and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO) derivative, then P-PLA was melt blended with neat PLA to produce flame-retardant PLA composite(FR-PLA). The flame-retardant properties of FR-PLAs were investigated by Limiting Oxygen Index(LOI), UL-94, and Cone Calorimeter Tests, the results indicated that the flame-retardant properties of PLA composites were significantly improved with the addition of P-PLA due to its excellent ability to carbonize and dilute combustible gases. The LOI value of FRPLA10 composite(consisting of 90 wt% neat PLA and 10 wt% P-PLA) increased from 20.5 to 27.8 and UL-94 rating reached up to V-1, the peak heat release rate and total heat release of FR-PLA composite were lower than those of neat PLA. The flame-retardant mechanism of FR-PLA depended on both condensed and gaseous phases,which was confirmed by the FTIR, Raman and TG-FTIR. Besides, the tensile strength of FR-PLA10 slightly decreased from 72.4 to 61.8 MPa, which met the requirements of most practical applications. Therefore, the modification method used in this work presented a feasible approach to prepare FR-PLA composite with satisfactory mechanical property.     

In vitro study of poly(ethylene carbonate) as a drug-eluting stent coating

An in vitro feasibility study of the use of poly(ethylene carbonate) (PEC) as a biodegradable coating material for drug-eluting stents is reported, and the performance of PEC is compared with that of poly(lactic-co-glycolic acid) (PLGA). Scanning electron microscopy (SEM) images of PEC and PLGA discs after treatment with an alkaline KO2 solution as a superoxide source showed that the PEC maintained its integrity whereas holes and small particles appeared during the treatment of PLGA. Sirolimus and paclitaxel were loaded into PEC and PLGA in order to study drug release performance. Attenuated total reflectance–infrared (ATR– FTIR) spectroscopy of sirolimus, PEC and the sirolimus-loaded PEC coating showed that no chemical reaction occurred between sirolimus and PEC. The results of atomic force microscopy (AFM) revealed that the mean roughness (Ra) values of the bare metal stent (BMS) and the drugeluting stent (DES) were 2.3 nm and 1.0 nm, respectively. After balloon expansion experiments, no delamination or destruction of the PEC coating was observed. The drug release profile of sirolimus was different from that of paclitaxel when PEC was employed as the drug carrier, and the release curves of sirolimus were different when PEC and PLGA were used as drug carriers. All the experimental results demonstrated that PEC was one of the best potential stent-coating materials.     

Protein adsorption on the poly（L-lactic acid） surface modified by chitosan and its derivatives

Surface modification of biomaterials has been adopted over the years to improve their biocompatibility. In this study, aiming to promote hydrophilicity and to introduce natural recognition sites onto poly（L-lactic acid） （PLLA） films, chitosan and its derivatives, carboxymethyl chitosan（CMC） and N-methylene phosphonic chitosan （NPC）, were used to modify the surface of PLLA films by an entrapment method. Radiolabeled （^125I） proteins were used to measure the amount of protein adsorbed to PLLA surfaces. Fibronectin （Fn） was used to study the protein adsorption on the modified PLLA surfaces, including isotherm adsorption and adsorption kinetics of single protein, competitive adsorption of binary proteins system and serum multi-proteins and the desorption behavior in serum solution. The results showed that in the isotherm adsorption, Fn had a larger adsorption capacity on the CS-modified surface at lower concentrations, but had a high adsorption capacity at CMC-modified surface at higher concentrations. In the study of absorption kinetics, Fn had a fastest adsorption equilibrium and a highest equilibrium adsorption capacity at the CS-modified surface, while it was opposite at the PCS-modified surface. When BSA and serum were added, it had the greatest effect on the adsorption of Fn on the PCS-modified surface. After 6 hours soaking in the desorpUon study, Fn had reached desorption equilibrium on all the modified surfaces, which had different effects on the desorption rate and the remaining percentage of Fn.     

聚苯撑乙炔与电子受体共聚物的合成及光伏研究

利用钯催化剂(Pd(PPh3)2Cl2)和相转移催化剂(PTC),采用Heck交叉偶联缩聚反应合成了聚(苯撑乙炔撑-苯并噻二唑)系列交替共聚物(PPE-BT),比较了聚合物的紫外吸收光谱和荧光光谱特征。PPE-BT与给体MEH-PPV构成器件时,其能量转换效率为2.54×10-3,说明电子在PPE-BT和PPE-DCNTB中的迁移率较小。