聚乙烯亚胺改性TiO2及光催化性能研究

纳米TiO2经3-氨丙基三乙氧基硅烷(APTES)改性后,再通过聚乙烯亚胺(PEI)单体在APTES-TiO2表面进行原位化学氧化接枝聚合,制备了基于共价键结合的PEI/APTES-TiO2纳米复合光催化材料。以甲基橙(MO)为目标降解物,研究了所制备复合材料在紫外光下和太阳光作用下的光催化性能。通过红外光谱(FTIR)、X射线衍射(XRD)、透射电镜(TEM)等对所制备的复合材料进行了表征。结果表明,TiO2经过有机改性后复合材料在紫外光和太阳光下都出现了较强的吸收,光能的利用率和光生载流子的分离效率得到提高,复合材料表现出较高的光催化活性。     

聚乙烯亚胺改性的双介孔氧化硅基因载体构建

为了开发一种新型的非病毒无机基因载体, 采用3-氨丙基三乙氧基硅烷(APTMS)和聚乙烯亚胺(PEI)对嵌入型双介孔氧化硅球(EDMSNs)进行改性, 分别得到EDMSNs-NH₂和EDMSNs-PEI, 并比较了两种载体结合和保护pCMV-EGFP-N1质粒(pDNA)的能力及细胞转染性能。利用透射电镜、动态光散射及氮气吸附-脱附实验对材料的颗粒形态, 动力学粒径, Zeta电位及孔结构参数进行表征。结果显示, EDMSNs-NH₂和EDMSNs-PEI均表现出明显的双介孔结构, 形貌为规整的球形且平均动力学粒径分别为343.2和338.9 nm, 表面电位分别为+18和+43 mV。琼脂糖凝胶电泳、CCK-8法及荧光显微镜结果表明, EDMSNs-PEI对pDNA的担载量为8%, 远高于EDMSNs- NH₂(1%)。与PEI和lipofectamine2000相比, EDMSNs-PEI载体展示出更低的细胞毒性。EDMSNs-PEI/pDNA质量比为33 : 1时, EDMSNs-PEI/pDNA对293T细胞的转染效率在72 h达到最大值。因此, 与EDMSNs-NH₂相比, EDMSNs-PEI具有更高的正电位及pDNA担载量, 可作为一类有前景的非病毒无机类基因载体用于重大疾病如恶性胶质瘤的治疗。     

Removal of Heavy Metals from Multicomponent Metal Mixtures by Polymer Enhanced Ultrafiltration: Effects of pH,Ionic Strength and Conformational Changes in Polymer Structure

Fractional separation of industrially important heavy metals (cadmium, nickel, zinc) from binary and ternary metal mixtures by continuous mode polymer enhanced ultrafiltration was studied. Polyethyleneimine (PEI) was used as a complexation polymer. Effects of pH and ionic strength on process efficiency were investigated. To gain insight about the characteristics of binding between highly branched PEI and metal ions and effect of salt concentration on this binding were investigated by performing dynamic and static light scattering measurements. It was observed that with optimum pH and salt concentration, fractional separation of metals can be achieved.     

聚乙烯亚胺修饰氧化石墨烯材料选择性吸附分离乌龙茶叶中无机砷的研究

摘要：目的 将聚乙烯亚胺(polyethyleneimine,PEI)修饰于氧化石墨烯(graphene oxide,GO)表面,制备PEI@GO合成材料以实现乌龙茶叶中无机砷的选择性吸附分离。方法 利用傅里叶红外光谱、电镜扫描、Zeta电位分析对PEI@GO进行表征,并建立基于PEI@GO的管尖固相萃取(pipette tip solid phase extraction,PTSPE)体系结合氢化物发生-原子荧光光谱法(hydride generation atomic fluorescence spectrometry,HG-AFS)实现乌龙茶中无机砷的选择性吸附分离和准确定量。结果 傅里叶红外光谱图中出现N-H特征峰,表明PEI成功修饰于GO的表面,电镜下PEI@GO呈现多孔的山脊山谷结构,Zeta电位分析其等电点约为9.7,在pH 6下,5 mg PEI@GO对As (V)溶液吸附率达95.84%,所建立的PTSPE-HG-AFS法最低检测限为0.027 μg/L,相对标准偏差为0.48%,不同品种乌龙茶样品中无机砷含量为13~122 μg/kg,回收率在86.48%~108.98%之间。结论 制备的PEI@GO材料可有效实现无机砷的选择性吸附分离,所建立的方法操作简便,灵敏度高,可准确用于实际茶叶样品中无机砷的分析检测。     

硅胶表面AuCl_4~-印迹聚乙烯亚胺的制备及识别特性研究

将功能高分子聚乙烯亚胺(polyethyleneimine,PEI)化学接枝在硅胶微粒表面,形成功能接枝材料PEI-g-SiO2;再以AuCl4-为模板离子,乙二醇二缩水甘油醚(EGDE)为交联剂,将接枝在硅胶表面的PEI大分子链进行交联,同时实施AuCl4-的印迹,制备了AuCl4-印迹材料IIP-PEI-g-SiO2。采用静态法考察了IIP-PEI-g-SiO2对AuCl4-的吸附特性。实验结果表明,IIP-PEI-g-SiO2对AuCl4-具有优良的吸附性能与较强的记忆识别能力。吸附容量可以达到23.59mg/g,相对于Cu2+,印迹材料对AuCl4-的选择性系数为32.45。此外,IIP-PEI-g-SiO2还具有优良的重复使用性能。     

A Shape‐Adaptive,Antibacterial‐Coating of Immobilized Quaternary‐Ammonium Compounds Tethered on Hyperbranched Polyurea and its Mechanism of Action

Quaternary‐ammonium‐compounds are potent cationic antimicrobials used in everyday consumer products. Surface‐immobilized, quaternary‐ammonium‐compounds create an antimicrobial contact‐killing coating. We describe the preparation of a shape‐adaptive, contact‐killing coating by tethering quaternary‐ammonium‐compounds onto hyperbranched polyurea coatings, able to kill adhering bacteria by partially enveloping them. Even after extensive washing, coatings caused high contact‐killing of Staphylococcus epidermidis, both in culture‐based assays and through confocal‐laser‐scanning‐microscopic examination of the membrane‐damage of adhering bacteria. In culture‐based assays, at a challenge of 1600 CFU/cm², contact‐killing was >99.99%. The working‐mechanism of dissolved quaternary‐ammonium‐compounds is based on their interdigitation in bacterial membranes, but it is difficult to envisage how immobilized quaternary‐ammonium‐molecules can exert such a mechanism of action. Staphylococcal adhesion forces to hyperbranched quaternary‐ammonium coatings were extremely high, indicating that quaternary‐ammonium‐molecules on hyperbranched polyurea partially envelope adhering bacteria upon contact. These lethally strong adhesion forces upon adhering bacteria then cause removal of membrane lipids and eventually lead to bacterial death.     

改性纤维素微球的制备及其对Pb2＋吸附性能的研究

利用绿色环保的碱／尿素／水溶剂体系直接制备纤维素溶液共混聚乙烯亚胺（PEI）,然后通过高压静电法制备再生纤维素微球,并与戊二醛交联固定化,制备了复合型吸附材料。借助吸附动力学和吸附等温方程研究了改性纤维素微球对Pb2＋的吸附性能,结果表明改性纤维素微球对Pb2＋具有较好的吸附容量达到9．46mg／g,相比空白微球提高50％以上,并且吸附过程符合准二级动力学方程和Freundlich等温方程。     

Comparison of Galactooligosaccharide Production in Free-Enzyme Ultrafiltration and in Immobilized-Enzyme Systems

ABSTRACT:  Galactooligosaccharides (GOSs) are prebiotics that have been shown to reduce colon cancer risk and enhance immunity. The GOSs can be formed enzymatically from whey lactose using β-galactosidase, but commercial application has been limited. Free- and immobilized-enzyme recycle batch processes were investigated and compared in this study. Optimum initial conditions were estimated using batch solutions. Using these optimum conditions, an ultrafiltration (UF) free-enzyme system was developed, and UF fluid pressure (100 to 400 p.s.i.) effect on enzyme performance was studied and compared with a 0 p.s.i. batch control. The optimum conditions were also used to develop an immobilized-enzyme process using polyethyleneimine (PEI), glutaraldehyde (GA), and cotton cloth. The PEI and GA immobilized agents were studied for their effect on enzyme inactivation. Finally, compatible free- and immobilized-enzyme recycle batch systems were compared for GOS production. Optimum initial enzyme conditions were estimated as 270 g/L initial lactose, 4.5 g/L initial enzyme ( Aspergillus oryzae, 9400 U/g), and 30-min incubation. Fluid pressure within the free-enzyme UF membrane system had no significant effect on enzyme performance. The highly agitated UF enzyme system was found to be superior to the less agitated 0 p.s.i batch control. In the immobilization process, approximately 50% to approximately 90% enzyme inactivation was found with the combination of PEI and GA. Equivalent free- and immobilized-enzyme systems showed very similar maximum GOS production of approximately 22% and approximately 20% (w/v) at approximately 15 to 17 min, or 50% conversion for free- and immobilized-systems, respectively.     

动态LBL组装聚离子膜对乙醇/水体系的渗透汽化性能

采用动态层-层吸附成膜法(动态LBL),以聚醚砜超滤膜为基膜,以聚丙烯酸(PAA)、聚乙烯亚胺(PEI)为聚离子制备了聚离子复合膜.考察了动态成膜与静态吸附成膜的膜性能比较,研究了动态过滤时间、聚离子浓度、进料浓度、温度等因素对该复合膜渗透汽化性能的影响;并对复合膜表面和截面做了扫描电镜分析.在40℃时,该复合膜对乙醇/水体系的分离因子可达1300,渗透通量约150 g/(m2.h),体现了较好的渗透汽化分离性能.