Protein–polymer interaction: Transfer loading at interfacial region of PES-based membrane and BSA

The adsorption of proteins onto polymeric surfaces is encountered in many natural and industrial processes and is a prerequisite to their efficient identification, separation, and purification by methods such as chromatography, and filtration. Nevertheless, the exact nature of the adsorption mechanisms and interfacial interactions is not easy to identify for a given protein–polymer system. Here, we aim to document the adsorption mechanism of a protein–polymer system by investigating the adsorption as well as desorption phenomenon of a protein [bovine serum albumin (BSA)] from the polymeric surface [polyethersulfone (PES)]. The analyses performed to document the adsorption mechanism of the BSA–PES system include scanning electron microscope (SEM), attenuated total reflection-Fourier transform infrared (FTIR), contact angle, zeta potential, surface charge density measurement, and Derjaguin–Landau–Verwey–Overbeek (DLVO). Here, SEM and FTIR identified the physical and chemical properties of pure PES and PES–BSA membranes. The low water contact angle of the PES–BSA membrane confirms its applicability for tissue engineering applications. Further, the zeta potential, surface charge density measurement, and DLVO analyses were performed to document the adsorption mechanism. The adsorption of BSA particles on the PES surface was carried out for pH values that ranged from 4 to 10 for contact times that ranged from 1 to 3 days. A monotonic increase in the zeta potential of the PES–BSA system indicated considerable adsorption of BSA particles on the PES surface. Further, BSA adsorption was very strong for pH values greater than 4.7 which confirms to strong electrostatic interactions between BSA and PES. The strong electrostatic interaction is also collaborated by low desorption rate, which was only ∼22% for pH 10 after 3 days of contact. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47931.     

Adhesion on polyethylene glycol and quaternary ammonium salt-grafted silicon surfaces: Influence of physicochemical properties

The aim of this work was to develop a new generation of antimicrobial materials. In order to restrict surface contamination by micro-organisms, the approach developed consisted in modifying the surface properties of a silicone wafer by grafting antimicrobial compounds such as quaternary ammonium salts (QAS) and polyethylene glycol (PEG). Under this approach, the grafted compound was endowed with a functionalised extremity which allowed it to react with the silicone wafer in order to form a covalent bond. The first part of this paper describes the synthesis of QAS and PEG molecules, and then the physicochemical characteristics of the modified silicon surfaces were determined. The second part concerned determination of the surface properties of the wafers and polystyrene beads used for adhesion tests. In line with the extended DLVO theory, it was thus possible to understand the mechanisms involved in the adhesion of polystyrene beads to the surface of QAS and PEG-modified silicon wafers.     

Bacterial biofilms associated with food particles in the human large bowel

Bacteria within the gastro-intestinal tract affect host function via production of short-chain fatty acids and synthesis of vitamins. Additionally, the commensal enteric bacteria modulate the immune system and provide protection from potentially pathogenic bacteria. Only recently heterogeneous bacterial biofilms were found to be associated with food particles within the intestinal tract. There are a number of studies investigating the formation and function of pathogenic and single-species biofilms, though few studies have investigated the dynamics of multispecies biofilms, especially with regard to food/microbial/host interactions. The scope of this review is to discuss the current knowledge of bacterial biofilms associated with food particles in the human large bowel, examine the established mathematical models depicting bacterial attachment, and elucidate key areas for further research.     

Interaction of reactive oily bubble in flotation of bastnaesite

To understand the flotation mechanism of bastnaesite using reactive oily bubble, the interaction between bastnaesite parti-cles and reactive oily bubbles was investigated by electro-kinetic studies, induction time measurements and small-scale flotation ex-periments. The bastnaesite flotation could be seen as a hetero-coagulation between bastnaesite particles and reactive oily bubbles which was confirmed by the zeta potential distribution and induction time measurements from pH 4.8 to pH 9.0. The small-scale flotation tests were consistent with the hetero-coagulation results, and showed a better flotation of reactive oily bubble than air bubble among all pH range. The interaction force between bastnaesite particles and reactive oily bubbles was evaluated by the classical DLVO theory. It indicated that the attachment could be predicted well by the DLVO theory only in a restricted pH range due to the absence of hydrophilic interaction repulsion force and chemical interaction force.     

水质硬度对煤泥水中煤和高岭石颗粒分散行为的影响

利用扩展的DLVO理论计算了2种硬度条件下煤和高岭石组成的煤泥水中颗粒之间的相互作用,建立了包括范德华作用能、静电作用能与界面极化作用能与颗粒间距的势能曲线,并进行了沉降试验.结果表明:当水质硬度为1.0 mmol/L时,煤颗粒之间、高岭石颗粒之间以及煤与高岭石颗粒之间都不凝聚而处于悬浮态;当水质硬度为10.0 mmol/L时,煤颗粒之间最易凝聚,其次是煤颗粒和高岭石颗粒凝聚,剩余的高岭石颗粒始终不凝聚而分散悬浮于水中.     

聚合物微球在Si片CMP中的作用机制

为了提高Si片的抛光速率,采用复合磨粒抛光液对Si片进行化学机械抛光。根据检测到的聚合物微球的Zeta电位,利用DLVO理论分析计算了PS,PMMA和BGF聚合物微球与SiO2磨粒在抛光液中的作用势能;利用TEM观察了SiO2磨粒与聚合物微球的吸附状况。分析计算和TEM观察均表明三种聚合物微球在抛光液中都能与SiO2磨粒相互吸附。通过Si片化学机械抛光实验,分别分析了抛光液中聚合物微球浓度、三种不同聚合物组成的复合磨粒抛光液对抛光速率的影响,研究了聚合物微球在Si片化学机械抛光中的作用机制。     

同步斩波法测量胶体粒子间相互作用势

本文介绍了CCD同步斩波装置与双光镊系统结合,构成的一套微小粒子相互作用势测量实验系统,并建立了相应的实验方法。利用该方法测量了1μm聚苯乙烯球悬浮液中两个小球间的相互作用势,其结果与经典DLVO理论相符。研究结果表明,我们所建立的实验系统和方法是行之有效的。并且测量方法具有较高的数据采集效率,该方法可望应用于粒子间不同类型相互作用势的测量。     

The effects of biofilm on the transport of stabilized zerovalent iron nanoparticles in saturated porous media

The transport of stabilized zerovalent iron nanoparticles (nZVI) has recently been the topic of extensive research due to its proven potential as an in situ remediation tool. However, these studies have ignored the effects of biofilms—complex aggregations of bacterial cells and excreted extracellular polymeric substances present in nearly all aquatic systems—on the transport of these particles. This study examines the effects of Pseudomonas aeruginosa (PAO1) biofilm, at a cell concentration similar to that reported for saturated aquifers, on the transport of commercially available, poly (acrylic acid) stabilized nZVI (pnZVI) in 14 cm long columns packed with saturated glass beads at salt concentrations of 1 and 25 mM NaCl. Compared to retention on uncoated columns, in the presence of biofilm the retention of pnZVI increased at higher ionic strength, while ionic strength played no role in retention of these nanoparticles in the absence of biofilm. The Tufenkji-Elimelech correlation equation predicts lower retention of pnZVI on biofilm coated columns compared to uncoated columns due to a lower Hamaker constant, and DLVO energy considerations predict the most favorable attachment to uncoated porous media at higher ionic strength. A steric (polymer-mediated) model that considers the combined influence of steric effects of polymers and DLVO interactions is shown to adequately describe particle retention in columns.     

聚氨酯-丙烯酸酯水分散体系稳定性研究

通过PUA水分散液一些物理性质 ,如 ζ电位、临界聚沉值 (C .C .C)、pH值、粒径及密度等的测量 ,用DLVO理论分析了聚氨酯 丙烯酸酯水分散体系的稳定性 ,并与实验测定的水分散液在不同条件下的稳定性相对照。结果表明 :用DLVO理论分析具有不同羧基 (—COOH)含量的PUA水分散液的稳定性时所得结果 ,与实验结果较吻合 ;而用该理论分析不同丙烯酸酯 (PA)含量的PUA水分散液时 ,与实验结果有偏差 ,可能与DLVO理论假设粒子形态为球形有关     

混凝土减水剂和泵送剂的临界掺量

探讨混凝土减水剂和泵送剂的临界掺量的概念,确定方法和影响因素,并通过产例说明临界掺量。