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Different Adsorption Behavior (different + adsorption_behavior)
Selected AbstractsComparative Study of the Solid,Liquid Interface Behavior of Amphiphilic Block and Block-Like CopolymersMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 3-4 2009Nikolay Bulychev Abstract Amphiphilic block and "block-like" copolymers based on poly(isobornyl acrylate) and poly(acrylic acid) were used as stabilizers for hydrophilic (titanium dioxide) and hydrophobic (copper phthalocyanine) pigments. As reflected by the dispersion stabilities and electrokinetic sonic amplitude (ESA) measurements, the molecular architecture of the copolymer is of great importance for its interaction with the pigment surface. It was observed that irrespective of polymer composition, block-like copolymers exhibit lower stabilization ability and quite different adsorption behavior in comparison to block copolymers with sharp block boundaries. Models for the adsorption behavior of both block and block-like copolymers are proposed. [source] Adsorption of 6-mercaptopurine and 6-mercaptopurine-ribosideon silver colloid: A pH-dependent surface-enhanced Raman spectroscopy and density functional theory study.BIOPOLYMERS, Issue 6 2005Abstract Surface-enhanced Raman spectroscopy (SERS) has been applied to characterize the interaction of 6-mercaptopurine-ribose (6MPR), an active drug used in chemotherapy of acute lymphoblastic leukemia, with a model biological substrate at therapeutic concentrations and as function of the pH value. Therefore, a detailed vibrational analysis of crystalline and solvated (6MPR) based on Density Functional Theory (DFT) calculations of the thion and thiol tautomers has been performed. 6MPR adopts the thion tautomeric form in the polycrystalline state. The SERS spectra of 6MPR and 6-mercaptopurine (6MP) recorded on silver colloid provided evidence that the ribose derivative shows different adsorption behavior compared with the free base. Under acidic conditions, the adsorption of 6MPR on the metal surface via the N7 and possibly S atoms was proposed to have a perpendicular orientation, while 6MP is probably adsorbed through the N9 and N3 atoms. Under basic conditions both molecules are adsorbed through the N1 and possibly S atoms, but 6MP has a more tilted orientation on the silver colloidal surface while 6MPR adopts a perpendicular orientation. The reorientation of the 6MPR molecule on the surface starts at pH 8 while in the case of 6MP the reorientation starts around pH 6. Under basic conditions, the presence of the anionic molecular species for both molecules is suggested. The deprotonation of 6MP is completed at pH 8 while the deprotonation of the riboside is finished at pH 10. For low drug concentrations under neutral conditions and for pH values 8 and 9, 6MPR interacts with the substrate through both N7 and N1 atoms, possibly forming two differently adsorbed species, while for 6MP only one species adsorbed via N1 was evidenced. © 2005 Wiley Periodicals, Inc. Biopolymers 78: 298,310, 2005 This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Purification of cell culture-derived modified vaccinia ankara virus by pseudo-affinity membrane adsorbers and hydrophobic interaction chromatographyBIOTECHNOLOGY & BIOENGINEERING, Issue 2 2010Michael W. Wolff Abstract A purification scheme for cell culture-derived smallpox vaccines based on an orthogonal downstream process of pseudo-affinity membrane adsorbers (MA) and hydrophobic interaction chromatography (HIC) was investigated. The applied pseudo-affinity chromatography, based on reinforced sulfated cellulose and heparin-MA, was optimized in terms of dynamic binding capacities, virus yield and process productivity. HIC was introduced as a subsequent method to further reduce the DNA content. Therefore, two screens were undertaken. First, several HIC ligands were screened for different adsorption behavior between virus particles and DNA. Second, elution from pseudo-affinity MA and adsorption of virus particles onto the hydrophobic interaction matrix was explored by a series of buffers using different ammonium sulfate concentrations. Eventually, variations between different cultivation batches and buffer conditions were investigated. The most promising combination, a sulfated cellulose membrane adsorber with subsequent phenyl HIC resulted in overall virus particle recoveries ranging from 76% to 55% depending on the product batch and applied conditions. On average, 61% of the recovered virus particles were infective within all tested purification schemes and conditions. Final DNA content varied from 0.01% to 2.5% of the starting material and the level of contaminating protein was below 0.1%. Biotechnol. Bioeng. 2010;107: 312,320. © 2010 Wiley Periodicals, Inc. [source] Adsorption of 4,4,-thiobisbenzenethiol on silver surfaces: surface-enhanced Raman scattering studyJOURNAL OF RAMAN SPECTROSCOPY, Issue 3 2008Yuling Wang Abstract Adsorption of 4,4,-thiobisbenzenethiol (4,4,-TBBT) on a colloidal silver surface and a roughened silver electrode surface was investigated by means of surface-enhanced Raman scattering (SERS) for the first time, which indicates that 4,4,-TBBT is chemisorbed on the colloidal silver surface as dithiolates by losing two H-atoms of the SH bond, while as monothiolates on the roughened silver electrode. The different orientations of the molecules on both silver surfaces indicate the different adsorption behaviors of 4,4,-TBBT in the two systems. It is inferred from the SERS signal that the two aromatic rings in 4,4,-TBBT molecule are parallel to the colloidal silver surface as seen from the disappearance of ,CH band (3054 cm,1), which is a vibrational mode to be used to determine the orientation of a molecule on metals according to the surface selection rule, while on the roughened silver electrode surface they are tilted to the surface as seen from the enhanced signal of ,CH. The orientation of the C-S bond is tilted with respect to the silver surface in both cases as inferred from the strong enhancement of the ,CS. SERS spectra of 4,4,-TBBT on the roughened silver electrode with different applied potentials reveal that the enhancement of 4,4,-TBBT on the roughened silver electrode surface may be related to the chemical mechanism (CM). More importantly, the adsorption of 4,4,-TBBT on the silver electrode is expected to be useful to covalently adsorb metal nanoparticles through the free SH bond to form two- or three- dimensional nanostructures. Copyright © 2007 John Wiley & Sons, Ltd. [source] | ||||||||||