Limitations of Size-Exclusion Chromatography in Analyzing Petroleum Asphaltenes: A Proof by Atomic Force Microscopy

2008 ◽  
Vol 22 (3) ◽  
pp. 1792-1798 ◽  
Author(s):  
Mahtab Behrouzi ◽  
Paul F. Luckham
Keyword(s):  
Atomic Force Microscopy ◽  
Size Exclusion Chromatography ◽  
Size Exclusion ◽  
Force Microscopy ◽  
Petroleum Asphaltenes ◽  
Atomic Force ◽  
Exclusion Chromatography

scholarly journals Gels of Amyloid Fibers

Biomolecules ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 210 ◽  
Author(s):  
Ruizhi Wang ◽  
Xiaojing Yang ◽  
Lingwen Cui ◽  
Hang Yin ◽  
Shaohua Xu
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Atomic Force Microscopy ◽  
Melting Point ◽  
Protein Concentration ◽  
Size Exclusion ◽  
Amyloid Fibers ◽  
Force Microscopy ◽  
Atomic Force ◽  
3D Network

Protein self-assembly and formation of amyloid fibers is an early event of numerous human diseases. Continuous aggregation of amyloid fibers in vitro produces biogels, which led us to suspect that amyloid plaques and neurofibrillary tangles in Alzheimer’s disease are of biogels in nature. We applied atomic force microscopy, size exclusion chromatography, and differential scanning calorimetry to elucidate the gel’s structure, kinetics of gel formation, and melting point. We found that (1) lysozyme gelation occurs when the protein concentration is above 5 mg/mL; (2) nonfibrous protein concentration decreases and plateaus after three days of gel synthesis reaction; (3) colloidal lysozyme aggregates are detectable by both atomic force microscopy (AFM) and fast protein liquid chromatography (FPLC); (4) the gels are a three-dimensional (3D) network crosslinked by fibers coiling around each other; (5) the gels have a high melting point at around around 110 °C, which is weakly dependent on protein concentration; (6) the gels are conductive under an electric field, and (7) they form faster in the presence than in the absence of salt in the reaction buffer. The potential role of the gels formed by amyloid fibers in amyloidosis, particularly in Alzheimer’s disease was thoroughly discussed, as gels with increased viscosity, are known to restrict bulk flow and then circulation of ions and molecules.

Chromatographic Separation of Single Wall Carbon Nanotubes

2006 ◽  
Vol 922 ◽  
Author(s):  
Barry J. Bauer ◽  
Vardhan Bajpai ◽  
Jeffrey A. Fagan ◽  
Matthew L. Becker ◽  
Erik K. Hobbie
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Modification ◽  
Size Exclusion ◽  
Covalent Attachment ◽  
Single Wall Carbon Nanotubes ◽  
Single Wall Carbon ◽  
Force Microscopy ◽  
Atomic Force ◽  
Exclusion Chromatography ◽  
Chromatographic Detection

AbstractSize exclusion chromatography (SEC) has been used to separate single wall carbon nanotubes (SWNT) dispersed by chemical modification in organic solvents and by DNA in aqueous solution. The chromatographic detection includes size sensitive detectors, multi-angle light scattering (MALS) and intrinsic viscosity (IV), which can provide information on the size and shape of the SEC fractions. The dispersions were also characterized by small angle neutron scattering (SANS) and atomic force microscopy (AFM). Chemical modification was accomplished by covalent attachment of octadecyl amine to acid treated SWNT and by covalent attachment of butyl groups through free radical grafting. Both covalent attachment methods produced dispersions that contained impurities or clusters of SWNT. The DNA dispersions produced the best dispersions, being predominately single nanotubes.

scholarly journals Colloidal Lignin Particles as Adhesives for Soft Materials

Nanomaterials ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1001 ◽  
Author(s):  
Maija-Liisa Mattinen ◽  
Guillaume Riviere ◽  
Alexander Henn ◽  
Robertus Nugroho ◽  
Timo Leskinen ◽  
...  
Keyword(s):  
Quartz Crystal ◽  
Soft Materials ◽  
Potential Method ◽  
Size Exclusion ◽  
Force Microscopy ◽  
Young’S Moduli ◽  
Atomic Force ◽  
Transmission Electron ◽  
Exclusion Chromatography ◽  
Adhesive Formulation

Lignin has interesting functionalities to be exploited in adhesives for medicine, foods and textiles. Nanoparticles (NPs) < 100 nm coated with poly (L-lysine), PL and poly(L-glutamic acid) PGA were prepared from the laccase treated lignin to coat nanocellulose fibrils (CNF) with heat. NPs ca. 300 nm were prepared, β-casein coated and cross-linked with transglutaminase (Tgase) to agglutinate chamois. Size exclusion chromatography (SEC) and Fourier-transform infrared (FTIR) spectroscopy were used to characterize polymerized lignin, while zeta potential and dynamic light scattering (DLS) to ensure coating of colloidal lignin particles (CLPs). Protein adsorption on lignin was studied by quartz crystal microbalance (QCM). Atomic force microscopy (AFM) was exploited to examine interactions between different polymers and to image NPs with transmission electron microscopy (TEM). Tensile testing showed, when using CLPs for the adhesion, the stress improved ca. 10 and strain ca. 6 times compared to unmodified Kraft. For the β-casein NPs, the values were 20 and 8, respectively, and for the β-casein coated CLPs between these two cases. When NPs were dispersed in adhesive formulation, the increased Young’s moduli confirmed significant improvement in the stiffness of the joints over the adhesive alone. Exploitation of lignin in nanoparticulate morphology is a potential method to prepare bionanomaterials for advanced applications.

Mucoadhesive interactions

2003 ◽  
Vol 31 (5) ◽  
pp. 1036-1041 ◽  
Author(s):  
S.E. Harding
Keyword(s):  
Analytical Ultracentrifugation ◽  
Physiological Solution ◽  
Size Exclusion ◽  
Molecular Processes ◽  
Adhesive Properties ◽  
Cationic Protein ◽  
Force Microscopy ◽  
Atomic Force ◽  
Imaging Probes ◽  
Exclusion Chromatography

The adhesive properties of certain types of biopolymer can be used to increase the residence time of orally or nasally administered drugs. A fuller understanding of the molecular processes underpinning such ‘mucoadhesive’ phenomena will help in the optimal design of delivery systems. The interactions involved are, however, less well defined compared with those often encountered in protein-recognition phenomena: mucoadhesive interaction products can be very large and polydisperse, so to probe them we need to adopt a different strategy to those used by protein biochemists. Reviewed herein is some of the recent work at physiological or near-physiological solution conditions involving molecular hydrodynamics – with analytical ultracentrifugation and SEC-MALLs (size-exclusion chromatography coupled to multi-angle laser light scattering) as the cornerstones – reinforced by viscometry and the imaging probes of electron microscopy and atomic force microscopy. These clearly demonstrate the mucoadhesive properties of both an unusual cationic protein [Deacon, Davis, Waite and Harding (1998) Biochemistry 37, 14108–14112] and more significantly chitosan polysaccharides of varying degrees of charge/acetylation as a function of solution conditions, and are providing the platform for the construction of stable formulations.

scholarly journals Colloidal Lignin Particles as Adhesives for Soft Materials

2018 ◽  
Author(s):  
Maija-Liisa Mattinen ◽  
Guillaume Riviere ◽  
Alexander Henn ◽  
Robertus Wahyu N. Nugroho ◽  
Timo Leskinen ◽  
...  
Keyword(s):  
Soft Materials ◽  
Potential Method ◽  
Size Exclusion ◽  
Force Microscopy ◽  
Young’S Moduli ◽  
Atomic Force ◽  
Transmission Electron ◽  
Exclusion Chromatography ◽  
Beta Casein ◽  
Adhesive Formulation

Lignin has interesting functionalities to be exploited in adhesives for medicine, foods and textiles. Nanoparticles (NPs) &lt;100 nm coated with poly(L-lysine), PL and poly(L-glutamic acid) PGA were prepared from the laccase treated lignin to coat nanocellulose fibrils (CNF) with heat. NPs ca. 300 nm were prepared, &beta;-casein coated and cross-linked with transglutaminase (Tgase) to agglutinate chamois specimens. Size exclusion chromatography (SEC) and Fourier-transform infrared (FTIR) spectroscopy were used to characterize polymerized lignin, zetapotential and dynamic light scattering (DLS) to ensure coating of colloidal lignin particles (CLPs). Protein adsorption on lignin was studied by quartz crystal microbalance (QCM). Atomic force microscopy (AFM) was exploited to examine interactions between different polymers and to image NPs with transmission electron microscopy (TEM). Tensile testing showed, when using CLPs for the adhesion, the stress improved ca. 10 and strain ca. 6 times compared to polymeric lignin. For the &beta;-casein NPs the values were 20 and 8, respectively, and for the &beta;-casein coated CLPs between these two cases. When NPs were dispersed in adhesive formulation, the Young's moduli confirmed significant improvement in the elasticity of the joints over the adhesive alone. Exploitation lignin in nanoparticulate morphology is a potential method to prepare bionanomaterials for advanced applications.

Effect of Ozonation on Assembly of Xylans

Holzforschung ◽  
2003 ◽  
Vol 57 (5) ◽  
pp. 496-502 ◽  
Author(s):  
Å. Linder ◽  
J. P. Roubroeks ◽  
P. Gatenholm
Keyword(s):  
Molecular Structure ◽  
Aqueous Solution ◽  
Molar Mass ◽  
Surface Structures ◽  
Size Exclusion ◽  
Aromatic Rings ◽  
Muconic Acid ◽  
Force Microscopy ◽  
Atomic Force ◽  
Exclusion Chromatography

Summary In this study the molecular structure of birch xylan was altered by ozonation. Longer ozonation times increased the cleavage of aromatic rings in the lignin residues attached to the xylan molecules, resulting in the formation of muconic acid derivatives and other carboxylic acid structures. Size exclusion chromatography showed a decreasing molar mass of xylan after ozonation. The ozonation improved xylan solubility as evidenced by the reduced amounts of aggregates in aqueous solution. Atomic force microscopy showed increases in the sizes of the aggregates. Furthermore, the ozonation resulted in a decreased ability of xylan to assemble into particle-like structures on cellulose surfaces. We therefore believe that there is a relationship between xylan aggregation in aqueous solution and the formation of xylan surface structures on cellulose.

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