Topographical characterization and surface force spectroscopy of the photochemical lignin model compound

Mićić, Miodrag; Radotić, Ksenija; Benitez, Ivan; Ruano, Melanie; Jeremić, Milorad; Moy, Vincent T.; Mabrouki, Mustapha; Leblanc, Roger M.

doi:10.1016/s0301-4622(01)00245-9

Cited by 17 publications

(17 citation statements)

References 21 publications

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“…The advantage of ESEM compared with traditional scanning electron microscopy is that the imaging of a sample is performed in a water vapor environment. This technique allows the imaging of surfaces of practically any specimen wet or dry, insulating or conducting, without any previous treatment of the sample 25. Hydrophilic samples remain intact and the observed topography represents the actual surface structure of the material.…”

Section: Resultsmentioning

confidence: 99%

Preparation and characterization of scleroglucan drug delivery films: The effect of freeze‐thaw cycling

François

Daraio

2009

J of Applied Polymer Sci

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This study examined the effect of the freeze-thaw process on the physical properties of films prepared from scleroglucan (Scl) hydrogels, suitable for drug delivery applications. Films made from Scl, using glycerol as plasticizer, were prepared from hydrogels by two procedures: a room temperature drying (RTD) method and a freeze-thaw cyclic process, before the application of RTD, which results in a reinforced physically cross-linked network. Films were characterized by studies of water vapor transmission (WVT), swelling, tensile tests, ESEM microscopy, FTIR, and drug release measurements. These determinations showed significant differences between films obtained by both treatments. The films prepared through freeze-thaw cycles showed an important increase of the tensile strength with respect to those corresponding to films only air dried and a decreasing swelling degree in direct relationship to the number of freeze-thaw cycles. A model drug, Theophylline, was included in these biocompatible films for in vitro drug release measurements, using a flat Franz cell. The physical differences observed between Scl films prepared with both methods can be explained proposing that the number of crosslinking points by hydrogen bonding increase when increasing the number of freezing and thawing cycles used for film preparation.

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Section: Resultsmentioning

confidence: 99%

Preparation and characterization of scleroglucan drug delivery films: The effect of freeze‐thaw cycling

François

Daraio

2009

J of Applied Polymer Sci

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“…Interestingly, the number of particles increases, whereas the particles still maintain the diameter of about 50 nm for the H‐2 and H‐6 sheet, with an increase of HPL content of 2–6 wt % as shown in Figure 3(b) and (c), indicating that HPL nanoparticles homogeneously disperse in the matrix without further aggregation. Lignin tends to form supramolecular structures as a result of the polyfunctionality and strong inter‐ and intramolecular interactions,10, 36 which suggests that HPL particles are attributed to the supramolecular structures of HPL 11, 37, 38. Moreover, the interface of HPL nanoparticles and matrices are indistinct, suggesting a strong interfacial interaction.…”

Section: Resultsmentioning

confidence: 99%

Effects of nanoscale hydroxypropyl lignin on properties of soy protein plastics

Chen

Zhang

Peng

et al. 2006

J of Applied Polymer Sci

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For the first time, soy protein isolate (SPI)/ hydroxypropyl alkaline lignin (HPL) composites have been successfully prepared by mixing them in aqueous solution containing a small amount of glutaraldehyde as compatibilizer, and then compression-molded to obtain plastic sheets. The structures of the SPI/HPL composites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, and scanning electron microscopy, indicating the existence of amorphous networks and nanoscale HPL dispersion in the SPI matrix. When HPL content was lower than 6 wt %, the HPL-domain occurred in SPI/HPL composites with a dimension of about 50 nm, indicating a high interfacial activity. Differential scanning calorimetry analysis showed that the glass transition temperature of the SPI/HPL sheets increased from 62.5 to 70.4°C with an increase of HPL content from 0 to 6 wt %. Moreover, the tensile strength of the SPI/HPL nanocomposite sheets with 6 wt % HPL and 3.3 wt % glutaraldehyde was enhanced from 8.4 to 23.1 MPa compared with that of the SPI sheets, suggesting that the nanoscale HPL dispersion significantly reinforced the SPI materials.

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“…Using microscopy, Micic and colleagues published a series of papers [131][132][133][134][135][136] describing the supramolecular self-assembly of lignin in model systems of in vitro DHPs and photopolymerization of coniferyl alcohol. They envisioned lignin at the nanoscale as being globular with elastic and viscoelastic properties due to intermolecular π-π interactions, hydrogen bonding and van der Waals forces amongst the macromolecular globules resulting in semi-ordered superstructures.…”

Section: Supramolecular Ligninmentioning

confidence: 99%

“…Therefore, one might expect guaiacyl-syringyl lignins of angiosperms to display more coiled spiral conformation with a greater longitudinal expansion relative to gymnosperm lignins, which have a higher content of β-β and β-5 bonds ( Figure 5). On the other hand, several investigators have reported a spherical, globular or disk like conformation for technical lignin or synthetic DHP [131][132][133][134][135][136]140]. Deconvolution fluorescence spectroscopy of DHPs suggested a multi-layered structure for lignin [141].…”

Section: Lignin Conformationmentioning

confidence: 99%

Supramolecular Self-Assembled Chaos: Polyphenolic Lignin’s Barrier to Cost-Effective Lignocellulosic Biofuels

et al. 2010

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Phenylpropanoid metabolism yields a mixture of monolignols that undergo chaotic, non-enzymatic reactions such as free radical polymerization and spontaneous selfassembly in order to form the polyphenolic lignin which is a barrier to cost-effective lignocellulosic biofuels. Post-synthesis lignin integration into the plant cell wall is unclear, including how the hydrophobic lignin incorporates into the wall in an initially hydrophilic milieu. Self-assembly, self-organization and aggregation give rise to a complex, 3D network of lignin that displays randomly branched topology and fractal properties. Attempts at isolating lignin, analogous to archaeology, are instantly destructive and nonrepresentative of in planta. Lack of plant ligninases or enzymes that hydrolyze specific bonds in lignin-carbohydrate complexes (LCCs) also frustrate a better grasp of lignin. Supramolecular self-assembly, nano-mechanical properties of lignin-lignin, ligninpolysaccharide interactions and association-dissociation kinetics affect biomass deconstruction and thereby cost-effective biofuels production. OPEN ACCESSMolecules 2010, 15 8642

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Topographical characterization and surface force spectroscopy of the photochemical lignin model compound

Cited by 17 publications

References 21 publications

Preparation and characterization of scleroglucan drug delivery films: The effect of freeze‐thaw cycling

Preparation and characterization of scleroglucan drug delivery films: The effect of freeze‐thaw cycling

Effects of nanoscale hydroxypropyl lignin on properties of soy protein plastics

Supramolecular Self-Assembled Chaos: Polyphenolic Lignin’s Barrier to Cost-Effective Lignocellulosic Biofuels

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