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Ah, Lewin; Me, Bos; Fc, Zusi; Nair, Xina; Whiting, Gary S.; Bouquin, Pamela L.; Tetrault, G.; Fi, Carroll

doi:10.1023/a:1018938920796

Cited by 21 publications

(14 citation statements)

References 7 publications

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“…The scattering amplitude for such a structure is given analytically as a sum of the amplitudes Φ(x) of the spheres 28 with Here, we have normalized A(s) such that A(0) ) 1 for a sphere of constant unit density F 1 ) F 2 ) ... F n ) 1. In our numerical study we calculate the corresponding intensities I(s) for spheres of n ) 100 and alternating layers of thicknesses d 1 and d 2 with respective densities F (1) and F (2) . The above sum is then evaluated with corresponding values for the even and odd integers j ) 2m and j ) 2m + 1.…”

Section: Scattering By Finite Lamellar Structures Of Onion-and Tart-t...mentioning

confidence: 99%

“…The above sum is then evaluated with corresponding values for the even and odd integers j ) 2m and j ) 2m + 1. We insert r 2m ) 2mR/n and r 2m+1 ) r 2m + d 1 using densities F 2m ) F (2) and F 2m+1 ) F (1) .…”

Section: Scattering By Finite Lamellar Structures Of Onion-and Tart-t...mentioning

confidence: 99%

“…1,2 Currently, a lot of interest is being focused on how to understand the role of retinoic acid in cell differentiation. This is done by investigating the binding properties of retinoids on specific proteins, 3,4 its role in malignant-tumor inhibition, 5,6 and its regulation of brain functions. 7 Natural retinoids need to be bound to specific retinoic-binding proteins to ensure their protection, solubility, and transport by body fluids.…”

Section: Introductionmentioning

confidence: 99%

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Immobilization of Retinoic Acid by Polyamino Acids: Lamellar-Structured Nanoparticles

Thünemann

Beyermann

Ferber³

et al. 1999

Langmuir

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We discuss the preparation, the X-ray spectra and their theory, and electron microscopy of nanoparticles showing a lamellar internal structure. Retinoic acid was immobilized by complexation with poly(L-arginine), poly(L-histidine), and poly(L-lysine). The resulting solid-state complexes were prepared as nanoparticles with diameters of 320-380 nm, and with internal structures, which are smectic A-like. By small-angle X-ray scattering the unit cell was determined to be in the range of 3.10-3.62 nm, thus depending linearly on the monomer mass. The X-ray scattering of finite lamellar structures of "onion"-and "tart"-type spherical nanoparticles were determined theoretically. The uniform boundary of the onion-type particles results in secondary maxima near the Bragg reflections. Further, the highest degree of polydispersity to find these secondary maxima in scattering experiments was determined to be about 1% if the particle size is 300 nm. When electron microscopy was used, it was shown that the particles consist of a complex-containing core surrounded by a dispersing agent-containing shell. The core was revealed to be more of the tart-than the onion-type. When circular dichroism was used, the conformation of poly(L-arginine) and poly(L-lysine) within the complexes was determined to be an R-helix, whereas that of poly(L-histidine) was predominantly of the coil-type.

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Section: Scattering By Finite Lamellar Structures Of Onion-and Tart-t...mentioning

confidence: 99%

Section: Scattering By Finite Lamellar Structures Of Onion-and Tart-t...mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Immobilization of Retinoic Acid by Polyamino Acids: Lamellar-Structured Nanoparticles

Thünemann

Beyermann

Ferber³

et al. 1999

Langmuir

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“…In addition to its important role of transducing pleiotropic effects on morphogenesis, differentiation, and homeostasis during embryonal and postnatal life, retinoic acid has great potential as a pharmacological agent. Currently it is used in the external therapy of serious cases of acne, and it is discussed for use in skin rejuvenation therapy . Further, there have been reports on malignant-tumor inhibition by retinoids. , …”

Section: Introductionmentioning

confidence: 99%

“…Currently it is used in the external therapy of serious cases of acne, and it is discussed for use in skin rejuvenation therapy. 4 Further, there have been reports on malignant-tumor inhibition by retinoids. 5,6 All retinoids possess the same characteristic highly UV active chromophor and are hardly soluble as well as chemically unstable in aqueous media.…”

Section: Introductionmentioning

confidence: 99%

Immobilization of Retinoic Acid by Cationic Polyelectrolytes

Thünemann

1997

Langmuir

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Retinoic acid was immobilized by precipitating its complexes with cationic polyelectrolytes from aqueous solution. Polyelectrolytes with different architectures, such as poly(ionene-6,3 bromide), poly(dimethyldiallylammonium chloride), and poly(N-methyl-4-vinylpyridinium chloride), form self-assembling complexes containing retinoic acid (70% (w/w)). All these complexes are thermodynamically stable and can be processed into mesomorphously ordered films with interesting physical properties. In contrast to the brittle crystalline retinoic acid the complexes with polyelectrolytes are highly deformable viscoelastic materials. All materials show lamellar mesophase structures; their T g value strongly depends on the polyelectrolyte. It is suggested that these materials have great potential as pharmaceutical agents as well as models for the investigation and the mimicking of chromophores in visual pigments and photosynthetic bacteria. The properties of the complexes are examined by X-ray diffraction, differential scanning calorimetry, polarization optical microscopy, UV−vis spectroscopy, and stress−strain measurements.

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