Subtle influence on alginate gel properties through host–guest interactions between covalently appended cyclodextrin and adamantane units

2021 ◽  
Author(s):  
Gabriela Ionita ◽  
Elena Irina Popescu ◽  
Ludmila Aricov ◽  
Sorin Mocanu ◽  
Iulia Matei ◽  
...  
Keyword(s):  
Daily Life ◽  
Structural Features ◽  
Gel Properties ◽  
Alginate Gel ◽  
Alginate Gels

Alginate gels have been explored in relevant domains for daily life such as pharmaceutics and environmental. The structural features of alginate allow functionalization which, in extension, can modify the gel...

Modified Microparticles of Calcium Alginate Gel for Controlled Release of Anesthetics

2007 ◽  
Vol 1060 ◽  
Author(s):  
Erkesh E. Batyrbekov ◽  
Turar N. Akylbekova ◽  
Rinat M. Iskakov
Keyword(s):  
Local Anesthetics ◽  
Calcium Alginate ◽  
Polymer Coating ◽  
Polymer Concentration ◽  
Alginate Beads ◽  
Physiological Solution ◽  
Polymeric Coating ◽  
Tail Flick ◽  
Alginate Gel ◽  
Alginate Gels

ABSTRACTThe aim of this work is the development of controlled delivery system immobilized by local anesthetics on the basis of modified microparticles of calcium alginate gels. The kazkain, rikhlokain, lidokain and novokain were used as local anesthetics. Modified microparticles were obtained by syringed dropwise a solution of ansthetics in sodium alginate into solution of polymers such as chitosan or polyethyleneimine in calcium chloride. The obtained modified alginate microparticles were contained immobilized anesthetics in core of particles and a surface layer of polymer. Effects of polymer concentration and exposure duration on the thickness of polymer coating were determined. The release of anesthetics from the modified alginate gel particles into a physiological solution with different thickness of coating were studied. All the release data show the typical pattern for a matrix controlled mechanism. The cumulative amount of drug released from alginate gels was linearly related to the square root of the time and the release rate decreased this time. The process is controlled by the diffusion of anesthetics through the polymeric coating. The data shown a possibility of the regulation of the rate of anesthetics release from the modified alginate particles by way of alternation of thickness of the polymer coating. The anesthetic effect of the alginate microparticles containing drugs was tested on rats by method “tail flick” according two criteria: full analgesia – the absence of reaction on pain and sufficient analgesia – exceeding of pain threshold sensibility two and more times. Medical-biological tests show that the duration of anesthetic activity for the drug-containing alginate beads increases at 5-8 times in comparison of free drugs.

scholarly journals Relevance of Rheological Properties of Sodium Alginate in Solution to Calcium Alginate Gel Properties

2011 ◽  
Vol 12 (2) ◽  
pp. 453-460 ◽  
Author(s):  
Shao Fu ◽  
Ankur Thacker ◽  
Diana M. Sperger ◽  
Riccardo L. Boni ◽  
Ira S. Buckner ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Sodium Alginate ◽  
Calcium Alginate ◽  
Gel Properties ◽  
Alginate Gel ◽  
Calcium Alginate Gel

scholarly journals Immobilization of Analgetic AB-101 into Calcium Alginate Gels

2017 ◽  
Vol 4 (4) ◽  
pp. 293 ◽  
Author(s):  
R.M. Iskakov ◽  
E.O. Batyrbekov ◽  
B.A. Zhubanov ◽  
Y.Y. Fomicheva ◽  
V. K. Yu ◽  
...  
Keyword(s):  
Average Diameter ◽  
Lag Time ◽  
Fickian Diffusion ◽  
Burst Release ◽  
Sodium Ions ◽  
Alginate Gel ◽  
Gel Beads ◽  
Alginate Gels ◽  
Calcium Alginate Gels ◽  
G Ratio

<p>A new analgetic drug AB-101 has been immobilized into Ca<sup>2+</sup>-alginate gel beads with average diameter of 1 mm. A series of the alginate gel contains with various mannuronic/guluronic (M/G) ratios has been chosen to control the diffusion of the drug. Release of the drug from the alginate gel beads into physiological solutions consisting of sodium ions has been examined. A discontinuous time of the Fickian diffusion of the drug depending on M/G ratio was followed by a burst release of the remaining drugs. The burst release was due to a swift disintegration of Ca<sup>2+</sup>-alginate with exchange on sodium ions. The preceding discontinuous lag time promotes a free dissociate exchange of sodium-calcium ions in M units, while the burst disintegration leads to fast dissociation of G units. The lag time can be control by M/G ratio of Ca<sup>2+</sup>-alginate gels. The lag time increases if a content of the M units decreases. The increase of M units was led to more extensive swelling of the gel beads. Such way could be promising for a controlled drug delivery or the use in implants with controlled drug effect.</p>

Electron microscopy and diffraction studies of polyimides

1983 ◽  
Vol 41 ◽  
pp. 28-29
Author(s):  
O.C. de Hodgins ◽  
K. R. Lawless ◽  
R. Anderson
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Structural Features ◽  
Inert Atmosphere ◽  
Polyimide Films ◽  
Resolution Electron ◽  
The Matrix ◽  
High Resolution Electron Microscope ◽  
Diffraction Patterns ◽  
Polymeric Samples

Commercial polyimide films have shown to be homogeneous on a scale of 5 to 200 nm. The observation of Skybond (SKB) 705 and PI5878 was carried out by using a Philips 400, 120 KeV STEM. The objective was to elucidate the structural features of the polymeric samples. The specimens were spun and cured at stepped temperatures in an inert atmosphere and cooled slowly for eight hours. TEM micrographs showed heterogeneities (or nodular structures) generally on a scale of 100 nm for PI5878 and approximately 40 nm for SKB 705, present in large volume fractions of both specimens. See Figures 1 and 2. It is possible that the nodulus observed may be associated with surface effects and the structure of the polymers be regarded as random amorphous arrays. Diffraction patterns of the matrix and the nodular areas showed different amorphous ring patterns in both materials. The specimens were viewed in both bright and dark fields using a high resolution electron microscope which provided magnifications of 100,000X or more on the photographic plates if desired.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Study of the Molecular Architecture of Keratin Filaments by Electron Microscopy

1982 ◽  
Vol 40 ◽  
pp. 118-119
Author(s):  
U. Aebi ◽  
P. Rew ◽  
T.-T. Sun
Keyword(s):  
Electron Microscopy ◽  
Structural Organization ◽  
Cell Types ◽  
Structural Features ◽  
Molecular Architecture ◽  
The Past ◽  
Keratin Filaments ◽  
Different Types ◽  
10 Nm Filaments ◽  
Different Cell Types

Various types of intermediate-sized (10-nm) filaments have been found and described in many different cell types during the past few years. Despite the differences in the chemical composition among the different types of filaments, they all yield common structural features: they are usually up to several microns long and have a diameter of 7 to 10 nm; there is evidence that they are made of several 2 to 3.5 nm wide protofilaments which are helically wound around each other; the secondary structure of the polypeptides constituting the filaments is rich in ∞-helix. However a detailed description of their structural organization is lacking to date.

Measurement and Reduction of Radiation Damage in Frozen Hydrated Crystalline Specimens

1978 ◽  
Vol 36 (3) ◽  
pp. 70-77 ◽  
Author(s):  
R.M. Glaeser ◽  
S.B. Hayward
Keyword(s):  
Diffraction Pattern ◽  
Structural Information ◽  
Structural Disorder ◽  
Structural Features ◽  
Biological Macromolecules ◽  
Diffraction Intensity ◽  
Object Structure ◽  
Specimen Material ◽  
Unit Cells ◽  
Identical Unit

Highly ordered or crystalline biological macromolecules become severely damaged and structurally disordered after a brief electron exposure. Evidence that damage and structural disorder are occurring is clearly given by the fading and eventual disappearance of the specimen's electron diffraction pattern. The fading and disappearance of sharp diffraction spots implies a corresponding disappearance of periodic structural features in the specimen. By the same token, there is a oneto- one correspondence between the disappearance of the crystalline diffraction pattern and the disappearance of reproducible structural information that can be observed in the images of identical unit cells of the object structure. The electron exposures that result in a significant decrease in the diffraction intensity will depend somewhat upon the resolution (Bragg spacing) involved, and can vary considerably with the chemical makeup and composition of the specimen material.

Some Structural Features of Metaphase Chromosomes of Mice and Men

1967 ◽  
Vol 25 ◽  
pp. 190-191
Author(s):  
Godfrey C. Hoskins ◽  
Betty B. Hoskins
Keyword(s):  
Electron Microscopy ◽  
Electron Micrographs ◽  
Structural Features ◽  
Metaphase Chromosomes ◽  
The Future ◽  
Of Mice And Men ◽  
Mouse Cells ◽  
Human And Mouse

Metaphase chromosomes from human and mouse cells in vitro are isolated by micrurgy, fixed, and placed on grids for electron microscopy. Interpretations of electron micrographs by current methods indicate the following structural features.Chromosomal spindle fibrils about 200Å thick form fascicles about 600Å thick, wrapped by dense spiraling fibrils (DSF) less than 100Å thick as they near the kinomere. Such a fascicle joins the future daughter kinomere of each metaphase chromatid with those of adjacent non-homologous chromatids to either side. Thus, four fascicles (SF, 1-4) attach to each metaphase kinomere (K). It is thought that fascicles extend from the kinomere poleward, fray out to let chromosomal fibrils act as traction fibrils against polar fibrils, then regroup to join the adjacent kinomere.

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