Herstellung, Struktur und Anwendung von ionotropen Gelen aus carboxygruppenhaltigen Polysacchariden. Fortschrittsbericht

Heinze, Thomas; Klemm, Dieter; Loth, F.; Philipp, B.

doi:10.1002/actp.1990.010410501

Cited by 24 publications

(9 citation statements)

References 79 publications

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“…In order to synthesize these flexible capsules, we surrounded tiny droplets of a ferrofluid emulsion with thin gel layers of calcium alginate. Further details on the crosslinking structure, the so-called egg-box model [4], is shown in the supplementary information, available at stacks.iop.org/JPhysCM/30/085101/ mmedia. Calcium alginate gels are non-toxic, biocompatible and porous with tunable release properties [5].…”

Section: Introductionmentioning

confidence: 99%

Production, deformation and mechanical investigation of magnetic alginate capsules

Zwar

Kemna

Richter

et al. 2018

J. Phys.: Condens. Matter

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In this article we investigated the deformation of alginate capsules in magnetic fields. The sensitivity to magnetic forces was realised by encapsulating an oil in water emulsion, where the oil droplets contained dispersed magnetic nanoparticles. We solved calcium ions in the aqueous emulsion phase, which act as crosslinking compounds for forming thin layers of alginate membranes. This encapsulating technique allows the production of flexible capsules with an emulsion as the capsule core. It is important to mention that the magnetic nanoparticles were stable and dispersed throughout the complete process, which is an important difference to most magnetic alginate-based materials. In a series of experiments, we used spinning drop techniques, capsule squeezing experiments and interfacial shear rheology in order to determine the surface Young moduli, the surface Poisson ratios and the surface shear moduli of the magnetically sensitive alginate capsules. In additional experiments, we analysed the capsule deformation in magnetic fields. In spinning drop and capsule squeezing experiments, water droplets were pressed out of the capsules at elevated values of the mechanical load. This phenomenon might be used for the mechanically triggered release of water-soluble ingredients. After drying the emulsion-filled capsules, we produced capsules, which only contained a homogeneous oil phase with stable suspended magnetic nanoparticles (organic ferrofluid). In the dried state, the thin alginate membranes of these particles were rather rigid. These dehydrated capsules could be stored at ambient conditions for several months without changing their properties. After exposure to water, the alginate membranes rehydrated and became flexible and deformable again. During this swelling process, water diffused back in the capsule. This long-term stability and rehydration offers a great spectrum of different applications as sensors, soft actuators, artificial muscles or drug delivery systems.

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Section: Introductionmentioning

confidence: 99%

Production, deformation and mechanical investigation of magnetic alginate capsules

Zwar

Kemna

Richter

et al. 2018

J. Phys.: Condens. Matter

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“…After the reduction, the obtained polysaccharide was water soluble even after dialysis and freeze-drying. Figure I (A) shows 13 C NMR spectrum of the poly(l) and Figure l(B) shows that of reduced polysaccharide. After the reduction, the absorptions of aromatic groups were hardly observed and the peak of carboxyl group was shifted from 174 ppm to 182 ppm, indicating that benzyl groups were practically removed and ester groups were hydrolyzed to carboxylate groups.…”

Section: Resultsmentioning

confidence: 99%

Syntheses of Polysaccharides Having Various Contents of Carboxyl Groups by Ring-Opening Copolymerization

Hatanaka

Minamisawa

Kan'no

1995

Polym J

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ABSTRACT:Polysaccharides having various contents of carboxyl group precursors were synthesized by ring-opening copolymerization of 1,6-anhydro-2,4-di-O-benzyl-3-O-1-(methoxycarbonyl)ethyl-jl-o-glucopyranose (I) with tri-O-benzyl-levoglucosan (2) with phosphorus pentafluoride as catalyst in methylene chloride at -60°C. The monomer reactivity ratios calculated by Kelen-Tiidiis method were r 1 = 0. 77 and r 2 = 0. 71. Birch reduction with lithium metal was quite effective for the deprotection of both methyl ester and benzyl ether groups of the polymer.

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“…These technologies are also important in pharmaceutical and medical applications such as drug delivery and cell encapsulation [1][2][3][4]. For these environmentally compatible encapsulation techniques gels of calcium alginate are frequently used because alginate is a cheap, non-toxic, easily polymerizable biopolymer with tuneable release properties [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…Alginate biopolymers are composed of blocks of two different polysaccharide components, α-L-guluronic acid and β-D-mannuronic acid [6][7][8]. The homopolymeric blocks in the chain are termed M (mannuronic acid) and G (guluronic acid).…”

Section: Introductionmentioning

confidence: 99%

Magneto-responsive alginate capsules

Degen

Zwar

Schulz

et al. 2015

J. Phys.: Condens. Matter

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Upon incorporation of magnetic nanoparticles (mNPs) into gels, composite materials called ferrogels are obtained. These magneto-responsive systems have a wide range of potential applications including switches and sensors as well as drug delivery systems. In this article, we focus on the properties of calcium alginate capsules, which are widely used as carrier systems in medicine and technology. We studied the incorporation of different kinds of mNPs in matrix capsules and in the core and the shell of hollow particles. We found out that not all particle-alginate or particle-CaCl2 solution combinations were suitable for a successful capsule preparation on grounds of a destabilization of the nanoparticles or the polymer. For those systems allowing the preparation of switchable beads or capsules, we systematically studied the size and microscopic structure of the capsules, their magnetic behavior and mechanical resistance.

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Herstellung, Struktur und Anwendung von ionotropen Gelen aus carboxygruppenhaltigen Polysacchariden. Fortschrittsbericht

Cited by 24 publications

References 79 publications

Production, deformation and mechanical investigation of magnetic alginate capsules

Production, deformation and mechanical investigation of magnetic alginate capsules

Syntheses of Polysaccharides Having Various Contents of Carboxyl Groups by Ring-Opening Copolymerization

Magneto-responsive alginate capsules

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