Inhomogeneous alginate gel spheres: An assessment of the polymer gradients by synchrotron radiation-induced x-ray emission, magnetic resonance microimaging, and mathematical modeling

Thu, Beate; Gåserød, Olav; Paus, Didrik; Mikkelsen, Arne; Skjåk‐Bræk, Gudmund; Toffanin, Renato; Vittur, Franco; Rizzo, Roberto

doi:10.1002/(sici)1097-0282(200001)53:1<60::aid-bip6>3.0.co;2-f

Cited by 130 publications

(89 citation statements)

References 26 publications

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“…With Ba 2+ , cross-linking times greater than 15 minutes has adverse effects on potassium channels. The drawback of cross-linking by using exclusively external Ba 2+ is microcapsule inhomogeneity as polymer gradients form during the cross-linking process [19,30]. Furthermore, the core of the microcapsules is less cross-linked than the periphery.…”

Section: Microcapsule Technologysupporting

confidence: 92%

Alginate-based encapsulation of cells: Past, present, and future

Zimmermann¹,

Shirley²,

2007

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Replacing dysfunctional endocrine tissues (eg, islets) with healthy, nonautologous material protected against the immune defense of the patient could soon become a reality. Recent advances have resulted in the development of alginate-based microcapsules that meet the demands of biocompatibility, long-term integrity, and function. Focus on the development of good manufacturing practice-conforming microfluidic chip technology for generation of immunoisolated transplants and on cryopreservation technology will bring the cell-based therapy to the market and clinics.

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Section: Microcapsule Technologysupporting

confidence: 92%

Alginate-based encapsulation of cells: Past, present, and future

Zimmermann¹,

Shirley²,

2007

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“…18 Several experimental investigations of the macroscopic properties of alginate gels in the presence of neutral electrolytes seem to support this view. 36,65 Preliminary gelation experiments actually show that, in the presence of an amount of NaCl as low as 0.1 M, the microscopic dynamics is drastically modied. In particular, the gel gets fully arrested, the restructuring kinetics also changes.…”

Section: Discussionmentioning

confidence: 99%

Biopolymer gels with “physical” cross-links: gelation kinetics, aging, heterogeneous dynamics, and macroscopic mechanical properties

et al. 2013

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Alginate is a natural biopolymer that forms, in the presence of divalent cations, ionic-bound gels typifying a large class of biological gels stabilized by non-covalent cross-links, and displaying a consistent restructuring kinetics. We investigate the kinetics of formation and aging of alginate gels by slow permeation of a curing CaCl 2 agent by means of photon correlation imaging, a novel optical technique that allows obtaining the microscopic dynamics of the sample, while retaining at the same time the spatial resolution of imaging techniques. Specifically, the gelling kinetics displays a peculiar non-diffusive behavior, and the subsequent restructuring of the gel structure shares several features in common with the aging of colloidal gels, in particular for what concerns the occurrence of heterogeneous dynamics effects. A comparative analysis of the gel macroscopic mechanical properties at different aging stages further highlights distinctive effects arising from the non-permanent nature of the bonds.

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“…During the gelling process, the bivalent Ca-ions diffuse from the surface into the bead and rapidly cross-link the alginate, resulting in a higher concentration near the surface than in the core (Skjak-Braek et al, 1989;Thu et al, 2000). For the bead production process used in this work, the alginate density distribution has been measured using Raman spectroscopy (Heinemann et al, 2005).…”

Section: Model Developmentmentioning

confidence: 99%