Control of physicochemical and cargo release properties of cross-linked alginate microcapsules formed by spray-drying

Encapsulation in dry cross-linked alginate microbeads has numerous applications in pharmaceutics, food, and agriculture. Recently, we developed an innovative, industrially scalable, and cost-effective method in which alginates are cross-linked in-situ during spray-drying to form cross-linked alginat...

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Bibliographic Details
Published in:Journal of drug delivery science and technology 2019-02, Vol.49, p.440-447
Main Authors: Strobel, Scott A., Scher, Herbert B., Nitin, Nitin, Jeoh, Tina
Format: Article
Language:English
Subjects:
alginates
Calcium alginate
calcium hydrogen phosphate
Controlled release
cost effectiveness
Cross-linking
crosslinking
Dextran
dissociation
drugs
encapsulation
Internal gelation
microbeads
Microencapsulation
particle size
spray drying
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Summary:Encapsulation in dry cross-linked alginate microbeads has numerous applications in pharmaceutics, food, and agriculture. Recently, we developed an innovative, industrially scalable, and cost-effective method in which alginates are cross-linked in-situ during spray-drying to form cross-linked alginate microcapsules (CLAMs), consolidating a series of unit operations into a single step. This study investigated the control of alginate matrix cross-linking by modulating the CaHPO4 content and explored the subsequent impact on CLAM physicochemical properties. Maximum cross-linking was achieved at CaHPO4 feed contents greater than 0.2% (w/w). CLAMs prepared with ≥0.25% CaHPO4 in the spray-dryer inlet feed contained residual insoluble CaHPO4, and particle morphology of such CLAMs tended to appear more spherical and less dramatically collapsed than less cross-linked CLAMs. Cross-linking of CLAMs did not influence particle size. The release of dextran from CLAMs was examined in the context of matrix hydration and the dissociation of non cross-linked alginate from the matrix. Dextran release was characterized by a brief delay, followed by rapid release, concluding within 2 h. Elevated cross-linking slightly hindered the early release of FITC-labeled dextran from CLAMs. Alginate dissociation was delayed and less extensive in highly cross-linked CLAMs, suggesting alginate dissociation may govern the early stage of cargo release. [Display omitted]
ISSN:1773-2247
DOI:10.1016/j.jddst.2018.12.011