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The microclimate pH in poly(d,l-lactide-co-hydroxymethyl glycolide) microspheres during biodegradation

Paper ID Volume ID Publish Year Pages File Format Full-Text
6664 510 2012 10 PDF Available
Title
The microclimate pH in poly(d,l-lactide-co-hydroxymethyl glycolide) microspheres during biodegradation
Abstract

The microclimate pH (μpH) in biodegradable polymers, such as poly(d,l-lactic-co-glycolic acid) (PLGA) 50/50, commonly falls to deleterious acidic levels during biodegradation, resulting in instability of encapsulated acid-labile molecules. The μpH distribution in microspheres of a more hydrophilic polyester, poly(d,l-lactide-co-hydroxymethyl glycolide) (PLHMGA), was measured and compared to that in PLGA 50/50 of similar molecular weight and degradation time scales. pH mapping in the polymers was performed after incubation under physiological conditions by using a previously validated ratiometric method employing confocal laser scanning microscopy (CLSM). Confocal μpH maps revealed that PLHMGA microspheres, regardless of copolymer composition, developed a far less acidic μpH during 4 weeks of incubation compared with microspheres from PLGA. A pH-independent fluorescent probe marker of polymer matrix diffusion of μpH-controlling water-soluble acid degradation products, bodipy, was observed by CLSM to diffuse ∼3–7 fold more rapidly in PLHMGA compared to PLGA microspheres, consistent with much more rapid release of acids observed from the hydrophilic polymer during bioerosion. Hence, PLHMGA microspheres are less susceptible to acidification during degradation as compared to similar PLGA formulations, and therefore, PLHMGA may be more suitable to deliver acid labile molecules such as proteins.

Keywords
Microclimate pH; Confocal laser scanning microscopy; Hydrophilic polyesters; Microsphere; pH distribution; Poly(lactic-co-glycolic acid)
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The microclimate pH in poly(d,l-lactide-co-hydroxymethyl glycolide) microspheres during biodegradation
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Publisher
Database: Elsevier - ScienceDirect
Journal: Biomaterials - Volume 33, Issue 30, October 2012, Pages 7584–7593
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us