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CLSM method for the dynamic observation of pH change within polymer matrices for oral delivery

Cook, M. T., Saratoon, T., Tzortzis, G., Edwards, A., Charalampopoulos, D. and Khutoryanskiy, V. V. (2013) CLSM method for the dynamic observation of pH change within polymer matrices for oral delivery. Biomacromolecules, 14 (2). pp. 387-393. ISSN 1525-7797

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To link to this item DOI: 10.1021/bm301569r


If acid-sensitive drugs or cells are administered orally, there is often a reduction in efficacy associated with gastric passage. Formulation into a polymer matrix is a potential method to improve their stability. The visualization of pH within these materials may help better understand the action of these polymer systems and allow comparison of different formulations. We herein describe the development of a novel confocal laser-scanning microscopy (CLSM) method for visualizing pH changes within polymer matrices and demonstrate its applicability to an enteric formulation based on chitosan-coated alginate gels. The system in question is first shown to protect an acid-sensitive bacterial strain to low pH, before being studied by our technique. Prior to this study, it has been claimed that protection by these materials is a result of buffering, but this has not been demonstrated. The visualization of pH within these matrices during exposure to a pH 2.0 simulated gastric solution showed an encroachment of acid from the periphery of the capsule, and a persistence of pHs above 2.0 within the matrix. This implies that the protective effect of the alginate-chitosan matrices is most likely due to a combination of buffering of acid as it enters the polymer matrix and the slowing of acid penetration.

Item Type:Article
Divisions:Interdisciplinary centres and themes > Chemical Analysis Facility (CAF) > Thermal (CAF)
Life Sciences > School of Chemistry, Food and Pharmacy > Department of Food and Nutritional Sciences > Food Research Group
ID Code:30770
Publisher:ACS Publications


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