Modelling Mucoadhesion by Use of Surface Energy Terms Obtained from the Lewis Acid–Lewis Base Approach. II. Studies on Anionic, Cationic, and Unionisable Polymers

Rillosi, M. and Buckton, G. (1995) Modelling Mucoadhesion by Use of Surface Energy Terms Obtained from the Lewis Acid–Lewis Base Approach. II. Studies on Anionic, Cationic, and Unionisable Polymers. Pharmaceutical Research, 12 (5). pp. 669-675. 10.1023/A:1016299223369.

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DOI: 10.1023/A:1016299223369

Abstract

Surface energies of carbopol, chitosan, hydroxypropyl cellulose (HPC) and poly(HEMA) were assessed from contact angle and surface tension experiments. The surface energy was considered in terms of an apolar Lifshitz-van der Waals term and a polar acid-base term, which in turn is divided into electron donor and electron receptor (Lewis acid-Lewis base) contributions. Using these surface energy terms the interaction of dry and hydrated polymer with mucin in the presence of either artificial gastric or intestinal fluid, or saline was predicted. The predictions were related to measured forces of detachment. There was a significant difference between the surface energy on dry and hydrated HPC and also for carbopol; for the other polymers either the surface energy of the hydrated material was not detectable, or the effect of hydration was minimal. There were good correlations between mucoadhesive strength and the calculated free energies of interaction between mucin and polymer in the presence of each of the fluids, for each individual polymer. Thus, two trends were observed, one for unionisable and the other for ionisable polymers. It is argued that the increased mucoadhesion seen with ionisable polymers (compared with the predicted value based on results of unionisable polymers) is a direct result of the ionic interaction. No attempt has been made to correct for the ionisation effect, but the surface energy predictions provide insight into the mechanism of the mucoadhesion process. This approach is useful for understanding and predicting interactions between different materials and biological components.

Item Type:Article
Uncontrolled Keywords:surface energy - Lewis acid-Lewis base - contact angle - mucoadhesion - mucin - carbopol - chitosan - cellulose - p(HEMA) - biocompatibility
Departments, units and centres:Department of Pharmaceutics > Department of Pharmaceutics
ID Code:3274
Journal or Publication Title:Pharmaceutical Research
Deposited By:Library Staff
Deposited On:18 May 2012 15:29
Last Modified:18 May 2012 15:29

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