ADSORPTION OF BETA-BLOCKERS ONTO POLY(ISOBUTYLCYANOACRYLATE) NANOPARTICLES - ADSORPTION MODEL AND DIELECTRIC INTERPRETATION

The objective of this report is to understand the boundary mechanism o f a model drug, propranolol hydrochloride, onto poly( isobutylcyanoacr ylate)nanoparticles stabilized with a mixture of dextran and dextran s ulfate, and to explain the similarity between depletion isotherms and the curves obtained with the dielectric method. The dramatic influence of the sulfate groups has been demonstrated by the dosage of the dext ran sulfate in the bulk aqueous medium as well as by the interpretatio n of the propranolol hydrochloride adsorption isotherm, Due to its sul fate groups, dextran sulfate is able to bind to propranolol hydrochlor ide by an ion exchange process and the resulting complex moves toward the nanoparticle surface, It is the first time that such a model is pr oposed. In addition, this model supports and explains the dielectric a nswer: indeed, we had demonstrated that the dielectric method makes it possible to determine the amount of drug loaded onto the nanoparticle s, without any ultracentrifugation or assay of the drug, Finally, the application field of the dielectric method may be enlarged to other ar eas such as ionic resins. (C) 1996 Academic Press, Inc.