EFFECT OF LYSOZYME ON THE STABILITY OF POLYESTER NANOCAPSULES AND NANOPARTICLES - STABILIZATION APPROACHES

The efficacy of colloidal particles as drug carriers is closely relate d to their interaction with proteins and enzymes in different body flu ids. In the present work, we analysed the interaction phenomenon betwe en lysozyme (LZM), a positively charged enzyme that is highly concentr ated in mucosas, and two different drug carriers: nanocapsules made of an oily core coated by the polymer poly-epsilon-caprolactone (PECL) a nd nanoparticles made solely of PECL. Results showed that the interact ion of LZM with these colloidal drug carriers is highly affected by th eir surface charge. Nanocapsules, because of their important negative charge (-40 mV), adsorbed a great amount of LZM, which is positively c harged. This adsorption process, which was also evidenced by the signi ficant reduction of the nanocapsules' negative surface charge, led to the degradation of the polymer coating and the aggregation of the nano capsules. In contrast, nanoparticles had a low negative surface charge (-8 mV) and adsorbed only a small amount of LZM, which did not cause the destabilization of the system. Furthermore, the molecular weight o f the polymer forming the nanoparticles did not change. Finally, it wa s observed that the destabilizing effects caused by the adsorption of LZM onto the nanocapsules can be prevented by previous adsorption of t he cationic poly(amino acid) poly-L-lysine. Using this approach the ad sorption of LZM was hindered and its consequences avoided. (C) 1997 El sevier Science Limited. All rights reserved.