Nanopartículas auto-organizadas de goma do cajueiro enxertada com a policaprolactona para encapsulamento do fármaco epirrubicina

Abstract

Copolymers based polysaccharides have been the focus of several research for the development of drug delivery systems, as they offer increase of solubility, bioavailability and cellular permeability of hydrophobic drugs. Cashew gum is a natural polysaccharide composed of galactose, glucose, arabinose, rhamnose and glucuronic acid that have gained prominence in the development of nanoparticles for pharmaceutical applications. Polycaprolactone is a non-toxic polyester, biodegradable and it is approved by the Food and Drug Administration for use as biomaterial in biomedical applications. Therefore, the present work proposed the preparation of nanoparticles from an amphiphilic copolymer obtained by grafting polycaprolactone onto cashew gum. The synthesis of three copolymers was performed with different percentages, by mass, of polycaprolactone, and it was confirmed by infrared spectroscopy and nuclear magnetic resonance. The copolymers showed self-assembled capacity in water with critical association concentration ranging from 42 to 60 μg mL-1. The nanoparticles were characterized by dynamic light scattering and scanning electron microscopy. The diameter of the nanoparticles show a decreasing trend with increasing polycaprolactone graft percentage (226 - 202 nm). Epirubicin was used as a hydrophobic drug model and incorporated into the nanoparticles. The hydrodynamic diameter of the nanoparticles with epirubicin increased in relation to the diameter of the unloaded nanoparticles (299 - 267 nm). All systems presented an unimodal size distribution, zeta potential above 30 mV in modulus and spherical structure. The stability of the nanoparticles was studied in water at 4 °C and in phosphate buffer pH 7.4 at 37 °C. For the unloaded nanoparticles, a not very common behavior for colloidal systems was observed, which is a decrease of the diameter during the stability study in water, called anti-Ostwald maturation. All loaded nanoparticles stability, both at physiological pH and during storage in water at 4 °C. The encapsulation efficiency of epirubicin in the nanoparticles ranged from 50 to 60% (w/w) and the drug load ranged from 5.0 to 6.0% (w/w).