Desenvolvimento, caracterização e estabilidade de um sistema de nanopartículas bicamadas para liberação controlada do óleo essencial da Piper nigrum

Abstract

The sensitivity of essential oils to environmental factors and their low aqueous solubility has limited their applications, making them interesting materials for nanotechnology insertion. In this research, a controlled-release bilayer polymeric nanosystem was developed to encapsulate the essential oil from P. nigrum. Poly-ε-caprolactone (PCL) and gelatin were used as carriers. The applied characterization techniques were Dynamic Light Scattering (DLS), Gas Chromatography/Flame Ionization Detector (CG/DIC), Gas Chromatography/Mass Spectrometry (CG/EM), Atomic Force Microscopy (AFM), Infrared-transform Fourier Spectroscopy Infrared (FTIR), Infrared Spectroscopy/Atomic Force Microscopy (AFM-IR) and Ultraviolet-visible Spectroscopy (UV-vis). The essential oil presented ß-caryophyllene (35%) as the major compound, followed by sylvestrene (14.17%) and sabinene (14.96%). The nanoparticles containing encapsulated essential oil presented average diameter of (290 ± 30) nm with PDI of (0.23 ± 0.03), zeta potential (-45 ± 3) mV and spherical morphology. The Encapsulation Efficiency (EE) was (98 ± 2) %. The stability of the encapsulated systems was evaluated by EE, electrical conductivity, turbidity, pH and organoleptic properties after the addition of specific preservatives, among which the mixture of phenoxyethanol/isotialzoni-3-one (NPNE system) resulted in enhanced stability of approximately 120 and 210 days in constant handling and shelf life tests, respectively. In the photostability evaluation, the carriers favored the prolonged protection of the essential oil up to approximately 168 h when compared to the essential oil in natura, which degraded after 6 h of exposure to ultraviolet radiation. The developed polymeric system, in addition to protecting the essential oil, presented similar controlled release in acidic, neutral or basic pH. The release curves showed the pulsatile release mechanism inherent to the design of the polymeric bilayers of nanoparticles.