Characterization of polymeric nanoparticles filled with Piper nigrum essential oil by atomic force microscopy

ABSTRACT

Essential oils derived from plants have attracted attention due to a several physico-chemical properties and biological activities. However, they have several limitations, as they are volatile and unstable in the presence of humidity, high temperatures, air and light and, thus, encapsulation techniques appear as an alternative to protect the functional properties of these oils while still providing a slow and controlled release. Due to the slow biological degradation of the materials that make up the capsule wall and the prolonged duration of the oil release action, micro and nanocapsules are of great scientific and technological interest. In this work, bilayer-based nanoparticles were developed using gelatin and poly-?-caprolactone to protect the essential oil of Piper nigrum through encapsulation and analyzed by atomic force microscopy. Nanoparticles with and without black pepper essential oil were prepared and dripped onto glass slides to form films that were investigated by images with resolutions of 256 x 256 pixels with areas of 5 x 5 mm². The oil was obtained through pepper seeds that were crushed and subjected to hydro distillation using a Clevenger type apparatus. Gelatin and poli-ε-caprolactane were used as wall material to increase the size of the nanoparticles and to obtain greater protection from the OE, resulting in an encapsulation efficiency of 98.50%. Nanoparticles with diameters ranging from 193.52 ± 40.14 to 295.54 ± 53.50 nm (without and with oil, respectively) were obtained. In addition, heights, densities and, average and root mean square roughness of the sample images were also compared, indicating a tendency of increase in these parameters due to the incorporation of essential oil in the synthesis, except in density due to the growth of other dimensions.

Keywords
Black pepper; Essential oil; Nanoencapsulation; Atomic force microscopy; Morphology