Polymeric nanoparticles containing an oily core, named nanocapsules (NCs),
have been widely studied in the life sciences field due to their
therapeutic potentialities of drug targeting in the body accompanied
also by its larger stability in the biological fluids compared to other
colloidal carriers. Many studies have shown different applications of
nanocapsules for therapeutic use concerning their properties [1] of
loading poorly water-soluble drugs, protection drugs from inactivation
in the gastro-intestinal tract [2], gastric mucosal toxicity protection
[3,4], increased drug permeation through mucous epithelium [5,6] and
prolongation of drugs in blood circulation for surface modified
nanocapsules [7]. The characterization of the nanocapsules is frequently
performed by mean size, surface charge of the particles (zeta
potential), hydrophobicity, drug loading yield and release kinetic [8].
These features are of great importance for biodistribution profile and
interactions with the cells of mononuclear phagocyte system of any
injected particles by intravenous route [1]. However, few data on
structural organization of the nanocapsules constituents are available
in literature and several hypotheses only suggest the presence of an oil
"capsular" structure surrounded by a polymeric envelope. Recently,
atomic force microscope (AFM) has been used as a method for imaging the
surfaces of colloidal systems, such as liposomes [9,10] and nanospheres
[11], supplying high resolution information in nanoscaled dimension. In
the present work, unloaded nanocapsules were deposited on mica in order
to analyze by AFM the diameter, height, particles polydispersion, and
topographic characteristics of nanocapsule surface.