CONICET | Buscador de Institutos y Recursos Humanos

Nanoencapsulation can protect a ligand from harsh environments, make it target-specific, increase its biodisponibility and control its release profile, therefore, nanocapsules are widely used in the farmaceutical industry as drug carrier systems.In this work, the encapsulating material of choice was chitosan (CS), a kind gift by the Microbiology Laboratory of INTI Mar del Plata, Argentina. Chitosan is a non-toxic, biocompatible and biodegradable biopolymer, with mucoadhesive and absorption-enhancing properties and it has been extensively employed for developing drug delivery systems. Insulin, one of the most used peptide drugs worldwide, was kindly donated by Denver Farma Laboratories, Buenos Aires, Argentina. Its concentration was kept constant at 0.2 %, w/w throughout the experiments.The aim of our work was to determine the most efficient conditions to enable the nanoencapsulation of Insulin, under the molecular "self-assembly? concept. Particle size distribution and ζ-potential measurements were registered by dynamic light scattering (Zetasizer Nano-Zs, Malvern Instruments, Worcestershire, UK). Measurements were made at pH of 6 to favor electrostatic interactions between the two species.Variations in the ζ-potential values of Insulin-CS mixtures were observed upon increasing concentrations of CS. The CS mass needed for insulin charge titration was 10-3 % w/w; this result would indicate the appropriate biopolymers mass ratio to ensure generation of core-shell nanocapsules. Thus, Insulin-CS mixtures particle size distribution was obtained for several CS concentrations, exhibiting a noticeable shift from free insulin size distribution. Additionally, CS may induce molecular changes in protein structure as determined by fluorescence spectroscopy at pH of 6.Finally, the nanocapsules's structure and topography were characterized by SEM.