Design of blue crab chitosan responsive nanoparticles as controlled-release nanocarrier: Physicochemical features, thermal stability and in vitro pH-dependent delivery properties.

In this study, carotenoproteins (CPs) were encapsulated in blue crab chitosan-tripolyphosphate and chitosan-protein isolate nanoparticles by ionotropic gelation and complex coacervation, respectively. The success of CPs encapsulation was confirmed by FT-IR spectroscopy, TGA and XRD techniques. Particles size and thermal stability of nanoparticles depend on the encapsulation method. Indeed, a regular distribution and spherical shape, with size range of about 300 nm (ionotropic gelation) - 600 nm (complex coacervation), were observed by SEM analysis. The encapsulation efficiency and loading capacity of CPs were about 74% and 31% for the complex coacervation and 89% and 47% for the ionotropic gelation approaches, respectively. In vitro release studies showed a fast initial release effect, followed by a slow CPs release. The highest amount of released CPs in a shorter time was observed with the ionotropic gelation method. Further, in vitro release kinetics of CPs were found to be medium dependent, where nanoparticles incubated in ethanol displayed higher released CPs amount in a longer release time, compared to nanoparticles immerged in PBS (pH ~ 6.8). These findings suggest that the encapsulation technique obviously affected the particles structure, and the glass transition temperature, and the mass loss of encapsulated materials. The better CPs thermal stabilization was obtained for the ionotropic gelation nanoparticles.