Characterisation and stability evaluation of bixin nanocapsules

The aim of this study was to produce bixin nanocapsules by the interfacial deposition of preformed poly-epsilon-caprolactone (PCL). PCL (250 mg), capric/caprylic triglyceride (400 mu L), sorbitan monostearate (95 mg) and bixin were dissolved in a mixture of acetone (60 mL) and ethanol (7.5 mL) under stirring (40 degrees C). This organic solution was added to the aqueous solution (130 mL) containing Tween 80 (195 mg). The size distributions in the formulations with bixin concentration from 11 to 100 mu g/mL were evaluated periodically during 3 weeks of storage at ambient temperature. The optimal formulation (bixin concentration of 16.92 +/- 0.16 mu g/mL) was characterised in terms of particle size distribution, zeta potential, bixin content and encapsulation efficiency, and showed a volume-weighted mean diameter (D-4.3) of 195 +/- 27 nm, around 100% of encapsulation efficiency and the nanocapsules were considered physically stable during 119 days of storage at ambient temperature. (C) 2013 Elsevier Ltd. All rights reserved.