Development and characterization of lipid nanoparticles for encapsulation of vitamin A

Vitamin A plays a major role in several key aspects of human biology and its deficiency is acknowledged as a public health problem, mostly in developing countries. The main goal of this work is to develop lipid nanoparticles (LNs) containing the vitamin, suitable for food fortification and that are not affected by its hydrophobicity, to overcome this issue. Firstly, we performed a screening of the solubility of retinyl acetate (RA), the chosen form of vitamin A, in different lipids. Gelucire 43/01 and stearic acid were selected for further studies. Solid lipid nanoparticles (SLNs) were synthetized by firstly melting the solid lipid and adding the RA. Tween 80 in water was then added and afterwards this mixture was sonicated to create a nanoemulsion. Nanostructured lipid carriers (NLCs) were prepared identically, except for the inclusion of a liquid lipid (oleic acid or Miglyol) in the melted solid lipid/RA mixture. A method for quantification of vitamin A in the LNs using UV/Vis spectrophotometry was developed and validated and applied to determine the incorporation of RA by a direct technique. Morphological characterisation was achieved by cryo-Scanning Electron Microscopy and the LNs size and zeta potential assessed by Dynamic Light Scattering. Using the hot ultrasonication method, SLNs and NLCs were successfully synthetized. The highest encapsulation efficiency (EE) was achieved for Gelucire SLNs (80%), followed by Gelucire/Miglyol NLCs (74%). All LNs had sizes in the range 162-612 nm and zeta potentials lower than -23 mV. LNs with higher EE will be optimized in further work. Nevertheless, these LNs are a promising approach towards the fortification of food with vitamin A.