Characterization of fatty acid based nanostructured lipid carrier (NLC) and their sustained release properties

Abstract

Nanostructured lipid carrier (NLC) is a second generation lipid nanoparticle formed by blends of solid and liquid lipids through hot homogenization technique. In this study, arachidic acid (C20) and erucic acid (C22:1) were used as solid lipids while oleic acid as liquid lipid in the preparation of NLC. Five types of NLC were prepared by varying the amount of oleic acid (C18:1) with respect to arachidic acid while maintaining the amount of erucic acid. Physical stability of the prepared NLC was characterized by its size and zeta potential for a period of 28 days. The results showed that the size of NLCs were between 200 to 260 nm with zeta potential of -55 to -40 mV. Differential scanning calorimetry (DSC) data showed that presence of oleic acid reduces the crystallinity of nanoparticle. Apart from that, depending on the compositions, the morphology of NLC examined under transmission electron microscopy’s (TEM) was round to elongate in shape. Then, active ingredients of ascorbic acid, caffeine and lidocaine with varied hydrophilicity were then loaded into the NLC. Lidocaine has an encapsulation efficiency of nearly 78% while caffeine reaches 43%. Surprisingly, ascorbic acid which is hydrophilic gave a comparative amount of encapsulation efficiency as caffeine at low concentration. This might relate to attraction between opposite charge of NLC and ascorbic acid. When the active ingredients loaded NLC was subjected to in vitro release, the active ingredients’ release profile suggested that NLC exhibit sustained release properties whereby the rate of release is concentration dependent.