Development of astaxanthin-loaded nanostructured lipid carriers using a combination of cetyl palmitate and soybean oil

The aim of this study was to formulate and evaluate the characteristics and stability of astaxanthin-loaded nanostructured lipid carriers (ASX-NLCs). Four ASX-NLC formulas were prepared using cetyl palmitate and soybean oil in ratios of 100:0, 90:10, 80:20, and 70:30, respectively. ASX-NLCs were prepared by high shear homogenization method, then characterized and evaluated for stability after 30 days of storage at 40 degrees C and 75% RH. Differential scanning calorimetry (DSC) analysis of solid lipid bulk (cetyl palmitate) and ASX-NLCs was also carried out. The characterization results showed that all ASX-NLCs had pH values suitable for skin application, with no significant differences between the four formulas, even after storage. All freshly produced ASX-NLCs yielded nanometer-sized particles with homogenous size distributions and provided quite good entrapment efficiency. DSC analysis results exhibited lower lipid crystallinity in ASX-NLCs compared to cetyl palmitate. After storage, there was an increasing trend in particle size and polydispersity index, while the entrapment efficiency and antioxidant activity decreased. However, ASX-NLC with a cetyl palmitate and soybean oil ratio of 70:30 showed an insignificant decrease in entrapment efficiency and antioxidant activity, thereby it was considered to have better stability than the other formulas.