Nanostructured lipid carriers (NLC) are a new generation of Solid Lipid Nanoparticles (SLN), with improved drug loading capacity, stability, skin permeation, and sustained release of the encapsulated active. The encapsulation of vitamin A, a chemically labile cosmetic ingredient for anti-aging therapy, is ensued for effective delivery of the active. The method used for the production of the lipid nano-carriers is the hot homogenization technique. Furthermore, this study entailed a 23-factorial model design of experiment, where the three factors changed in the eight NLC formulation were surfactant to solid lipid ratio, Vitamin A Palmitate (RP), and prickly pear (PP) oil. The purpose of this study was to investigate the formulation and characterization of the NLCs, in an aim to find trends in changing the three factors constituting the matrix of the carrier on their exhibited characteristics, in order to arrive at an optimal formulation for the delivery of vitamin A to the skin in terms of particle size, polydispersity index (PDI), zeta potential (ZP), entrapment efficiency (EE%), in-vitro release and ex-vivo skin permeation. The results attained from the parameters investigated were further analyzed using a statistical program, Design Expert. The particle size for the eight NLC carriers were in the range of 197.6 nm to 240.2 nm. The overall PDI for most of the formulations was lower than 0.3. The SLN had a much bigger particle size of 296.7 nm and PDI of 2.47. The release patterns in both in-vitro and ex-vivo showed differences in trends for the two types of carriers. The ZP of the formulations was not indicative of their predicted stability. Instead, the relative constitution of the solid to liquid lipid was pivotal in assessing the variation witnessed in both particle size and PDI upon storage for 6 weeks. The EE% showed a close dependence on the amount of PP oil in the matrix, where an equal or higher composition to the RP is required for effective incorporation. The thermal behavior assessed using Differential Scanning Calorimetry (DSC), of the 9 formulations showed a similar trend for 7 NLC, where minimal transitions suggesting amorphous characteristics were observed. The remainder NLC formulation exhibited similar transitions to that of the SLN, suggesting a higher order of crystallinity. The lower melting point of the NLCs in comparison to the pure solid lipid is an indication to the incorporation of the RP within the matrix. The total release of the in-vitro trials showed a close dependence on the amount of RP, where a higher composition of the latter lead to enhanced diffusion, and total release for the NLCs. The initial diffusion flux, however, was different and showed a close relation to the EE%. Formulations with high EE% showed a more sustained release, as opposed to more pronounced burst release exhibited by formulations with low EE%. The formulations that exhibited the highest in-vitro release were further assessed for skin permeation studies across a natural, rat skin membrane using Franz Diffusion Cell (FDC). The formulation with the higher surfactant ratio has shown higher permeation across the membrane, but lower skin retention. This was confirmed by slicing and extracting RP from various skin sections after the ex-vivo experiment. Imaging using Scanning Electron Microscopy (SEM) has also been performed on the SLN and NLC. Finally, changes in the constituting matrix of the nano-lipidic carrier gives wide variation in its properties, and hence allows it to be tinkered and adjusted for a particular use. Finally, the NLC formulations, in general, exhibited differences in their respective assessed parameters, all showing an improvement compared to the SLN. The optimal formula consisted of a higher composition of all lipidic constituents, namely Vitamin A and PP oil content, and a lower surfactant to solid lipid ratio. Its choice was based on stability and EE% as the most important parameters. The exhibited particle size and PDI of this formulation was 236.8 nm, and 0.24 upon formulation, and 265.3 nm and 0.27 after storage for 6 weeks, respectively. The EE% was 95.1 ï‚± 1.1%, ZP -32.87 ï‚±0.25 mV and total in-vitro release was 43 ï‚±7.3%.
MS in Chemistry
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(2017).Vitamin a palmitate-loaded NLCs vs. SLN for cosmetic application with a study of their controlled release, skin permeation and characterization. [Master's Thesis, the American University in Cairo]. AUC Knowledge Fountain.
AlZahabi, Sham Mohamad Ayman. Vitamin a palmitate-loaded NLCs vs. SLN for cosmetic application with a study of their controlled release, skin permeation and characterization.. 2017. American University in Cairo, Master's Thesis. AUC Knowledge Fountain.