Nanostructured Lipid Carriers With Liquid Crystal Structure Encapsulating 377:preparation And Characterization

377 (PR) is a relatively new and highly effective whitening agent which is 22 times more effective than kojic acid. However, its instability and poor solubility stands in the way of being applied in the cosmetic products. Nanostructured lipid carriers (NLC) have been gradually applied in medicine and cosmetic industry as a new type of carrier system. Its stability is excellent, the particle size is very small, and can achieve controlled drug release. The liquid crystal structure possess very good affinity to human skin due to its structural similarity to the skin. Therefore, the combining of liquid crystal structure and NLC could eventually be a promising delivery vehicle in cosmetic dermal products.In this paper, the preparation of the NLC was studied first. After some experiments, the preparation was determined as follow:homogenized at 16000rpm for 3min, then ultrasonicated at 30% power for 5min. After that, the formulation was optimized. The emulsifier and the solid lipid was screened by stability, mobility and the liquid crystal structure. Then the liquid lipid was chosen by dispersivity test and the particle size and PDI of the emulsion it formed. And the response surface method was used to determine the exact amount of every material.The final formulation is:Cetearyl Glucoside as emulsifier 1.6%, Behenyl Alcohol as solid lipid 2%, Triglyceride of Caprylic apricacid (GTCC) as liquid lipid 1%, and PR 1%. The effect of the additives adding into the formulation on particle size and PDI was also studied.This paper described the characterization and in vitro evaluation of the nanostructured lipid carriers with liquid crystal structure encapsulating Phenylethyl Resorcinol (PR-LC-NLC). The results showed that the nanostructured lipid carriers with liquid crystal structure were spherical under scanning electron microscope and transmission electron microscope. The particle size and PDI were 153.9±8.3 nm and 0.23±0.01. The absolute value of the zeta potential was 38.8±0.6mv, negative. In 9 weeks of storage, the mean particle size were in the range of 157.4 nm to169.3 nm and PDI values were lower than 0.3. The entrapment efficiencies determined by ultrafiltration and high performance liquid chromatography was 98.70%. Fourier transform infrared spectra was exploited to investigate the possible drug-lipid complex formation. Differential scanning calorimetry was used to detect the thermal transitions involving energy changes. Small angle X-ray scattering and Karl Fischer titration identified and characterized the liquid crystal structure of the PR-LC-NLC. In vitro drug release studies revealed a sustained drug release, and in vitro penetration studies showed an increase of retention amount of PR in the skin. Therefore, the combining of liquid crystal structure and NLC might eventually be a promising delivery vehicle in cosmetic dermal products.Finally, the application of the PR-LC-NLC in cosmetic products was studied. The additives could be used in cosmetic products such as moisturizing agent, water-soluble oil and reheology control agent.