Preparation and characterization of size and sun protection factor (SPF) for solid lipid nanoparticles (SLNs) using asymmetrical flow field-flow fractionation (AsFlFFF) and relative techniques

다국어 초록 (Multilingual Abstract)

Solid lipid nanoparticles (SLNs) have a particle structure in which a surfactant surrounds a lipid-containing material such as drug or cosmetics. SLNs have some merits that they can be mass-produced in a short period of time and that they can be used as a colloidal carrier in various types of products including cosmetics. It can carry ingredients such as UV filters, improving chemical and physical storage stability, and improving skin occlusion. Studies have shown that the UV protection effectiveness of UV filters encapsulated in SLN is affected by the size of SLNs.
In this study, SLNs of various sizes were prepared by controlling the composition of lipid, surfactant, and UV filter. Then, the sizes of SLNs were characterized by using asymmetrical flow field-flow fractionation coupled with a photodiode array detector (AsFlFFF-PDA). The AsFlFFF conditions were optimized with the channel flow rate of 1.0 mL/min, cross-flow rate of 4.0 mL/min, and the composition of the carrier liquid of water containing 0.02% NaN₃. Results showed that the SLNs size increases with increasing lipid concentration and decreasing surfactant concentration.
Sunscreen formations were prepared using the SLNs, and the sun protection factor (SPF), a UV protection index, was measured. The SPF tends to increase as the size of SLN decreases. However, the SPF values were relatively low, probably due to prolonged homogenization process during the SLN preparation. It is suggested to shorten the homogenization time.