The effect of particle size on the deposition of solid lipid nanoparticles in different layers of skin

Abstract

Introduction: Nowadays, carrier systems in nanometric scale attract growing interest for topical treatment of skin diseases to improve the skin penetration of drugs and to reduce side effects. Among them lipid based nanocarriers such as solid lipid nanoparticles (SLNs) have showed more promising future. SLNs were used in topical formulations, not only for pharmaceutical ingredients but also for cosmetic products. Investigation on the distribution pattern, penetration depth and rate of SLNs would provide important and exciting information for researchers working on dermal and transdermal drug delivery with the aid of nanoparticles. Aim: In the present study the effect of particle size, as a substantial parameters in skin penetration, on the deposition depth and rate of SLNs in different layers of skin was explored. Methods: SLNs in different particle size ranges (80, 333 and 971 nm) made of Precirol as solid lipid were prepared using hot melt homogenization (HMH) technique and pigmented by Rhodamine B to be able to be tracked in the skin under inspection of fluorescent microscopy. After 0.5 h, 3 h, 6 h and 24 h of SLNs administration on rat skin, animals were sacrificed and exercised skins were sliced by a cryocut. The images were taken from normal light and fluorescence microscopy of the same area and evaluate quantitatively. Results: The size of SLNs played a crucial role in the penetration to deep skin layers. The sub 100 nm size range of SLNs showed the most promising skin penetration rate and depth mainly via hair follicles. Conclusion: The results of the present study indicated that the selection of an appropriate size of particles may be a valuable factor impacting the therapeutic outcomes of dermal drug administration.