The Impact of Skin Massage Frequency on the Intrafollicular Transport of Silica Nanoparticles: Validation of the Ratchet Effect on an Ex Vivo Porcine Skin Model

The study investigated the effect of massage frequency on the penetration depth of cyanine 5-labeled silica nanoparticles (Cy5-SNPs) in hair follicles using an ex vivo porcine skin model. It was found that lower massage frequencies, particularly 4.2 Hz, resulted in deeper follicular penetration of nanoparticles compared to higher frequencies of 50 Hz and 100 Hz. Additionally, nanoparticles with a diameter of 676 nm penetrated more deeply than those with diameters of 300 nm and 1000 nm. These findings supported previous in silico predictions and suggested that low-frequency massage could be beneficial for drug delivery applications targeting hair follicles.