The effect of silver nanoparticles on the penetration properties of the skin and quantification of their permeation through skin barrier

Transdermal delivery of drugs represents a non-invasive alternative treatment used not only for skin diseases. As one of the possible penetration enhancing agents, various types of nanoparticles (NPs) could be used. Silver NPs (AgNPs) could be used for some medical purposes considering their antibacterial and antiinflammatory properties. We demonstrate a novel method of quantification of permeated AgNPs, detection of AgNPs dissolving while passing the skin, and examination of interactions between skin and systems with AgNPs. Several AgNPs (exhibiting defined mean diameters of 20, 40, 60, and 100 nm) were added individually to the pure solvents commonly used in pharmaceuticals, namely ethanol, methanol, dimethyl sulfoxide, and demineralized water. AgNP dispersions in different solvents were applied to untreated samples of the skin. Attenuated total reflection technique was used for monitoring the kinetic series of infrared spectra to elucidate the time-dependent changes in the uppermost layer of the skin. The depth profiling spectra series were measured using confocal Raman microspectrometer. All recorded vibrational spectra were evaluated by multivariate statistical methods. A strong influence of AgNP size on the structural changes of the skin surface was evident. The largest changes of the skin structure were caused by the 20-nm and 40-nm AgNPs. Permeation of used AgNPs was studied on vertical Franz diffusion cells with detection of permeated AgNPs by new method based on single-particle inductively coupled plasma mass spectrometry.