Study of plasmonic nanoparticles interactions with skin layers by vibrational spectroscopy.

The healing effects of silver and gold nanoparticles (AgNPs, AuNPs) are already known from ancient times. In addition considering to their antibacterial and anti-inflammatory effects speculations are being lead with respect to these nanoparticles (NPs) also about enhancement of skin penetration properties. In this work the interactions of pig skin (PS) layers and ointments with additions of AgNPs or AuNPs prepared by standard procedures and also by "green" synthesis in a different weight proportion by vibrational spectroscopy were studied. Spectra of untreated skin and skin treated by pure ointment were measured, as well as by ointment modified by vitamins without addition of NPs or with different proportion of NPs. Kinetics of interactions of modified ointments with skin was monitored during two hours with a five-minutes interval between each two consecutive measurements. The obtained series of spectra were analyzed by multivariate statistical methods namely Partial Least Squares (PLS), Principal Component Analysis (PCA) and Soft Independent Modelling of Class Analogy (SIMCA) which revealed observation of spectral changes in time-dependent spectra and variations of the peak intensity ratios. The study showed that the effects of quantity and type of NPs on skin penetration characteristics are evident.