Penetration of silver nanoparticles into porcine skinex vivousing fluorescence lifetime imaging microscopy, Raman microscopy, and surface-enhanced Raman scattering microscopy

Abstract

In order to investigate the penetration depth of silver nanoparticles (Ag NPs) inside the skin, porcine ears treated with Ag NPs are measured by two-photon tomography with a fluorescence lifetime imaging microscopy (TPT-FLIM) technique, confocal Raman microscopy (CRM), and surface-enhanced Raman scattering (SERS) microscopy. Ag NPs are coated with poly-N-vinylpyrrolidone and dispersed in pure water solutions. After the application of Ag NPs, porcine ears are stored in the incubator for 24 h at a temperature of 37°C. The TPT-FLIM measurement results show a dramatic decrease of the Ag NPs' signal intensity from the skin surface to a depth of 4 μm. Below 4 μm, the Ag NPs' signal continues to decline, having completely disappeared at 12 to 14 μm depth. CRM shows that the penetration depth of Ag NPs is 11.1 ± 2.1 μm. The penetration depth measured with a highly sensitive SERS microscopy reaches 15.6 ± 8.3 μm. Several results obtained with SERS show that the penetration depth of Ag NPs can exceed the stratum corneum (SC) thickness, which can be explained by both penetration of trace amounts of Ag NPs through the SC barrier and by the measurements inside the hair follicle, which cannot be excluded in the experiment.

Ultrafast imaging Raman spectroscopy of large-area samples without stepwise scanning

“…The weak pigmented spots at (3/15) and (13/5) are also identifiable in the Raman image. The obtained Raman spectra are similar, with Raman spectra of porcine skin obtained using another Raman microscope (Zhu et al, 2015).…”

A Method for Quantification of Penetration of Nanoparticles through Skin Layers Using Near-Infrared Optical Imaging

“…Confocal fluorescence microscopy and other spectroscopic techniques are commonly used to detect and study the penetration of nanoparticles through skin [9]. Microscopy is frequently combined with use of a mechanical sectioning technique called tape stripping, which allows for examination of thin skin layers of progressive depth [10].…”

Non-invasive diagnostic techniques in the diagnosis of squamous cell carcinoma

“…The optical resolution of MPT is typically about 0.5 μm in lateral and 1-2 μm in axial direction with a field of view (FOV) of 350 x 350 μm and an imaging depth of 200 μm. 57,58 Klemp et al 59 in their study proved that MPT can be a valuable non-invasive imaging methode for in vivo detection and discrimination of AK and SCC from health skin. They showed that the cell nuclei of AK and SCC were significantly larger compared to healthy skin cells in all cell layers, and cell density in AK and SCC was significantly lower than in the basal and spinous cell layers of healthy skin.…”