Qualitative detection of single submicron and nanoparticles in human skin by scanning transmission x-ray microscopy

Abstract

First results on single particle detection in human skin samples by x-ray microscopy are reported. 94+/-6 and 161+/-13 nm gold core particles with silica shells and 298+/-11 nm silica particles coated with a gold shell on ultramicrotome sections of human skin were determined. The particles were applied on fresh intact skin samples, which were sectioned prior to imaging. After screening the sections by conventional microscopy techniques, defined areas of interest were qualitatively investigated by scanning transmission x-ray microscopy at the Swiss Light Source. In studies on the percutaneous penetration of 161+/-13 nm particles on human skin samples, x-ray microscopy yielded high-resolution images of single particles spreading on the superficial layer of the stratum corneum and on the epithelium in superficial parts of hair follicles. No deeper penetration was observed. The present work using x-ray microscopy provides the unique opportunity to study qualitative penetration processes and membrane-particle interactions on the level of single particles. This goes beyond present approaches using optical microscopy. Further improvement of this approach will allow one to study particles with different physicochemical properties and surface modifications, including responses of the exposed tissue.

Stability of fluorescent labels in PLGA polymeric nanoparticles: Quantum dots versus organic dyes

“…These results indicated the possibility of using any of the markers for the shortterm skin permeation experiments. Similar results have been observed in previous reports for polymeric nanoparticles with fluorescent markers (Abdel-Mottaleb et al, 2011;AlvarezRoman et al, 2004;Graf et al, 2009). The same was observed for QDs when their penetration was tested in intact rat skin and in flexed, tape stripped (30 times) and abraded skin (using sandpaper 60 times to remove the stratum corneum) in a flow through cells.…”

In vitro percutaneous penetration and characterization of silver from silver-containing textiles

“…Moreover, Graf et al found that gold particles with dimensions of 161±13 nm were able to penetrate the superficial layers of the SC and hair follicles. 34 Also in the study by Graf et al, no deeper penetration was observed. 34 It was noted in the present study that silver-containing aggregates …”

“…34 Also in the study by Graf et al, no deeper penetration was observed. 34 It was noted in the present study that silver-containing aggregates …”

Lysine-functionalized nanodiamonds as gene carriers: development of stable colloidal dispersion for in vitro cellular uptake studies and siRNA delivery application

“…This calculation was based on the assumption that formation of a protein corona around NDs resembles a classical ligand binding model and thus follows the law 59 Soft X-rays also provide spatial resolution of 25-30 nm 60 and spectral resolution on the order of 100 meV 61,62 that can differentiate between classes of biomolecules and can identify NPs as therapeutic carriers in cells and tissues. 57 The spectrum of lys-NDs (red; Figure 3A) recorded as a reference shows identifiable peaks at 288.2 eV, 292.5 eV, and 297.5 eV, indicated by arrows, which are absent in the spectrum of intracellular proteins (green; Figure 3A) obtained from the untreated cells. For detailed evaluation, untreated cells and lys-ND-treated cells were scanned separately through STXM at wide range of photon energies.…”

“…It allows high-resolution imaging that enables evaluation of interactions on the level of individual particles. [56][57][58] Most importantly, it can be applied to fully hydrated biological materials, which allows functional analysis of molecular mechanisms in a living cell under zeta potential as a function of incubation time with FBS. Upon visual inspection, the lys-NDs showed no visible sedimentation up to 3 days ( Figure 2C), indicating good dispersibility.…”