J. Cosmet. Sci., 59, 225–232 (May/June 2008) AFM capabilities in characterization of particles and surfaces: from angstroms to microns*

Abstract

The skin's uppermost thin layer, stratum corneum, plays a crucial role in protecting the body against unwanted influences from the environment. Disruption of the stratum corneum, by tape stripping or chemical injury, results in epidermal recovery of the skin barrier. Soy phytosterols are widely used in the cosmetic field as active ingredients in creams and lipsticks. Furthermore, they deserve an important place among nutracosmeceuticals; in fact, after their absorption from the diet they are transferred from the plasma to the skin, playing an important role in the constitution of skin surface lipids. The aim of the present work was to study the effect of the topical application of soybean phytosterols on skin barrier recovery in human volunteers using the extent of methyl nicotinate (MN)induced erythema in damaged skin as a parameter to evaluate the rate of stratum corneum recovery. MN was chosen as an erythematogenous substance for its capability to cause an erythema whose intensity and duration are proportional to the quantity of the substance that has entered the living epidermis over time. MN-induced erythema was monitored using reflectance spectrophotometry as a non-invasive instrumental technique. The results show clearly that soy phytosterols exert positive results on skin repair; in fact, 3 days after tape stripping, the sites treated with a formulation containing phytosterols showed an appreciable recovery of barrier function compared to those treated with a vehicle control without soy phytosterols.

Tumor-derived microvesicles: shedding light on novel microenvironment modulators and prospective cancer biomarkers

“…Unlike NTA, however, dynamic light scattering measures fluctuations in the intensity of scattered light that can then be used to mathematically determine size distributions (Lawrie et al 2009). This method is capable of measuring particles ranging in size from 1 nm to 6 mm in diameter but is best suited to monodisperse samples (Starostina et al 2008;Dieckmann et al 2009). Raman spectroscopy may also be used to determine the diameter of particles that fit within the probe volume (on the order of 0.3 mm 3 ), including microvesicles.…”

Overview of Nanomaterial Characterization and Metrology

“…AFM can be used to characterize height, size, shape, aspect ratio, and surface morphology of individual particles. 49 In AFM experiments, particle size is defined as the maximum height of the particle and particle size distributions may be calculated using three-dimensional analysis software. AFM images have three dimensions of data, which allow for nanomaterial diameter, volume, and surface area to be calculated.…”

3d Imaging of Individual Particles: a Review

“…The sample preparation and above all the cleanliness of the surface are a big matter of concern. The vertical resolution in ideal conditions is below the angström, whereas lateral resolution can easily reach atomic resolution (Friedbacher et al, 1991;Rao et al, 2007;Starostina et al, 2008).…”