In-Vitro Measurement methods
MTT Viability TestCosmetics are designed to promote and support the vitality of the skin. A recognized method for determining the vitality of tissues is the MTT Viability test.
In this case, living cells in titer plates (see below) are treated with the product to be examined. If then MTT, actually a yellow salt, is added, only living cells convert the MTT into the purple-blue Formazan.
On the basis of the intensity of the color change, the effect of a product on the vitality of the cells can be measured by means of photometry. The intensity of the color is then directly proportional to the proportion of living cells.of substances, establishment phase.
Interleukin detection by enzyme-linked immunosorbent assay (ELISA)The epidermis is a metabolic-active tissue, which is subject to a process of permanent renewal. By an acute or long-term injury or infection of the epidermis, messengers, e.g. Biomarkers are released. These messengers include, inter alia, interleukin-1α (IL-1α), which also results in activation of further inflammatory factors (e.g., IL-6 and IL-8, etc.). The liberated IL-1α can be removed from the epidermis by washing the skin in its quantity and then determined by an analytical method (ELISA) as an inflammatory marker.
The ELISA variant used here is characterized as the so-called sandwich ELISA, in which two antibodies bind specifically to the antigen to be detected. The amount of interleukin can be determined photometrically by a subsequent enzymatic reaction, in which a color change is formed.
Schematic representation ELISA
The first antibody is firmly bound to the incubation chamber (A). Interleukin 1α binds to the first and second antibodies (B-C). After addition of the streptavidin-HRP (D) and the substrate (E), an enzymatic reaction takes place which converts the substrate into a blue dye. By the stop solution, the dyestuff changes from blue to yellow.
TEER (transepithelial electrical resistance)
Measurement to determine skin barrier function
The integrity and stability of the stratum corneum is of crucial importance for the integrity of the skin barrier. In simple terms, one can compare the structure of the skin barrier with a wall. The superimposed skin cells (corneocytes) are held together by the hard-skin fats. This composition is an essential prerequisite for a healthy and resistant skin. The individual skin cells are additionally closely linked to each other by so-called "tight junctions", direct cell-cell contacts. They occlude the cell interspaces and form a paracellular barrier (diffusion barrier) that is finely regulated and extremely dynamic. This barrier restricts the free diffusion and thus regulates the transport of water and solutes. The density (tissue-specific) is usually described by transepithelial electrical resistance.