Papers by Cao hoc Hoa Ly Thuyet va Hoa Ly
Nanotechnology can be used to modify the drug permeation/penetration of encapsulated substances, ... more Nanotechnology can be used to modify the drug permeation/penetration of encapsulated substances, through the manipulation of many different factors, including direct contact with the skin surface and controlled release. In general, nanoparticles cannot cross the skin barrier, which can be explained by the cell cohesion and lipids of the stratum corneum, the outermost skin layer. The device most commonly used to study the transport of substances and nanoparticles across the skin is the Franz vertical diffusion cell, followed by the substance quantification in the receptor fluid or determination of the amount retained in the skin. Microscopy techniques have also been applied in skin penetration or permeation experiments. This chapter will present the fundamental considerations regarding the transport of encapsulated substances and/or nanoparticles across the skin, the experimental models applied in these studies and a review of the main studies reported in the literature in order to allow the reader to gain insight into the current knowledge available in this area. * Reprinted (Adapted) with permission from Rouse et al., 2007. Since the skin is an organ with multiple layers, it can be used during in vitro skin permeation/penetration studies with its two basic layers, epidermis and dermis (full-thickness skin) or it can be submitted to treatments that separate its layers supplying different types of membranes (split-thickness skin) to be used for in vitro studies [26, 42, 43]. The choice of the membrane is related to the focus of the study (permeation or penetration). In the full-thickness skin membranes only the subcutaneous tissue is removed [26, 42, 43]. On the other hand, split-thickness skin can be obtained in several ways [26, 42, 43] and the isolation of one specific layer of a skin sample with a controlled thickness can be made using heat and force (heat-separated epidermis), dermatome (dermatomed skin) or enzymatic processes (trypsin-isolated stratum corneum) [44, 45]. Epidermis and stratum corneum membranes are more fragile and some mass balance techniques, such as tape stripping, cannot be applied [27]. Divergences can be found in the literature concerning the effect that these processes can have on the skin characteristics. Some studies have demonstrated that the skin barrier is reestablished with the hydration of these membranes [46, 47]. On the other hand, some reports have claimed that the viability of the skin and the flow through the epidermis can be disturbed by these processes [26, 48, 49].
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Papers by Cao hoc Hoa Ly Thuyet va Hoa Ly