Wyniki wyszukiwania - BazTech

1

Rheology of drugs for topical and transdermal delivery

Walicka A., Falicki J., Iwanowska-Chomiak B.

International Journal of Applied Mechanics and Engineering

|

2019

|

Vol. 24, no. 1

179--198

EN

Skin drug delivery systems are a constant source of interest because of the benefits that they offer to overcome many drawbacks associated with other modes of drug delivery (i.e. oral, intravenous, etc.). Because of the impermeable nature of the skin, designing a suitable drug delivery vehicle that penetrates the skin barrier is challenging. Skin drug delivery can be subdivided into topical and transdermal (Fig.1). In a topical administration the drug is intended to act at skin level, this is indicated for the treatment of skin diseases. The aim of transdermal administration is getting a systemic release and in this case the skin represents a barrier not a target. The availability of drugs or other active substances through the skin depends basically on two consecutive steps: the release of these drugs or substances from vehicle or carrier and their subsequent permeation through the skin. Hence, studies on the specific properties of vehicles or carriers, such as their rheological behaviours, are of great interest in the field of pharmaceutical products. The objective of the present study is to systematically characterize a nonlinear rheological behaviour and flow properties of drugs and drug carriers into topical and transdermal administration. To this aim, one- and threedimensional rheological models are presented, which may be used to describe drug release through the skin and through the extracellular and interstitial matrix structures. Finally, the rheological measurements of some commercial creams and ointments were made.

2

Zastosowanie analizy wieloskalowej do detekcji ludzkiej skóry w obrazach cyfrowych

Jarosiński Ł., Kawulok M.

Studia Informatica

|

2011

|

Vol. 32, nr 2A

565-577

PL

Celem prac przedstawionych w niniejszym artykule była poprawa precyzji detekcji ludzkiej skóry w obrazach cyfrowych na podstawie barwy. Wcześniejsze badania autorów wskazywały na możliwość znacznej redukcji błędów segmentacji poprzez zastosowanie analizy obszarów spójnych. W ramach prezentowanych prac zastosowany został mechanizm wieloskalowej analizy ekstremów lokalnych w obrazie transformacji falkowej, pozwalający na wybranie tych obszarów spójnych, które istotnie przedstawiają ludzką skórę. Przedstawione wyniki badań eksperymentalnych potwierdziły skuteczność proponowanych rozwiązań.

EN

This paper is focused on improving color-based human skin detection in digital images. Our earlier works indicated that the segmentation errors can be significantly reduced using blob detection. The main contribution of this work is the multiscale analysis of local extrema in the wavelet domain, which allows selecting the blobs that indeed represent the human skin. The experimental results have confirmed that the proposed method is effective and reduces the segmentation error.

3

Rola składników aktywnych w procesie starzenia się skóry

Łubkowska B., Grobelna B., Maćkiewicz Z.

Wiadomości Chemiczne

|

2010

|

[Z] 64, 11-12

1053-1071

EN

Skin is the coating of all human and animal organisms. It is a kind of space where different processes take place. Skin is the largest and the heaviest organ in the body. Also, it is a barrier, that stops water and the part of body, which should be particularly protected [1]. The skin is composed of three main layers: epidermis (Fig. 1), dermis (Fig. 3) and subcutaneous tissue (Fig. 5). Each of these layers has completely different role and is characterized by various properties. Epidermis is the outermost layer of skin. It consists of a living and a dead zone. The living area forms new cells which are the subject to further changes, while in the zone of dead cells they are highly flattened and devoid of nuclei [2]. In the epidermis, exactly in the reproductive output layer there are melanocytes, which are cells responsible for production of the pigment - melanin (Fig. 2). Melanin is responsible for color of hair, eyes and skin. It is formed from tyrosine as a result of numerous biochemical reactions [3]. Biological activity of melanin is determined by the presence of appropriate peptide. The sequences of its active components are: Ser-Tyr, Ser-Met-Glu-His-Phe-Arg, and Trp-Gly-Lys-Pro-Val. It is possible to protect the skin also against the solar radiation. The hormone MSH absorbs and reflects UV radiation. Under the influence of UV radiation the amount of melanin increases, causing temporary changes in skin color [3]. Under the epidermis there is a proper skin, which is composed of elastic fibers, collagen fibers, and the basic substance, which fuses the fiber elements. The elastic fibers are scattered among collagen fibers. Proper skin is the place where a valuable protein - very important in cosmetics - occurs - the native collagen. It is the main protein of connective tissue. Collagen has a very high tensile strength and is a major component of tendons. It is responsible for skin elasticity. Loss of collagen from the skin causes wrinkles [4]. A distinctive layer of skin is the subcutaneous tissue. It combines dermis with muscles. It is composed of fat cells separated by connective tissue. The size and the shape of fat cells vary depending on gender, diet and also age [5]. Skin, like other authorities is aging. These process may be accelerated or delayed under the influence of various endogenous and exogenous elements (Tab. 1). Also genetic predisposition are of significant importance. It seems that, as soon as we age, we inherit from our ancestors. To delay the aging process, it is necessary to properly take care of and protect the skin. There are many ways to delay aging of the skin. The most successful, for example cosmetics with active ingredients such as peptides, will be presented here.

4

Wpływ surfaktantów na zwilżalność ciał stałych ze szczególnym uwzględnieniem skóry ludzkiej

Harkot J., Jańczuk B.

Wiadomości Chemiczne

|

2007

|

[Z] 61, 9-10

707-731

EN

This paper reviews wetting phenomena in relation to different types of solids and human skin in the presence of surfactants. Wettability of solids by surfactants is important for many technological applications. The addition of surfactants is necessary to achieve a better wettability of a given solid. In the first part of this article the definition of a contact angle and an interfacial tension along with methods of their determination is presented. Next, a relationship between a liquid--air, a solid-air and a solid-liquid interfacial tensions and wettability of solids is shown. Three types of wetting are discussed in this work: a spreading wetting, an adhesional wetting, and an immersional wetting. Wettability forces of hard surface and powders are also described in this part of the article. In the third part of the article main aspects related to the solids critical surface tension of wetting are presented. Different problems of solids' wetting critical surface tension are described, since there is still no unambiguous method to determine this value. Later, based on the Lucassen-Reynolds equation we described the dependence between the adsorption of surfactants at the interfaces, mainly in a solid-water-air systems and wetting of solids, because they are both strongly related. From this equation the slope of a plot of ?LVcos? (adhesion tension) versus ?LV (surface tension) gives us the information about the surface concentration of the surfactant at water-air and a solid-water interfaces in a solid--water-air system including both non-polar (low-energy) and polar (high-energy) solids. We have also shown that in the case of hydrophobic solids, for several types of surfactants, there is a constant negative slope of ?LV cos?-?LV curve. However, for high-energy polar solids the positive slope of this curve is observed and there is no linear dependence between adhesional and surface tension. Thus, for a high energy solid-aqueous surfactant solution-air systems it is difficult to establish synonymous mutual relationships between the adsorption of surfactant at a solid-air, a solid-liquid and a liquid-air interfaces and wettability of high-energy hydrophilic solids. At the end we presented main problems dealing with wettability of human skin surface, which is the most important factor of the skin protective function. It minimizes water loose, prevents entry of a foreign matter and chemicals, and defines smoothness and elasticity of the skin. Surprisingly, this subject has received a little attention in the literature. The human skin surface, after the extraction of sebum (skin surface lipids) belongs to hydrophobic surfaces (low-energy) in terms of critical surface tension and polar and dispersion components of a free surface energy. El-Shimi and Goddard compared the skin surface with polymer surfaces such as polyvinylchloride, polytetrafluoroethylene and polyethylene, but we have to remember that the human skin is a living matter and in the presence of sebum becomes hydrophilic. In order to remove this fatty film from the skin surface cleansing products, which contain many various surfactants, are used. Good wetting and cleansing effects of such products depend on surfactants ability to adsorb on the skin surface and reduce an interfacial tension at water-skin interface in skin-water-air system.