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The Modification of Cellulosic Surface with Fatty Acids via Plasma Mediated Reactions

Posted on:2011-09-17Degree:Ph.DType:Thesis
University:North Carolina State UniversityCandidate:Nada, Ahmed Ali AhmedFull Text:PDF
GTID:2441390002463544Subject:Chemistry
Abstract/Summary:
Much attention has been paid recently to understand the healing process made by the human body, in order to develop new approaches for promoting healing. The wound healing process includes four main phases, namely, hemostatic, inflammatory, proliferation, and remodeling, which take place successively. The human body can provide all the requirements of the healing process in normal wounds, unless there is a kind of deficiency of the skin function or massive fluid losses of vast wounds. Therefore, wound care of non-healing wounds has recently been the growing concern of many applications.;The goal of this work is to explore the development of a new cellulose-based wound dressing composite that contain or release wound healing agents attained via dry textile chemical finishing techniques (thermal curing-plasma treatment). The synthesis of different wound healing agents derived from fatty acids and attached chemically to cellulose or even delivered through cyclodextrine modified cellulose are reported in this work.;First, free fatty acids, which are obtained from commercial vegetable oils, were identified as wound healing agents. Many of these free acids are known to bind with and deactivate the proteases associated with inflammation at a wound site. Linoleic acid is extracted from commercial products of safflower seed oil while ricinoleic acid is obtained from castor oil. Conjugated linoleic acid was synthesized. Un-conjugated linoleic acid was used to prepare two derivatives namely linoleic azide and allylic ketone of linoleic acid.;Different cellulose derivatives such as cellulose peroxide, iododeoxycellulose and cellulose diazonium salt in different degree of substitutions were synthesized in order to facilitate the free radical reaction with the fatty acid derivatives.;New modified cellulosic products were synthesized by reacting the cellulosic and the linoleic acid derivatives via thermal or plasma technique and characterized by FT-IR ATR, the wettability test, etc. The cyto-compatiability of the new product was investigated using the cytotoxicity test to identify the cytotoxic potentials of the grafted samples. The highest yield was obtained in the thermal curing (at 140°C, 3 min, and a 20% solution of azide derivative -- 170°C, 3 min, and a 2.5% solution of allylic ketone derivatives) of the iododeoxycellulose fabrics with either linoleic azide or the allylic ketone derivative. Atmospheric plasma machines were used for this study such as NCAPS (dielectric barrier discharge plasma) and APJeT. APJet plasma machine was used in two different modes namely downstream and in-situ. Although, the plasma treatment uses a lower energy to achieve the chemical reactions between the two components, the APJet obtained good results in the in-situ mode (at 800 Watts/cm3 RF power, 45 sec. exposure time) while retaining sufficient tensile strength. In general samples treated with the allylic ketone of linoleic acid treated samples showed higher graft yield than the azide derivative, especially those treated via thermal curing. Moreover, they are more cytologically compatible than the plasma treated samples.;In the course of producing a wound healing product that contains or releases fatty acids, allylic beta-CD was synthesized for first time as a textile finishing agent. Per(2, 3, 6-tri-O-allyl)-beta-CD was synthesized and characterized using spectral analysis. Cellulosic derivatives were treated with per(2, 3, 6-tri-O-allyl)-beta-CD via either pad-thermofixation technique or plasma treatment. Thermal treatment showed superior efficiency over plasma techniques to activate the vinyl groups and creating a self-assembled CD network chemically bonded with the cellulose derivatives (at 180°C, 3 min, and a 20% solution of Per(2, 3, 6-tri-O-allyl)-beta-CD). APJeT machine (in-situ mode) succeeded only to activate cellulose/allylic CD reaction, but however, it could not offer enough energy to stimulate vinyl-vinyl reactions.;Oleic acid with its semi-linear chemical structure tends to include in the CD cavity faster and to higher levels, than the others after 4 hrs at 25°C. At higher temperatures the equilibrium of free and included oleic acid shifts and a remarkable decrease in the total inclusion was observed. However, ricinoleic acid anions showed very poor tendency for inclusion either with high temperature or at long time which may be attributed to its chemical structure, which is too large for the CD cavities. Also, un-conjugated linoleic acid anions showed higher inclusion than the conjugated ones.;MMT assay was used to determine the cyto-compatibility for the newly modified samples. Generally speaking, the highest fixation yields the highest cyto-compatibility of the treated samples. Iododeoxycellulose samples in both thermal and plasma curing reported high cyto-compatibility either with allylic ketone or azide derivative of linoleic acid over the other cellulose derivatives. Pure extracted fatty acids or included ones showed high cyto-compatibility towards L929 mouse cell line.
Keywords/Search Tags:Acid, Plasma, Healing, Derivatives, Via, Cellulosic, Allylic ketone, Cyto-compatibility
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