Universiẗat, Diss., 2001--Mainz.

Zugl.: Dresden, Techn. Univ., Diss., 2006

Zugl.: Erlangen, Nürnberg, Universiẗat, Diss., 2009.

The presented diploma thesis deals with a targeted modification of the structural properties of hydrogels, which is closely related to the application properties of these materials (eg transport). Due to the desired pharmacological applications of the use of these materials for targeted drug release, hydrogels based on chitosan and polyvinyl alcohol as substances with good biocompatibility were selected for the study. The combination of these polymers ensured swelling (controlled by the presence of chitosan) and viscoelastic (influenced by the presence of polyvinyl alcohol) properties, which were characterized by a wide range of analytical and physicochemical methods (swelling, tensile strength, rheology, atomic force microscopy or specific surface area, etc.). Information on structural properties played a crucial role not only for a detailed description of the studied materials in terms of whether the structural properties can be changed in a targeted manner, but also served as an explanation for the different release of the active substance diclofenac from the hydrogel matrix. With regard to the literature search, the effect of pH and crosslinking was chosen to modify the properties. From the measured results it was found that even a slight change in pH has an effect on the transport or release of the active substance. The results obtained in this work may be useful in the formation of hydrogel matrices with drugs depending on the intended medical applications.

Vitiligo is a skin disease with 2 % prevalence in a worldwide population. It is characterised by loss or decrease in activity of epidermal melanocytes, which lead to skin and hair depigmentation. It has negative impact on psyche, social relationships of patients and reduces the protection of the organism against UV radiation. One of the treatment methods is autologous transplantation of melanocytes or suspension of melanocytes with keratinocytes. Use of the biocompatible membrane, which allows the cultivation of these cells with resulting transplantation on the depigmented lesion, could improve treatment and make it more efficient. The main goal of this work was to create the biocompatible membrane from nanofiber layers of polyvinylalcohol (PVA) which can stand as a carrier for cell transplants in vitiligo therapy. PVA scaffolds were prepared by electrostatic spinning and later on modified by cold methane plasma (CH4) for lowering their hydrofility. Samples of modified nanofiber carriers were analysed according to their physical and chemical characteristics (visualization fiber morphology by SEM, XPS and surface Zeta potential analysis and contact angle). Consequently, adhesion, proliferation and metabolic activity of cultivating mice cell lines of melanocytes (Melan-a) and keratinocytes (XB2) were examined...

Electrospinning is widely used technique to produce nanoscale constructs for tissue engineering. This technique can be used to spin wide range of polymers. One of them is polyvinyl alcohol (PVA), which has very good properties for use in this field. PVA is nontoxic, has good mechanical strength and it's degradable and biocompatible. Electrospun PVA nanofibers have limitations because of their -OH side groups. These groups cause solubility of PVA in water. The solubility can be adjusted with crosslinking techniques, but PVA still remains very hydrophilic, which is causing low adhesion of cells. In recent research we decided to reduce the hydrophilicity of PVA using plasma modification. Polymer modification with cold plasma is an economic and quite simple process to change the surface chemistry without side effects that come with conventional chemical treatment. With radical, formed by discharge, we have deposited hydrocarbons on the PVA surface and we rapidly increased hydrophobicity of the polymer surface. The change of surface chemistry has only a little effect on the fiber morphology. The increase of hydrophobicity allowed better adhesion of mesenchymal stem cells on plasma modified PVA as compared to non-modified PVA and a huge change in cell morphology was observed. These changes suggest that we...

Universiẗat, Diss., 2003--Dortmund.

This diploma thesis focuses on the problematics of preparation of biodegradable starch based packaging. The aim of the thesis is to optimize the preparation and verify the characteristics for further adaptation and production technologies. The films consisted of starch, PVA and glycerol. Four types of starches, three types of PVA and different ratios of glycerol were tested. Films were prepared by casting with glycerol as a plasticizer, instead of distilled water, to reduce the energy cost of the preparation. The mechanical properties of the films were tested as well. The experimentally determined values of elongation at break and tensile strength of the wheat starch films were compared with a semiempirical model. Results revealed that the preparation of thermoplasticization of starch with glycerol leads to a considerable increase in elongation at break but at the same time to a marked decrease in tensile strength compared to the preparation from solution. The rheological properties of the prepared films were also investigated. Infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to study the structure of the films.

This diploma thesis deals with the study of inkjet print degradation on handmade paper modified by polymer layer containing light stabilizers and inorganic filler. The polymer layer coated on the medium consisted of polyvinylalcohol, titanium dioxide and light stabilizer. The influence of light promoted degradation and light stabilizers was observed. The experiments were carried out on Q-SUN Xenon Test Chamber device, Model Xe-1-B/S. Colorimetric values of test chart were measured and the influence of different light stabilizers on the color difference between original and faded sample was evaluated.

Dizertační práce se zabývala syntézou a studiem kompozitních materiálů pro potenciální lékařské využití. Teoretická část je zaměřena na biomateriály, zejména na kompozity složené z polyvinylalkoholu a hydroxyapatitu(PVA/HA). Byly připraveny kompozitní membrány složené z polyvinylalkoholu s různým hmotnostním zastoupením hydroxyapatitu - 0%, 10%, 20%, 30%, 40% a 50%. Hydroxyapatit (HA) byl připraven srážecí metodou z hydrogenfosforečnanu amonného a tetrahydrátu dusičnanu vápenatého ve vodném alkalickém prostředí. Vzniklá suspenze se smísila s roztokem polyvinylalkoholu, který byl připraven rozpuštěním ve vodě o teplotě 85° C. Jednotlivé směsi byly odlity do formy a sušeny po dobu 7 dní při teplotě 30 ° C, vzniklé 0,5 mm tenké membrány byly analyzovány ATR-FTIR spektroskopií k identifikaci funkčních skupin v kompozitu, dále byla provedena XRD analýza. Zkouška tahem a TGA měření byly realizovány k určení vlivu HA na mechanické vlastnosti, respektive změnu tepelné odolnosti kompozitů ve srovnání s čistým PVA. Byla provedena zkouška bioaktivity v simulovaném krevním roztoku (SBF) po dobu 2h, 7 a 28 dnů. SEM byla použita k charakterizaci povrchové mikrostruktury biocompositních membrán před a po ponoření do SBF. Na povrchu testovaných membrán vznikla vrstva apatitu, která je charakteristická pro bioaktivní materiály. Bylo zjištěno, že s rostoucím množstvím HA částic docházelo ke vzniku aglomerátů v kompozitu, které vznikly mimo jiné jako důsledek růstu krystalů HA během sušení membrán. Bioaktivita rostla s delším působením SBF na vzorky.