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Opis: In the scope of the Doctoral Dissertation, a polysaccharide based stimuli-responsive smart material with controlled drug release was developed by using electrospinning technique, which allowed to form stimuli-responsive nanofibers with rapid visual detection of pH change in the wound bed along with anti-inflammatory activity. Incorporation of halochromic dyes into electrospun nanofibers has been an intriguing area for wound healing applications. Furthermore, it is known that the pH value within the wound milieu directly and indirectly influences all biochemical reactions taking place in the process of wound healing. It has been proven that the surface pH of a wound plays an important role in wound healing as it helps control infection and increases the antimicrobial activity, oxygen release, angiogenesis, protease activity, and bacterial toxicity. Therefore, visual pH monitoring without the need of removing the wound dressing was one of the aims of the Doctoral Dissertation. Produced stimuli-responsive wound dressings were characterized according to their morphological and chemical properties using well-known techniques such as, rheometry, conductivity, Scanning Electron Microscopy (SEM),CIE Lab, Thermogravimetric Analysis (TGA), UV/VIS Spectrophotometry, and Attenuated Total Reflection Infra-Red Spectroscopy (ATR-IR). Responsiveness of the nanofibers were achieved by integration of different halochromic dyes [bromocresol green (BCG), bromothymol blue (BTB) and thymol blue (TB)] to obtain a range of pH values. To tackle the problem of leaching of the dyes, a complexing agent; poly-diallyldimethylammonium chloride (PDADMAC) was integrated and an analysis on the formation of complexation was performed by using pH-potentiometric titration and Quartz Crystal Microbalance with Dissipation (QCM-D) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) techniques. Additionally, release tests were performed to prove that the leaching of the halochromic dyes is reduced significantly up to 97%. Furthermore, the responsiveness of the nanofibers was investigated by exposing the nanofibers to different buffer solutions with pH values 4, 7 and 10. The color change of the nanofibers were analyzed using the CIE Lab system while a visual color shift was observed according to their characteristics. Lastly, diclofenac (DFC), an anti-inflammatory drug molecule was integrated to the system and drug release studies were performed by using Franz diffusion cells. A controlled release of the drug molecule (DFC) to the wound bed is achieved and quantitative evaluations were done. Consequently, the drug release from the smart wound dressings were identified to have two separate profiles during the release. The mathematical models that were identified to fit to the kinetics are, first-order, Korsmeyer-Peppas, and Higuchi release model, confirming the controlled drug release.
Ključne besede: stimuli-responsive, polysaccharides, wound dressings, halochromism, controlled drug release, smart materials
Objavljeno v DKUM: 06.10.2023; Ogledov: 426; Prenosov: 37
Celotno besedilo (8,48 MB)

Opis: Responsive materials, i.e., smart materials, have the ability to change their physical or chemical properties upon certain external signals. The development of nanofibrous halochromic materials, specifically combining the pH-sensitive functionality and unique nanofiber properties, could yield interesting new applications, especially when the common problem of dye leaching is successfully tackled. Therefore, in this article, we studied the fabrication process of polysaccharide-based halochromic nanofibrous materials by using a combination of various halochromic dyes (bromothymol blue, bromocresol green, and thymol blue) and cellulose acetate in a spinning solution using a one-pot strategy. The inhibition of leaching was addressed by using a complexing agent: poly-diallyl-dimethylammonium chloride (PDADMAC). The preparation of hybrid spinning solutions, their characterization, and ability to form continuous nanofibers were studied using a high production needle-less electrospinning system. The produced hybrid solutions and nanofibers were characterized, in terms of their rheological properties, chemical structure, morphology, and functionality. Fabricated nanofibrous halochromic structures show a clear color change upon exposure to different pH values, as well as the reduced leaching of dyes, upon the addition of a complexing agent. The leaching decreased by 61% in the case of bromocresol green, while, in the case of bromothymol blue and thymol blue, the leaching was reduced by 95 and 99%, respectively.
Ključne besede: halochromism, responsive polymers, polysaccharides, electrospinning
Objavljeno v DKUM: 31.07.2023; Ogledov: 424; Prenosov: 54
Celotno besedilo (5,54 MB)
Gradivo ima več datotek! Več...

Ključne besede: textiles, metallisation
Objavljeno v DKUM: 11.10.2021; Ogledov: 1203; Prenosov: 42
Celotno besedilo (354,59 KB)

Opis: The introduction of the Laboratory Manual gives the theoretical bases on cellulose and its derivatives, which are used as starting polymers for the preparation of multifunctional polymers with three different advanced techniques - spin coating, electrospinning and 3D printing. In the following, each technique is presented in a separate Lab Exercise. Each exercise covers the theoretical basics on techniques for polymer processing and methods for their characterisation, with an emphasis on the application of prepared materials. The experimental sections contain all the necessary information needed to implement the exercises, while the added results provide students with the help to implement correct and successful exercises and interpret the results.
Ključne besede: multifunctional polymers, polysaccharides, cellulose, electrospun, spin coating, 3D printing, nanofibers, thin films, multifunctional materials, laboratory manuals
Objavljeno v DKUM: 09.03.2021; Ogledov: 965; Prenosov: 24
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Opis: Magnetne tekočine sodijo v kategorijo nanomaterialov zaradi velikostnega razreda suspendiranih magnetnih nanodelcev v nosilni tekočini. Njihova uporabnost se kaže na različnih področjih inženiringa, znanosti in medicine. Ena izmed pomembnejših lastnosti magnetne tekočine je viskoznost, ki je bila predmet opazovanja v magistrski nalogi. Vpliv viskoznosti smo preverili teoretično kot tudi eksperimentalno. V teoretičnem delu smo uporabili in prilagodili matematični model izračuna izgub magnetne tekočine v visokofrekvenčnem magnetnem polju ter raziskali vpliv različnih modelov viskoznosti suspenzije in različnih nosilnih tekočin. Za validacijo matematičnega modela izgub smo na izbranem vzorcu opravili serijo meritev izgub po kalorimetrični metodi, pri kateri se glede na temperaturni odziv merjenca ugotovi specifična stopnja absorpcije (SAR). V eksperimentalnem delu naloge smo opravili meritve viskoznosti možnih nosilnih tekočin po dveh različnih metodah, in sicer najprej s Hoepplerjevim in nato z rotacijskim viskozimetrom. V sklopu meritev z rotacijskim viskozimetrom smo sistematično skušali ugotoviti temperaturno odvisnost in dokazati pojav magnetoreologije.
Ključne besede: magnetne tekočine, specifična absorpcijska stopnja, viskoznost, magnetne izgube, magnetno polje
Objavljeno v DKUM: 22.11.2019; Ogledov: 1470; Prenosov: 147
Celotno besedilo (4,32 MB)