Estudo do comportamento cinético de sistemas fotocrómicos

Dissertação de mestrado integrado em Engenharia TêxtilPhotochromic colourants have found some applications, such as spectacle lenses, textile designs, and molecular switches. However, their somewhat high cost, lack of standardized laboratory procedures, and technological limitations are preventing them from entering the mainstream market and industry. To overcome this problem, a prototype (the Photochrom-2), consisting of a modified spectrophotometer, was developed at the Technical University of Liberec (TUL) to accurately perform dynamic measurements on photochromic and thermochromic materials. This device allows the user to control the sample’s temperature, the time of exposure to the exciting light source, and the time of decay. Using the Photochrom-2, textile samples screen-printed with the Matsui Photopia Purple (MPP) pigment were studied. The main goal was to analyse the kinetic behaviour of the compound over five consecutive cycles while varying the pigment concentration, the temperature, and the time of exposure to the exciting light source. Six distinct pigment concentrations, five temperatures, and two exposure times were tested. After defining the maximum absorption wavelength and the appropriate decay time, the five cycle assays began. By direct application of the Kubelka-Munk transform, graphics of / values as a function of time were obtained. From there, it was possible to evaluate the influence of concentration, temperature, and exposure time on the resulting colour strength. Then, the / values were run through the one-phase decay mathematical model with the aid of the GraphPad Prism software to evaluate how the photochromic response is lost throughout consecutive cycles of activation and decay. During the first stage of data analysis, it was concluded that higher concentrations and lower temperatures were able to produce greater colour strength. In the second stage, the kinetic behaviour of the pigment was analysed. It was concluded that the half-life strongly correlates to pigment concentration and temperature. During decay, the pigment increasingly acquired residual colour over consecutive cycles, regardless of the parameters. Overall, it was concluded that the pigment does withstand five consecutive cycles of exposure and decay without a significant loss of photochromic response. Moreover, the parameters selected were suitable for the proposed objective, and, thus, are a valuable contribution to research on photochromic colourants and can be used as a model for further research.Os corantes fotocrómicos têm algumas aplicações, exemplos incluem lentes fotocrómicas, designs têxteis e interruptores moleculares. No entanto, o seu custo elevado, a falta de standards laboratoriais e certas limitações tecnológicas impedem-nos de entrar no mercado e na indústria mainstream. Para superar esse problema, um protótipo (o Photochrom-2) foi desenvolvido na Universidade Técnica de Liberec (TUL) para realizar medições dinâmicas com precisão em materiais fotocrómicos e termocrómicos. Este dispositivo permite que o usuário controle a temperatura da amostra, o tempo de exposição à fonte de luz excitante e o tempo de decaimento. O Photochrom-2 foi usado para estudar amostras têxteis estampadas com o pigmento Matsui Photopia Purple (MPP). O objetivo principal foi analisar o comportamento cinético do composto ao longo de cinco ciclos consecutivos enquanto se variava a concentração do pigmento, a temperatura e o tempo de exposição à fonte de luz excitante. Seis concentrações de pigmento distintas, cinco temperaturas e dois tempos de exposição foram testados. Depois de definir o comprimento de onda de absorção máximo e o tempo de decaimento apropriado, os ensaios de cinco ciclos começaram. Pela aplicação direta da transformada de Kubelka- Munk, gráficos dos valores / em função do tempo foram obtidos. A partir daí, foi possível avaliar a influência da concentração, temperatura e tempo de exposição na intensidade da cor resultante. Em seguida, os valores de / foram tratados com o modelo matemático de decaimento exponencial com o software GraphPad Prism para avaliar como a resposta fotocrómica é perdida ao longo de ciclos consecutivos de ativação e decaimento. Durante a primeira etapa de análise dos dados, concluiu-se que maiores concentrações e menores temperaturas produzem maior intensidade de cor. Na segunda etapa, foi analisado o comportamento cinético do pigmento. Conclui-se que o tempo de meia vida varia com a temperatura e concentração de pigmento. Durante o decaimento, as amostras adquiriram cada vez mais cor residual em ciclos consecutivos, independentemente dos parâmetros. Em geral, concluiuse que o pigmento resiste a cinco ciclos consecutivos de exposição e decaimento sem perda significativa da resposta fotocrómica. Para além disso, os parâmetros seleccionados foram adequados ao objetivo proposto; estes são uma valiosa contribuição para a investigação de corantes fotocrómicos e futuramente podem ser utilizados como modelo para outros trabalhos

Production and application of textile materials

This specialized publication is dedicated to technical and technological solutions in textile production. Engineering solutions in the production of fibers and fabrics for both technical and domestic use are considered. Particular attention in the book is given to the study of textile products for biomedical applications. Modern medical fabrics and fibers are used as dressing and suture material and significantly accelerate the recovery processes after surgical operations and burn injuries. Fibers and fabrics are currently often used as a reinforcing element in the production of various composite materials, which are often used in mechanical engineering and in the construction sector. A separate chapter is devoted to textile reinforcing materials. Environmental problems in textile production are mainly related to the dyeing process and the chemical treatment of fabrics and fibers. Some aspects of textile dyeing and wastewater treatment processes are also discussed in this publication. The book will be useful to specialists involved in textile production and related industries

High Performance Textiles

High-performance or hi-tech textiles represent the keystone of the present and the future for all industrial sectors, which require lightening, flexibility, and the high mechanical resistance as well as thermal stability of the materials. As described within this Special Issue, the applications of these advanced systems are innovative and also highly technological: from water-repellent to stain-resistant fabrics, from being flame-resistant to antibacterial/antifouling, from being insulating to conductive, and from environmental protection systems to smart textiles. High-performance textiles also meet all of the actual requirements of sustainability and environmental protection of modern industry

Ingeniería de una lacasa fúngica como biocatalizador para síntesis orgánica

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Biológicas, Departamento de Genética, Fisiología y Microbiología, leída el 06-03-2020Laccases (EC 1.10.3.2) are multicopper oxidases with the capability to oxidize a great variety of aromatic compounds and some metals. Their substrate versatility and their low catalytic requirements turn these enzymes into biocatalysts of interest for different sectors. One of the most promising applications of laccases is the synthesis of high value organic compounds, providing higher selectivity than chemical reactions and generating less toxic residues. For many of these reactions fungal high redox potential laccases are required due to their higher oxidation capabilities. One of these reactions is the synthesis of polyaniline (PANI), an electroconductive polymer with a large number of applications. However, the reaction conditions (acid pH and surfactants presence) and the high redox potential of aniline at acid pH hinder laccase activity, requiring the engineering of the enzyme to optimize their activity and stability under these conditions. In previous works, two high redox potential fungal laccases were evolved in the laboratory for their expression in Saccharomyces cerevisiae. These enzymes were thereafter recombined to obtain a library of chimeric laccases with different activities and stabilities. Among them, 7D5 laccase was selected as starting point for this Doctoral Thesis...Las lacasas (EC 1.10.3.2) son oxidasas multicobre capaces de oxidar una gran variedad de compuestos aromáticos y ciertos metales. Su versatilidad de sustrato y sus bajos requerimientos catalíticos hacen de estas enzimas biocatalizadores de interés para distintos sectores. Una de las aplicaciones más interesantes de las lacasas es la síntesis de compuestos orgánicos de alto valor añadido, ofreciendo una mayor selectividad que las reacciones químicas y con menor generación de residuos tóxicos. Para muchas de estas reacciones, se requiere el empleo de lacasas fúngicas de alto potencial redox debido a su mayor poder oxidativo. Tal es el caso de la polimerización de anilina para obtener polianilina (PANI), un polímero electroconductor con una amplia variedad de aplicaciones. Sin embargo, las condiciones de reacción (pH ácido y presencia de surfactantes) y el alto potencial redox de la anilina a pH ácido dificultan la acción de la enzima, haciendo necesaria su ingeniería para optimizar su actividad y estabilidad en dichas condiciones. En estudios previos, dos lacasas fúngicas de alto potencial redox fueron evolucionadas en el laboratorio para su expresión en Saccharomyces cerevisiae. Posteriormente, se recombinaron dichas enzimas para obtener una librería de lacasas quiméricas con diferentes actividades y estabilidades. De entre ellas, se seleccionó la lacasa 7D5 como punto de partida de esta Tesis Doctoral...Fac. de Ciencias BiológicasTRUEunpu

Recent progress in gelatin hydrogel nanocomposites for water purification and beyond

Innovative characteristics of hydrogels such as swellability, modifiability and hydrophilicity make them materials of choice for water treatment and other applications. Hydrogels have shown excellent adsorptive performance for different types of water pollutants comprising toxic dyes, nutrients and heavy metals. Among different types of hydrogel based materials, hydrogel-nanomaterials combination represent a highly viable method to further improve the properties of hydrogel for numerous applications. The combination of hydrogel and nanomaterials leads to the development of hybrid hydrogel with multifunctional network. This novel combination gives synergistic effect to the newly formed novel hydrogel materials. In this article, we briefly review the recent progress in gelatin based hydrogel nanocomposites with particular emphasis on wastewater treatment along with biomedical applications

Recent progress in gelatin hydrogel nanocomposites for water purification and beyond

Innovative characteristics of hydrogels such as swellability, modifiability and hydrophilicity make them materials of choice for water treatment and other applications. Hydrogels have shown excellent adsorptive performance for different types of water pollutants comprising toxic dyes, nutrients and heavy metals. Among different types of hydrogel based materials, hydrogel-nanomaterials combination represent a highly viable method to further improve the properties of hydrogel for numerous applications. The combination of hydrogel and nanomaterials leads to the development of hybrid hydrogel with multifunctional network. This novel combination gives synergistic effect to the newly formed novel hydrogel materials. In this article, we briefly review the recent progress in gelatin based hydrogel nanocomposites with particular emphasis on wastewater treatment along with biomedical applications

Perspectives on Tannins

Tannins are a family of versatile, natural phenolic biomolecules whose key role is to protect plants against insects and fungi. They are also valuable in use for humans. We show tannins' antioxidant and antibacterial properties, in addition to their potential application in the food industry. We prove the accessibility of condensed tannins to a wide range of potential applications, including NH3 neutralizer, the building block of numerous porous materials, such as foams, organic, and carbon gels. Finally, they are known as wood adhesives, heavy metal scavengers, and corrosion inhibitors. With this book, we want to present the most promising perspectives of tannin

Cyclodextrin Chemistry and Toxicology

This is a reprint of the Special Issue "Cyclodextrin Chemistry and Toxicology”. This is a collection of eleven articles and three reviews that was published in Molecules that provides an overview of the applications of cyclodextrins, implements the information regarding the use of cyclodextrins and their inclusion complexes, considering both experimental and theorists approaches and using various scientific and technological tools

Dual-function nanoparticles enzymatically conjugated with a custom-made polyurethane hydrogel for chronic wound treatment

Hydrogels are attractive drug delivery systems with the potential to protect their cargo and control its release. In particular, hydrogels based on synthetic polymers are gaining increasing interest by virtue of their controllable chemistry, ease of modification, and reproducibility. Moreover, the presence of specific side chains and pending functional groups in the polymer structure allows for the conjugation of drugs and other compounds resulting in improved control over drug release. Enzymes that catalyse reactions in a very specific way could also be used to control the conjugation of compounds to the polymeric chains to improve reproducibility and biocompatibility of the conjugation process. This contribution describes an innovative system for drug delivery comprising a bioartificial supramolecular hydrogel based on a customised polyurethane and α- cyclodextrins, and nanoparticles, for application in the treatment of chronic wounds. The system has the potential to reduce inflammation and eradicate infection by virtue of dual-function nanoparticles which incorporate cobalt as antimicrobial agent, and phenolated lignin as antioxidant. The nanoparticles are enzymatically conjugated to the hydrogel by means of the amine side groups exposed along the backbone of the ad-hoc synthesised polyurethane. The oxidase enzyme laccase is exploited to oxidize the phenol groups of lignin, to allow their interaction with the amines on the hydrogel. The effects of nanoparticles conjugation to the hydrogel are studied through gelification tests, stability tests, and rheology. Moreover, the release of nanoparticles from the hydrogel and their effects on patients’ wound fluids and against relevant bacterial strains are analysed in vitro