Dissertations / Theses on the topic 'Textile -Antimicrobial'

The need to develop new materials for a variety of applications is greatly promoting academic and industrial research. In this thesis work antimicrobial textiles were prepared. To contribute to this topic, we started a research program that heavily relies on our expertise in the field of antibacterial peptides. Among the many polymeric materials available, cellulose fibers are particularly attractive, being naturally occurring, and easy to functionalize. Peptides and dendrimers were immobilized, as antimicrobial agent, onto cotton fabrics. Preparation of immobilized peptide-cotton materials was obtained using different innovative synthetic methods. Characterization analysis by FT-IR, XPS, UV-Vis, TGA and EPR was also performed for qualitative and quantitative determination of cotton functionalization. Moreover, enzymatic degradation was carried out allowing the application of NMR spectroscopy in solution. Antimicrobial activity of samples were tested against Staphylococcus aureus (Gram positive bacteria) and Escherichia coli (Gram negative bacteria). Promising results were obtained against the Gram positive strain, while only few samples show good activity against Gram negative bacteria.
La necessità di sviluppare nuovi materiali per una varietà di applicazioni sta interessando fortemente la ricerca accademica e industriale. In questo lavoro di tesi sono stati preparati dei tessuti antimicrobici. Per contribuire a questo argomento, abbiamo avviato un programma di ricerca che si basa sulla nostra esperienza nel campo dei peptidi antibatterici. Peptidi e dendrimeri sono stati immobilizzati, come agenti antimicrobici, su tessuti. Tra i molti materiali polimerici disponibili, le fibre di cellulosa sono particolarmente attraenti, essendo esse presenti in natura e facile da funzionalizzare. Caratterizzazioni FT-IR, XPS, UV-Vis, TGA e EPR sono state effettuate per la determinazione qualitativa e quantitativa della funzionalizzazione del cotone. Inoltre, la degradazione enzimatica ha consentito l'applicazione della spettroscopia 1H-NMR in soluzione. L'attività antimicrobica dei campioni è stata testata contro lo Staphylococcus aureus (batterio Gram-positivo) e l’Escherichia coli (batterio Gram-negativo). Risultati promettenti sono stati ottenuti contro i batteri Gram-positivi, mentre solo pochi campioni hanno mostrato una buona attività contro i batteri Gram-negativi.

Ce travail de thèse s’inscrit dans la partie caractérisation d’un projet collaboratif ayant pour objectif d’élaborer des textiles antimicrobiens pour différents domaines d’application, en particulier les domaines de la santé et de l’agroalimentaire. La démarche analytique a consisté à combiner différentes techniques d’analyse de surface (techniques microscopiques (SEM, AFM, TEM) et spectroscopiques (XPS, ToF-SIMS, SIMS, EELS)) avec des analyses microbiologiques pour aider à la compréhension des mécanismes de protection antimicrobienne des textiles traités. Les agents antimicrobiens, l’argent et le Poly HexaMéthylène Biguanide (PHMB), ont été déposés respectivement par plasma (PVD / PECVD) et par foulardage. Les contraintes liées aux domaines d’application des textiles étudiés (implants herniaires et vêtements professionnels) ont été prises en compte (respectivement, quantité minimale de l’agent antimicrobien et résistance au lavage industriel). Malgré certaines contaminations inhérentes à des procédés industriels, les analyses de surface se sont révélées être un ensemble d’outils essentiel au développement des procédés (qualité du dépôt, influence des conditions de dépôt, influence du lavage). Selon les domaines d’application, l’analyse à très haute sensibilité en extrême surface et l’étude de la distribution en profondeur de l’agent antimicrobien ont été des étapes clés pour la compréhension des propriétés antimicrobiennes observées pour les dépôts, démontrant la pertinence de l’approche multi-analytique choisie dans ce travail de thèse
This thesis work concerns the characterization effort within a cooperation project aiming at developing antimicrobial textiles for various application fields, particularly health applications and food-processing industry. The analytical approach combined different surface analysis techniques (microscopy techniques (SEM, AFM, TEM) and spectroscopy techniques (XPS, ToF-SIMS, SIMS, EELS)) to microbiological tests in order to understand the antimicrobial activity of deposits at the surface of textiles. Silver and Poly Hexamethylene Biguanide (PHMB) antimicrobial agents were deposited by plasma (PVD / PECVD) and padding, respectively. Specific constraints related to the application fields (hernia implants and clothing) were considered (minimum concentration in antimicrobial agent and resistance to industrial washing, respectively). Despite some ubiquitous contamination related to industrial processes, surface analysis techniques proved to be an essential help to develop these processes (deposit quality, influence of deposition conditions, influence of washing). Depending on the application fields, high sensitivity surface analysis at the extreme surface and in-depth distribution of the antimicrobial agent were essential to understand the antimicrobial properties of the deposits, which confirms the relevance of the multi-analytical approach used in this thesis work

The goal of this thesis work was to investigate the antimicrobial effect of chitosan from zygomyzetes cell wall material in nonwoven textiles and compare it to commercially available chitosan. This was done using two methods, a somewhat modified version of AATCC Test Method 100-2004 (a standard method for quantitative testing of antimicrobial effect in textiles developed by the AATCC Committee) focusing on CFU, and TTC, a tetrazolium salt that changes from colourless to red in the presence of living microorganisms under the right conditions. The CFU method was also used to detect if it is possible to add chitosan earlier in the production stages, by scanning for any antimicrobial effect in test samples produced that way. Commercial chitosan added to the test samples in 2 % citric acid showed the strongest antimicrobial effect, even reaching the detection limit of approximately 99.5 % inhibition for both E. coli and K. pneumoniae without any incubation. Medium molecular weight commercial chitosan added in 2 % citric acid solution was also the only tested compound that could eliminate C. ablicans after 24 h incubation. Both commercial chitosan added as a powder and cell wall extract showed a mediocre inhibition without incubation, but were able to reach >99 % inhibition after 24 h incubation. Generally speaking, the chitosan investigated is comparable to the chitosan available commercially today, even if it required somewhat longer to reach the same levels of inhibition. The other method for addition of chitosan, however, did not work properly.
Uppsatsnivå: D

Textiles, today, are no more just traditional textiles. With the advancements in nano and fiber technology, they find various technical applications and are known as technical textiles. Antimicrobial functionalization is an integral requirement for some of these applications that include medical textiles, aerospace textiles and textiles used in filtration. Various organic and inorganic antimicrobial agents are being explored for antimicrobial functionalization of textiles with the objective to obtain effective, durable and broad spectrum antimicrobial properties. However, these antimicrobial agents may have their own advantages and disadvantages. Some of them may lack broad spectrum antimicrobial properties as well as complex method of their synthesis and application which may not always be environmental friendly. Silver is well known inorganic antimicrobial agent with effective antimicrobial action against broad spectrum of microbes. Silver is being intensively studied in nano particle form for the functionalization of textiles. However, mostly the synthesis and application of silver nano particles to textiles is carried through wet routes. These may have environmental considerations due to possible use of toxic reducing and stabilizing agents. In addition their solution or colloidal based application to textiles is intense in water and energy consumption along with production of waste water and necessitating its treatment. This may not help reduce environmental burden of textile industry which is regarded as one of the most polluting industrial sector of the world. Therefore, along with providing antimicrobial protection, the process of obtaining antimicrobial textiles itself should not create adverse environmental impact. In this context, ecofriendly processes for textile industry have always been in focus of research. The objective of this thesis was to achieve “antimicrobial functionalization of technical textiles for medical, aerospace and civil applications” via a simple and single step environment friendly technique known as radio frequency “co-sputtering”. Sputtering is a plasma based process and is mostly used in automotive, tools and electronics industry. It is not yet fully explored in textile industry. This study aimed at obtaining antimicrobial textiles via co-sputtering and exploring some of the its key strengths and weaknesses for textiles. In the adopted co-sputtering technique, an antimicrobial silver nano clusters/silica composite coating was deposited on four different textile substrates. The deposition parameters of both silica and silver were controlled independently such that silica constituted the matrix of the composite coating and silver was deposited in the form of nano clusters embedded in the silica matrix. The four textile substrates used in this study were: cotton fabric intended for medical applications, high performance Kevlar® and Vectran® fabrics for aerospace applications and activated carbon fabric (ACF) to be used in air filtration. The morphology and composition of the deposited coating was investigated in detail using FESEM, EDX and XPS which showed that silver nano clusters (25-50 nm) were uniformly distributed and firmly embedded in the silica matrix. Total silver concentration in the composite coating was evaluated through ICP_MS and was found to be dependent on deposition time and thus on coating thickness. Silver ion release test in water and in artificial sweat showed a progressive and gradual release of silver ions, beneficial for prolonged antimicrobial activity. The nature of the fabric substrate was also found to influence the release of silver ions. The coating showed effective antimicrobial properties against Gram positive (S. aureus, S. epidermidis), Gram negative (E. coli) bacteria and fungus (C. albicans) with varying intensity of the action depending upon the microbe as well as silver ion release profiles. Water contact angle and sorption tests revealed hydrophilic nature of the coating. Moisture management properties evaluated by Moisture Management Tester showed that coating imparted fast absorbing and quick drying characteristic to the fabric. The coating was highly conformal and did not altered air permeability of the substrates which is a highly desirable characteristic to preserve thermo physiological comfort of the fabric as well as maintain filtration capacity of ACF. However, the washing stability of the coating was found not to be completely satisfactory. The work was carried with in the frame wok of an Italian regional project with several other project partners. Some results from these partners, duly acknowledged, are also discussed in this thesis and summarized in conclusion.

Healthcare associated infections (HCAI) impose significant financial and environmental problems for modern healthcare settings, therefore it is important to develop novel strategies to combat HCAIs and the causative microorganisms. This study investigates the use of an encapsulated essential oil (EO) antimicrobial coating for textiles in the healthcare environment. The antimicrobial activity of several EOs were studied, individually and in blends, against five microorganisms associated with HCAI (Staphylococcus aureus, methicillin resistant Staphylococcus aureus, Candida albicans, Escherichia coli, and Pseudomonas aeruginosa). A 1:1 blend of cinnamon (CIN) and clove oils (CLO) containing 94.8 % (v/v) eugenol (by GC-MS) showed the highest antimicrobial efficacy and gave a minimum inhibitory concentration (MIC) of less than 0.25% (v/v). Mesoporous silica nanoparticles (MSN) were used to encapsulate volatile EOs. The MSNs displayed narrow size distribution, high surface area and pore size between 1.8-2.2 nm. MSNs, directly loaded with CIN:CLO blend (72 % by mass of MSN), achieved bactericidal values (25-50 mg/mL) against the test microorganisms. Dynamic killing profiles of the EO loaded MSNs against the test microorganisms were recorded. The highest kill rates were observed during the first 15 minutes of contact. Organically modified silica (ormosil) gels were synthesised to provide thin film coverage of synthetic fibres. Gamma-methacryloxypropyltrimethoxysilane (-MPS) was used to attach un-loaded MSNs to the ormosil coating. A layer-by-layer treatment method provided good coverage of synthetic fibres with MSNs, as evidenced by scanning electron microscopy (SEM). Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was used to monitor the layer-by-layer treatment sequence. Head space GC-MS sampling of EO loaded MSN treated textile coupons showed that EO was able to diffuse from the MSN mesopores after being bonded to the synthetic fibres. The EO loaded MSN textile coupons were microbiologically challenged using a method based on AATCC 100. The EO loaded MSN textile coupons displayed good antimicrobial activity over five washing cycles using a method based on (AATCC 61 and 135) thereby indicating a degree of controlled release.

Proyecto Integrador (IQ)--FCEFN-UNC, 2017
Propone otorgar capacidad antimicrobiana a hilos de algodón, utilizando metodologías sencillas, de bajo costo y aplicación industrial viable y fácil. Estas metodologías se basarán en la modificación de celulosa mediante reacciones de injerto de ácidos policarboxílicos

The multi-million-dollar medical uniform industry has not utilized advancements in garment and textile technology that could positively impact the protection of healthcare professionals and patients. In most cases the uniforms meet basic requirements – they clothe the professional in a recognizable way. Little innovation in design, function and performance, has been applied to these garments. This is particularly evident in the case of the stereotypical white lab coat worn by many physicians, despite evidence indicating that these lab coats may carry contamination and play a role in the spread of deadly bacteria. Healthcare Associated Infections (HAIs) are among the most serious problems facing modern medical care, costing millions of lives and dollars annually worldwide. This research investigates the design and use of the physician’s lab coat – an immediately recognizable symbol of Western medicine. The research identifies the medical, functional, cultural and symbolic roles of the lab coat within the hospital environment and beyond, to the larger the global society. This thesis examines the extent to which the design of medical wear can impact the effect of hospital-acquired infections, support doctor/patient relationships and enhance the performance and behavior of the healthcare professional by envisioning a future lab coat which offers increased protection for physician and patient, aids in communication and enhances the performance of the doctor by utilizing digital technologies incorporated into the lab coat whereby the lab coat becomes the only tool necessary for the physician.

Thesis (MScAgric)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: Soil texture, plant available water and fertilizer N would influence growth, biomass production and antimicrobial properties of locally used medicinal plants.This research was aimed at investigating how various soil textures (loamy sand, sandy loam and loam) with varying amounts of plant available water (PAW) and nitrogen fertilizer rates would influence the biomass production and antimicrobial properties of Mentha longifolia L. In this research, a two-way factorial experiment was used. It was produced by 3 X 3 factors, viz. three different soil textures (loam, sandy loam and loamy sand) and three levels of PAW in the first trial (0 %, 50 % and 90 % depletion of PAW) and three levels of N fertilizer rates in the second trial. The elemental fertilizers KNO3, K2SO4, KH2PO4, KCl Ca (NO3)2.2H2Oz, CaSO4.2H2O and Mg SO4.7H2O were used to prepare a nutrient solution for fertigation to meet 0Kg ha-1, 150Kg ha-1 and 250Kg ha-1 fertilizer N. This was replicated four times. The experiment was conducted in a tunnel. From the first trial the highest biomass production was obtained from 0% depletion of PAW treatments whereas 50% and 90% depletion of PAW matched each other at lower biomass productions. In terms of soil texture a higher biomass production was gained from loamy sand followed by loam and sandy loam. In the second trial similar influences of soil texture were evident and the significant biomass productions were highest, intermediate and low from 250Kg ha-1, 150Kg ha-1 and 0Kg ha-1 of fertilizer N, respectively. Accordingly, Mentha longifolia L revealed a minimal bacterial inhibition activity at 20g 100ml-1 against Staphylococcus aureus (gram positive bacteria) under Minimum Inhibitory Concentration assay–susceptibility test. It was therefore concluded that soil texture does influence biomass production. In a like manner, the PAW had a significant impact on the total biomass production. An increase in N fertilizer increased vegetative biomass production. Plant material obtained from Mentha longifolia L has antimicrobial properties. Medically the plant can be used to combat Staphylococcus aureus – a major and ubiquitous pathogen for humans. The significance of this study is thus that it will benefit and help the medical community and future research as the guide to sustainable production and utilization of Mentha longifolia L.
AFRIKAANSE OPSOMMING: Grondtekstuur, plant beskikbare water en kunsmis N sal plantegroei, biomassaproduksie en antimikrobiese-eienskappe van plaaslike medisinale plante affekteer. Die doel van die navorsing was om die effek van grondteksture, plant beskikbare water (PAW) en stikstof op die biomassaproduksie en antimikrobieseeienskappe van Mentha longifolia L. te bestudeer. 'n Tweerigting-faktoriaal-eksperiment is gebruik deur drie verskillende grondteksture (leem, sanderige-leemgrond en leemsand) en drie vlakke van PAW in die eerste geval (0%, 50% en 90% uitputting van PAW) en drie vlakke van N-kunsmistoedienings in die tweede geval. Die basiese kunsmis KNO3, K2SO4, KH2PO4, KClCa(NO3)2.2H2Oz, CaSO4.2H2O en MgSO4.7H2O is gebruik in so „n mate dat 0Kg ha-1, 150kg ha-1 en 250 kg ha-1 Nas sproeibemesting toegedien is. Dit is vier keer herhaal. Die eksperiment is uitgevoer in 'n tonnel. Die hoogstebiomassaproduksie is van die eerste geval verkry van 0% uitputting van PAW behandelings, terwyl 50% en 90% uitputting van PAW ooreenstem met mekaar op laer biomassaproduksies. In terme van grondtekstuur is 'n hoër biomassaproduksie verkry in leemsand gevolg deur leem en sanderigeleem. In die tweede geval is soortgelyke invloede van grondtekstuur duidelik en die beduidende biomassaproduksies was die hoogste, intermediêre en laagste van 250 kg ha-1, 150kg ha-1 en 0Kg ha-1 van kunsmis N, onderskeidelik. Gevolglik, Mentha longifolia L onthul 'n minimale bakteriese inhibisie aktiwiteit op 20g 100ml-1 teen Staphylococcus aureus (gram positiewebakterieë) onder Minimum inhiberende konsentrasie assay-vatbaarheidtoets. Die gevolgtrekking is dus dat grondtekstuu biomassaproduksie beïnvloed. In 'n soortgelykewyse, het PAW 'n beduidende impak op die totale biomassaproduksie. 'n Toename in N-kunsmis verhoog vegetatiewe biomassaproduksie. Plantmateriaalverkry van Mentha longifolia L het antimikrobiale-eienskappe en kan as Die medisinale plante gebruik word om Staphylococcus aureus te bestry - 'n groot en alomteenwoordige patogeen in die mens. Die belangrikste bydrae van die navorsing is die bydra wat dit tot die mediesegemeenskap gemaak het. Die studie het ook riglyne gestel vir toekomstige navorsing vir volhoubare produksie van Mentha longifolia L.
NRF and DST for the funding of this study through the Seboka Project

Nowadays, millions of people become infected with bacteria that cause hospital infections, which is a major cause of mortality in hospitals, killing 700,000 people per year in the world. It is even projected that the number of deaths in hospitals will grow to 10 million by 2050. The use of antimicrobial textiles, especially in close contact with the patients and in the immediate and non-immediate surroundings, may significantly reduce the risk of infections. However, they should possess broad spectrum biocidal properties, be safe for use and highly effective against antibiotic resistant microorganisms, including those that are commonly involved in hospital-acquired infections. Most nosocomial infections are primarily by opportunistic microorganisms, i. e., they rarely cause diseases in a healthy immune system, but seek to exploit any weaknesses in the body of immunocompromised patients, such as victims of burns, cancer patients or beddriden with open wounds, in order to cause infections. These strains have the ability to grow in any environment, present important virulence factors, and have resistance to a large variety of antibiotics. Several antimicrobial agents have been tested in textiles. Quaternary ammonium compounds, silver, polyhexamethylene biguanides and triclosan have been used, with limited success. They have powerful bactericidal activity, however, the majority have a reduced spectrum of microbial inhibition and may cause skin irritation, citotoxicity, ecotoxicity and bacterial resistance. In addition, its incorporation in the textiles reduces their activity substantially and limits availability. Moreover, the biocide can gradually lose activity during the use and textile repeated laundering. To overcome these disadvantages, natural compounds such as L-Cysteine (L-Cys), bacteriophages and antimicrobial peptides (AMPs), were tested in this work as antimicrobial agents for fibrous materials. As such, in a first approach we carried out studies in order to confer antimicrobial properties on textile and polymeric surfaces in such a way that they could irreversibly attract, bind and eliminate microorganisms, paving the way to a dynamic protective barrier. For this purpose, the amino acid L-Cys and the AMPs Magainin I, LL-37, and Cys-LC-LL-37 were used in order to provide antimicrobial properties to cotton fibrous materials . L-Cys was selected due to its proven antimicrobial properties granted by its thiol group and also proved its capacity to ensure antioxidant activity by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) reagent. Covalent and non-covalent immobilization strategies were tested on different fibrous materials and subjected to intensive washing cycles, such as cotton, silk, polycaprolactone, and polypropylene, in order to immobilize L-Cys in a durable manner. For a better understanding of the interactions material-L-Cys-bacteria, cotton textile substrates were chemically modified with N, N-carbonyldiimidazole (CDI) and subsequently functionalized with different concentrations of L-Cys. These studies revealed that there was a specific amount of CDI activator (4%) which would be ideal to more efficiently bind L-Cys (5%). These results revealed a higher antimicrobial efficiency, when compared to another study, in which the cotton substrate was non-covalently immobilized with Magainin I and LL-37. Cotton-L-Cys caused most death among bacteria, after washing cycles, due exclusively to its covalent bound that was able to immobilize L-Cys more permanently. In support of this hypothesis, a polymer difficult to modify - polypropylene - was grafted with L-Cys, which strengthened its nanostructure and endowed it with thiol groups that allowed to bind the peptide Cys-LC-LL-37 via disulfide bond (covalent). It was found that Cys-LC-LL-37 resisted to successive wash cycles, and the flexibility of this peptide was unique to the elimination of the microorganisms. Subsequently, the knowledge acquired when using cotton and polypropylene were transferred to silk and polycaprolactone, in order to test the applicability of this developed concept to other fibrous structures potentially to be used as antimicrobial textiles. Different percentages of L-Cys were immobilized, by different chemical reactions, on samples of aforementioned polymers with biomedical potential, and X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), calorimetry (DSC), Ellman's reagent, and contact angle were used to chemically check L-Cys immobilization, as well as antimicrobial and cytotoxicity assays, so as to ensure that the applications would not be toxic to humans. Also, silk and polycaprolactone samples covalently bound by 1 and 5% L-Cys, respectively, eliminated very well the microorganisms. In addition, these samples retained L-Cys during several wash cycles. At this stage, after the work developed and the knowledge acquired, enabled us to move into a new strategy of immobilization of bacteriophages in fibrous materials. The covalent coupling of the vB-Pae-Kakheti phage capsid to the surface of polycaprolactone nanofibers produced by electrospinning was performed, so that the phage had its tail facing outwards, maintaining its infectivity. The results again confirm that not only the presence of an antimicrobial, but also the way it is immobilized, makes all the difference in the development strategy of antimicrobial textiles. It was concluded, therefore, that an optimized amount of "new" antimicrobial compounds alternative to antibiotics and synthetic biocides, as well as their specific orientation, consisted of a better performance upon contact and elimination of bacteria, being crucial for the development of biomaterials for contact with skin and mucosa.
Os têxteis são substratos propícios ao crescimento e proliferação microbiana sob as condições apropriadas de humidade, nutrientes e temperatura. Em ambiente hospitalar, podem ser uma fonte perigosa de bactérias e fungos que contaminam pacientes e profissionais de saúde. As bactérias e fungos, patogénicos ou não, são normalmente encontrados na pele humana, na cavidade nasal e na área genital. A libertação de microrganismos do nosso corpo contribui para a contaminação e proliferação sobre o vestuário e têxteis. Vários estudos sustentam que a contaminação de têxteis usados em ambiente hospitalar pode contribuir para a libertação de agentes patogénicos no ar, contaminando o ambiente e sendo, presumivelmente, das causas mais prováveis de infeções hospitalares. A maioria das infecções nosocomiais são causadas por microorganismos oportunistas, i.e., raramente causam doenças num sistema imunológico saudável, mas conseguem explorar o estado debilitado de pacientes imunocomprometidos, como vítimas de queimaduras, pacientes oncológicos ou acamados com feridas abertas, para causar infecções. Estas estirpes têm a capacidade de crescer em qualquer ambiente, apresentam importantes fatores de virulência e têm resistência a uma grande variedade de antibióticos. Milhões de pessoas são infetadas com bactérias que causam infecções hospitalares, sendo uma das principais causas de mortalidade em hospitais, causando anualmente a morte de cerca de 700 mil pessoas a nível mundial. O uso de têxteis antimicrobianos, especialmente em contato próximo com pacientes, mas também no ambiente circundante, pode reduzir significativamente o risco de infecções. Contudo, vários requisitos se impõem: os têxteis bioativos devem possuir propriedades biocidas de largo espectro, ser seguros para o utilizador e altamente eficazes no combate aos microrganismos resistentes a antibióticos, incluindo os que são usados no tratamento de infeções hospitalares, e não devem permitir o desenvolvimento de microrganismos resistentes ao composto ativo usado nem ser a causa de irritação da pele. Vários agentes antimicrobianos têm sido testados em têxteis. Os compostos de amónio quaternário, a prata, o polihexametileno de biguanidina e o triclosano são usados como agentes antimicrobianos para têxteis, com sucesso, já que possuem uma atividade bactericida poderosa, como indicado pelo MIC (concentração mínima inibitória). No entanto, a maioria dos agentes antimicrobianos tem um espectro reduzido de inibição microbiana e pode causar irritação da pele, ecotoxicidade e resistência bacteriana. Além disso, a sua incorporação nos têxteis reduz substancialmente a atividade e limita a disponibilidade dos grupos bioativos, obrigando à utilização de concentrações elevadas nos processos de funcionalização. O biocida pode também perder gradualmente a sua atividade durante o uso e lavagens dos materiais têxteis. Assim, grandes quantidades são aplicadas aos têxteis para controlar o crescimento bacteriano e manter a sua durabilidade. Na tentativa de superar estas desvantagens, vários compostos como o quitosano, ácido hialurónico e extractos de plantas têm sido avaliados como potenciais agentes antimicrobianos para têxteis. A par disso, a exigência dos consumidores por vestuário higiénico e o mercado crescente dos têxteis médicos e bioativos estimularam a investigação nesta área. Baseada numa revisão cuidada da literatura, a nossa proposta prevê uma estratégia totalmente nova: o uso de aminoácidos L-cisteína (L-Cys), bacteriofágos e péptidos antimicrobianos (AMPs) como agentes bioativos em têxteis. Assim sendo, numa primeira abordagem realizámos estudos no sentido de conferir propriedades antimicrobianas a superfícies têxteis e poliméricas de forma a que atraissem, ligassem e eliminassem os microorganismos, de forma irreversível, originando uma barreira protectora dinâmica. Para este efeito, foram utilizados o aminoácido L-Cys e os AMPs Magainina I, LL-37, e Cys-LC-LL-37, de modo a conferir propriedades antimicrobianas a materiais fibrosos de algodão. A seleção da L-Cys deveu-se ao facto das suas reconhecidas propriedades antimicrobianas conferidas pelo seu grupo tiol e que, para além disso, provou ter capacidades antioxidantes, pelo reagente 2,2-difenil-1-picrilidrazil (DPPH). Estratégias de imobilização covalentes e não covalentes foram testadas em diferentes materiais fibrosos e submetidos a ciclos de lavagem intensos, tais como algodão, seda, policaprolactona, e polipropileno, com o objectivo de imobilizar a L-Cys de forma durável. Para uma melhor compreensão das interacções material-L-Cys-bactéria, substratos têxteis de algodão foram quimicamente modificados com N,N-carbonyldiimidazole (CDI) e posteriormente funcionalizados com diferentes concentrações de L-Cys. Estes estudos revelaram que havia uma quantidade específica de ativador CDI (4%) que seria a ideal para ligar com mais eficiência L-Cys (5%). Estes resultados revelaram uma maior eficiência antimicrobiana em comparação com outro estudo, no qual o substrato de algodão foi imobilizado não covalentemente com Magainina I e LL-37. O algodão-L-Cys provocou maior morte microbiana, após ciclos de lavagem, devido exclusivamente à sua ligação covalente que conseguiu imobilizar a L-Cys, de forma mais permanente. Para corroborar esta hipótese levantada, modificou-se um polímero difícil de ser modificado – polipropileno – com L-Cys, o que fortaleceu a sua estrutura em nanofibras e dotou-o com grupos tiol que permitiram ligar o péptido Cys-LC-LL-37 por ligação dissulfureto (covalente). Verificou-se que esta Cys-LC-LL- 37 resistiu aos sucessivos ciclos de lavagem, e a flexibilidade deste péptido foi ímpar para a eliminação dos microorganismos. Posteriormente, os conhecimentos adquiridos aquando da utilização do algodão e polipropileno foram transferidos para seda e policaprolactona, de forma a testar a aplicabilidade do conceito desenvolvido a outras estruturas fibrosas potencialmente usadas como têxteis antimicrobianos. Foram imobilizadas, por diferente química de superfície, diferentes percentagens de L-Cys em amostras destes polímeros com potencial biomédico, e realizados também ensaios de espectroscopia de raios X (EDS), espectroscopia de infravermelho da transformada de Fourier (FT-IR), calorimetria exploratória diferencial (DSC), reagente de Ellman, e ângulo de contacto para verificar químicamente a imobilização de LCys, bem como ensaios antimicrobianos e de citotoxicidade, para assegurar que as aplicações não seriam tóxicas para o ser humano. Também com seda e policaprolactona, as amostras ligadas covalentemente por 1 e 5% de L-Cys, respetivamente, eliminaram os microorganismos de forma bastante boa. Para além disto, estas amostras retiveram L-Cys durante diversos ciclos de lavagem. O trabalho desenvolvido e o conhecimento adquirido nesta fase permitiu evoluir para uma nova estratégia de imobilização de bacteriofagos em materiais fibrosos. Testou-se, assim, a ligação covalente da cápside do fago vB-Pae-Kakheti25 à superfície de nanofibras de policaprolactona produzidas por electrospinning, de forma a que o fago ficasse com a sua cauda orientada para o exterior das nanofibras, mantendo a sua infectividade. Os resultados mais uma vez confirmaram que não só a presença de um antimicrobiano, mas também a forma como este está ligado, faz toda a diferença na estratégia de desenvolvimento de têxteis antimicrobianos. Concluiu-se, portanto, que uma quantidade optimizada de “novos” compostos antimicrobianos alternativos a antibióticos e biocidas sintéticos, bem como uma orientação específica, traduz-se num melhor desempenho no contato e eliminação de bactérias, sendo crucial para o desenvolvimento de biomateriais para contacto com a pele e mucosas.

Η παρούσα εργασία μελετά την ανάπτυξη ενός ευέλικτου συστήματος αντιμικροβιακής προστασίας για εφαρμογή σε είδη ρουχισμού και υφάσματα οικιακής χρήσης. Πιο συγκεκριμένα αναπτύχθηκαν διασυνδεδεμένα πολυμερικά νανοσφαιρίδια πολυστυρολίου-διβινυλοβενζολίου στα οποία ενσωματώθηκε Triclosan, μία ευρέος φάσματος εμπορική αντιμικροβιακή ουσία. Σημειώνεται ότι στο πλαίσιο ανάσχεσης των ενδονοσοκομειακών λοιμώξεων η ανάπτυξη αντιμικροβιακών νοσοκομειακών στολών, σεντονιών και άλλων σχετικών κλωστοϋφαντουργικών προϊόντων αποτελούν τις τελευταίες δεκαετίες αντικείμενο έντονου επιστημονικού ενδιαφέροντος. Το μέγεθος των νανοσωματιδίων βρέθηκε μετά από εξέταση με ηλεκτρονική μικροσκοπία σάρωσης (SEM) και δυναμική σκέδαση φωτός (DLS) να κυμαίνεται μεταξύ 35-350 nm ανάλογα την σύσταση. H θερμική συμπεριφορά τους μελετήθηκε μέσω διαφορικής θερμιδομετρίας σάρωσης (DSC) και διαπιστώθηκε σημείο τήξεως στους ~425 οC. Χρησιμοποιώντας την φασματοσκοπία UVVis προσδιορίστηκε ο πραγματικός εγκλωβισμός του αντιμικροβιακού στο σύστημα κατά μέσο όρο σε ποσοστό ~72% του ονομαστικού και παρακολουθήθηκε ο ρυθμός αποδέσμευσης του σε διαλύματα αιθανόλης-νερού. Επιπλέον, τα σφαιρίδια που όπως διαπιστώθηκε παρουσιάζουν χαρακτηριστικά ελεγχόμενης αποδέσμευσης ενσωματώθηκαν σε μήτρες πολυπροπυλενίου οι οποίες υπό την μορφή φιλμ εφελκύστηκαν μονοαξονικά. Τέλος κάνοντας χρήση της δονητικής φασματοσκοπίας Raman εκτιμήθηκε ο μοριακός προσανατολισμός που επιβλήθηκε στα εφελκυσμένα φιλμ και συσχετίσθηκε με την παρατηρούμενη μείωση που επιτεύχθηκε στην κινητική αποδέσμευσης της εγκλωβισμένης δραστικής ουσίας. Το πρώτο κεφάλαιο της παρούσας εργασίας ασχολείται με το πρόβλημα της μικροβιακής επιμόλυνσης υφασμάτων, τις διάφορες λύσεις που έχουν προταθεί κατά καιρούς και τέλος αναλύει τον στόχο της παρούσας εργασίας. Στο δεύτερο κεφάλαιο επεξηγείται η έννοια της ελεγχόμενης αποδέσμευσης και περιγράφονται οι διάφορες κατηγορίες συστημάτων ελεγχόμενης χορήγησης μαζί με χαρακτηριστικά παραδείγματα. Τα νανοσωματίδια, η σύστασή, οι μοναδικές ιδιότητες, οι εφαρμογές και οι διάφοροι τρόποι σύνθεσης και χαρακτηρισμού τους συζητούνται στο τρίτο κεφάλαιο. Το τέταρτο κεφάλαιο αναφέρει πληροφορίες για τα υλικά και επεξηγεί τις τεχνικές που χρησιμοποιήθηκαν στην σύνθεση, την επεξεργασία και τον χαρακτηρισμό των νανοσωματιδίων και των μιγμάτων τους. Τέλος στο πέμπτο κεφάλαιο παρουσιάζονται τα αποτελέσματα των πειραμάτων που πραγματοποιήθηκαν και ακολουθεί ο σχολιασμός τους.
The present thesis studies the development of a versatile system of antimicrobial protection for use in clothing and household products. In particular Triclosan incorporated crosslinked polystyrenedinylbenzene nanobeads were developed; triclosan is a widely used antimicrobial agent. It is noted that the health hazards arising during nosocomial treatment due to infections caused by microbial pathogens and the means to protect oneself against such threats have become the subject of many research activities during the last few decades. The size of the nanoparticles after examination with scanning electron microcopy (SEM) and dynamic light scattering (DLS) was found to vary between 35-350 nm depending on the system formulation. Their thermal behavior was studied with differential scanning calorimetry (DSC) and their melting point was measured at ~425 oC. Using UV-Vis spectroscopy the real encapsulation efficiency of the antimicrobial in the system was determined at ~72% and its release kinetics were studied in a water-ethanol solution. The nanobeads possess controlled release properties; they were furthermore incorporated into polypropylene matrixes which were uniaxially drawn in film form. Finally utilizing polarized Raman spectra, the draw induced molecular orientation of the films was correlated to the relevant variation of the related antimicrobial release kinetics. The first chapter of the present thesis reviews the textile microbial infections and the various solutions that have been proposed showing up the specific research goal targeted. In the second chapter the meaning of controlled release is explained and the basic system categories involved are presented along with characteristic examples. The nanoparticles, their composition, special attributes, applications, synthesis and characterization techniques are the subject of the third chapter. The fourth chapter reports information about the materials and the methods used in the synthesis, postprocessing and characterization of the nanoparticles and their blends. Finally the last chapter presents the experimental results and relevant comments.

Polyelectrolyte multilayer coatings have become a new and general way to functionalize a variety of materials. Particularly, the Layer-by-Layer (LbL) method is a technique developed for the coating of solid surfaces. The LbL technique presents a unique mean to construct surface coatings that can conform to a variety of biomaterial surfaces and serve as matrices enabling controlled delivery of bioactive molecules from surface. As the deposition process is achieved in aqueous medium, incorporation of active agents is possible since the coatings obtained by LbL are less densely packed and this is advantageous for diffusion through the coating. The coating is constructed by the alternate adsorption of oppositely charged polyelectrolytes at the surface of the material, easily obtained when it is dipped in polyelectrolyte solutions. A deposition cycle creates a layer, and these cycles can be repeated as often as needed. This study aims to obtain novel bioactive textiles with potential application as wound-dressings. The biopolymers chosen for the functionalization of cotton (substrate), were chitosan (CH) and alginate (ALG). The multilayer coating of cotton with CH and ALG is constructed by the adsorption of CH and ALG with opposite charge on the surface of cotton substrates. The successive deposition of multilayers of CH and ALG was analyzed by three different techniques. Contact angle between a water droplet and the surface of the sample, cationic dye staining method and analysis by ATR-FTIR (Fourier Transform Infrared spectroscopy with Attenuated Total Reflection). These techniques showed that there was alternating deposition between CH and ALG and the presence of electrostatic bonds between the layers. In order to evaluate the antibacterial activity of the functionalized cotton, the Japanese standard JIS L 1902:2002 for the halo method (qualitative assay), and the absorption method (quantitative test) were assessed. These tests revealed an antibacterial effect on the functionalized cotton for both Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Klebsiella pneumoniae). In addition a method was optimized for incorporating L-cysteine (L-cys) between the layers of CH and ALG deposited on cotton samples by the LbL, in order to obtain a better antimicrobial effect. Several strategies were used and the best results were obtained by the method where the ALG turns into a gel in the presence of calcium, since L-cys can be incorporated directly between the layers of CH and ALG without any covalent bond. Thus, the bioactive L-cys agent was immobilized without losing its bioactive characteristics. These new samples were analyzed for the antibacterial activity against Staphylococcus aureus and Klebsiella pneumoniae according with the previously used standard, and the results showed an increase in the antibacterial effect due to the presence of L-cys. This new coating method has the great advantage to able to select other types of bioactive agents without needing further optimization. In this way, L-Cys was replaced by antimicrobial peptides (AMPs). The reason for the use of AMPs is related with the continuous use of antibiotics which resulted in multiresistant bacterial strains all over the world. Consequently, there is an urgent need to search for alternatives for antibiotics. The AMPs are the new generation of antimicrobials. Four AMPs of different features were used. The depth in which each AMPs is incorporated between the layers was determined by energy dispersive analysis of X-rays (Energy Dispersive X-ray EDS). Results showed, that all AMPs used have a higher antimicrobial effect when compared with previous samples (with and without L-Cys) for both microorganisms and are non-cytotoxic to normal human dermal fibroblasts at the tested Concentrations. This confirms that this new functionalization approach of cotton coated with layers of CH and ALG by the LbL technique with incorporated AMPs leads to good antibacterial and cytotoxicity results, which make them suitable to be used as wound dressings.
Nos últimos anos, o uso de têxteis com capacidade antimicrobiana tem vindo a aumentar significativamente. Compostos sintéticos antimicrobianos utilizados em artigos têxteis são muito eficazes face a uma grande gama de microrganismos. Mas o uso de têxteis antimicrobianos de forma contínua pode levar à resistência bacteriana e sensibilização dos utilizadores, bem como causar problemas ao meio ambiente. Para minimizar estes riscos existe atualmente uma grande procura de têxteis antimicrobianos produzidos com compostos naturais não tóxicos e amigos do ambiente. A baixa incidência de efeitos adversos com origem em compostos naturais relativamente aos compostos sintéticos pode ser explorada como uma alternativa atraente e promissora para aplicações têxteis. O método de funcionalização por camada sobre camada (Layer-by-Layer, LbL) pode fornecer novos tipos de revestimentos em materiais têxteis. Esta técnica LbL tem ganho uma grande aceitação na investigação académica e a nível industrial. Foi proposta por Decher e seus colaboradores no início dos anos 90 e desde então o seu impacto positivo pode ser comprovado através do crescente número de trabalhos publicados. Revestimentos por multicamadas de polieletrólitos naturais bioativos tornam-se num processo novo de funcionalização de superfícies. Esta técnica é desenvolvida em meio aquoso e envolve tipicamente a adsorção alternada de polieletrólitos de cargas opostas. A possibilidade de fabricar tais camadas, graças às interações eletrostáticas, permite a funcionalização de superfícies de praticamente qualquer tamanho e forma. Este conceito não é novo para algumas aplicações como seja a libertação de fármacos, mas é relativamente novo para aplicações têxteis. Na revisão da literatura foram encontrados alguns, mas poucos, trabalhos de investigação relativamente à aplicação do LbL em substratos têxteis naturais, como seja o caso do algodão. O uso de polímeros naturais para obter estas camadas pode auxiliar na resolução de problemas que ocorrem com os polímeros sintéticos. Relativamente aos polímeros naturais mais utilizados encontram-se o quitosano (CH) e o alginato (ALG) que são polissacarídeos bastante conhecidos por serem biocompatíveis, biodegradáveis, antimicrobianos e não tóxicos. Neste trabalho apresentam-se os resultados sobre a viabilidade e sucesso da deposição de camadas de polieletrólitos de CH e de ALG pela técnica do LbL em fibras de algodão. O revestimento do algodão por multicamadas de CH e ALG é construído através da adsorção de CH de carga positiva e oposta à carga da superfície do algodão, seguida pela adsorção de ALG de carga negativa, ou seja oposta á carga do CH. O substrato de algodão utilizado para a deposição das várias camadas foi pré-tratado antes da deposição dos polieletrólitos, de forma a ativar a sua superfície deixando-a com cargas negativas. A deposição sucessiva das multicamadas de polieletrolitos foi analisada por 3 técnicas diferentes. Cálculo do ângulo de contacto entre uma gota de água e a superfície da amostra, coloração com um corante catiónico e análise por ATR-FTIR (Fourier Transform Infrared Spectroscopy with Attenuated Total Reflection). Estas técnicas indicaram que houve uma deposição alternada entre o CH e o ALG e também a presença de ligações eletrostáticas entre as camadas. Ficou assim demonstrado o sucesso na deposição de CH e ALG pela técnica do LbL em substrato têxtil de origem natural, neste caso o algodão. Com o fim de avaliar a atividade antibacteriana das amostras de algodão funcionalizadas, seguiu-se a norma Japonesa JIS L 1902:2002 para o método do halo (teste qualitativo) e método de absorção (teste quantitativo). Estes testes revelaram um efeito antibacteriano das amostras funcionalizadas, tanto para bactérias Gram-positivas (Staphylococcus aureus) como Gramnegativas (Klebsiella pneumoniae). Com estes resultados verificou-se que era possível preparar estruturas com propriedades específicas. Este método permite assim a possibilidade de desenvolver novos produtos têxteis funcionais para aplicações biomédicas, podendo também com este método do LbL obter amostras que tenham um papel no desenvolvimento de um sistema de libertação de fármacos no local pretendido. As amostras anteriores foram ainda analisadas por microscopia eletrónica de varrimento (Scanning Electron Microscopy, SEM). Esta análise teve como objetivo visualizar o grau do dano sofrido na estrutura das bactérias testadas por ação do CH e ALG. A fase seguinte consistiu em otimizar um método para incorporação de L-cisteína (L-cys), que é um agente antimicrobiano, entre as camadas de CH e ALG depositadas em amostras de algodão pelo método do LbL. Entre os diversos métodos utilizados para incorporar a L-cys, o que melhores resultados produziu foi aquele onde se fez uso da propriedade do ALG em formar gel na presença de cálcio. Verificamos que a L-cys pode ser incorporada diretamente entre as camadas de CH e ALG sem que ocorra qualquer ligação covalente entre a L-cys e os polieletrólitos de CH e ALG. Desta forma o agente bioativo (L-cys) ficou imobilizado sem perder as suas características bioativas e tem como grande vantagem a possibilidade de podermos selecionar outros tipos de agentes bioativos sem a necessidade de nova otimização do método de incorporação. Nestas novas amostras foram analisadas as propriedades antibacterianas para o Staphylococcus aureus e para Klebsiella pneumoniae segundo a norma já referida anteriormente, e os resultados mostraram um aumento no efeito antibacteriano devido à presença da L-cys. Por último, a L-cys foi substituída por péptidos antimicrobianos (antimicrobial peptides, AMPs), já que são a nova geração de antimicrobianos. Foram utilizados 4 AMPs de características diferentes. A profundidade em que cada AMPs se encontra incorporado entre as camadas foi determinada por análise de energia dispersiva de raios X (Energy Dispersive X ray, EDS). Para estas últimas amostras foram feitos os testes antibacterianos e analisada a citotoxicidade para o valor das concentrações usadas. Foram também analisadas as curvas de libertação para o exterior dos AMPs incorporados no algodão funcionalizado. Com os resultados obtidos confirma-se que esta nova funcionalização de algodão revestido com camadas de CH e ALG pela técnica do LbL e com incorporação de AMPs, conduz a bons resultados antimicrobianos e de citotoxicidade, podendo assim estas amostras ser utilizadas na área da saúde, especificamente como compressas.