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Authors
Abstract(s)
O nível de exigência sobre a produção de produtos manufaturados tem aumentado nos
últimos anos, com especial atenção a ser dada à pegada ambiental do setor industrial. O
setor têxtil é uma indústria com um consumo elevado de recursos (água, energia, etc.),
utiliza químicos perigosos e tóxicos e produz águas residuais extremamente poluídas.
Numa tentativa de produzir soluções mais amigas do ambiente, a indústria têxtil substituiu
o tradicional conceito “tratamento da poluição” pelo conceito de “prevenção da poluição”.
Assim sendo tecnologias e conceitos que favoreçam este conceito são vantajosas e de
grande interesse de um ponto de vista industrial e económico.
O primeiro passo deste trabalho teve por objetivo caracterizar e otimizar a produção de
nanopartículas de quitosana capazes de incorporar corantes têxteis para serem utilizadas
nas restantes fases deste trabalho. A otimização da produção de nanopartículas foi
realizada através de gelificação iónica com 3 fatores físicos (tempo de adição de
tripolifosfato, tempo de reação e velocidade de rotação) a serem avaliados. Os resultados
obtidos mostraram que foi possível definir parâmetros físicos ótimos de produção das
nanopartículas e que estas foram homogeneamente produzidas a pH 5. Adicionalmente, a
caracterização das nanopartículas mostrou que estas eram biocompatíveis com células
HaCat e estáveis à liofilização e armazenamento na presença de 10% (m/v) de manitol.
A segunda fase desta tese focou-se na produção de corantes têxteis nanoencapsulados e no
estudo da ligação destes a têxteis. Corantes têxteis reativos e dispersos foram
nanoencapsulados com sucesso com a obtenção de percentagens de encapsulação médias
superiores a 90% e as nanopartículas produzidas a possuírem um potencial zeta positivo e
tamanho entre 190 e 800 nm. Adicionalmente, os corantes nanoencapsulados não
apresentaram qualquer citotoxicidade relativamente a células HaCat e, acima de tudo, para
as nanopartículas produzidas não foi observada a tradicional especificidade corante-tecido
dado que estas foram capazes de corar todos os tecidos naturais e sintéticos testados.
Após os corantes terem sido nanoencapsulados com sucesso, o foco seguinte do trabalho
foi a validação das propriedades biológicas das nanopartículas e dos seus constituintes.
Para alcançar esse objetivo foi elaborada uma abordagem multi-etapas, com a fase inicial a
consistir na validação da atividade biológica, em ambiente planctónico e séssil, da
quitosana e depois de nanopartículas vazias a ser validada relativamente a vários
microrganismos patogénicos da pele resistentes a antibióticos (e.g. MRSA, MRSE e VRSA). Os resultados obtidos mostraram que tanto a quitosana como as suas
nanopartículas vazias apresentaram concentrações mínimas inibitórias e bactericidas (CMI
e CMB) baixas, reduziram rapidamente o número de contagens bacterianas viáveis,
inibiram a adesão bacteriana e formação de biofilme e, as nanopartículas vazias, foram
capazes de reduzir as contagens viáveis in vivo num modelo de infeção de células HaCat.
No seguimento destes resultados a atividade biológica das nanopartículas de corante foi
avaliada contra os mesmos microrganismos da pele resistentes a antibióticos, com os
resultados obtidos a mostrarem que os corantes têxteis nanoencapsulados inibiram o
crescimento de todos os microrganismos testados em ambientes planctónico e séssil. Em
crescimento planctónico as nanopartículas registaram valores de CMI entre 0.5 e 2 mg/mL
e de CMB entre 1 a 3 mg/mL. Relativamente à atividade sobre a biofilmes bacterianos as
nanopartículas foram eficazes na inibição da formação de biofilme e do mecanismo de
quorum sensing, com percentagens de inibição entre 30 e 87% a serem registradas para o
primeiro e atingirem ca. 100% para o segundo. Adicionalmente, as nanopartículas de
corante têxtil não tiveram qualquer efeito adverso no metabolismo e integridade da
membrana da linhagem celular HaCat e foram capazes de reduzir significativamente as
contagens viáveis intracelulares e extracelulares de MRSA num modelo de infeção de
células HaCat.
Como as nanopartículas de corantes mostraram ser capazes de corar têxteis e possuem uma
atividade biológica assinalável, a última fase desta tese teve por objetivo encontrar resposta
à pergunta – serão os têxteis corados com esta metodologia biologicamente ativos? Os
resultados obtidos mostraram que os têxteis corados não possuíam qualquer efeito
citotóxico sobre a linhagem celular HaCat e que o processo de tingimento também
funcionaliza os têxteis, pois o algodão corado com nanopartículas foi capaz de reduzir
efetivamente as contagens viáveis de MSSA, MRSA e Acinetobacer baumannii.
Adicionalmente, a análise da interação das nanopartículas com o algodão mostrou que esta
ocorre através de interação iónica e de pontes de hidrogénio e que as nanopartículas
cobrem cada fibra individual ficando achatadas na superfície das mesmas.
Em resumo, a metodologia de tingimento têxtil proposta demonstra ser um processo fácil e
que possibilita em um só passo tingir e funcionalizar têxteis. Considerando que este
processo não requer adição de sais ou adjuvantes químicos e que não existe qualquer
especificidade corante-tecido, a aplicação desta metodologia na indústria têxtil poderá
alterar o modo como a mesma ópera e diminuir a sua pegada ambiental.
In later years demands upon the manufacturing of consumer goods have increased, with special attention being given to industrials sectors and companies environmental footprint. The textile sector while being one of the largest worldwide sectors in terms of sales is also one of the most polluting ones, as it is a resource intensive (water, energy, etc.) industry, which employs hazardous and poisonous chemicals, large quantities of water and produces heavily polluted wastewaters. In an effort to be more environment friendly, the wastewater management concept of this industry has shifted from treatment to prevention, as such technologies/approaches favoring a “pollution prevention” concept are of great interest and advantageous from an industrial and economic standpoint. The first step of the present work aimed to optimize and characterize the production of the chitosan nanoparticles to be used throughout the work. A study of the impact of three physical parameters (TPP addition time, reaction time and rotation velocity) at two different pH levels upon chitosan nanoparticles production through ionic gelation was carried out in order to define the optimum conditions for nanoparticle production. The results showed that nanoparticles were more homogeneously produced at pH 5 and that it was possible to define a set of optimum production conditions. Additionally, through particle characterization it was possible to validate the biocompatibility of chitosan nanoparticles towards HaCat cells and to establish that they were stable to be freeze dried and stored in the presence of 10 (w/v) of mannitol. The second stage of this thesis focused on the production of nanoencapsulated textile dyes and on screening their connection to textiles. Reactive and disperse textile dyes were successfully nanoencapsulated through ionic gelation with average entrapment efficacies obtained being above 90% and the nanoparticles produced presenting positive charge and sizes between 190 and 800 nm. Furthermore, nanoencapsulated dyes presented no toxicity towards HaCat cells and, above all, no dye-fabric specificity was observed with the produced nanoparticles being capable of dyeing, with various efficacies of dye uptake, the synthetic and natural fabrics tested. Once a successful nanoencapsulation of textiles dyes was achieved the thesis focus shifted towards validation of the biological properties of the nanoparticles and their constituents. To do so a multistep approach was taken, where on an initial phase chitosan solution, first, and then void nanoparticles were used as benchmarks. Their biological activity was validated against various pathogenic microorganisms associated with skin diseases, including drug resistant ones (e.g. MRSA, MRSE, VRSA, A. baumannii), with low minimal inhibitory and bactericidal concentrations, rapid reduction of bacterial counts and high inhibition percentages of bacterial adhesion and biofilm formation being registered. Furthermore, void nanoparticles were also capable of reducing bacterial counts in a HaCat cellular infection model. Based on these results it was then decided to evaluate the biological potential of dye nanoparticles against skin pathogens. The results obtained showed that for the skin pathogens tested low MICs (0.5 – 2 mg/mL) and MBCs (1-3 mg/mL) were registered and effective inhibition of biofilm formation and quorum sensing signaling was observed. Additionally, dye nanoparticles did not impair HaCat metabolism or damaged its cell wall and were capable of managing MRSA capacity to infect HaCat cells as they significantly reduced intracellular and extracellular bacterial counts. The last phase of this thesis focused upon textiles dyed with nanoencapsulated dyes and on answering the question - are the dyed textiles biologically active? The results obtained showed that nanoparticle dyed cotton had no cytotoxic effect upon HaCat cells and that the dyeing process imparted functionality upon cotton, as nanoparticle dyed cotton effectively reduced MSSA, MRSA and A. baumannii bacterial counts. Additionally, dye nanoparticles interaction with cotton was shown to occur through ionic interaction and hydrogen bonding with particles flattening themselves upon the fibre surfaces and coating cotton individual fibres. Overall, the dyeing methodology hereby proposed exhibited capacity to in an easy, onestep process dye and functionalize textiles. With no textile-dye specificity being observed and no salts and chemical adjuvants being used, this process has the potential to alter the way the textile industry operates and diminish its environmental footprint.
In later years demands upon the manufacturing of consumer goods have increased, with special attention being given to industrials sectors and companies environmental footprint. The textile sector while being one of the largest worldwide sectors in terms of sales is also one of the most polluting ones, as it is a resource intensive (water, energy, etc.) industry, which employs hazardous and poisonous chemicals, large quantities of water and produces heavily polluted wastewaters. In an effort to be more environment friendly, the wastewater management concept of this industry has shifted from treatment to prevention, as such technologies/approaches favoring a “pollution prevention” concept are of great interest and advantageous from an industrial and economic standpoint. The first step of the present work aimed to optimize and characterize the production of the chitosan nanoparticles to be used throughout the work. A study of the impact of three physical parameters (TPP addition time, reaction time and rotation velocity) at two different pH levels upon chitosan nanoparticles production through ionic gelation was carried out in order to define the optimum conditions for nanoparticle production. The results showed that nanoparticles were more homogeneously produced at pH 5 and that it was possible to define a set of optimum production conditions. Additionally, through particle characterization it was possible to validate the biocompatibility of chitosan nanoparticles towards HaCat cells and to establish that they were stable to be freeze dried and stored in the presence of 10 (w/v) of mannitol. The second stage of this thesis focused on the production of nanoencapsulated textile dyes and on screening their connection to textiles. Reactive and disperse textile dyes were successfully nanoencapsulated through ionic gelation with average entrapment efficacies obtained being above 90% and the nanoparticles produced presenting positive charge and sizes between 190 and 800 nm. Furthermore, nanoencapsulated dyes presented no toxicity towards HaCat cells and, above all, no dye-fabric specificity was observed with the produced nanoparticles being capable of dyeing, with various efficacies of dye uptake, the synthetic and natural fabrics tested. Once a successful nanoencapsulation of textiles dyes was achieved the thesis focus shifted towards validation of the biological properties of the nanoparticles and their constituents. To do so a multistep approach was taken, where on an initial phase chitosan solution, first, and then void nanoparticles were used as benchmarks. Their biological activity was validated against various pathogenic microorganisms associated with skin diseases, including drug resistant ones (e.g. MRSA, MRSE, VRSA, A. baumannii), with low minimal inhibitory and bactericidal concentrations, rapid reduction of bacterial counts and high inhibition percentages of bacterial adhesion and biofilm formation being registered. Furthermore, void nanoparticles were also capable of reducing bacterial counts in a HaCat cellular infection model. Based on these results it was then decided to evaluate the biological potential of dye nanoparticles against skin pathogens. The results obtained showed that for the skin pathogens tested low MICs (0.5 – 2 mg/mL) and MBCs (1-3 mg/mL) were registered and effective inhibition of biofilm formation and quorum sensing signaling was observed. Additionally, dye nanoparticles did not impair HaCat metabolism or damaged its cell wall and were capable of managing MRSA capacity to infect HaCat cells as they significantly reduced intracellular and extracellular bacterial counts. The last phase of this thesis focused upon textiles dyed with nanoencapsulated dyes and on answering the question - are the dyed textiles biologically active? The results obtained showed that nanoparticle dyed cotton had no cytotoxic effect upon HaCat cells and that the dyeing process imparted functionality upon cotton, as nanoparticle dyed cotton effectively reduced MSSA, MRSA and A. baumannii bacterial counts. Additionally, dye nanoparticles interaction with cotton was shown to occur through ionic interaction and hydrogen bonding with particles flattening themselves upon the fibre surfaces and coating cotton individual fibres. Overall, the dyeing methodology hereby proposed exhibited capacity to in an easy, onestep process dye and functionalize textiles. With no textile-dye specificity being observed and no salts and chemical adjuvants being used, this process has the potential to alter the way the textile industry operates and diminish its environmental footprint.