BNC textile: bacterial nanocellulose as a new and sustainable material for textile yarn

Dissertação de mestrado integrado em Engenharia BiológicaNeste trabalho, são discutidas tecnologias de produção de fios para aplicações têxteis tendo a celulose como base. São referidas tendências recentes que visam poupar o ambiente de exploração massiva, como o uso de nanocelulose bacteriana, procurando também responder às necessidades crescentes por fibras alternativas obtidas por processos sustentáveis. A avaliação do ciclo de vida de vários métodos de produção de fibras de celulose foi também abordada. O objetivo deste trabalho foi a produção de fios a partir de fibras alternativas às existentes no mercado utilizando a nanocelulose bacteriana como matéria-prima. A nanocelulose bacteriana possui características como elevada resistência mecânica, capacidade de retenção de água, estabilidade dimensional, cristalinidade, biocompatibilidade e biodegradabilidade, o que permite explorar a sua utilização em várias áreas como biomédica, cosmética, alimentar, têxtil e papel. Além disso, a sua produção tem um impacte ambiental menor onde não ocorre a destruição de florestas e a sua produção é feita em apenas algumas semanas, um tempo bastante inferior comparativamente ao análogo vegetal que demora meses ou anos. Foram produzidos filamentos utilizando diferentes concentrações de nanocelulose bacteriana e dois sistemas de dissolução diferentes: o método de dissolução em fase sólida e o método tradicional de produção de Liocel. Pelo primeiro método foi possível obter filamentos com módulo de Young de 20,8 ± 5,4 GPa, resistência à tração de 1201,9 ± 149,2 MPa e alongamento de 11,5 ± 0,1 %. Pelo segundo, foi obtido um módulo de Young de 35,0 ± 17,2 GPa, resistência à tração de 1100,0 ± 480,0 MPa e alongamento de 6,8 ± 4,0 %. De forma a respeitar os critérios de produção de filamentos pelo processo Liocel, foi realizado, posteriormente, um estudo de despolimerização da nanocelulose bacteriana. O grau de polimerização da nanocelulose bacteriana foi reduzido do seu valor original (cerca de 2000) para 602-531, que normalmente é considerado adequado para o processo de Liocel. Métodos alternativos de produção de filamentos sem a dissolução da nanocelulose bacteriana foram também testados – dry-spinning e wet-drawing, obtendo-se resultados semelhantes em ambos os métodos, com um módulo de Young de 5,4 ± 2,2 GPa e 7,9 ± 3,4 GPa, resistência à tração de 194,6 ± 53,2 MPa e 220,2 ± 98,4 MPa , e alongamento de 9,1 ± 6,3 % e 14,3 ± 1,8 %, respetivamente. São necessários mais estudos de forma a perceber se a despolimerização da nanocelulose bacteriana é realmente necessária para o processo de Liocel. A produção de fibras sem solventes também requer um estudo mais aprofundado, sendo estas as formas mais sustentáveis de produção de fibras têxteis.In this work, the technologies for the production of cellulose-based textiles, their surface modification and the recent trends aiming at sparing the forest from massive exploitation are discussed. The life cycle assessment of several cellulose fibre production methods is also addressed. The objective of this work was the production of cellulose filaments using an alternative source of cellulose – bacterial nanocellulose – as raw material. Bacterial nanocellulose has impressive characteristics such as high mechanical strength, water-holding capacity, dimensional stability, crystallinity, biocompatibility and biodegradability, allowing to explore its use in several areas, namely in the biomedical, cosmetic, food, textile and paper areas. Besides that, its production has less impact on the environment as no forests are destroyed and its production is faster. Filaments were produced using different BNC concentrations and two different dissolving systems: the solid-phase dissolution method and the traditional Lyocell production method. From the first method it was possible to obtain filaments with Young’s modulus of 20,8 ± 5,4 GPa, tensile strength of 1201,9 ± 149,2 MPa and elongation of 11,5 ± 0,1 %. Through the second was obtained Youngs’ modulus of 35,0 ± 17,2 GPa, tensile strength of 1100,0 ± 480,0 MPa and elongation of 6,8 ± 4,0 %. In order to meet Lyocell's production criteria, the degree of polymerization of bacterial nanocellulose was lowered from its original value (around 2000) to 602-531, which is normally considered suitable for the Lyocell process. Although it has been possible to achieve the depolymerization of BNC in a simple way using a chemical treatment, it would be preferable to process the original cellulose, without depolymerization. Alternative methods of filament production without dissolution were also tested – dry spinning and wet-drawing. Similar results were obtained for both methods with a Young’s modulus of 5,4 ± 2,2 GPa and 7,9 ± 3,4 GPa, tensile strength of 194,6 ± 53,2 MPa and 220,2 ± 98,4 MPa, and elongation of 9,1 ± 6,3 % and 14,3 ± 1,8 %, respectively. Further study on this subject is needed to understand if BNC depolymerization is really needed on a pilot or commercial scale for the Lyocell process. Fibres without solvents also need to be further studied as they are the more sustainable ways of fibre production and there is a growing need for these types of fibres on market

Estimativa médico-legal da idade pela mineralização e erupção dentária numa população portuguesa subadulta: validação do atlas de Schour & Massler e de Londres

Tese de Mestrado, Medicina Dentária, Universidade de Lisboa, Faculdade de Medicina Dentária, 2014Este projeto teve como objetivo validar, numa população portuguesa, dois métodos de estimativa médico-legal da idade dentária o atlas de Schour & Massler e o atlas de Londres. A amostra populacional foi composta por 108 radiografias panorâmicas de indivíduos vivos e de idade conhecida. A idade dentária foi estimada de acordo com cada um dos métodos. A idade cronológica foi, então, comparada com a idade dentária estimada utilizando os testes estatísticos t de Student para amostras independentes e para amostras emparelhadas. O nível de significância foi definido em 5%. Os resultados mostraram que o atlas de Schour & Massler subestima a idade enquanto o atlas de Londres sobrestima. O atlas de Londres demonstrou um melhor desempenho estatístico em todos os testes aplicados. As diferenças médias entre a idade estimada e a idade cronológica para o atlas de Londres e de Schour & Massler foram de 0,1389 e 5,4167 meses, respetivamente. Aplicando o atlas de Schour & Massler obteve-se uma diferença significativa entre a idade dentária e a idade cronológica (p <0,05). Conclui-se que, na população analisada, a estimativa da idade pelo atlas de Londres difere, com significância estatística, da obtida pelo atlas de Schour & Massler e que a primeira é a que mais se aproxima da idade cronológica. Foram encontradas diferenças entre a estimativa obtida para o sexo feminino e masculino em ambos os métodos. Mais estudos devem ser feitos com uma amostra populacional maior.The aim of this project was to validate, on a portuguese population, two forensic methods of dental age estimation Schour & Massler charts and the London atlas. The test sample was composed by 108 dental radiographs of living and known-age individuals. Dental age was estimated according to each method. Chronological age was then compared to the estimated dental age using individual t-test and paired t-test. Results showed that the Schour & Massler charts under-estimated age and the London atlas overestimated age. Nevertheless, the London atlas performed better in all measures. Mean differences for both the London atlas and Schour & Massler were 0,1389 and -5,4167 months respectively. Schour & Massler charts showed significant statistical difference between dental age and chronological age (p <0,05). We conclude that, in the evaluated sample, age estimation using the London atlas represents an improvement in forensic age estimation from developing teeth. Further studies should be done with a larger population sample

Desafios da escola de hoje : o projeto Apolo e o perfil do aluno para o séc. XXI

A escola uniformizada da era industrial insiste em persistir, desencantando progressivamente quem lá passa, pelo desconforto do desajuste. Nos últimos três anos, contudo, parece anunciar-se na educação uma vontade de metamorfose da engenharia escolar, que se quer mais consentânea com a necessidade de preparar os alunos para a diversidade, a mudança e a incerteza em que vivemos. Para que “aprendam a aprender” e aprendam ao longo da vida. Em 2009, a escolaridade obrigatória alargou-se para todas as crianças e jovens com idades compreendidas entre os seis e os dezoito anos, dando origem ao Perfil do Aluno à Saída da Escolaridade Obrigatória (2016), matriz de base humanista que orienta as decisões inerentes ao processo educativo. Ainda no âmbito das prioridades definidas pelo XXI Governo Constitucional para a área da educação, foi autorizada, em regime de experiência pedagógica, a implementação do Projeto de Autonomia e Flexibilidade Curricular dos Ensinos Básico e Secundário (2017), autonomizando as escolas para uma gestão flexível e contextualizada do currículo. O trabalho de investigação aqui apresentado, um estudo de caso de paradigma qualitativo, centra-se num projeto desenvolvido no ano letivo 2017/2018, numa escola de ensino particular portuguesa. O estudo selecionou uma turma do 5º ano (2º ciclo) e duas turmas do 7º ano (3º ciclo), alocadas ao projeto, bem como os respetivos professores, num total de cerca de 50 alunos e 23 professores. Procurou-se perceber se o projeto Apolo, na perspetiva dos agentes envolvidos, permite trabalhar as competências descritas no Perfil do aluno para o Século XXI. Neste processo foram convocadas perspetivas teóricas sobre os modelos escolares e a evolução do conceito de sucesso educativo no modelo escolar português, políticas educativas atuais e perspetivas para a mudança educativa. Os dados recolhidos e analisados neste estudo conduzem-nos a concluir que, na perspetiva dos agentes envolvidos, o projeto criado permite desenvolver as competências do Perfil do Aluno para o séc. XXI mas que há, contudo, aspetos de melhoria, tais como: um maior envolvimento do dos alunos com a comunidade envolvente; mais tempo em horário letivo para o desenvolvimento do projeto; mais tempo para preparação do mesmo e em conjunto com as restantes disciplinas para que haja uma maior implicância das mesmas e se cumpram com mais eficácia os objetivos propostos. E apesar da verificação das mais-valias de uma metodologia centrada na aprendizagem baseada na resolução de problemas para o desenvolvimento das competências do Perfil do Aluno para o século XXI, é testemunhada a dificuldade e o acréscimo de trabalho resultantes da coexistência de um novo paradigma a par de uma gramática envelhecida.The uniformed school of the industrial age insists on persisting, progressively disenchanting those who pass by the discomfort of misfit. In the last three years, however, there seems to be a proclamation in metamorphosis of school engineering that is more in line with the need to prepare students for the diversity, change and uncertainty in which we live in. So that they “learn how to learn” and learn throughout their lives. In 2009, compulsory schooling was extended to all children and young people aged between six and eighteen, giving rise to the Student Profile on leaving compulsory school (2016), a humanist-based matrix that guides inherent decisions to the educational process. Also within the scope of the priorities defined by the 21st Constitutional Government for the area of education, the implementation of the Curriculum Autonomy and Flexibility Project for Basic and Secondary Education (2017) was authorized under a pedagogical experience regime, empowering schools for flexible management and contextualized curriculum. The research work presented here, a case study of qualitative paradigm, focuses on a project developed in the school year 2017/2018, in a Portuguese private school. The study selected one 5th grade (2nd cycle) class and two 7th grade (3rd cycle) classes allocated to the project, as well as their teachers, totaling about 50 students and 23 teachers. We tried to understand if the Apolo project, from the perspective of the agents involved, allows us to work on the skills described in the Student Profile for the 21st Century. In this process, theoretical perspectives on school models and the evolution of the concept of educational success in the Portuguese school model, current educational policies and perspectives for educational change were summoned. The data collected and analyzed in this study lead us to conclude that, from the perspective of the agents involved, the project created allows the development of Student Profile skills for the 19th century. But there are, however, aspects of improvement, such as: greater involvement of students with the surrounding community; more time in school hours for project development; more time for its preparation with the other disciplines so that they are more implicated and the proposed objectives are more effectively met. And while verifying the added value of a problem-solving learning-based methodology for the development of 21st Century Student Profile skills, it is also witnessed the difficulty and increased work resulting from the coexistence of a new paradigma and an aged grammar

Trends on the cellulose-based textiles: raw materials and technologies

There is an emerging environmental awareness and social concern regarding the environmental impact of the textile industry, highlighting the growing need for developing green and sustainable approaches throughout this industrys supply chain. Upstream, due to population growth and the rise in consumption of textile fibers, new sustainable raw materials and processes must be found. Cellulose presents unique structural features, being the most important and available renewable resource for textiles. The physical and chemical modification reactions yielding fibers are of high commercial importance today. Recently developed technologies allow the production of filaments with the strongest tensile performance without dissolution or any other harmful and complex chemical processes. Fibers without solvents are thus on the verge of commercialization. In this review, the technologies for the production of cellulose-based textiles, their surface modification and the recent trends on sustainable cellulose sources, such as bacterial nanocellulose, are discussed. The life cycle assessment of several cellulose fiber production methods is also discussed.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684) and BioTecNorte Operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020– Programa Operacional Regional do Norte. Support from The Navigator Company through the I&D n◦ 21874, “Inpactus– Produtos e Tecnologias Inovadores a partir do Eucalipto,” funded through the Fundo Europeu de Desenvolvimento Regional (FEDER) and the Programa Operacional Competitividade e Internacionalização (POCI) is acknowledged.info:eu-repo/semantics/publishedVersio

Controlled release of cinnamon leaf oil from chitosan microcapsules embedded within a sodium alginate/gelatin hydrogel-like film for Pseudomonas aeruginosa elimination

Pseudomonas aeruginosa is considered a public threat, with antibiotics increasing their resistance. Essential oils (EOs) have demonstrated significant effects against microorganisms. However, due to their volatile nature, they cannot be used in their free-state. Here, hydrogel-like films were produced from a combination of sodium alginate (SA) and gelatin (GN) to serve as delivery platforms for the controlled release of cinnamon leaf oil (CLO) entrapped within chitosan (CS) microcapsules. The minimum inhibitory concentration (MIC) of CLO was established at 39.3 mg/mL against P. aeruginosa. CS microcapsules were prepared via ionotropic gelation with tripolyphosphate (TPP), encapsulating CLO at MIC. Successful production was confirmed by fluorescent microscopy using Nile red as a detection agent. Microcapsules were embedded within a biodegradable SA/GN polymeric matrix processed by solvent casting/phase inversion with SA/GN used at 70/30 polymer ratio at 2 wt.% SA concentration. A concentration of 2 wt.% CaCl2 was used as a coagulation bath. The CLO-containing CS microcapsules’ homogeneous distribution was guaranteed by successive vortex and blending processes applied prior to casting. CLO controlled release from the films was monitored in physiological pH for 24 h. Hydrated films were obtained, with the presence of loaded CS capsules being confirmed by FTIR. Qualitative/quantitative antimicrobial examinations validated the loaded film potential to fight P. aeruginosa.Authors acknowledge the Portuguese Foundation for Science and Technolog

Spun biotextiles in tissue engineering and biomolecules delivery systems

Nowadays, tissue engineering is described as an interdisciplinary field that combines engineering principles and life sciences to generate implantable devices to repair, restore and/or improve functions of injured tissues. Such devices are designed to induce the interaction and integration of tissue and cells within the implantable matrices and are manufactured to meet the appropriate physical, mechanical and physiological local demands. Biodegradable constructs based on polymeric fibers are desirable for tissue engineering due to their large surface area, interconnectivity, open pore structure, and controlled mechanical strength. Additionally, biodegradable constructs are also very sought-out for biomolecule delivery systems with a target-directed action. In the present review, we explore the properties of some of the most common biodegradable polymers used in tissue engineering applications and biomolecule delivery systems and highlight their most important uses.Authors acknowledge the Portuguese Foundation for Science and Technology (FCT), FEDER funds by means of Portugal 2020 Competitive Factors Operational Program (POCI) and the Portuguese Government (OE) for funding the project PEPTEX with reference PTDC/CTM-TEX/28074/2017 (POCI-01-0145- FEDER-028074). Authors also acknowledge project UID/CTM/00264/2020 of Centre for Textile Science and Technology (2C2T), funded by national funds through FCT/MCTES

Analog electronic teaching – a new approach for bipolar transistors

a) This work was based in a single individual sample; b) Learning Support Means (LSM) received poor acceptance; c) Other Alternative Support Means are under development; d) For these, a broader test sample was used; e) Preliminary results from this test are encouraging to further pursue this workN/

Nanoparticle synthesis and their integration into polymer-based fibers for biomedical applications

The potential of nanoparticles as effective drug delivery systems combined with the versatility of fibers has led to the development of new and improved strategies to help in the diagnosis and treatment of diseases. Nanoparticles have extraordinary characteristics that are helpful in several applications, including wound dressings, microbial balance approaches, tissue regeneration, and cancer treatment. Owing to their large surface area, tailor-ability, and persistent diameter, fibers are also used for wound dressings, tissue engineering, controlled drug delivery, and protective clothing. The combination of nanoparticles with fibers has the power to generate delivery systems that have enhanced performance over the individual architectures. This review aims at illustrating the main possibilities and trends of fibers functionalized with nanoparticles, focusing on inorganic and organic nanoparticles and polymer-based fibers. Emphasis on the recent progress in the fabrication procedures of several types of nanoparticles and in the description of the most used polymers to produce fibers has been undertaken, along with the bioactivity of such alliances in several biomedical applications. To finish, future perspectives of nanoparticles incorporated within polymer-based fibers for clinical use are presented and discussed, thus showcasing relevant paths to follow for enhanced success in the field.This research was funded by the Portuguese Foundation for Science and Technology (FCT) via grants UIDP/00264/2020 of 2C2T Strategic Project 2020–2023 and project PTDC/CTMTEX/28074/2017. This project has been funded by a Research Grant (2022) from the European Society of Clinical Microbiology and Infectious Diseases (ESCMID) to J.C.A., J.M.D. and C.S.M. also acknowledge FCT for PhD grants 2020.07387.BD and 2020.08547.BD, respectively, and H.P.F. for auxiliary researcher contract 2021.02720.CEECIND

Modification of Ca2+-Crosslinked Sodium Alginate/Gelatin films with Propolis for an improved antimicrobial action

Problems associated with microbial resistance to antibiotics are growing due to their overuse. In this scenario, plant extracts such as the propolis extract (PE) have been considered as potential alternatives to antibiotics in the treatment of infected wounds, due to its antimicrobial properties and ability to induce tissue regeneration. To improve the long-term effectiveness of PE in wound healing, polymeric films composed of biodegradable and biocompatible polymers are being engineered as delivery vehicles. Here, sodium alginate/gelatin (SA/GN) films containing PE were prepared via a simple, green process of solvent casting/phase inversion technique, followed by crosslinking with calcium chloride (CaCl2) solutions. The minimum inhibitory concentration (MIC) of PE was established as 0.338 mg/mL for Staphylococcus aureus and 1.353 mg/mL for Pseudomonas aeruginosa, the most prevalent bacteria in infected wounds. The PE was incorporated within the polymeric films before (blended with the polymeric solution) and after (immobilization via physisorption) their production. Flexible, highly hydrated SA/GN/PE films were obtained, and their antibacterial activity was assessed via agar diffusion and killing time kinetics examinations. Data confirmed the modified films effectiveness to fight bacterial infections caused by S. aureus and P. aeruginosa and their ability to be applied in the treatment of infected wounds.Portuguese Foundation for Science and Technol-ogy (FCT), FEDER funds by means of Portugal 2020 Competitive Factors Operational Program (POCI), and the Portuguese Government (OE) for funding the project PEPTEX with reference PTDC/CTM-TEX/28074/2017 (POCI-01-0145-FEDER-028074). The authors also acknowledge project UID/CTM/00264/2020 of Centre for Textile Science and Technology (2C2T), funded by national funds through FCT/MCTE

Sodium alginate/polycaprolactone co-axial wet-spun microfibers modified with N-carboxymethyl chitosan and the peptide AAPV for Staphylococcus aureus and human neutrophil elastase inhibition in potential chronic wound scenarios

In chronic wound (CW) scenarios, Staphylococcus aureus-induced infections are very prevalent. This leads to abnormal inflammatory processes, in which proteolytic enzymes, such as human neutrophil elastase (HNE), become highly expressed. Alanine-Alanine-Proline-Valine (AAPV) is an antimicrobial tetrapeptide capable of suppressing the HNE activity, restoring its expression to standard rates. Here, we proposed the incorporation of the peptide AAPV within an innovative co-axial drug delivery system, in which the peptide liberation was controlled by N-carboxymethyl chitosan (NCMC) solubilization, a pH-sensitive antimicrobial polymer effective against Staphylococcus aureus. The microfibers' core was composed of polycaprolactone (PCL), a mechanically resilient polymer, and AAPV, while the shell was made of the highly hydrated and absorbent sodium alginate (SA) and NCMC, responsive to neutral-basic pH (characteristic of CW). NCMC was loaded at twice its minimum bactericidal concentration (6.144 mg/mL) against S. aureus, while AAPV was loaded at its maximum inhibitory concentration against HNE (50 μg/mL), and the production of fibers with a core-shell structure, in which all components could be detected (directly or indirectly), was confirmed. Core-shell fibers were characterized as flexible and mechanically resilient, and structurally stable after 28-days of immersion in physiological-like environments. Time-kill kinetics evaluations revealed the effective action of NCMC against S. aureus, while elastase inhibitory activity examinations proved the ability of AAPV to reduce HNE levels. Cell biology testing confirmed the safety of the engineered fiber system for human tissue contact, with fibroblast-like cells and human keratinocytes maintaining their morphology while in contact with the produced fibers. Data confirmed the engineered drug delivery platform as potentially effective for applications in CW care.Authors acknowledge the Portuguese Foundation for Science and Technology (FCT), FEDER funds by means of Portugal 2020 Competitive Factors Operational Program (POCI) and the Portuguese Government (OE) for funding the project PEPTEX with reference PTDC/CTMTEX/28074/2017 (POCI-01-0145-FEDER-028074). Authors also acknowledge project UIDP/00264/2020 of 2C2T and UID/QUI/00686/2020 of CQ, funded by national funds through FCT/MCTES. C.S.M. and H.P.F. also acknowledge FCT for PhD funding via scholarship 2020.08547.BD and for auxiliary researcher contract via 2021.02720.CEEIND, respectively