32 research outputs found

    Chelidonium majus L. incorporated emulsion electrospun PCL/PVA_PEC nanofibrous meshes for antibacterial wound dressing applications

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    Presently, there are many different types of wound dressings available on the market. Nonetheless, there is still a great interest to improve the performance and efficiency of these materials. Concerning that, new dressing materials containing natural products, such as medicinal plants that protect the wound from infections but also enhance skin regeneration have been or are being developed. Herein, we used for the first time a needleless emulsion electrospinning technique for incorporating Chelidoniummajus L. (C. majus), a medicinal plant widely known for its traditional therapeutic properties, in Polycaprolactone (PCL)/Polyvinyl Alcohol (PVA)_Pectin (PEC) nanofibrous meshes. Moreover, the potential use of these electrospun nanofibers as a carrier for C. majus was also explored. The results obtained revealed that the produced PCL/PVA_PEC nanofibrous meshes containing C. majus extract displayed morphological characteristics similar to the natural extracellular matrix of the skin (ECM). Furthermore, the produced meshes showed beneficial properties to support the healing process. Additionally, the C. majus-loaded PCL/PVA_PEC nanofibrous meshes inhibited Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) growth, reaching a 3.82 Log reduction, and showed to be useful for controlled release, without causing any cytotoxic effect on the normal human dermal fibroblasts (NHDF) cells. Hence, these findings suggest the promising suitability of this novel wound dressing material for prevention and treatment of bacterial wound infections.The authors are also grateful for the funding support given by FibEnTech Research Unit (Project UIDB/00195/2020). Cl√°udia Mouro acknowledges a PhD fellowship from the Foundation for Science and Technology (FCT) (PD/BD/113550/2015)

    Development of electrospun wound-dressings incorporating medicinal plant-extracts

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    Human skin is a remarkably effective barrier against the invasion of external pathogens. However, when the occurrence of wounds compromises the skin‚Äôs integrity, the possibility of pathogenic microorganisms to colonize the wound site increase as well as the risk of acquiring an infection. In particular, the presence and permanence of high levels of pathogenic bacteria in the wound have been identified as the main responsible for the delay or failure in the healing process, especially in patients with a compromised immune system. The skin and soft tissue infections (SSTIs), particularly those caused by bacteria, are among the most common infections that can progress quickly to life-threatening complications. Besides, the aging population, combined with the increased rates of obesity and chronic diseases, like diabetes, have contributed to a higher prevalence of wounds susceptible to bacterial colonization and infection. In this context, to prevent the penetration of bacteria at the wound site and its growth and proliferation, wound dressings have been produced from different materials, with diverse shapes, containing antimicrobial agents into their structure. Among these agents, antibiotics, nanoparticles (NPs), and natural products have been the most used. However, the excessive and indiscriminate use of antibiotics has triggered an alarming rate of multidrug-resistant bacteria. Also, the possible toxicity associated with the use of NPs has limited its application in dressing materials. In this way, we have been witnessing an increasing demand for compounds obtained from natural sources, in particular from medicinal plants, as a more effective and efficient alternative. Medicinal plants are natural sources of bioactive substances that may exert significant effects on the management and treatment of wounds. Besides, the numerous therapeutic properties of the medicinal plants, such as antimicrobial, anti-inflammatory, antioxidant, anesthetic, and analgesic, are helpful in the treatment of injured skin by enhancing fibroblast proliferation, angiogenesis, and collagen biosynthesis. Thus, wound dressing materials containing plant extracts and some compounds obtained from plants, with intrinsic antimicrobial activity and ability to accelerate the healing process, have captured the interest of researchers in recent years in order to avoid or even eliminate undesirable pathogenic infections. Among the different techniques used to produce wound dressing materials, the electrospinning has been highlighted in the development of wound dressings based on bioactive nanofibers due to its simplicity, cost-effectiveness, and versatility. The nanofiber membranes produced by electrospinning have demonstrated properties with remarkable therapeutic potential, such as a 3D architecture that mimics the morphological features of the skin‚Äôs extracellular matrix (ECM), a high surface area to volume ratio, and porosity that allow them to control the exudate effectively. These characteristics are also able to maintain a moist environment at the wound site and ensure a continuous supply of nutrients and oxygen that promotes wound healing. Furthermore, the electrospun nanofibrous membranes have been incorporated with different types of bioactive or therapeutic agents, improving the desirable wound healing properties. Therefore, in this doctoral work, new electrospun wound dressing materials containing crude medicinal plant extracts and plant essential oils with remarkable antimicrobial and healing effects were developed from several strategies to protect the wound from both external agents and pathogenic invasion, as well as improve the skin tissue regeneration. In a first approach, Eugenol (EUG), an essential oil extracted from cloves, was incorporated into a polymeric blend composed of Polycaprolactone (PCL), Polyvinyl Alcohol (PVA), and Chitosan (CS) by electrospinning from water-in-oil (W/O) and oil-in-water (O/W) emulsions. From this work, it was achieved better wound healing properties when O/W emulsion was used. However, although emulsion electrospinning shows promising potential for preserving the EUG‚Äôs stability and bioactivity, the essential oils require large amounts of raw material, as well as multiple step preparation methods and special laboratory facilities. To overcome the limitations presented by essential oils, two different crude medicinal plant extracts, which are easily obtained from dried and milled plants, were prepared through a simple, easy to perform, and low-cost extraction method, and then incorporated in two different polymeric blends by emulsion electrospinning to corroborate the effectiveness and potential of this technique. Regarding that, a crude extract of Hypericum perforatum L. (HP) was incorporated into a polymeric blend of Poly(L-lactic acid) (PLLA), PVA, and CS, while a crude extract of Chelidonium majus L. (CM) was loaded into a blend of PCL, PVA, and Pectin (PEC). The results revealed that the manufactured nanofiber membranes exhibited suitable properties for use as wound dressing materials. Besides, these membranes have been shown to inhibit the growth of pathogenic bacteria, namely Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa), and proved to be versatile systems for controlled release of bioactive and/or therapeutic agents. From these studies, the CM extract loaded into electrospun PCL/PVA_PEC nanofibrous membrane achieved a better antibacterial activity, reaching a ~4 Log reduction. Therefore, emulsion electrospinning has demonstrated to exhibit the incomparable ability to produce, in a single step, single-layer wound dressings incorporated with natural products, and the replacement of EUG by crude medicinal plant extracts proved to be an attractive and promising alternative. In a different approach, double-layered electrospun nanofibrous membranes containing crude medicinal plant extracts were produced, aiming to restore the structure and functions of the native skin. Concerning that, two different double-layer materials were developed from electrospinning. PLLA and PCL‚Äôs top layers were designed to act as breathable and waterproof protective barriers, capable of preventing bacteria penetration into the wound. In turn, lower layers of Polyethylene oxide (PEO), CS, and HP, as well as Chitosan-Sodium Tripolyphosphate (CS-TPP), combined with PVA and Centella asiatica L. (CA) were produced to improve the biologic performance of these materials. Due to their properties, the lower layers demonstrated to be able to promote the healing process and inhibit the growth of S. aureus and P. aeruginosa without inducing any cytotoxic effect. However, the PVA_CS-TPP_CA revealed a higher bacterial inhibitory effect, reaching a 3 Log reduction. Finally, a cotton gauze bandage, traditionally used to provide support and confer robust protection against external threats, was successfully combined with PVA and CS nanofibers containing Agrimonia eupatoria L. (AG) to produce a nano-coating capable of inhibiting the growth of bacteria at the wound site and support skin regeneration. Overall, the scientific work performed in this thesis has been conducted to encourage the scientific community to give more attention to the potential benefits of bioactive natural products as medicinal plants, which exhibit a low tendency to develop bacterial resistance. Moreover, it has been shown that the use of relatively simple, versatile, and low-cost strategies to produce wound dressing materials displaying antimicrobial properties have an essential impact on the control of bacterial colonization but also prevent bacterial wound infection and consequently accelerate the healing process.A pele constitui uma barreira notavelmente eficaz contra a invas√£o de agentes patog√©nicos externos. No entanto, quando a integridade da pele √© comprometida pela ocorr√™ncia de feridas, a possibilidade de microrganismos patog√©nicos colonizarem o local e desencadearem uma infe√ß√£o, aumenta. Normalmente, logo ap√≥s a les√£o ocorrer, inicia-se uma s√©rie sequencial e ordenada de eventos regulada pelo sistema imunit√°rio, de forma a restaurar a estrutura e as fun√ß√Ķes da pele nativa. Contudo, m√ļltiplos fatores podem impedir que o processo de cicatriza√ß√£o ocorra de maneira eficaz. Entre estes, a presen√ßa e perman√™ncia de elevados n√≠veis de bact√©rias patog√©nicas na ferida, mais comum em pacientes imunocomprometidos, prevalecem como um dos principais respons√°veis pelo atraso ou falha no processo de cicatriza√ß√£o. As infe√ß√Ķes da pele e tecidos moles (IPTM), especialmente as causadas por bact√©rias, est√£o entre as infe√ß√Ķes mais comuns que podem progredir rapidamente para complica√ß√Ķes potencialmente fatais. Al√©m disso, o envelhecimento da popula√ß√£o, a obesidade e o consequente aumento da incid√™ncia de doen√ßas cr√≥nicas t√™m contribu√≠do para uma maior preval√™ncia de feridas suscet√≠veis √† coloniza√ß√£o bacteriana e infe√ß√£o. Neste contexto, para prevenir a penetra√ß√£o de bact√©rias no local da ferida e evitar o seu crescimento e prolifera√ß√£o, t√™m sido produzidos pensos para feridas, a partir de diferentes materiais, com formas distintas, contendo agentes antimicrobianos na sua estrutura para aprimorar as propriedades antimicrobianas destes materiais. Entre estes agentes, destacam-se os antibi√≥ticos, as nanopart√≠culas (NPs) e os produtos de origem natural. Contudo, apesar de estarem dispon√≠veis v√°rios antibi√≥ticos para o tratamento de infe√ß√Ķes de feridas, o seu uso recorrente e indiscriminado tem desencadeado uma taxa alarmante de bact√©rias multirresistentes capazes de resistir mesmo aos antibi√≥ticos mais recentes e eficazes. Nesse sentido, as NPs surgiram como uma alternativa terap√™utica aos antibi√≥ticos mais comuns. No entanto, a poss√≠vel toxicidade associada √† sua utiliza√ß√£o tem limitado a sua aplica√ß√£o em pensos. Deste modo, temos vindo a assistir a uma crescente procura por compostos obtidos a partir de fontes naturais, em particular a partir de plantas medicinais, como uma alternativa mais eficaz e segura. As plantas medicinais t√™m sido consideradas desde os tempos ancestrais poderosos suplementos naturais por desempenharem um papel importante na cura e tratamento de diferentes tipos de feridas. Estas s√£o de f√°cil acesso e reconhecidas devido √†s in√ļmeras propriedades terap√™uticas que exibem, como propriedades antimicrobianas, anti-inflamat√≥rias, antioxidantes, anest√©sicas e analg√©sicas, as quais est√£o relacionadas com a presen√ßa de uma vasta gama de subst√Ęncias bioativas. Al√©m disso, as plantas medicinais s√£o tamb√©m capazes de melhorar o processo de cicatriza√ß√£o por exibirem a capacidade de acelerar a prolifera√ß√£o de fibroblastos, revasculariza√ß√£o, s√≠ntese e deposi√ß√£o de colag√©nio. Desta forma, pensos para feridas contendo compostos naturais provenientes de plantas, mais ecol√≥gicos, sustent√°veis, eficazes e seguros, bem como economicamente vi√°veis, com atividade antimicrobiana intr√≠nseca e, ao mesmo tempo, com a capacidade de acelerar o processo de cicatriza√ß√£o, t√™m-se revelado de extrema import√Ęncia e despertado o interesse dos investigadores nos √ļltimos anos a fim de prevenir ou mesmo eliminar infe√ß√Ķes indesej√°veis. Entre as diferentes t√©cnicas utilizadas para produzir pensos para feridas, o electrospinning tem merecido um maior destaque no desenvolvimento de membranas nanofibrosas devido √† sua simplicidade, rela√ß√£o custo-efic√°cia e versatilidade. Al√©m disso, as membranas produzidas por electrospinning t√™m demonstrado propriedades com not√°vel potencial terap√™utico, tais como uma estrutura tridimensional que mimetiza as caracter√≠sticas morfol√≥gicas da matriz extracelular da pele (ECM), uma elevada √°rea de superf√≠cie e porosidade que lhes permite controlar o exsudado e gerir o ambiente h√ļmido no local da ferida, bem como garantir a oxigena√ß√£o e o fornecimento necess√°rio de nutrientes. Estes materiais t√™m ainda a capacidade de promover a ades√£o e prolifera√ß√£o celular e potencial para libertar compostos bioativos no local da ferida. Assim sendo, e de forma a proteger as feridas de agress√Ķes externas e evitar poss√≠veis complica√ß√Ķes, a nossa proposta prev√™ a utiliza√ß√£o de diferentes estrat√©gias/ metodologias para produzir, atrav√©s de electrospinning, materiais com as caracter√≠sticas adequadas para aplica√ß√£o na √°rea do tratamento de feridas. Com esse objetivo, os trabalhos realizados ao longo deste projeto exploram diferentes misturas de biopol√≠meros com pol√≠meros sint√©ticos biodegrad√°veis e biocompat√≠veis, bem como v√°rios extratos brutos de plantas medicinais e seus derivados, como √≥leos essenciais, com reconhecidas propriedades antimicrobianas, a fim de reduzir o risco de infe√ß√£o bacteriana e permitir que a cicatriza√ß√£o ocorra num curto espa√ßo de tempo. Numa primeira abordagem, o Eugenol (EUG), um √≥leo essencial extra√≠do do cravo-da-√≠ndia, conhecido por apresentar propriedades terap√™uticas muito interessantes, foi incorporado com sucesso em uma mistura polim√©rica composta de Policaprolactona (PCL), √Ālcool Polivin√≠lico (PVA) e Quitosano (CS) por electrospinning de emuls√£o. O EUG foi incorporado pela primeira vez em duas emuls√Ķes distintas, √°gua-em-√≥leo (A/O) e √≥leo-em-√°gua (O/A), para investigar qual seria a combina√ß√£o que apresentava melhores propriedades para aplica√ß√£o como penso para feridas. Neste estudo, o EUG incorporado na emuls√£o do tipo O/A revelou resultados mais promissores e demonstrou capacidade para inibir o crescimento de Staphylococcus aureus (S. aureus) e Pseudomonas aeruginosa (P. aeruginosa) sem induzir qualquer efeito citot√≥xico em fibroblastos d√©rmicos humanos normais (NHDF). No entanto, apesar do electrospinning de emuls√£o se ter revelado uma t√©cnica auspiciosa para preservar a estabilidade e bioatividade do EUG, a obten√ß√£o de √≥leos essenciais exige quantidades elevadas de planta, requer m√©todos de prepara√ß√£o que envolvem v√°rias etapas, bem como equipamentos espec√≠ficos de laborat√≥rio. Al√©m disso, estes derivados de plantas podem ser facilmente degradados e s√£o suscet√≠veis a perdas por volatiliza√ß√£o e/ou decomposi√ß√£o t√©rmica. Para superar as limita√ß√Ķes apresentadas pelos √≥leos essenciais, dois diferentes extratos brutos de plantas medicinais foram preparados e incorporados em duas misturas polim√©ricas distintas, por electrospinning de emuls√£o, a fim de corroborar a efic√°cia e potencialidade desta t√©cnica. Os extratos brutos destacam-se dos √≥leos essenciais por serem facilmente obtidos a partir de plantas secas e mo√≠das, atrav√©s de m√©todos de extra√ß√£o simples, de f√°cil execu√ß√£o e baixo custo. Al√©m disso, os extratos brutos s√£o misturas ecologicamente sustent√°veis que possuem diversas subst√Ęncias com m√ļltiplas propriedades terap√™uticas e t√™m demonstrado ser mais efetivos, comparativamente aos seus derivados, devido √† sua disponibilidade e acessibilidade. Tamb√©m as intera√ß√Ķes sin√©rgicas estabelecidas entre os diferentes compostos t√™m-se revelado favor√°veis e resultado em uma melhor prote√ß√£o contra poss√≠veis degrada√ß√Ķes. Neste sentido, um extrato bruto de Hypericum perforatum L. (HP) foi incorporado numa mistura polim√©rica de Poli (L-√°cido l√°ctico) (PLLA), PVA e CS enquanto um extrato bruto de Chelidonium majus L. (CM) foi incorporado numa mistura composta por PCL, PVA e Pectina (PEC). Os resultados revelaram que as membranas de nanofibras fabricadas a partir de emuls√Ķes A/O contendo os extratos brutos de plantas medicinais exibiram propriedades adequadas para utiliza√ß√£o como pensos para feridas. Al√©m disso, estas membranas demonstraram ser capazes de inibir o crescimento de bact√©rias patog√©nicas e comprovaram ser sistemas vers√°teis para liberta√ß√£o controlada de agentes bioativos e/ou terap√™uticos. Por√©m, a membrana de nanofibras em que o extrato de CM foi incorporado na mistura polim√©rica PCL/PVA_PEC demonstrou uma maior atividade antibacteriana, obtendo-se um ~4 Log de redu√ß√£o. Portanto, o electrospinning de emuls√£o comprovou exibir a inigual√°vel capacidade de produzir, numa √ļnica etapa, pensos para feridas compostos de uma √ļnica camada incorporados com produtos naturais e a substitui√ß√£o do EUG por extratos brutos de plantas medicinais revelou-se uma alternativa atrativa e promissora. Por outro lado, materiais produzidos por deposi√ß√£o de duas diferentes camadas foram desenhados na tentativa de mimetizar a estrutura nativa da pele, bem como as suas fun√ß√Ķes e tornar o processo de cicatriza√ß√£o mais r√°pido e eficaz. Assim, uma membrana de dupla camada constitu√≠da por uma camada superior de PLLA, desenhada para atuar como uma barreira protetora contra a entrada de agentes patog√©nicos, e uma camada inferior de √ďxido de Polietileno (PEO), CS e HP, destinada a ser utilizada em contacto com a ferida, a fim de dotar a membrana com propriedades antimicrobianas e promover a regenera√ß√£o da pele, foi fabricada com sucesso por electrospinning. Os resultados obtidos revelaram que a camada superior pode atuar como uma barreira imperme√°vel, mas respir√°vel, capaz de impedir a entrada de bact√©rias no local da ferida, enquanto a camada inferior exibiu a porosidade, molhabilidade e swelling (inchamento por efeito de absor√ß√£o de l√≠quidos) adequados √† manuten√ß√£o de um ambiente h√ļmido favor√°vel ao processo de cicatriza√ß√£o. Al√©m disso, as propriedades antimicrobianas do CS e HP foram demonstradas pela capacidade desta camada inibir o crescimento de S. aureus e P. aeruginosa, sem causar efeitos citot√≥xicos. Similarmente, uma membrana de dupla camada foi produzida por electrospinning com uma camada superior de PCL. Esta camada exibiu a porosidade e a molhabilidade desej√°veis para atuar como uma barreira f√≠sica contra amea√ßas externas, nomeadamente contra a invas√£o de bact√©rias. Por sua vez, o CS foi reticulado com tripolifosfato de s√≥dio (TPP) e combinado com PVA a fim de testar a sua adequabilidade para atuar como um transportador de Centella asiatica L. (CA), a ser libertada no local da ferida e melhorar o potencial terap√™utico da camada inferior. Devido √†s suas propriedades, esta camada demonstrou ser capaz de promover o processo de cicatriza√ß√£o e de oferecer uma liberta√ß√£o controlada de CA, desej√°vel para evitar o crescimento bacteriano no local da ferida, observando-se uma redu√ß√£o de S. aureus e P. aeruginosa de 3 Log. Finalmente, o Algod√£o, normalmente utilizado em pensos para feridas, foi combinado com nanofibras de PVA e CS incorporadas com Agrimonia eupatoria L. (AG) a fim de produzir um nano-coating capaz de acelerar o processo de cicatriza√ß√£o. Para isso, o algod√£o foi primeiramente oxidado com o radical 2,2,6,6-tetrametil-1-piperidinoxil (TEMPO) para dota-lo com cargas negativas e de seguida foi utilizado como substrato na produ√ß√£o das nanofibras de PVA, CS e AG. Atrav√©s dos resultados obtidos foi poss√≠vel verificar que a camada de nanofibras incorporada com o extrato de AG exibiu propriedades adequadas para prevenir a desidrata√ß√£o, bem como a ades√£o das fibras de algod√£o ao leito da ferida. Al√©m disso, as nanofibras revelaram-se n√£o t√≥xicas para fibroblastos humanos, bem como apropriadas para inibir o crescimento bacteriano quando em contacto com a pele lesada. No geral, o trabalho realizado no √Ęmbito desta tese pretende incentivar a comunidade cient√≠fica a dar particular relev√Ęncia aos produtos de origem natural com baixa propens√£o ao desenvolvimento de resist√™ncias bacterianas e ao uso de estrat√©gias relativamente simples, vers√°teis e de baixo custo para obten√ß√£o de materiais avan√ßados para a fabrica√ß√£o de pensos para feridas com propriedades antimicrobianas, adequados para combater poss√≠veis infe√ß√Ķes e melhorar o processo de cicatriza√ß√£o

    Electrospun Nanofibers for Biomedical Applications

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    Electrospinning is a versatile and effective technique widely used to manufacture nanofibrous structures from a diversity of materials (synthetic, natural or inorganic). The electrospun nanofibrous meshes‚Äô composition, morphology, porosity, and surface functionality support the development of advanced solutions for many biomedical applications. The Special Issue on ‚ÄúElectrospun Nanofibers for Biomedical Applications‚ÄĚ assembles a set of original and highly-innovative contributions showcasing advanced devices and therapies based on or involving electrospun meshes. It comprises 13 original research papers covering topics that span from biomaterial scaffolds‚Äô structure and functionalization, nanocomposites, antibacterial nanofibrous systems, wound dressings, monitoring devices, electrical stimulation, bone tissue engineering to first-in-human clinical trials. This publication also includes four review papers focused on drug delivery and tissue engineering applications

    In situ crosslinked electrospun gelatin nanofibers for skin regeneration

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    Due to its intrinsic similarity to the extracellular matrix, gelatin electrospun nanofibrous meshes are promising scaffold structures for wound dressings and tissue engineering applications. However, gelatin is water soluble and presents poor mechanical properties, which generally constitute relevant limitations to its applicability. In this work, gelatin was in situ crosslinked with 1,4-butanediol diglycidyl ether (BDDGE) at different concentrations (2, 4 and 6 wt%) and incubation time-points (24, 48 and 72 h) at 37 ¬įC. The physico-chemical and biological properties of BDDGE-crosslinked electrospun gelatin meshes were investigated. Results show that by changing the BDDGE concentration it is possible to produce nanofibers crosslinked in situ with well-defined morphology and modulate fiber size and mechanical properties. Crosslinked gelatin meshes show no toxicity towards fibroblasts, stimulating their adhesion, proliferation and synthesis of new extracellular matrix, thereby indicating the potential of this strategy for skin tissue engineering.info:eu-repo/semantics/acceptedVersio

    Green optimization of glutaraldehyde vapor-based crosslinking on poly(vinyl alcohol)/cellulose acetate electrospun mats for applications as chronic wound dressings

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    In the last years, chronic wounds have become more prevalent, leading to a huge burden on the healthcare and social systems by requiring specialized protection. Indeed, wound dressings capable of assisting in the healing process are in urgent need. To that effect, nanofibrous dressings with a structure resembling the extracellular matrix have been engineered by electrospinning from combinations of poly(vinyl alcohol) (PVA) and cellulose acetate (CA) and optimized to endure physiological media contact and mechanical stress after crosslinking. Mats were prepared at different PVA/CA ratios, 100/0, 90/10 and 80/20 v/v%, at 10 w/v% concentration in acetic acid and water in a 75/25 v/v% proportion and processed via electrospinning. Processing conditions were optimized to obtain uniform, continuous, bead free mats, with a flexible structure. The instant solubilization of the PVA portion of the mat in aqueous media was surpassed via crosslinking. Even though there are many chemical agents available to accomplish such task, glutaraldehyde (GA) is by far the most common due to its efficiency, ease of access and processing, and low cost. Further, in its vapor form, GA has demonstrated reduced or no cytotoxic effects. The amount of GA, crosslinking time, temperature, and drying procedure were optimized to guarantee mechanically resilient mats by means of the greenest methodology possible. Indeed, it was determined that GA vapor at 25% in water could be applied for 7 h at 60 ¬įC, using 6 mL of solution, in a 130 √ó 120 mm2 mat with optimal results. All traces of GA were then eliminated from the mats in a controlled environment (41% relativehumidity and 19 ¬įC). In the end, it was seen that the mechanical resilience and thermal stability of the mats were improved after the application of the modified, green GA-based crosslinking, revealing the engineered methodology potential for applications in biomedical devices.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 UID/CTM/00264/2021 of Centre for Textile Science and Technology (2C2T), funded by national funds through FCT/MCTES. M.A.T. acknowledges FCT for the PhD grant with reference SFRH/BD/148930/2019. SEM studies were performed at the Materials Characterization Services of the University of Minho (SEMAT/UM)

    Nanofibrous Scaffolds for Skin Tissue Engineering and Wound Healing Based on Synthetic Polymers

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    Nanofibrous scaffolds are popular materials in all areas of tissue engineering, because they mimic the fibrous component of the natural extracellular matrix. In this chapter, we focused on the application of nanofibers in skin tissue engineering and wound healing, because the skin is an organ with several vitally important functions, particularly barrier, thermoregulatory, and sensory functions. Nanofibrous meshes not only serve as carriers for skin cells but also can prevent the penetration of microbes into wounds and can keep appropriate moisture in the damaged skin. The nanofibrous meshes have been prepared from a wide range of synthetic and nature-derived polymers. This review is concentrated on synthetic non-degradable and degradable polymers, which have been explored for skin tissue engineering and wound healing. These synthetic polymers were often combined with natural polymers of the protein or polysaccharide nature, which improved their attractiveness for cell colonization. The nanofibrous scaffolds can also be loaded with various bioactive molecules, such as growth factors, hormones, vitamins, antioxidants, antimicrobial, and antitumor agents. In advanced tissue engineering approaches, the cells on the nanofibrous scaffolds are cultured in dynamic bioreactors enabling appropriate mechanical stimulation of cells and at air-liquid interface. This chapter summarizes recent results achieved in the field of nanofiber-based skin tissue engineering, including results of our research group

    Electrospun Functional Nanofibrous Scaffolds for Tissue Engineering

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    Tetracycline-Loaded Electrospun Poly(L-lactide-co-őĶ-caprolactone) Membranes for One-Step Periodontal Treatment

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    In this research, a one-step periodontal membrane, with the required function and properties, has been designed as an alternative method of tissue regenerative treatments. Designed nanoporous prototypes from poly(l-lactide-co-őĶ-caprolactone) (PLCL, 70:30 mol %) were fabricated by electrospinning, denoted as S-PLCL. They were subsequently loaded with tetracycline (TC) in order to enhance periodontal regeneration and deliver an anti-inflammatory and antibiotic drug. It was found that TC loading did not have any significant effect on the fiber diameter but did increase hydrophilicity. With the increase in TC loading, the water vapor permeability (WVP) of the S-PLCL membrane decreased within the range of 31‚Äď56% when compared with neat S-PLCL membranes, while in the solvent-cast film (F-PLCL), no significant change in WVP was observed. Moreover, S-PLCL demonstrated a controllable slow release rate of TC. S-PLCL loaded with 1500 őľg/mL of TC showed a release concentration of 30 ppm over a certain time period to promote greater levels of human oral fibroblast and human oral keratinocyte cell proliferation and plaque inhibition. In conclusion, a TC-loaded S-PLCL fibrous membrane has been designed and fabricated to provide the ideal conditions for cell proliferation and antibiotic activity during treatment, outperforming nonfibrous F-PLCL loaded with TC at the same concentration

    Fucoidan immobilized at the surface of a fibrous mesh presents toxic effects over melanoma cells, but not over non-cancer skin cells

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    The use of fucoidan, a marine-origin bioactive polymer, is herein proposed as a component of an innovative and effective strategy against melanoma, one of the most aggressive skin cancers. First, fucoidan antitumor activity, in its soluble form, was assessed presenting increased cytotoxicity over melanoma cells when compared to human dermal fibroblasts and keratinocytes. After this antitumor activity validation and trying to develop a more targeted and local strategy aiming to diminish the cytotoxic effects over noncancer cells, fucoidan was immobilized at the surface of an electrospun nanofiber mesh (NFM_Fu), envisioning the development of a therapeutic patch. The maximum immobilization concentration was 1.2 mg mL√Ę 1, determined by the Toluidine Blue Assay and confirmed by XPS. Furthermore, NFM_Fu is more hydrophilic than NFM, presenting a contact angle of 36√ā¬į, lower than the 121√ā¬į of the control condition. NFM_Fu was able to reduce human melanoma cell viability by 50% without affecting human dermal fibroblasts and keratinocytes. Taken together, these results set the basis for a valuable approach for melanoma treatment.This work was developed under the scope of the Structured Projects for R&D&I NORTE-01-0145-FEDER-000021 and NORTE-01-0145-FEDER-000023 supported by the Northern Portugal Regional Operational Programme (NORTE 2020),under the Portugal 2020 Partnership Agreement. The authors would like also to thank NORTE 2020 for financing the Ph.D.scholarship of C.O.‚ÄúNorte-08-5369-000037‚ÄĚand the Portuguese Foundation for Science and Technology for the Investigator Grant of A.M. (IF/00376/2014). Dr. LuiŐĀsa Rodrigues is acknowledged by the XPS analysis

    3D Nonwoven Fabrics for Biomedical Applications

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    Fibrous materials are attractive for biomedical applications owing to their structural superiorities, which include large surface-area-to-volume ratio, high porosity, and pore interconnectivity in a controlled manner. Among the various methods of fiber fabrication, electrospinning has emerged as an attractive nanotechnology to produce ultrafine fibrous materials for myriad applications, including tissue scaffolding. In this technique, processing parameters, such as the solution properties, tip-to-collector distance, applied voltage, etc., can be tailored to obtain the fibers of the desired morphology and physicochemical properties. Ideal scaffolds should meet the basic requirements, such as three-dimensional (3D) architecture, proper mechanical properties and biodegradability, and the sufficient surface characteristics for cell adhesion and proliferation. However, most of the electrospun nanofiber-based scaffolds have densely packed two-dimensional (2D) array which hinders the cell infiltration and growth throughout the scaffolds, thereby limiting their applicability in tissue regeneration. To overcome this problem, several attempts have been made to develop a biomimetic three-dimensional, nanofibrous scaffold. This chapter deals with noble techniques including gas foaming (GF), charge repulsion-assisted fabrication, post-processing, liquid-assisted collection, collector modification, and porogen-assisted methods for the fabrication of 3D nanofibrous scaffold for biomedical applications
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