Opportunistic bacteria that cause life-threatening infections are still a central problem associated with a healthcare setting. Bacteriophage capsid immobilization on nanostructured polymers maximizes its tail exposure and looks promising in applications toward skin-infections as alternative to antibiotics standardly used. The main goal of this work was to investigate the covalent immobilization of vB_Pae_Kakheti25 bacteriophage capsid on polycaprolactone (PCL) nanofibers (non-woven textile), as a potential effective antimicrobial, laundry resistant and non-toxic dressing for biomedical use. Surface analyses showed that the immobilization of vB_Pae_Kakheti25 bacteriophage capsid on PCL nanofibres oriented bacteriophage tails to interact with bacteria. Furthermore, antimicrobial assays showed a very effective 6 log bacterial reduction, which was equivalent to 99.9999%, after immediate and 2 hours of contact, even following 25 washing cycles (due to covalent bond). The activity of PCL-vB_Pae_Kakheti25 against P. aeruginosa was immediate and its reduction was complete.

Cardiovascular disease is the leading cause of morbidity and mortality among industrialized countries. Vascular grafts are often required for the surgical treatments. Considering the limitations associated with the use of autografts and with the currently available synthetic materials, a growing demand in tissue engineered vascular grafts has been registered. During the work here described, electrospinning technique was used to prepared fibrous matrices to be applied as vascular implants. For that purpose, electrospun polycaprolactone (PCL) fibrous mats were produced and afterwards coated with different hydrogel formulations based in photocrosslinkable gelatin (GelMA) and the macromers poly(ethylene glycol) acrylate (PEGA) and poly(ethylene glycol) diacrylate (PEGDA). These were further photocrosslinked under UV irradiation using Irgacure® 2959 (by BASF) as the photoinitiator. The suitability of the coated scaffolds for the intended application, was evaluated by assessing their chemical/physical properties as well as their interaction with blood and endothelial cells.

A pectina, é um polímero natural que apresenta vantagens como biodegradabilidade, solubilidade em água, baixa toxicidade e propriedades bioadesivas. Estas vantagens convertem-na numa forte candidata a ser utilizada em aplicações biomédicas. Deste modo, o objetivo deste trabalho teve por base a produção de fibras de Pectina através de electrospinning. No entanto, apesar da sua utilização ser vantajosa, a pectina apresentou uma fraca electrospinnability, que é provocada pelas cargas elétricas, nomeadamente pelas forças repulsivas existentes entre os polianiões. Desta forma, para inverter esta dificuldade adicionou-se um polímero sintético, o poli (vinil álcool) (PVA). A adição do PVA resultou numa mistura com as características desejáveis, uma vez que a interação entre o PVA e as cadeias poliméricas da Pectina reduziu as forças repulsivas existentes. Assim, aumentou substancialmente a electrospinnability da Pectina e consequentemente foram produzidas as nanofibras pretendidas. A morfologia das nanofibras de Pectina/PVA obtidas a partir do electrospinning foram, posteriormente, analisadas por microscopia eletrónica de varrimento (SEM). O resultado esperado verificou-se quando uma solução de 4% Pectina foi misturada com uma solução 10% de PVA numa proporção 30:70 (v/v), respetivamente. Nesta proporção observouse fibras uniformes e homogéneas com diâmetro de 287 nm. Posteriormente, a L-Cisteína foi adicionada à solução Pectina/PVA 30:70 (v/v). Esta adição teve como objetivo avaliar a bioactividade da L-Cisteína na mistura. Para estimar a quantidade de L-Cisteína a ser adicionada à mistura Pectina/PVA a sua concentração mínima inibitória (MIC) foi determinada, através do método de microdiluição em caldo. Os valores de MIC obtidos para a solução de Pectina/PVA 30:70 com L-Cisteína foram de 5 mg/ml para Staphyloccocus aureus e de 10 mg/ml para Klebsiella pneumoniae. Estes valores, confirmam que a L-Cisteína funciona como agente antimicrobiano, o que pode ser muito útil em aplicações biomédicas.

Skin wounds have significant morbidity and mortality rates associated. This is explained by the limited effectiveness of the currently available treatments, which in some cases do not allow the reestablishment of the structure and functions of the damaged skin, leading to wound infection and dehydration. These drawbacks may have an impact on the healing process and ultimately prompt patients’ death. For this reason, researchers are currently developing new wound dressings that enhance skin regeneration. Among them, electrospun polymeric nanofibres have been regarded as promising tools for improving skin regeneration due to their structural similarity with the extracellular matrix of normal skin, capacity to promote cell growth and proliferation and bactericidal activity as well as suitability to deliver bioactive molecules to the wound site. In this review, an overview of the recent studies concerning the production and evaluation of electrospun polymeric nanofibrous membranes for skin regenerative purposes is provided. Moreover, the current challenges and future perspectives of electrospun nanofibrous membranes suitable for this biomedical application are highlighted.

Electrospun polymeric meshes are known to exhibit promising properties for the regeneration of several soft tissues. Herein, electrospun polymeric meshes were prepared from blends of polycaprolactone and functionalized gelatin. The meshes were then photocrosslinked under UV light using Irgacure® 2959 as the photoinitiator, aiming to improve membranes’ stability in biological fluids. Moreover, meshes suitability to be used as vascular grafts was evaluated by characterizing their chemical/physical properties as well as their haemo and biocompatibility in vitro. The obtained results show that the blended polymeric meshes are biodegradable and those with a higher content of gelatin display a lower water contact angle. Blood compatibility studies showed that the photocrosslinked membranes are haemocompatible, i.e. they display low values of thrombogenicity and do not trigger any haemolytic effect. Also, Normal Human Dermal Fibroblasts cells were incubated in the presence of the produced membranes and they were able to adhere and proliferate, thus revealing the biocompatibility of the photocrosslinked meshes.

As a specialized and complex structure, bone is a tissue with the capacity to self-regenerate that play different functions in our body. However, when there is a critical bone defect the self-regenerative capacity is lost. Currently clinical treatments are based on bone grafts and other bone substitutes which possess several limitations. Hereupon, Tissue Engineering arises as a new scientific field that combines life sciences and engineering knowledges to create biological substitutes capable of restoring defects and lesions of biological tissues. In this context, a new strategy to mimic the extracellular matrix of bone and cellular microenvironment was developed in this work. Therefore, the electrospinning apparatus was used to produce poly(ε-caprolactone), polyethylene oxide-sodium alginate and poly(vinyl)pirrolidone nanofibers. Subsequently, the same procedure was used for coating the alginate aggregated microparticle scaffold. In addition, polycaprolactone electrospun nanofiber membranes were also produced in order to improve the mechanisms on phase separation area. These membranes were subjected to a coating process in order to improve specific properties, such as pore size, fibers diameter and surface interactions. The biological properties of the coated scaffolds were evaluated through in vitro cytotoxicity assays. The results showed that all the coated scaffolds had their biological performance improved when compared to the same scaffolds without coating. The membranes showed to be useful for the separation of biomolecules.

The demanding ever-increasing quantities of highly purified biomolecules by bio-industries, has triggered the development of new, more efficient, purification techniques. The application of membrane-based technologies has become very attractive in this field, for their high throughput capability, simplicity of operation and scale-up. Herein we report the production of a bi-layer membrane by electrospinning (ES), in which a support of poly ε-caprolactone nanofibers was coated with a polyethylene oxide/sodium alginate layer, and subsequently cross-linked with calcium chloride. The membranes were characterized by SEM, ATR-FTIR, contact angle measurements, and were applied in the recovery process of a plasmid. The results show that membranes retained the suspended solids while allowing the permeation of plasmid DNA, with high recovery yields and improved RNA retention. Moreover, they also showed a very low fouling tendency. To the best of our knowledge it is the first time that ES membranes are applied in this type of bioprocess.

Frequently, skin is subjected to damaging events, such as deep cuts, burns or ulcers, which may compromise the integrity of this organ. To overcome such lesions, different strategies have been employed. Among them, wound dressings aimed to re-establish skin native properties and decreased patient pain have been pursued for a long time. Herein, an electrospun membrane comprised by deacetylated/arginine modified chitosan (CH-A) was produced to be used as a wound dressing. The obtained results showed that the membrane has a highly hydrophilic and porous three-dimensional nanofibrous network similar to that found in human native extracellular matrix. In vitro data indicate that human fibroblasts adhere and proliferate in contact with membranes, thus corroborating their biocompatibility. This nanofiber-based biomaterial also demonstrated bactericidal activity for two bacterial strains. In vivo application of CH-A nanofibers in full thickness wounds resulted in an improved tissue regeneration and faster wound closure, when compared to non-modified membranes. Such findings support the suitability of using this membrane as a wound dressing in a near future.

O vínculo com os têxteis é um dos mais antigos presentes na humanidade, sendo que no cenário da moda e no contexto histórico os têxteis e a indumentária tratam acerca da cultura material. Para salvaguardar esse património ainda é necessária alguma investigação sobretudo no que diz respeito à criação de um material voltado para embalagens e proteção de têxteis museológicos, devido aos riscos que estes artigos sofrem, em particular a contaminação por microrganismos que promovem a aceleração da degradação. Assim, o presente trabalho vem no sentido de contribuir para um melhor entendimento das práticas de conservação dos têxteis, e desenvolver novos materiais antimicrobianos como contributo tecnológico para a conservação de património museulógico potenciador de inspiração para o designer. Para o efeito, o trabalho desta dissertação faz inicialmente um levantamento bibliográfico acerca dos processos que causam a degradação de artigos têxteis, assim como as técnicas utilizadas na conservação preventiva e materiais. Sabendo da importância e da busca por melhorias na conservação de têxteis museológicos a par do conhecimento dos têxteis antimicrobianos mais adequados, objetiva-se formar um material à base de policaprolactona (PCL) e óleo essencial de Lavandula luisieri, como barreira de protecção antimicrobiana, na forma de um substrato não tecido, de modo a possibilitar a sua aplicação como protetores para têxteis museológicos, de forma sustentável. Assim, esta dissertação propõe-se a realizar um projeto de pesquisa que combine as áreas do design e da tecnologia, mantendo uma iniciativa que ajude a sociedade a salvaguardar e preservar os acervos têxteis por mais tempo para as gerações futuras.

Bone-limited capacity to fully repair large defects requires the development of new implants. In this context, new approaches have been used to promote bone regeneration and also to avoid the side effects associated with the therapeutics currently used in the clinic. Herein, 3D tricalcium phosphate/alginic acid scaffolds were produced and then coated with an electrospun mesh loaded with two different antibacterial agents, silver nanoparticles, and salicylic acid. The obtained results showed that the produced scaffolds have suitable mechanical properties, swelling, biodegradation, biomineralization activity, enhanced cellular adhesion/proliferation and bactericidal activity, and features essential for bone regeneration.