Poly(vinylidene fluoride-trifluoroethylene), P(VDF-TrFE), microstructures have been produced using different solvents, including green ones, by different techniques, such as solvent casting, screen-printing, replica molding, electrospray, and electrospinning. The obtained microstructures span from simple porous and dense films to spheres, fibers, and patterned three-dimensional architectures, with no significant variation in their physicochemical and electrical properties. The simplicity, low cost, and reproducibility of the processing techniques allied to their versatility to adapt to other materials to produce controlled and tailored microstructures with specific properties demonstrate their potential in a wide range of technological applications, including biomedical, energy storage, sensors and actuators, and filtration.

Environmentally resilient antimicrobial coatings are becoming increasingly required for a wide range of applications. For this purpose, nanocomposite thin films of poly(vinylidene fluoride) (PVDF) filled with several types of functionalized nanodiamonds (NDs) were processed by solvent casting. The effects of ND inclusion and functionalization in their morphological, structural, optical, thermal, and electrical properties were evaluated taking into account the type of the nanofiller and a concentration up to 2 wt %. The morphology, structure, and thermal features of the polymer matrix are governed by the processing conditions, and no noticeable changes occurred due to the presence of the ND fillers. The polymer crystallized mainly in the α phase with a crystallinity of ≈60%. In turn, the optical transmittance from 200 to 800 nm and the dielectric constant effectively depended on the ND type and content. The inclusion of the ND particles effectively provided antimicrobial properties to the films, which depended on the ND functionalization. This study thus shows that the incorporation of functionalized NDs into PVDF allows the development of antimicrobial coatings with tailorable optical and dielectric properties, which could be of great importance to face nowadays pandemic crisis scenario.

Oral fast-dispersible film was prepared by utlizing donepezil hydrochloride (drug) and various cellulose derivatives such as hydroxypropyl methyl cellulose (hypermellose) (HPMC), microcrystalline cellulose (MCC) and nanocrystalline cellulose (NCC) to treat Alzheimer’s disease. NCC was synthesized by ultra-sonication method using MCC and this was converted to thinfilm formulation (NCC-F) using solvent casting technique. The interaction between the polymer and the drug was investigated by spectral analysis such as UV, FTIR, and 1H- NMR. FTIR confirmed that the compatibility of drug and polymer in ODF formulation. NCC-F has shown an average surface roughness of 77.04 nm from AFM and the average particle size of 300 nm from SEM analysis. Nano sized particle of NCC-F leads faster in vitro dissolution rate (94.53%) when compared with MCC-F and F3 formulation. Animal model (in vivo) studies of NCC-F formulation has reached peak plasma concentration (Cmax) up to 19.018 ng/mL in the span of (tmax) 4 h with greater relative bioavailability of 143.1%. These results suggested that high surface roughness with nanosized NCC-F formulation attained extended drug availability up to (t1/2) 70 h.

Antioxidant and antimicrobial free-standing films composed of nanofibrillated cellulose (NFC) and a polyphenolic-rich extract, viz. mango leaf extract (MLE), were produced via supercritical solvent impregnation (SSI) and conventional solvent casting film-processing methodologies. The CO2-assisted impregnation of NFC with MLE created robust films with thermal stability up to 250 °C, good mechanical performance (Young's modulus > 4.7 GPa), UV-light barrier properties, antioxidant capacity with maximum inhibition percentage of ca. 84%, and antimicrobial activity against Staphylococcus aureus (growth inhibition ≈ 37%) and Escherichia coli (growth inhibition ≈ 91%). The comparison of the NFC/MLE films prepared by SSI with those fabricated via solvent casting shows a clear advantage of the SSI methodology. Particularly, the antioxidant and antimicrobial activities are visibly higher in the films fabricated by the CO2-assisted impregnation of MLE into NFC. In fact, for the SSI films, the MLE components are mostly adsorbed at the surface and not in the bulk of the biopolymeric matrix, which translates into faster migrations and, hence, higher active properties. All these findings evinced the potential performance of the NFC/MLE films prepared by the eco-friendly SSI as UV-blocking, antioxidant, and antimicrobial bio-based materials for application as sustainable active food packaging.

Bone tissue engineering has been developed in the past decades, with the engineering of bone substitutes on the vanguard of this regenerative approach. Polycaprolactone-based scaffolds are fairly applied for bone regeneration, and several composites have been incorporated so as to improve the scaffolds’ mechanical properties and tissue in-growth. In this study, hydroxyapatite is incorporated on polycaprolactone-based scaffolds at two different proportions, 80:20 and 60:40. Scaffolds are produced with two different blending methods, solvent casting and melt blending. The prepared composites are 3D printed through an extrusion-based technique and further investigated with regard to their chemical, thermal, morphological, and mechanical characteristics. In vitro cytocompatibility and osteogenic differentiation was also assessed with human dental pulp stem/stromal cells. The results show the melt-blending-derived scaffolds to present more promising mechanical properties, along with the incorporation of hydroxyapatite. The latter is also related to an increase in osteogenic activity and promotion. Overall, this study suggests polycaprolactone/hydroxyapatite scaffolds to be promising candidates for bone tissue engineering, particularly when produced by the MB method.

A forma farmacêutica Película (do inglês “Films”) é definida genericamente nas Farmacopeias como uma fina folha composta por uma ou várias camadas com ou sem fármaco, que se destina a ser colocado na cavidade oral. Estas películas são geralmente preparadas por técnicas como solvent-casting ou extrusão, podendo ser preparadas com o objetivo de apresentarem desintegração rápida ou lenta e / ou permitirem uma absorção gastrointestinal ou através mucosa oral do fármaco. Estas diferenças podem ser alcançadas por uma simples modificação da composição da formulação base. Esta versatilidade associada a outras vantagens conhecidas como a portabilidade e facilidade de administração, justificam o elevado interesse de muitas empresas no desenvolvimento desta forma farmacêutica. Foram estes os motivos que conduziram ao interesse em explorar o conhecimento em torno das películas orodispersíveis. Inicialmente, foi efetuada uma revisão bibliográfica aprofundada de forma a reunir informação que permitisse o desenvolvimento de uma Película nova e inovadora. Esta informação foi sumariada e criticamente discutida num artigo de revisão dividido em duas partes, descortinando-se desde o seu desenvolvimento primordial até ao seu crescimento e sustentabilidade de mercado. Esta extensa avaliação conduziu e confluiu para importantes orientações do trabalho experimental. Películas disponíveis comercialmente foram analisadas e caracterizadas para desenvolver conhecimento experimental e parâmetros adequados de processo e qualidade do produto. Este trabalho teve como base ferramentas estatísticas específicas como Desenho de Experiências e Quimiometria. Paralelamente, foi efetuada uma triagem a inúmeros polímeros e 3 novas películas foram desenvolvidas. Mas apenas uma, a que apresentou resultados mais promissores, foi optimizada. Esta optimização foi efetuada com base em instrumentos e abordagens sistemáticas que permitissem o controlo e melhoramento da qualidade do produto, como o conceito Quality by Design). Esta tendência regulamentar e de qualidade associada à novidade, processo de fabrico peculiar e composição complexa, desencadeou a necessidade de estabelecer linhas de orientação ou directrizes para o seu desenvolvimento. Assim, o perfil de qualidade do produto alvo foi delineado e os atributos críticos de qualidade estabelecidos para poder definir os parâmetros críticos de processo e servirem como critério de qualidade e aceitação no desenvolvimento de novas películas. A maioria das películas com rápida desintegração, normalmente designadas por películas orodispersíveis (do inglês “Orodispersible Films”) são constituídas por polímeros hidrofílicos. Esta característica costuma estar associada a baixa estabilidade e originar texturas e aparências pouco apelativas e indesejáveis, especialmente quando expostos às condições ambientais. Assim, e considerando o panorama de propriedade intelectual existente na área, películas mais estáveis e robustas foram selecionadas e preparadas. Consequentemente, películas orodispersíveis compostas por polímeros hidrofóbicos foram desenvolvidas, contribuindo para uma aplicação de patente, baseada na novidade dos polímeros utilizados e como solução alternativa para colmatar necessidades tecnológicas e terapêuticas. Finalmente, 2 fármacos diferentes foram incorporados na película orosdispersível desenvolvida e optimizada, e uma pequena transposição de escala foi também efetuada. Aproximadamente 90% de Doentes de Parkinson (DP) e cerca de 33% de doentes com Doença Neurodegenerativa (DN) apresentam ou irão desenvolver disfagia (problemas de deglutição). As películas orodispersíveis desenvolvidas, uma com Pramipexole (tratamento na DP) e outra com fármaco para tratamento da DN, são constituídas por uma matriz hidrofóbica, incluindo acetato de polivinilo, alcóol polivinilico, trietilcitrato e caraboximetilcelulose sódica. A película orodispersível para tratamento de DN foi ainda preparada numa escala ligeiramente superior de acordo com as Boas Práticas de Fabrico, de forma a obter amostras suficientes para delinear um estudo de estabilidade adequado e posteriormente efectuar um estudo de biodisponibilidade comparativa entre películas orodispersíveis e as cápsulas de fármaco para DN disponíveis no mercado (produto de referência). Esta abordagem servirá essencialmente como prova de conceito para testes posteriores de transposição de escala para um nível comercial. Em termo de conclusão, foi ainda elaborada uma pequena revisão que foca os desafios técnicos encontrados durante o processo de investigação e desenvolvimento e transposição de escala; a qual reúne informação da experiência prática, suportada com consulta bibliográfica, sugerindo igualmente possíveis alternativas e soluções para os problemas apontados. Esta tese, inclui o desenvolvimento e caracterização de inúmeras películas orodispersíveis, mas permitiu também gerar conhecimento relevante e inovação. Foi demonstrado que é possível desenvolver películas orodispersíveis constituídas essencialmente por uma matriz hidrofóbica sem comprometer a sua rápida desintegração, destronando um forte paradigma desta área de investigação. Foram ainda elucidadas e sugeridas diferentes técnicas de caracterização e métodos de análise alternativos que podem ser úteis no desenvolvimento desta forma farmacêutica. Para além disso, foram ainda desenvolvidas películas orodispersíveis de Pramipexole e películas orodispersíveis para tratamento de DN que poderão vir a colmatar as necessidades dos doentes com DP e DN, maioritariamente associadas a problemas de deglutição das formas farmacêuticas atualmente disponíveis.

Biodegradable nanocomposite films were prepared by incorporation of cellulose nanofibrils (CNF) into alginate biopolymer using the solution casting method. The effects of CNF content (2.5, 5, 7.5, 10 and 15 wt %) on mechanical, biodegradability and swelling behavior of the nanocomposite films were determined. The results showed that the tensile modulus value of the nanocomposite films increased from 308 to 1403 MPa with increasing CNF content from 0% to 10%; however, it decreased with further increase of the filler content. Incorporation of CNF also significantly reduced the swelling percentage and water solubility of alginate-based films, with the lower values found for 10 wt % in CNF. Biodegradation studies of the films in soil confirmed that the biodegradation time of alginate/CNF films greatly depends on the CNF content. The results evidence that the stronger intermolecular interaction and molecular compatibility between alginate and CNF components was at 10 wt % in CNF alginate films.

: Chitosan solubility in aqueous organic acids has been widely investigated. However, most of the previous works have been done with plasticized chitosan films and using acetic acid as the film casting solvent. In addition, the properties of these films varied among studies, since they are influenced by different factors such as the chitin source used to produce chitosan, the processing variables involved in the conversion of chitin into chitosan, chitosan properties, types of acids used to dissolve chitosan, types and amounts of plasticizers and the film preparation method. Therefore, this work aimed to prepare chitosan films by the solvent casting method, using chitosan derived from Litopenaeus vannamei shrimp shell waste, and five different organic acids (acetic, lactic, maleic, tartaric, and citric acids) without plasticizer, in order to evaluate the effect of organic acid type and chitosan source on physicochemical properties, degradation and cytotoxicity of these chitosan films. The goal was to select the best suited casting solvent to develop wound dressing from shrimp chitosan films. Shrimp chitosan films were analyzed in terms of their qualitative assessment, thickness, water vapor permeability (WVP), water vapor transmission rate (WVTR), wettability, tensile properties, degradation in phosphate buffered saline (PBS) and cytotoxicity towards human fibroblasts using the resazurin reduction method. Regardless of the acid type employed in film preparation, all films were transparent and slightly yellowish, presented homogeneous surfaces, and the thickness was compatible with the epidermis thickness. However, only the ones prepared with maleic acid presented adequate characteristics of WVP, WVTR, wettability, degradability, cytotoxicity and good tensile properties for future application as a wound dressing material. The findings of this study contributed not only to select the best suited casting solvent to develop chitosan films for wound dressing but also to normalize a solubilization protocol for chitosan, derived from Litopenaeus vannamei shrimp shell waste, which can be used in the pharmaceutical industry.

Flexible self-powered sensors have great potential in the medical field, offering a means of continuous monitoring of patients, helping to prevent and diagnose diseases. The present work explores biodegradable and low-cost alternatives to produce flexible sensors, from polylactic acid, for biomedical applications. Flexible sensors are composed of 3 main parts: transducers, electrodes, and substrate. In this work, the flexible sensors object of study are constituted by an incapsulating substrate of transparent adhesive tape, electrodes produced by 3D printing of a conductive composite of polylactic acid doped with carbon black and by 2 types of transducers; poly-L-lactic (PLLA) and commercial polylactic acid (PLA) To produce the poly-L-lactic acid (PLLA) and polylactic acid (PLA) transducers, two production methods were used: solvent cast and electrospinning, corona pooling methodology was used to change its electrical state. The response of sensors to mechanical and electrical stimuli was investigated and compared. The results show that both PLA and PLLA work based on the principle of piezoelectricity and triboelectricity and respond to mechanical deformation, the best results were obtained by transducers produced by solvent casting treated by corona pooling.

Bone tissue engineering has been developed in the past decades, with the engineering of bone substitutes on the vanguard of this regenerative approach. Polycaprolactone-based scaffolds are fairly applied for bone regeneration, and several composites have been incorporated so as to improve the scaffolds’ mechanical properties and tissue in-growth. In this study, hydroxyapatite is incorporated on polycaprolactone-based scaffolds at two different proportions, 80:20 and 60:40. Scaffolds are produced with two different blending methods, solvent casting and melt blending. The prepared composites are 3D printed through an extrusion-based technique and further investigated with regard to their chemical, thermal, morphological, and mechanical characteristics. In vitro cyto-compatibility and osteogenic differentiation was also assessed with human dental pulp stem/stromal cells. The results show the melt-blending-derived scaffolds to present more promising mechanical properties, along with the incorporation of hydroxyapatite. The latter is also related to an increase in osteogenic activity and promotion. Overall, this study suggests polycaprolactone/hydroxyapatite scaffolds to be promising candidates for bone tissue engineering, particularly when produced by the MB method.