ESB - Dissertações de Mestrado / Master Dissertations
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- Valorização da funcionalidade da biomassa de chlorellaPublication . Aldana, Paula Andrea Martínez; Barros, Ana Isabel Faustino; Pereira, Camilly FratelliAs microalgas têm ganho crescente relevância devido ao seu elevado valor nutricional e ao potencial para aplicação em produtos alimentares sustentáveis. A Chlorella branca (Chlorella sp. “white variant”), obtida por cultivo heterotrófico e caracterizada pelo baixo teor de clorofila, apresenta vantagens sensoriais face às microalgas verdes convencionais, tornando-se um ingrediente promissor para formulações de base vegetal. Este trabalho foi desenvolvido no âmbito do estágio curricular realizado na Allmicroalgae – Natural Products S.A., e teve como objetivo avaliar o potencial tecnológico e alimentar da biomassa de Chlorella branca. O estudo foi dividido em três partes: (i) análise do efeito da variação do rácio C/N na composição da biomassa, (ii) caracterização das propriedades tecno-funcionais da biomassa húmida e em pó e (iii) incorporação da biomassa numa bebida vegetal. Na primeira parte verificaram-se alterações no teor de amido e proteína em função do rácio C/N, embora esses efeitos não tenham sido reproduzidos à escala de fermentador. A segunda parte mostrou que a biomassa apresenta propriedades tecnológicas relevantes, nomeadamente solubilidade dependente da temperatura e elevada capacidade emulsificante, com a biomassa seca a revelar maior estabilidade em emulsão. A análise colorimétrica indicou ainda boa estabilidade cromática em condições térmicas moderadas. Na terceira parte, a formulação de uma bebida vegetal contendo 3% de biomassa em pó demonstrou um perfil nutricional favorável, permitindo alegações nutricionais de: “fonte de fibra”, “fonte de proteína” e “alto teor de vitamina B12”. Contudo, a avaliação sensorial revelou uma diminuição da aceitação global com a adição de Chlorella branca, especialmente ao nível do sabor, textura e apreciação global, quando comparada com a bebida base e a referência comercial. Em conclusão, a Chlorella branca apresenta potencial tecnológico para aplicação alimentar, sobretudo como agente funcional e emulsificante natural. No entanto, o impacto sensorial observado realça a necessidade de otimização futura das formulações para melhorar a aceitação do consumidor.
- Beyond bandages : a smart, glucose-responsive polyurethane for diabetic chronic wound treatmentPublication . Magalhães, Adriana Isabel Gomes; Laurano, RossellaThe treatment of diabetic chronic wounds represents a significant clinical challenge due to impaired healing capacity and complex local microenvironments, contributing to the high occupancy of acute hospital beds in Europe (up to 50 %). In this context, glucose-responsive materials offer a promising strategy for intelligent drug delivery systems adaptable to hyperglycaemic conditions. This work describes the synthesis and characterisation of a poly (ether)urethane-based hydrogel functionalised with phenylboronic acid groups, with potential for payload release in response to glucose. The synthesis of the multi-stimuli responsive polymer followed a three-step procedure: chain extension of Pluronic® P407 via diisocyanate mediated coupling with N-Boc diethanolamine, acid-mediated Boc deprotection, and functionalisation with 3-carboxyphenylboronic acid (3-CPBA). Characterisation by Attenuated Total Reflectance Fourier Transform Infrared spectroscopy and Size Exclusion Chromatography confirmed urethane bond formation and polymer integrity upon Boc cleavage, while the colourimetric Kaiser test revealed a 93 % increase in accessible amines after Boc removal. Furthermore, Proton Nuclear Magnetic Resonance spectroscopy indicated feed-dependent incorporation, with levels ranging from 6.0 × 1018 to 1.7 × 1019 molecules⁄gram by increasing the COOH:NH ratio from 2:1 to 10:1; Swelling and dissolution assays demonstrated that the functionalised hydrogel (GlucoDHP; 15 % (w/v) polymeric concentration) maintained structural stability over 72 h and exhibited lower mass loss compared to the non-functionalised control—i.e., D-DHP407 hydrogels) (p<0.05). Indirect Cytocompatibility assays using NIH-3T3 fibroblasts confirmed all formulations were non-toxic, with GlucoDHP5 promoting a 23.5 ± 3.2 % increase in cell viability compared to D-DHP407 (p < 0.01). In conclusion, the developed hydrogel showed improved stability, biocompatibility, and chemical responsiveness, supporting its potential for application in diabetic wound treatment. Future work will involve therapeutic agent encapsulation (e.g., insulin) and in vitro release assays to assess responsiveness under hyperglycaemic conditions.
- Desenvolvimento do plano HARPC da Prozis.NowPublication . Sousa, Beatriz Isabel Silva e; Hogg, Timothy AlunA segurança alimentar constitui um desafio central num mercado cada vez mais globalizado, caracterizado por cadeias de abastecimento cada vez mais exigentes e complexas. No âmbito do estágio realizado na Prozis, desenvolvido na unidade Prozis.Now, o projeto teve como objetivo responder aos requisitos do Food Safety Modernization Act (FSMA), com especoal foco na metodologia Hazard Analysis and Risk-Based Preventive Controls (HARPC). Este trabalho articula a componente analítica e prática, resultando na elaboração de um plano que abrange a análise de perigos, a definição de controlos de risco, a rastreabilidade, a higienização, a gestão da cadeia de fornecimento e os planos de recall. Para além de assegurar a conformidade legal, o estágio contribuiu para o desenvolvimento de competências técnicas e operacionais na área da segurança alimentar, reforçando a compreensão da importância dos sistemas preventivos em contextos organizacionais complexos.
- Validation of an automatic projective mapping acquisition system used in the sensory description of food by consumersPublication . Laverde Martinez, Diego Alejandro; Rocha, Célia Ferreira da; Lima, Rui Jorge Moreira da CostaProjective mapping is a sensory analysis technique widely used for the evaluation of consumer perceptions based on the application of a similarity criteria and represented spatially on a two-dimensional map. Traditionally, this method is conducted on a sheet of paper, in which the participants place and describe product samples, using additional methods like Ultra-flash Profile (UFP) for attribute generation. This methodology has been successfully applied with panels of consumers as well as trained assessors, providing similar insights as the descriptive analysis, although the traditional paper-based approach presents efficiency limitations as well. This study introduces a new and alternative projective mapping approach, focusing on the digitalization of the positioning data acquisition by implementing an automatic system that effectively identifies and captures the coordinates of the samples placed over the designated mapping area, with the objective of streamlining the development of projective mapping sessions and considerably reducing the time required. The method was established using robust detection hardware paired with an enhanced sample marker identification system and integrated to the projective mapping software developed by Sense Test. To validate the method, seven Verdinho canned fish samples were evaluated using three approaches: the traditional paper-based method, the proposed digital projective mapping and the screen-based projective mapping method developed by Sense Test. Additionally, the panellists evaluated the overall liking of the product samples through a nine point hedonic scale. Results showed that the digital projective mapping method strongly correlated with the traditional paper-based approach (R² = 0.9922), confirming its efficiency improving and error reducing capabilities. Moreover, the screen-based projective mapping showed a moderate correlation with the paper-based method (R² = 0,7028) as well as with the digital projective mapping (R² = 0,7000), proving to be a resourceful alternative.
- Design of thermoreversible peptide loaded liposomes for atopic dermatitisPublication . Carvalho, Laura Judite Benge Dias de; Costa, Eduardo Manuel Aguiar da; Pintado, Maria Manuela EstevezAtopic dermatitis (AD) is a chronic inflammatory skin disorder associated with impaired barrier function, immune dysregulation and intense pruritus, severely affecting patients’ quality of life. Despite its high prevalence, current therapies remain centred on symptomatic control and often show limited efficacy, highlighting the need for safer and more sustainable alternatives. This study explored bioactive marine peptides (<3 kDa) derived from fishery by-products as therapeutic agents, incorporated into liposomal nanosystems designed for topical delivery. The formulations defined as optimal, which included two systems composed of different amounts of lecithin and one containing both lecithin and cholesterol, exhibited encapsulation efficiencies between 89.7% and 91.3% and polydispersity index values ranging from 0.188 to 0.577 at laboratory scale. After scale-up, these same formulations maintained average particle sizes below 20 nm and low PDI (<0.4), with encapsulation efficiencies between 50.8% and 80.9%. The cholesterol-containing system demonstrated the greatest stability and resilience throughout the scale-up process, confirming the importance of moderate cholesterol content in maximising peptide retention and preserving colloidal stability. FTIR and DSC analyses revealed constituent compatibility and bilayer reorganisation without achieving thermoreversibility, as transition temperatures remained above the physiological range. Release studies fitted the Korsmeyer–Peppas model, indicating diffusion-controlled release, with cholesterol promoting a more gradual and sustained peptide delivery. No antimicrobial effects were observed against Staphylococcus aureus. Cytotoxicity was concentration-dependent, with all formulations biocompatible at 0.3 mg/mL, while the free peptide showed no cytotoxicity. Under these conditions, the phospholipid-rich formulation and cholesterol containing formulation induced metabolic stimulation. Overall, this work demonstrates the feasibility of integrating marine peptides into stable liposomal carriers for topical administration. The cholesterol based formulation stands out as the most balanced system in terms of encapsulation, stability and release performance, providing a solid foundation for future nanotechnology driven strategies in AD therapy that also promote sustainable valorisation of marine resources.
- Electrospinning a mechano-biocompatible external support for the Ross procedurePublication . Reis, Mariana Sofia Gomes; Mignon, Arn; Ribeiro, Viviana PintoThe Ross procedure is a surgical technique used to treat aortic valve diseases, in which the diseased aortic valve is replaced with the patient9s own pulmonary valve, offering unique advantages. However, progressive autograft dilatation remains a major limitation. To mitigate this problem some external supports currently exist, such as Dacron wraps, PEARS meshes or semi-resorbable grafts, which provide reinforcement but restrict root9s valve motion, or have biocompatibility challenges. This thesis aimed to develop a temporary, biodegradable and bioactive electrospun support capable of preventing early dilatation while allowing long-term tissue remodeling. The electrospun support was composed of polycaprolactone (PCL), elastin and decellularized extracellular matrix (dECM). dECM was optimized to achieve 97.4% deoxyribonucleic acid (DNA) reduction while preserving key extracellular matrix (ECM) components, including 61% elastin and 92% insoluble collagen. It was processed into fine powder (~24 µm) and incorporated into PCL:elastin electrospun blends to fabricate tubular scaffolds. Morphological analysis of the optimized structure (PCL:elastin:dECM, 19:0.5:0.5 w/v%) exhibited a well distributed fiber network, with partial circumferential alignment on the outer surface and randomly oriented fibers on the inner surface. Mechanical tests demonstrated a low-strain modulus of ~2 MPa and compliance values of ~2.2 %/100 mmHg. Accelerated degradation showed a more controlled mass loss profile than pure PCL. In conclusion, the PCL:elastin:dECM scaffold demonstrates potential as a resorbable external support for the Ross procedure, balancing compliance and benefiting from the presence of elastin and dECM, which may contribute to improved adaptation. Future studies should combine computational modelling and in vivo validation to confirm long-term performance.
- Exploring the potential of Portuguese thermal spring water as an ingredient for cosmetic formulationsPublication . Rocha, Pedro Emanuel de Almeida; Madureira, Ana Raquel Mendes Ferreira Monteiro de; Pedrosa, Sílvia Marlene Almeida SantosThermal spring waters (TSW), utilized for centuries for their health benefits, are increasingly recognized scientifically for their therapeutic potential. These are largely attributed to their unique mineral compositions derived from long-term water-rock interactions. Properties like immunomodulation, antioxidant activity, and skin barrier reinforcement have spurred interest in TSW within the cosmetics industry, driven by consumer demand for natural and effective ingredients. This thesis aims at investigating the cosmetic potential of TSW from Chaves, Portugal, a historically recognized spring whose properties remained scientifically underexplored. The initial phase characterized Chaves TSW and evaluated its dermatological bioactivities. In vitro studies revealed anti-inflammatory potential, evidenced by reduced IL-6 levels in human keratinocytes (HaCaT) exposed to urban pollutants, alongside with anti-elastase activity. A clinical study on 23 human volunteers demonstrated that Chaves TSW significantly improved skin hydration on dry skin volunteers and reduced transepidermal water loss (TEWL), suggesting skin barrier enhancement without disrupting the resident skin microbiota. Based on these positive skin findings, a cosmetic formulation incorporating Chaves TSW was developed with a high natural index (96% based on ISO 16128). The research scope was extended to evaluate the effects on hair, a less common application for TSW. While Chaves TSW alone did not significantly alter bleached hair fiber’s properties, the formulation improved hair combability, likely due to included surfactants. Conversely, the formulation decreased the thermal denaturation temperature of hair keratin, potentially linked to surfactant-keratin interactions observed via DSC and ATR-FTIR analyses. Finally, the base formulation's potential was further explored by incorporating Mallow (Malva sylvestris); endemic to the region; and Cucumber (Cucumis sativus) extracts, known for their skin benefits, such as antioxidant potential. Three formulations containing both extracts and a mixture of both were developed, and subsequent testing revealed significantly improved bioactivities. Notably, a strong synergistic Fe2+ chelating capacity emerged, exceeding that of the formulation's chelating agent alone. This correlated with enhanced antioxidant activity and significantly increased inhibition of the age-related enzymes collagenase and tyrosinase, likely due to cofactor chelation. The combination of extracts also yielded potent elastase inhibition. Furthermore, the anti-inflammatory effects were re-evaluated using a mixture containing TSW extracts, and sodium phytate (chelating agent), which nonetheless exhibited anti-inflammatory properties like those of water but effectively reducing IL-1α levels. In conclusion, this work validates the beneficial properties of Chaves TSW for skincare, particularly its anti-inflammatory and barrier-reinforcing effects. It further demonstrates that formulating TSW, especially when enhanced with synergistic natural extracts like Mallow and Cucumber, can create multifunctional cosmetic ingredients with significantly amplified antioxidant, anti-enzyme, and anti-inflammatory activities, offering promise for advanced skin and potentially scalp care applications.
- Potential bacterial carriers of antibiotic resistance in aquaculture and aquaponicsPublication . Amado, Nefissa Carlie; Moreira, Ivone Cristina Vaz; Rodrigues, Célia Maria ManaiaAquaculture (aquatic animal farming) and Aquaponics (an integration of aquaculture and soilless plant cultivation) systems are increasingly used to simultaneously produce fish and plants within the same circulating water system. Fish skin mucus is in direct contact with the environment, functioning as a physical, biochemical, and semipermeable barrier for the fish. Moreover, the bacterial communities within fish skin mucus may reflect the bacterial diversity of the surrounding water and consequently of the resistome (group of genes associated to antibiotic resistance). Fish skin mucus is also described as having associated antimicrobial activity. This dissertation aimed to assess whether fish and plants cultivated in aquaculture/aquaponics systems can be colonized by antibiotic resistant bacteria and antibiotic resistance genes, and if fish skin mucus are more prone to accumulate antibiotic resistance than aquaculture biofilms. For that, both culture dependent and culture independent methods were used to study the occurrence of antibiotic resistant bacteria and genes in samples from the fish skin mucus, biofilms of the aquaculture tanks and in plants growing in an experimental aquaponic system. Bacterial growth was assessed on GSP agar (selective for Pseudomonads and Aeromonads) and GSP agar supplemented with cefotaxime (4 mg/L) and streptomycin (50 mg/L). Isolates (n=114) were selected for phenotypic antibiotic resistance profiling and genotypic analysis targeting resistance genes for β-lactams (blaCTX, blaSHV, and blaOXA), and genes associated to mobile genetic elements (intI1 and incF). Bacterial isolates (n=22) harboring the intI1 gene were further analyzed for the presence of class 1 integrons and integron variable regions sequenced. Additionally, qPCR was used for the quantification of the 16S rRNA gene as well as the intI1 integrase gene, a biomarker for antibiotic resistance, in samples of water and lettuce roots from the experimental aquaponics system. The highest bacterial growth occurred on GSP without selective pressure, while the addition of streptomycin to the GSP culture medium resulted in the most inhibitory effect on the growth of bacteria especially in the biofilm and roots samples (<1.4% of tolerant bacteria). Overall, 3.6-38.6% (average values) of the cultivable bacteria growing on GSP tolerated the 4 mg/L of cefotaxime while just 0.2-3.9% (average values) tolerated the 50 mg/L of streptomycin. Most of the bacterial isolates recovered were Gram-negative (111/114), catalase positive and cytochrome c oxidase negative. When observing the antibiograms results, resistance to cephalothin and streptomycin were among the most prevalent (60-98% and 34-70%, respectively) in the isolates of the different origins. In contrast isolates showed a low prevalence of resistance to tetracycline, meropenem, ciprofloxacin or colistin (<15%). Multi drug resistances were mainly observed in isolates recovered from biofilms and roots. Fish skin mucus isolates were identified to be mainly Acinetobacter johnsonii, Achromobacter spp., and Flavobacterium spp. while the isolates recovered from the biofilms present in the same aquaculture system were predominantly identified as E. coli and Achromobacter spp. The main species identified in the lettuce roots were Pseudomonas monteilii and Enterobacter ludwigii. Genes associated with mobile elements intI1 and incF were detected in <20% of isolates mostly E. coli from biofilms. The blaSHV gene was just detected in E. coli isolates from biofilm, for which were also detected the genes intI1 and incF. Class 1 integrons were detected in 18 isolates mostly from biofilms, with one present in a biofilm E. coli isolate, confirmed to carry the aminoglycoside resistance gene aadA1. These results demonstrate that biofilms are a major hotspot for bacteria and genes associated with antibiotic resistance, while fish skin mucus and lettuce roots were not identified as important hotspots.
- CardioRiskAI : a clinical application for rapid and affordable cardiovascular risk assessment using ECG analysis and machine learningPublication . Silva, Martim José de Pinho Gutierres; Rodrigues, Pedro Miguel de Luís; Guimarães, Vânia Margarida CardosoCardiovascular diseases (CVDs) are the leading global cause of death, yet traditional risk assessment is often slow and resource-intensive. This work investigates a novel approach for rapid, accessible CVD risk assessment using engineered electrocardiography (ECG) features combined with minimal clinical data (age, BMI, smoking, and diabetes status). By leveraging increasingly portable and inexpensive ECG technology, we aim to provide a cost-effective alternative to lab-dependent methods like the Framingham score. An ECG processing pipeline was developed to extract 102 features, which were used to train classification and regression models targeting the Framingham risk score. The models demonstrated excellent performance: binary classification distinguishing between low- and high-risk patients achieved 97.4% accuracy (AUC 0.99); the multiclass comparison among low-, moderate-, and high-risk groups reached 86.79% accuracy (AUC = 0.88); and regression analysis produced RMSE of between 4 to 6 percentage points. To translate these findings into practice, a clinical application was co-developed with cardiologists, integrating secure authentication, patient management, explainable AI, and automated reporting. The results indicate that a compact set of ECG-derived features, coupled with basic clinical information, can provide rapid and cost-effective cardiovascular risk assessment. This approach holds the potential to democratize risk assessment in low-resource settings and accelerate urgent care evaluations. If validated for generalizability, these models could significantly reduce the reliance on extensive and costly blood laboratory tests for cardiovascular risk stratification.
- Quantitative sensor for glucose monitoring in pet's salivaPublication . Aroso, Maria Francisca Paes Cardoso de Lacerda; Mesquita, Raquel Beatriz Ribeiro de; Rangel, António Osmaro Santos SilvaDiabetes mellitus is a common endocrine disease in dogs and cats, with diagnosis and monitoring traditionally relying on invasive blood sampling, often associated with stress, discomfort, and inconsistent results. Saliva has emerged as a promising non-invasive alternative for detecting biomarkers such as glucose. This work aimed to develop and optimize a paper-based microfluidic device (µPAD) for quantitative glucose detection in dogs' and cats' saliva. The sensor was designed using layered paper discs loaded with enzymatic reagents (glucose oxidase and peroxidase) and o-dianisidine as a chromogenic substrate, generating a colourimetric response directly proportional to glucose concentration. Optimization studies focused on paper type, sample volume, and enzyme concentration, resulting in a detection limit of 6.7 mg/L and a dynamic range of 22.0 – 220 mg/L, covering both physiological and pathological glucose concentrations in dogs. The device showed good reproducibility (RSD = 4%) and low fabrication costs (< €5 per unit). Tests with canine saliva confirmed the ability to detect glucose, although limited by the reduced number and volume of samples available. Overall, the developed µPAD demonstrates strong potential as a non-invasive tool for monitoring glycemia in pets, supporting more accessible, affordable, and animal-friendly diabetes management.