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Sobre

Sobre

Colaboro no INESCTEC desde 2014, onde me encontro integrado no CAP | Centre for Applied Photonics. Como Químico de formação, tenho uma formação e experiência extensas em síntese, caracterização e (numa longa lista de) diversas técnicas laboratoriais, entre as quais as de determinação de propriedades fotofísicas. A minha experiência começou numa área mais focada na bioquímica com estudos relacionados com a saúde, com aplicações de suplementação animal para melhoria de propriedades e posteriormente com métodos de valorização de sub-produtos de indústria primária. No âmbito do 7th FP da UE (SNIFFER) ajudei no desenvolvimento de uma rede inteligente capaz de detectar ameaças tanto na cadeia alimentar como na prevenção de (bio)terrorismo. Foram desenvolvidos sensores bem como líquidos iónicos com diferentes propriedades, passíveis de serem usados como "pontes" a outros sensores ou estruturas sensitivas, ou de agirem como sensores eles próprios. No âmbito do CORAL, desenvolvi sensores para detecção de espécies químicas em meio aquoso (NO3-, NO2- e PO4-), com vista a criar condições para sustentabilidade social e económica na exploração marinha. Desenvolvi e ajudei a desenvolver o protótipo que resultou do projecto AGRINUPES que visava criar condições de sustentabilidade na exploração agrícola, nomeadamente através do uso sustentado de água e nutrientes; pelo desenvolvimento de tecnologia sensitiva capaz de determinar a sua concentração "in situ", desta forma assegurando uma fertilização adequada, promovendo economia ecológica e financeira. Actualmente encontro-me enquadrado no Smart Fertilizers, um projecto de Agricultura 4.0, que visa desenvolver espalhadores e cisternas inteligentes, com vista ao aumento da eficiência da operação de fertilização, para melhorias operacionais e competitivas.

Tópicos
de interesse
Detalhes

Detalhes

003
Publicações

2022

Point-of-Care Using Vis-NIR Spectroscopy for White Blood Cell Count Analysis

Autores
Barroso, TG; Ribeiro, L; Gregorio, H; Monteiro Silva, F; dos Santos, FN; Martins, RC;

Publicação
CHEMOSENSORS

Abstract
Total white blood cells count is an important diagnostic parameter in both human and veterinary medicines. State-of-the-art is performed by flow cytometry combined with light scattering or impedance measurements. Spectroscopy point-of-care has the advantages of miniaturization, low sampling, and real-time hemogram analysis. While white blood cells are in low proportions, while red blood cells and bilirubin dominate spectral information, complicating detection in blood. We performed a feasibility study for the direct detection of white blood cells counts in canine blood by visible-near infrared spectroscopy for veterinary applications, benchmarking current chemometrics techniques (similarity, global and local partial least squares, artificial neural networks and least-squares support vector machines) with self-learning artificial intelligence, introducing data augmentation to overcome the hurdle of knowledge representativity. White blood cells count information is present in the recorded spectra, allowing significant discrimination and equivalence between hemogram and spectra principal component scores. Chemometrics methods correlate white blood cells count to spectral features but with lower accuracy. Self-Learning Artificial Intelligence has the highest correlation (0.8478) and a small standard error of 6.92 × 109 cells/L, corresponding to a mean absolute percentage error of 25.37%. Such allows the accurate diagnosis of white blood cells in the range of values of the reference interval (5.6 to 17.8 × 109 cells/L) and above. This research is an important step toward the existence of a miniaturized spectral point-of-care hemogram analyzer.

2021

Antimicrobial Activity of Myrtus communis L. and Rosmarinus officinalis L. Essential Oils against Listeria monocytogenes in Cheese

Autores
Saraiva, C; Silva, AC; Garcia Diez, J; Cenci Goga, B; Grispoldi, L; Silva, AF; Almeida, JM;

Publicação
FOODS

Abstract
Listeria monocytogenes has been referred to as a concern microorganism in cheese making due to its ability to survive and grow in a wide range of environmental conditions, such as refrigeration temperatures, low pH and high salt concentration at the end of the production process. Since cheese may be a potential hazard for consumers, especially high-risk consumers (e.g., pregnant, young children, the elderly, people with medical conditions), efforts of the dairy industry have been aimed at investigating new conservation techniques based on natural additives to meet consumers' demands on less processed foods without compromising the food safety. Thus, the aim of this study was to evaluate the efficacy of Myrtus communis L. (myrtle) and Rosmarinus officinalis L. (rosemary) essential oils (EO) against Listeria monocytogenes ATCC 679 spiked in sheep cheese before ripening. After the cheesemaking process, the samples were stored at 8 degrees C for 2 h, 1 d, 3 d, 14 d and 28 d. The composition of EO was identified by gas chromatography-mass spectrometry (GC-MS) analysis. Constituents such as 1,8-cineole, limonene, methyl-eugenol, alpha-pinene, alpha-terpineol, alpha-terpinolene and beta-pinene were present in both EO, accounting for 44.61% and 39.76% from the total of chemical compounds identified for myrtle and rosemary EO, respectively. According to the chemical classification, both EO were mainly composed of monoterpenes. Minimum inhibitory concentration (MIC) against L. monocytogenes was obtained at 31.25 mu L/mL to myrtle EO and at 0.40 mu L/mL to rosemary EO. Then, cheeses were inoculated with L. monocytogenes (Ca. 6 log CFU/mL) and EO was added at MIC value. The addition of rosemary and myrtle EO displayed lower counts of L. monocytogenes (p < 0.01) (about 1-2 log CFU/g) during the ripening period compared to control samples. Ripening only influences (p < 0.001) the growth of L. monocytogenes in control samples. Since rosemary and myrtle EO do not exert any negative impact on the growth of native microflora (p > 0.05), their use as natural antimicrobial additives in cheese demonstrated a potential for dairy processors to assure safety against L. monocytogenes.

2021

Synthesis of Catechol Derived Rosamine Dyes and Their Reactivity toward Biogenic Amines

Autores
Monteiro Silva, F; Queiros, C; Leite, A; Rodriguez, MT; Rojo, MJ; Torroba, T; Martins, RC; Silva, AMG; Rangel, M;

Publicação
MOLECULES

Abstract
Functional organic dyes play a key role in many fields, namely in biotechnology and medical diagnosis. Herein, we report two novel 2,3- and 3,4-dihydroxyphenyl substituted rosamines (3 and 4, respectively) that were successfully synthesized through a microwave-assisted protocol. The best reaction yields were obtained for rosamine 4, which also showed the most interesting photophysical properties, specially toward biogenic amines (BAs). Several amines including n- and t-butylamine, cadaverine, and putrescine cause spectral changes of 4, in UV-Vis and fluorescence spectra, which are indicative of their potential application as an effective tool to detect amines in acetonitrile solutions. In the gas phase, the probe response is more expressive for spermine and putrescine. Additionally, we found that methanolic solutions of rosamine 4 and n-butylamine undergo a pink to yellow color change over time, which has been attributed to the formation of a new compound. The latter was isolated and identified as 5 (9-aminopyronin), whose solutions exhibit a remarkable increase in fluorescence intensity together with a shift toward more energetic wavelengths. Other 9-aminopyronins 6a, 6b, 7a, and 7b were obtained from methanolic solutions of 4 with putrescine and cadaverine, demonstrating the potential of this new xanthene entity to react with primary amines.

2021

Unravelling Plant-Pathogen Interactions: Proximal Optical Sensing as an Effective Tool for Early Detect Plant Diseases

Autores
Reis-Pereira, M; Martins, RC; Silva, AF; Tavares, F; Santos, F; Cunha, M;

Publicação
Chemistry Proceedings

Abstract
This study analyzed the potential of proximal optical sensing as an effective approach for early disease detection. A compact, modular sensing system, combining direct UV–Vis spectroscopy with optical fibers, supported by a principal component analysis (PCA), was applied to evaluate the modifications promoted by the bacteria Xanthomonas euvesicatoria in tomato leaves (cv. cherry). Plant infection was achieved by spraying a bacterial suspension (108 CFU mL-1) until run-off occurred, and a similar approach was followed for the control group, where only water was applied. A total of 270 spectral measurements were performed on leaves, on five different time instances, including pre- and post-inoculation measurements. PCA was then applied to the acquired data from both healthy and inoculated leaves, which allowed their distinction and differentiation, three days after inoculation, when unhealthy plants were still asymptomatic.

2021

Hydroponics Monitoring through UV-Vis Spectroscopy and Artificial Intelligence: Quantification of Nitrogen, Phosphorous and Potassium

Autores
Silva, AF; Löfkvist, K; Gilbertsson, M; Os, EV; Franken, G; Balendonck, J; Pinho, TM; Boaventura-Cunha, J; Coelho, L; Jorge, P; Martins, RC;

Publicação
Chemistry Proceedings

Abstract
In hydroponic cultivation, monitoring and quantification of nutrients is of paramount importance. Precision agriculture has an urgent need for measuring fertilization and plant nutrient uptake. Reliable, robust and accurate sensors for measuring nitrogen (N), phosphorus (P) and potassium (K) are regarded as critical in this process. It is vital to understand nutrients’ interference; thusly, a Hoagland fertilizer solution-based orthogonal experimental design was deployed. Concentration ranges were varied in a target analyte-independent style, as follows: [N] = [103.17–554.85] ppm; [P] = [15.06–515.35] ppm; [K] = [113.78–516.45] ppm, by dilution from individual stock solutions. Quantitative results for N and K, and qualitative results for P were obtained.