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"Carvalho, Ana P."
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Photocatalytic Degradation of Pharmaceuticals Carbamazepine, Diclofenac, and Sulfamethoxazole by Semiconductor and Carbon Materials: A Review
2019
The presence of pharmaceutical compounds in the environment is a reality that calls for more efficient water treatment technologies. Photocatalysis is a powerful technology available but the high energy costs associated with the use of UV irradiation hinder its large scale implementation. More sustainable and cheaper photocatalytic processes can be achieved by improving the sunlight harvesting and the synthesis of semiconductor/carbon composites has proved to be a promising strategy. Carbamazepine, diclofenac, and sulfamethoxazole were selected as target pharmaceuticals due to their recalcitrant behavior during conventional wastewater treatment and persistence in the environment, as properly reviewed. The literature data on the photocatalytic removal of carbamazepine, diclofenac, and sulfamethoxazole by semiconductor/carbon materials was critically revised to highlight the role of the carbon in the enhanced semiconductor performance under solar irradiation. Generally it was demonstrated that carbon materials induce red-shift absorption and they contribute to more effective charge separation, thus improving the composite photoactivity. Carbon was added as a dopant (C-doping) or as support or doping materials (i.e., nanoporous carbons, carbon nanotubes (CNTs), graphene, and derived materials, carbon quantum dots (CQDs), and biochars) and in the large majority of the cases, TiO2 was the semiconductor tested. The specific role of carbon materials is dependent on their properties but even the more amorphous forms, like nanoporous carbons or biochars, allow to prepare composites with improved properties compared to the bare semiconductor. The self-photocatalytic activity of the carbon materials was also reported and should be further explored. The removal and mineralization rates, as well as degradation pathways and toxicity of the treated solutions were also critically analyzed.
Journal Article
Candida albicans: the current status regarding vaginal infections
by
Ferreira, Carlos M. H.
,
Pereira, Ana Margarida
,
Carvalho, Ana P.
in
Adaptive immunity
,
Antibiotics
,
Antifungal agents
2025
Vaginal infections caused by
Candida albicans
are a significant global health concern due to their recurrence and negative impact on quality of life. This review examines the pathogenesis of
C. albicans
infections, emphasizing critical virulence factors such as biofilm formation, adherence, and phenotypic switching. Risk factors include immune system suppression, antibiotic use, and hormonal changes, all of which can lead to fungal overgrowth and infection. Current prevention and/or treatment strategies primarily rely on antifungal therapies, personal hygiene practices, and probiotics. However, challenges like antifungal resistance, recurrence, and limited treatment efficacy highlight the need for innovative approaches. Therefore, emerging methods such as novel antifungal agents, vaccines, and nanotechnology-based delivery systems offer promising advancements to improve infection control. Additionally, the immune system plays a key role in preventing
C. albicans
infections, with both innate and adaptive immunity acting to restrict fungal colonization and growth. Commercially available products, such as antifungal creams, vaginal probiotics, and hygiene solutions, are practical options but often lack long-term efficacy. Persistent challenges, including resistance, patient noncompliance, and restricted access to emerging therapies, hinder comprehensive prevention and treatment efforts. Thus, future research should focus on promoting interdisciplinary approaches, integrating personalized medicine, and enhancing healthcare accessibility. This review intends to present the current state of the art within the abovementioned issues and to enhance the understanding of the multifactorial nature of
C. albicans
infections and advanced prevention strategies, which are essential to reduce the burden of vaginal candidiasis worldwide and improve patient quality of life outcomes.
Key points
•
Candida albicans pathogenesis involves biofilms, adherence, and phenotypic switching.
•
Vaccines, nanotechnology, and new drugs offer improved prevention and treatment.
•
Addressing antifungal resistance and patient compliance is key for prevention success.
Graphical Abstract
Journal Article
Experimental Sodalis infection eliminates ancient insect symbiont
2026
Many insects benefit from ancient nutrient-supplementing endosymbionts. While symbiont losses and replacements occur on evolutionary timescales, their dynamics remain enigmatic due to the lack of experimentally tractable systems. Here, we report on the experimental establishment of the culturable bacterium
Sodalis praecaptivus
in a grain pest beetle (
Oryzaephilus surinamensis
) and its effect on the native symbiont
Shikimatogenerans silvanidophilus
, which produces the tyrosine precursor prephenate. Injection of
Sodalis
into female beetles led to systemic intracellular infection and efficient transovarial vertical transmission but reduced host survival and reproduction. Interestingly,
Sodalis
also invaded the host’s bacteriomes, causing irregular morphology and rapid loss of
Shikimatogenerans
within three beetle generations. Transcriptomics revealed a strong upregulation of host immune effectors upon
Sodalis
infection, but little reaction from
Shikimatogenerans
, indicating that the ancient symbiont is incapable of responding adaptively to the introduced competitor. The rapid elimination of the native symbiont in
O. surinamensis
showcases the fragility of ancient beneficial symbioses and experimentally recapitulates a crucial step towards a functional symbiont replacement.
Many insects harbour bacterial endosymbionts that provide them with essential nutrients. Here, Krüsemer et al. show that introduction of a tractable bacterium into a beetle host leads to efficient vertical transmission of the bacterium and rapid elimination of the host’s native symbiont, thus establishing a model system to study symbiont loss and replacement.
Journal Article
Effect of Graphene vs. Reduced Graphene Oxide in Gold Nanoparticles for Optical Biosensors—A Comparative Study
by
Fantoni, Alessandro
,
Ribeiro, Ana P. C.
,
Carvalho, Ana P. G.
in
Analytical Chemistry
,
AuNPs
,
Biocompatibility
2022
Aiming to develop a nanoparticle-based optical biosensor using gold nanoparticles (AuNPs) synthesized using green methods and supported by carbon-based nanomaterials, we studied the role of carbon derivatives in promoting AuNPs localized surface plasmon resonance (LSPR), as well as their morphology, dispersion, and stability. Carbon derivatives are expected to work as immobilization platforms for AuNPs, improving their analytical performance. Gold nanoparticles (AuNPs) were prepared using an eco-friendly approach in a single step by reduction of HAuCl4·3H2O using phytochemicals (from tea) which act as both reducing and capping agents. UV–Vis spectroscopy, transmission electron microscopy (TEM), zeta potential (ζ-potential), and X-ray photoelectron spectroscopy (XPS) were used to characterize the AuNPs and nanocomposites. The addition of reduced graphene oxide (rGO) resulted in greater dispersion of AuNPs on the rGO surface compared with carbon-based nanomaterials used as a support. Differences in morphology due to the nature of the carbon support were observed and are discussed here. AuNPs/rGO seem to be the most promising candidates for the development of LSPR biosensors among the three composites we studied (AuNPs/G, AuNPs/GO, and AuNPs/rGO). Simulations based on the Mie scattering theory have been used to outline the effect of the phytochemicals on LSPR, showing that when the presence of the residuals is limited to the formation of a thin capping layer, the quality of the plasmonic resonance is not affected. A further discussion of the application framework is presented.
Journal Article
Extraction of Nannochloropsis Fatty Acids Using Different Green Technologies: The Current Path
by
Freitas, Ana Cristina
,
Sousa, Sérgio Cruz
,
Gomes, Ana Maria
in
Algae
,
Aquatic microorganisms
,
Cavitation
2023
Nannochloropsis is a genus of microalgae widely recognized as potential sources of distinct lipids, particularly polyunsaturated fatty acids (PUFA). These may be obtained through extraction, which has conventionally been performed using hazardous organic solvents. To substitute such solvents with “greener” alternatives, several technologies have been studied to increase their extraction potential. Distinct technologies utilize different principles to achieve such objective; while some aim at disrupting the cell walls of the microalgae, others target the extraction per se. While some methods have been utilized independently, several technologies have also been combined, which has proven to be an effective strategy. The current review focuses on the technologies explored in the last five years to extract or increase extraction yields of fatty acids from Nannochloropsis microalgae. Depending on the extraction efficacy of the different technologies, distinct types of lipids and/or fatty acids are obtained accordingly. Moreover, the extraction efficiency may vary depending on the Nannochloropsis species. Hence, a case-by-case assessment must be conducted in order to ascertain the most suited technology, or tailor a specific one, to be applied to recover a particular fatty acid (or fatty acid class), namely PUFA, including eicosapentaenoic acid.
Journal Article
Light requirements in microalgal photobioreactors: an overview of biophotonic aspects
2011
In order to enhance microalgal growth in photobioreactors (PBRs), light requirement is one of the most important parameters to be addressed; light should indeed be provided at the appropriate intensity, duration, and wavelength. Excessive intensity may lead to photo-oxidation and -inhibition, whereas low light levels will become growth-limiting. The constraint of light saturation may be overcome via either of two approaches: increasing photosynthetic efficiency by genetic engineering, aimed at changing the chlorophyll antenna size; or increasing flux tolerance, via tailoring the photonic spectrum, coupled with its intensity and temporal characteristics. These approaches will allow an increased control over the illumination features, leading to maximization of microalgal biomass and metabolite productivity. This minireview briefly introduces the nature of light, and describes its harvesting and transformation by microalgae, as well as its metabolic effects under excessively low or high supply. Optimization of the photosynthetic efficiency is discussed under the two approaches referred to above; the selection of light sources, coupled with recent improvements in light handling by PBRs, are chronologically reviewed and critically compared.[PUBLICATION ABSTRACT]
Journal Article
Paracetamol Removal from Aqueous Media Through Fenton Reaction Using ZSM-5 Zeolite Produced from Fly Ash
2026
The purpose of this study is the exploration of the catalytic performance of a ZSM-5 zeolite produced from iron-rich fly ash, without any additional iron loading, in removing paracetamol via a heterogenous Fenton reaction. The structural and textural characterization by powder X-ray diffraction and N2 adsorption isotherms showed that a pure ZSM-5 phase was synthesized, but lower crystallinity and textural parameters were obtained when compared with commercial ZSM-5. The XPS analysis revealed significant amounts of iron and yttrium, which enhanced the electronic properties of the samples’ surface when compared with iron-impregnated commercial ZSM-5. The catalytic reaction was followed through UV-spectroscopy and kinetic models were applied to the data; the best fit was obtained for a pseudo-first-order model. All fly ash-based zeolites showed increased paracetamol removal when compared with commercial iron-loaded ZSM-5, which may be attributed to the more disordered structure, able to accommodate large paracetamol species (dimers). On the other hand, the effect of yttrium on the electronic properties of iron sites may increase the ●OH radical formation, thus increasing the paracetamol removal rate, despite the progressive drop on paracetamol removal upon regeneration–reuse cycles due to Fe leaching.
Journal Article
Hierarchical Zeolites Prepared Using a Surfactant-Mediated Strategy: ZSM-5 vs. Y as Catalysts for Friedel–Crafts Acylation Reaction
by
Martins, Angela
,
Santos, M. Soledade C. S.
,
Amaro, Beatriz
in
Friedel–Crafts acylation
,
furan
,
hierarchical Y and ZSM5 zeolites
2024
Hierarchical ZSM5 and Y zeolites were prepared through a surfactant-mediated strategy with NH4OH changing the duration of the treatment and the amount of CTAB surfactant and taking as reference multiples of the critical micellar concentration (CMC). The materials were characterized using powder X-ray diffraction, N2 adsorption isotherms at −196 °C, and SEM and TEM microscopy. The catalytic performance was evaluated in Friedel–Crafts acylation of furan with acetic anhydride at 80 °C. The alkaline surfactant-mediated treatment had different effects on the two zeolites. For ZSM5, the CTAB molecular aggregates can hardly diffuse inside the medium-size pores, leading mainly to intercrystalline mesoporosity and increased external surface area, with no positive catalytic impact. On the other hand, for large-pore Y zeolite, the CTAB molecular aggregates can easily diffuse and promote the rearrangement of crystal units around micelles, causing the enlargement of the pores, i.e., intracrystalline porosity. The optimized Y-based sample, treated for 12 h with a CTAB amount 32 times the CMC, shows an increase in product yield and rate constant that was not observed when a higher amount of surfactant was added. The reuse of spent catalysts upon thermal treatment at 400 °C shows a regeneration efficiency around 90%, showing good potentialities for the modified catalysts.
Journal Article
Can Growth of Nannochloropsis oculata under Modulated Stress Enhance Its Lipid-Associated Biological Properties?
2022
Nannochloropsis oculata is well-recognized as a potential microalgal source of valuable compounds such as polyunsaturated fatty acids, particularly, eicosapentaenoic acid (EPA). The content and profile of these lipids is highly dependent on the growth conditions and can, therefore, be tailored through modulation of the growth parameters, specifically, temperature. Moreover, biological activities are composition dependent. In the present work, lipid extracts obtained from N. oculata, grown under constant temperature and under modulated temperature stress (to increase EPA content; Str) were characterized by GC-FID and several bioactivities were evaluated, namely, antioxidant (L-ORACFL), cytotoxic (MTT), adipolytic, anti-hepatic lipid accumulation (steatosis), and anti-inflammatory properties. Both extracts exhibited antioxidant activity (c.a. 49 µmol Troloxequivalent/mgextract) and the absence of toxicity (up to 800 µg/mL) toward colon and hepatic cells, adipocytes, and macrophages. They also induced adipolysis and the inhibition of triglycerides hepatic accumulation, with a higher impact from Str. In addition, anti-inflammatory activity was observed in the lipopolysaccharide-induced inflammation of macrophages in the presence of either extract, since lower levels of pro-inflammatory interleukin-6 and interferon-β were obtained, specifically by Str. The results presented herein revealed that modulated temperature stress may enhance the health effects of N. oculata lipid extracts, which may be safely utilized to formulate novel food products.
Journal Article
Valorization of By-Products from Commercial Fish Species: Extraction and Chemical Properties of Skin Gelatins
2017
Fish skins constitute an important fraction of the enormous amount of wastes produced by the fish processing industry, part of which may be valorized through the extraction of gelatins. This research exploited the extraction and characterization of gelatins from the skin of three seawater fish species, namely yellowfin tuna (Thunnus albacares), blue shark (Prionace glauca), and greenland halibut (Reinhardtius hippoglossoides). Characterization included chemical composition, rheology, structure, texture, and molecular weight, whereas extraction studies intended to reduce costly steps during extraction process (reagents concentration, water consumption, and time of processing), while maintaining extraction efficiency. Chemical and physical characterization of the obtained gelatins revealed that the species from which the gelatin was extracted, as well as the heat treatment used, were key parameters in order to obtain a final product with specific properties. Therefore, the extraction conditions selected during gelatin production will drive its utilization into markets with well-defined specifications, where the necessity of unique products is being claimed. Such achievements are of utmost importance to the food industry, by paving the way to the introduction in the market of gelatins with distinct rheological and textural properties, which enables them to enlarge their range of applications.
Journal Article