Publications

Abstract Wastewater-based epidemiology (WBE) has emerged as a powerful approach for population-level monitoring of chemical exposure, health status, and disease transmission by analysing wastewater. Although chromatographic and molecular techniques remain the gold standard in WBE, their high cost, infrastructural demands, and limited suitability for decentralized and real-time monitoring motivate the development of complementary sensing technologies. In this context, optical (bio)sensors, particularly fluorescence-based platforms, have attracted increasing attention due to their high sensitivity, rapid response, and potential for on-site monitoring. This review discusses recent advances in fluorescent optical (bio)sensors for WBE, with a particular focus on carbon dots (CDs), including waste- and biomass-derived CDs produced via green synthesis as well as CDs obtained from commercial chemicals. The applicability of CD-based sensors to wastewater-relevant analytes is evaluated, highlighting current achievements, as well as existing limitations and challenges related to real-sample validation and the translation of these platforms into robust, field-deployable systems for their implementation in sustainable wastewater monitoring and public health surveillance.

Abstract Urban parks are essential to sustainable cities, providing climate regulation, supporting biodiversity, and offering vital spaces for recreation and overall well-being. At the same time, their soils can act as long-term reservoirs for persistent organic pollutants (POPs), reflecting decades of atmospheric deposition, diffuse urban emissions, and historical land-use practices. This review synthesises current knowledge on the occurrence, sources, and environmental behaviour of priority POPs, including OCPs, PCBs, PCDD/Fs, PBDEs, PFAS, and PAHs, in the soils of urban parks and gardens worldwide. Evidence from multiple regions reveals consistent patterns: urban parks accumulate complex mixtures of legacy and emerging contaminants, reflecting both historical inputs and ongoing urban activities. These contaminants primarily contribute to scenarios of chronic, low-level exposure through the ingestion of soil and dust, inhalation of resuspended particles, dermal contact, and, in some cases, dietary intake when food is cultivated in contaminated park soils. While such exposure pathways have been associated with a range of adverse health outcomes in toxicological and epidemiological studies, the presence of POPs in park soils does not imply that urban parks represent hazardous environments. Instead, it emphasises the importance of proportionate, evidence-based assessments within spaces that yield substantial net benefits to public health. Despite growing research interest, significant gaps remain, including limited understanding of mixture toxicity, insufficient data on temporal trends, a lack of harmonised monitoring strategies, and the absence of exposure scenarios specifically tailored to recreational soils. This review also examines major international and European regulatory frameworks and soil-quality guideline approaches relevant to urban and recreational soils, identifying mismatches between scientific evidence and regulatory practice. By integrating perspectives from environmental chemistry, toxicology, urban ecology, and policy, this review highlights the importance of targeted monitoring and context-specific management strategies to ensure that urban parks remain safe, healthy, and equitable components of increasingly complex urban landscapes.

Abstract The presence of emerging organic contaminants in water and effluents, including antibiotics, poses significant environmental and health risks. Moreover, while photocatalysis is a promising approach for their removal, the inefficient utilization of natural sunlight by common photocatalysts limits its large-scale use. This work demonstrates the enhanced sunlight-driven photodegradation of the antibiotic Ciprofloxacin (CIP) using a nanocomposite composed of carbon dots (CDs) and TiO2 (NC50:50). The CDs were obtained from corn stover, a major agricultural waste product. Initial testing was performed under artificial solar radiation: CIP was virtually fully degraded within 20 min, with a rate constant of 0.2372 min(-1) and a 217% enhancement of catalytic activity over commercial TiO2. Validation under real-world irradiation conditions was subsequently made by performing photocatalytic assays under natural sunlight on different days under diverse meteorological conditions. The performance of NC50:50 was retained, degrading CIP within 30 min under natural conditions. Notably, while degradation by-products were identified under both artificial and natural sunlight, they were subsequently photodegraded by the nanocomposite under these conditions. This enhanced performance was attributed to a combination of effects resulting from CDs' incorporation, namely, improved absorption of visible light, enhanced charge separation, and increased specific surface area. Furthermore, the addition of CDs resulted in changes in the reactive species generation profile, which can alter the available degradation pathways. Thus, this study provides insight that can be useful for strategies aimed at the rational design of sunlight-active TiO2-based photocatalysts with tunable surface reactivity.

Abstract While heteroatom doping is widely used to enhance the fluorescence of carbon dots, the actual mechanism underlying this claimed enhancement remains unclear. Herein, we report a systematic comparison between nitrogen-doped carbon dots (N-CDs) and nitrogen/sulfur co-doped carbon dots (N,S-CDs) synthesized hydrothermally, with ethylenediamine and sodium thiosulfate as the N- and S-dopants, respectively. Contrary to expectations, the inclusion of the S-precursor significantly reduced the quantum yield by 63%, from 35.9% to 13.2%, while leaving the emission profile and response largely unchanged. Characterization assays revealed that S-doping in N,S-CDs was residual, whereas the surface oxygen content increased markedly, indicating surface oxidation. The data suggest that sodium thiosulfate acted not as a dopant but overall as an oxidant, generating oxygen-based surface defects that introduced nonradiative recombination pathways. Thus, our findings show that co-doping with this S-precursor can decrease the quantum yield by promoting surface oxidation and the effective formation of more oxidized N-CDs, rather than heteroatom incorporation and production of co-doped CDs. This decreasing effect on the quantum yield was also observed when using thiourea as the S-precursor. Future work should include the study of other common S-precursors. In conclusion, our research shows that specific heteroatom-based precursors can alter the optical characteristics of CDs through redox/surface-modification effects instead of actual compositional doping, and thus, claims based on heteroatom doping may need closer examination.

Abstract <jats:p>Persistent organic pollutants accumulate in urban soils, yet information on the occurrence, spatial variability and human health implications of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) remains limited, particularly in Portugal. Surface soils were collected from six urban and peri-urban green spaces across the Porto Metropolitan Area, encompassing contrasting land-use histories and anthropogenic settings. Seventeen sampling locations were analysed for the 17 WHO-priority PCDD/F congeners and the 12 dioxin-like PCB congeners. The total number of 2005 toxic equivalents (TEQs) was determined, and screening-level human health risks were evaluated for adults considering incidental soil ingestion, dermal contact and inhalation of resuspended soil particles. PCDD/Fs and dl-PCBs were detected at all sampling locations, with total TEQ concentrations ranging from 1.91 to 330.9 ng TEQ kg⁻¹ dry weight. PCDD/Fs accounted for most of the overall toxicity. The majority of the samples under analysis can be considered representative of the urban background level in Porto, at 2.51 ± 0.54 ng TEQ kg⁻¹ dw. TEQ concentrations at most sites were consistent with diffuse urban background levels reported internationally, whereas one informal urban allotment constituted a distinct contamination hotspot. This spatial pattern was reflected in the risk assessment. Non-carcinogenic and carcinogenic risks remained below widely accepted screening thresholds at all locations except the hotspot, where children exhibited a hazard index (HI) of 1.50 and an incremental lifetime cancer risk (ILCR) of 1.17 × 10⁻⁵. Incidental soil ingestion was the predominant exposure pathway; dermal contact contributed modestly, and inhalation contributed negligibly. Sensitivity analysis demonstrated that these conclusions were robust to alternative assumptions about soil ingestion. These findings suggest that historical land use is a major determinant of site-specific PCDD/F and dl-PCB contamination and associated human health risks in urban green spaces. Incorporating land-use history into urban soil assessments could improve contamination hotspot identification and strengthen environmental monitoring and risk management strategies.</jats:p>

Abstract TiO2 nanoparticles are promising photocatalysts due to their oxidizing strength and inertness. However, their inability to efficiently absorb visible light limits industrial applications that could use sunlight. The addition of carbon dots to TiO2 has been recently shown to have the potential to address this issue by enhancing the visible light-driven photocatalytic efficiency of the resulting nanocomposites. However, concrete data on their sustainable development and fabrication is lacking. Herein, we performed a life cycle assessment (LCA) study to understand the environmental impacts of different TiO2-carbon dots nanocomposites with enhanced visible light-driven photocatalytic activity. It was found that the nanocomposites with the highest photocatalytic activity were the ones whose synthesis was associated with lower environmental impacts. Furthermore, the carbon dots generally have little to moderate contributions to most impact categories, except for marine eutrophication. Finally, the most critical parameter was found to be the source of TiO2 for the nanocomposites.

Abstract Biosurfactants/bioemulsifiers (BSs/BEs) can be defined as surface-active biomolecules produced by microorganisms with a broad range of applications. In recent years, due to their unique properties like biodegradability, specificity, low toxicity, and relative ease of preparation, these biomolecules have attracted wide interest as an eco-friendly alternative for several industrial sectors, escalating global microbial BS/BE market growth. Recently, Gordonia alkanivorans strain 1B, a bacterium with significant biotechnological potential, well known for its biodesulfurizing properties, carotenoid production, and broad catabolic range, was described as a BS/BE producer. This study focuses on the characterization of the properties of the lipoglycopeptide BSs/BEs produced by strain 1B, henceforth referred to as gordofactin, to better understand its potential and future applications. Strain 1B was cultivated in a chemostat using fructose as a carbon source to stimulate gordofactin production, and different purification methods were tested. The most purified sample, designated as extracted gordofactin, after lyophilization, presented a specific emulsifying activity of 9.5 U/mg and a critical micelle concentration of 13.5 mg/L. FT-IR analysis revealed the presence of basic hydroxyl, carboxyl, ether, amine/amide functional groups, and alkyl aliphatic chains, which is consistent with its lipoglycopeptide nature (60% lipids, 19.6% carbohydrates, and 9% proteins). Gordofactin displayed remarkable stability and retained emulsifying activity across a broad range of temperatures (30 degrees C to 80 degrees C) and pH (pH 3-12). Moreover, a significant tolerance of gordofactin emulsifying activity (EA) to a wide range of NaCl concentrations (1 to 100 g/L) was demonstrated. Although with a great loss of EA in the presence of NaCl concentrations above 2.5%, gordofactin could still tolerate up to 100 g/L NaCl, maintaining about 16% of its initial EA for up to 7 days. Furthermore, gordofactin exhibited growth inhibition against both Gram-positive and Gram-negative bacteria, and it demonstrated concentration-dependent free radical scavenging activity for 2,2-diphenyl-1-picrylhydrazyl (IC50 approximate to 1471 mg/L). These promising features emphasize the robustness and potential of gordofactin as an eco-friendly BS/BE alternative to conventional surfactants/emulsifiers for different industrial applications.

Abstract Polypore mushrooms have been widely recognized for centuries for their use in food and medicine due to their strong capacity to produce numerous biomolecules with beneficial effects on human health. Fomes fomentarius is one such species that remains poorly explored, particularly when growing in Morocco. Herein, this study aimed to characterize the bioactive compounds of F. fomentarius and evaluate its pharmacological properties. Spectrophotometric analysis showed that F. fomentarius revealed high levels of total phenolics (75.83 mg GAE/g dme) and flavonoids (37.62 mg CE/g dme). Gas chromatography-mass spectrometry (GC-MS) analysis identified 109 volatile and non-volatile compounds, primarily sugars (24), fatty acids (23), alcohols (10), organic acids (9), and terpenoids (6). In addition, liquid chromatography-mass spectrometry (LC-MS) analysis allowed the identification of 24 phenolic compounds, with isorhamnetin (2734.00 mu g/g), p-hydroxybenzoic acid (409.00 mu g/g), and kaempferol (351.10 mu g/g) as the most abundant. Regarding pharmacological properties, F. fomentarius extract demonstrated strong antioxidant activity, with the DPPH radical-scavenging assay showing the highest potency, followed by beta-carotene bleaching inhibition and ferric ion-reducing power, with EC50 (half maximal effective concentration) values of 114.40, 174.50, and 250.70 mu g/mL, respectively. Additionally, it exhibited broad-spectrum antimicrobial activity against all seven human pathogenic microorganisms, with Epidermophyton floccosum being the most susceptible ((minimum inhibitory concentration (MIC)) = 2 mg/mL and minimal fungicidal concentration (MFC) = 4 mg/mL) and A. fumigatus the most resistant (MIC = 26.67 mg/mL and MFC >= 64 mg/mL). Overall, the result indicated that Moroccan F. fomentarius is a rich source of diverse bioactive compounds with potent antioxidant and antimicrobial activities, supporting its potential for various applications.

Abstract Steel consumption in the construction sector is one of the main contributors to global greenhouse gas emissions. Therefore, developing processes for the reuse of steel-based products with lower environmental impacts is essential for the sustainability of the construction sector. One example is the reuse of metal road guardrail beams on highways. This study investigated the environmental sustainability of a reconditioning process for such beams, instead of using new guardrails. The environmental impacts of the process were studied and compared with the impacts of the traditional production process using a Life Cycle Assessment (LCA) approach. This study revealed that most of the impacts of the reconditioning process derive from the use of electricity. The comparison with the traditional beam production process revealed that when primary raw materials are replaced by reused raw materials, the environmental impacts associated with the production process decrease significantly. Of the 19 impact indicators assessed, 18 were lower, and 17 had a drop of more than 90 percent compared to the traditional production process. The results indicate that the reconditioning process has the potential to significantly reduce environmental impacts by avoiding the consumption and transportation of primary raw materials, which were identified as the main sources of impacts in the traditional production process, as well as minimizing waste generation.

Abstract Syngas fermentation is a promising carbon capture and utilization (CCU) technology for producing carboxylic acids while transforming low-cost waste gas into high-value products. This study evaluates the two bioreactor feeding strategies for synthesis gas (syngas) fermentation by Eubacterium callanderi (formerly Butyribacterium methylotrophicum) strain Marburg-on-demand feeding (ODF) and continuous feeding (CF)-with a synthetic syngas mixture of 23 vol% CO2, 29 vol% CO, 32 vol% H2, and 16 vol% CH4, mimicking the syngas from lignocellulosic gasification. The ODF assay achieved a maximum syngas consumption rate of 112 mL/h, yielding 24.1 g/L acids, namely 22.9 g/L acetate and 1.3 g/L butyrate. CF of syngas at 223 mL/h required more gas (62.9 L) to produce 22.7 g/L total acids, from which 19.0 g/L acetate and 3.7 g/L butyrate were achieved. The CF-specific production rate (gproduct/gdry_cell_weight/hour) reached 0.5 g/gDCW/h (acetate) and 0.17 g/gDCW/h (butyrate), outperforming ODF with 0.3 and 0.02 g/gDCW/h, respectively. ODF minimized gas wastage and enabled CH4 accumulation inside the bioreactor up to approximately 78 vol%, while CF led to CO2 accumulation, indicating a need for more efficient CO2 utilization strategies, such as sequential fermentations. This work highlights the critical impact of the two feeding options studied with regard to scaling up the carbon-efficient production of carboxylic acids, and indicates that both strategies can have potential applications. ODF is ideal for increasing carbon fixation and achieving, simultaneously, gas cleaning, while CF fermentations are better suited to maximizing the acid production rate.