Publications

Abstract The surface of highly crystalline hollow TiO2 microspheres was nanostructured to contain recognition sites for bilirubin and simultaneously doped with Ag to achieve a photocatalytic response to visible light irradiation. The molecular imprinting technique was employed to obtain the recognition sites, whereas Ag-doping was tested either during the synthesis or after the complete synthesis by impregnation. Different Ag:Ti molar proportions were studied (1:2; 1:4 and 1:6). From the absorbance spectra in suspensions of the different microspheres, the ratio of 1:6 molAg/molTi was established as allowing for a greater capacity of absorption of visible light. It was possible to confirm a positive catalytic effect of Ag-doping, either with ultraviolet or visible light, especially for molecularly imprinted hollow microspheres doped during the synthesis. The increases in kinetic constants were much higher for molecularly imprinted hollow microspheres doped during the synthesis and calcined at 250 degrees C (12 min- 1 and 9 min- 1, for ultraviolet and visible light) compared to the corresponding undoped microspheres (8 min- 1 and 5 min- 1, for ultraviolet and visible light), leading to imprinting factors of 1.6 and 1.9, for ultraviolet and visible light, respectively. Selective photocatalysis was also confirmed with alpha values of 1.4 and 1.3 for ultraviolet and visible light, respectively. In conclusion, it was possible to obtain, with success, selective Agdoped hollow TiO2 microspheres with a higher rate of bilirubin degradation compared to undoped hollow TiO2 microspheres, even with visible light irradiation.

Abstract Carbon materials derived from marine waste have been drawing attention for supercapacitor applications. In this work, chitins from squid and prawn marine wastes were used as carbon precursors for further application as electrodes for energy storage devices. Chitins were obtained through a deproteinization method based on enzymatic hydrolysis as an alternative to chemical hydrolysis as commonly presented in the literature. The obtained porous carbons were characterized using a BET surface area analyzer to determine the specific surface area and pore size, as well as scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), Raman spectroscopy, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), to characterize their morphology, composition, and structure. The electrochemical characterization was performed using a glassy carbon (GC) electrode modified with marine waste-based porous carbons as the working electrode through cyclic voltammetry and galvanostatic charge/discharge using ethaline, a choline chloride-based deep eutectic solvent (DES), as an eco-friendly and sustainable electrolyte. Squid and prawn chitin-based carbons presented a surface area of 149.3 m(2) g(-1) and 85.0 m(2) g(-1), pore volume of 0.053 cm(3) g(-1) and 0.029 cm(3) g(-1), and an associated specific capacitance of 20 and 15 F g(-1) at 1 A g(-1), respectively. Preliminary studies were performed to understand the effect of -OH groups on the chitin-based carbon surface with DES as an electrolyte, as well as the effect of aqueous electrolytes (1 mol L-1 sulphuric acid (H2SO4) and 1 mol L-1 potassium hydroxide (KOH)) on the capacitance and retention of the half-cell set up. It is provided, for the first time, the use of chitin-based carbon materials obtained through a one-step carbonization process combined with an eco-friendly DES electrolyte for potential application in energy storage devices.

Abstract The treatment of bacterial infections has been troubled by the increased resistance to antibiotics, instigating the search for new antimicrobial therapies. Phytochemicals have demonstrated broad-spectrum and effective antibacterial effects as well as antibiotic resistance-modifying activity. In this study, perillyl alcohol and hydrocinnamic acid were characterized for their antimicrobial action against Escherichia coli. Furthermore, dual and triple combinations of these molecules with the antibiotics chloramphenicol and amoxicillin were investigated for the first time. Perillyl alcohol had a minimum inhibitory concentration (MIC) of 256 mu g/mL and a minimum bactericidal concentration (MBC) of 512 mu g/mL. Hydrocinnamic acid had a MIC of 2048 mu g/mL and an MBC > 2048 mu g/mL. Checkerboard and time-kill assays demonstrated synergism or additive effects for the dual combinations chloramphenicol/perillyl alcohol, chloramphenicol/hydrocinnamic acid, and amoxicillin/hydrocinnamic acid at low concentrations of both molecules. Combenefit analysis showed synergism for various concentrations of amoxicillin with each phytochemical. Combinations of chloramphenicol with perillyl alcohol and hydrocinnamic acid revealed synergism mainly at low concentrations of antibiotics (up to 2 mu g/mL of chloramphenicol with perillyl alcohol; 0.5 mu g/mL of chloramphenicol with hydrocinnamic acid). The results highlight the potential of combinatorial therapies for microbial growth control, where phytochemicals can play an important role as potentiators or resistance-modifying agents.

Abstract <jats:p>This review focus on a critical analysis of nanocatalysts for Advanced Reductive Processes (ARP) and Oxidation Processes (AOP) designed for the degradation of poly/perfluoroalkyl substances (PFAS) in water. Ozone, ultraviolet and photocatalyzed ARP and/or AOP will be the basic treatment technologies. Besides the review of the nanomaterials with greater potential as catalyst for advanced processes of PFAS in water, the perspectives for its future development considering sustainability considerations will be discussed. Moreover, a brief analysis of the current state of the art of the ARP and AOP for the treatment of PFAS in water will be presented.</jats:p>

Abstract Escherichia coli is a Gram-negative commensal bacterium of the normal microbiota of humans and animals. However, several E. coli strains are opportunistic pathogens responsible for severe bacterial infections, including gastrointestinal and urinary tract infections. Due to the emergence of multidrug-resistant serotypes that can cause a wide spectrum of diseases, E. coli is considered one of the most troublesome human pathogens worldwide. Therefore, a more thorough understanding of its virulence control mechanisms is essential for the development of new anti-pathogenic strategies. Numerous bacteria rely on a cell density-dependent communication system known as quorum sensing (QS) to regulate several bacterial functions, including the expression of virulence factors. The QS systems described for E. coli include the orphan SdiA regulator, an autoinducer-2 (AI-2), an autoinducer-3 (AI-3) system, and indole, which allow E. coli to establish different communication processes to sense and respond to the surrounding environment. This review aims to summarise the current knowledge of the global QS network in E. coli and its influence on virulence and pathogenesis. This understanding will help to improve anti-virulence strategies with the E. coli QS network in focus. This review highlights the latest findings in the field of cell-to-cell communication systems in Escherichia coli and discusses the relevance of this complicated signalling network for the virulence and pathogenesis of this bacterium.

Abstract The quorum sensing (QS) system is related to cell-to-cell communication as a function of population density, which regulates several physiological functions including biofilm formation and virulence gene expression. QS inhibitors have emerged as a promising strategy to tackle virulence and biofilm development. Among a wide variety of phytochemicals, many of them have been described as QS inhibitors. Driven by their promising clues, this study aimed to identify active phytochemicals against LuxS/autoinducer-2 (AI-2) (as the universal QS system) from Bacillus subtilis and LasI/LasR (as a specific QS system) of Pseudomonas aeruginosa, through in silico analysis followed by in vitro validation. The optimized virtual screening protocols were applied to screen a phytochemical database containing 3479 drug-like compounds. The most promising phytochemicals were curcumin, pioglitazone hydrochloride, and 10-undecenoic acid. In vitro analysis corroborated the QS inhibitory activity of curcumin and 10-undecenoic acid, however, pioglitazone hydrochloride showed no relevant effect. Inhibitory effects on LuxS/AI-2 QS system triggered reduction of 33-77% by curcumin (at 1.25-5 mu g/mL) and 36-64% by 10-undecenoic acid (at 12.5-50 mu g/mL). Inhibition of LasI/LasR QS system was 21% by curcumin (at 200 mu g/mL) and 10-54% by 10-undecenoic acid (at 15.625-250 mu g/mL). In conclusion, in silico analysis allowed the identification of curcumin and, for the first time, 10-undecenoic acid (showing low cost, high availability, and low toxicity) as alternatives to counteract bacterial pathogenicity and virulence, avoiding the imposition of selective pressure usually related to classic industrial disinfection and antibiotics therapy.

Abstract The present study proposes two unique systems using free radical-induced grafting reactions to combine Ag, chitosan (CS) and gallic acid (GA) into a single particulate nanostructure. GA-grafted-CS (GA-g-CS) was used to reduce Ag+ to Ag0, and producing Ag-GA-g-CSNPs (hybrid NPs I). Also, GA was grafted into CS-AgNPs, to form GA-g-CS AgNPs (hybrid NPs II). Although there were previous attempts to graft GA into CS, this is first time to graft GA into CS-AgNPs. The study aimed to enhance biocompatibility, antibacterial and antioxidant properties of CS-AgNPs via grafted GA. Grafting GA into CS-AgNPs was confirmed by UV-Vis, DLS, DSC/TGA, XRD, EDX and FTIR. The morphology and size of NPs were studied by TEM and SEM. The decrease of zeta-potential from +50 mV in CS-Ag NPs to +33 and + 29 mV, in the presented 2 nanoforms hybrid NPs I and II, respectively, is an indication for the successful GA graft. Among all samples, hybrid NPs II showed lower toxicity, higher antiox-idant and antibacterial activity. The obtained results revealed that grafting GA to CS-AgNPs, as a new method to combine Ag, CS and GA in a uniparticulate structure, is a unique process which may deserve a more future consideration.

Abstract Antibiotics are a staple in current medicine for the therapy of infectious diseases. However, their extensive use and misuse, combined with the high adaptability of bacteria, has dangerously increased the incidence of multi-drug-resistant (MDR) bacteria. This makes the treatment of infections challenging, especially when MDR bacteria form biofilms. The most recent antibiotics entering the market have very similar modes of action to the existing ones, so bacteria rapidly catch up to those as well. As such, it is very important to adopt effective measures to avoid the development of antibiotic resistance by pathogenic bacteria, but also to perform bioprospecting of new molecules from diverse sources to expand the arsenal of drugs that are available to fight these infectious bacteria. Filamentous fungi have a large and vastly unexplored secondary metabolome and are rich in bioactive molecules that can be potential novel antimicrobial drugs. Their production can be challenging, as the associated biosynthetic pathways may not be active under standard culture conditions. New techniques involving metabolic and genetic engineering can help boost antibiotic production. This study aims to review the bioprospection of fungi to produce new drugs to face the growing problem of MDR bacteria and biofilm-associated infections.

Abstract This work studies the antimicrobial activity of benzyldimethyldodecyl ammonium chloride (BDMDAC)-coated microparticles with distinct morphological structures. Functionalized microparticles were prepared by the layer-by-layer (LbL) self-assembly technique on hydroxyapatite (Hap), calcium carbonate (CaCO3) and glass beads (GB) cores. All particles were characterized, before and after functionalization, by Fourier-Transform Infrared Spectroscopy (FTIR), Brunner-Emmett-Teller (BET) and Scanning Electron Microscopy (SEM) analyses. Antimicrobial activity was tested against planktonic Pseudomonas fluorescens. Planktonic bacteria were exposed to 100 mg/L, 200 mg/L and 400 mg/L of BDMDAC-coated microparticles for 240 min. This strategy promoted a complete bacteria reduction at 200 mg/L for Hap microparticles after 240 min. No release of biocide was detected through HPLC analyses during 2 weeks, suggesting that bacteria inactivation may be attributed to a contact killing mechanism.

Abstract This research focus on the evaluation of the impact on students' attitudes towards the environment, fostered by their involvement in an educational citizen science project related to the monitoring of physicochemical properties and the detection of (micro)plastics in Portuguese coastal waters. We developed an attitude scale, comprising four dimensions (Collective, Personal, Recycling and Reuse and Microplastics), which was applied, as a pre-test and post-test, to 574 middle school students (aged 12-14): 442 in the experimental group and 132 in the control group. Initially, based on pre-test results, both groups revealed positive attitudes. In the experimental group, the post-test results revealed that significantly positive attitude changes were promoted in all dimensions, whereas, in the control group, this occurred only in the Personal dimension. The control group also exhibited significantly negative attitude changes in the collective dimension. Students' engagement in sustainability-related citizen science projects can enhance environmentally literate society.