Degree: Doctor



Showing 5 latest publications. Total publications: 185
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1. Sustainability Assessment of Highly Fluorescent Carbon Dots Derived from Eucalyptus Leaves, Johny, A; da Silva, LP; Pereira, CM da Silva, JCGE in ENVIRONMENTS, 2024, Volume: 11, 
Article,  Indexed in: crossref, scopus, wos  DOI: 10.3390/environments11010006 P-00Y-KGJ
Abstract Biomass-derived carbon dots (CDs) are gaining much interest in recent times, as they provide a sustainable option with abundant availability, a low cost and tunable luminescence. Herein, we report a simple green synthesis method to produce highly fluorescent CDs from Eucalyptus globulus leaves using the one-pot hydrothermal approach. The fabricated CDs exhibit strong blue fluorescence with an excitation and emission maxima of 320 nm and 445 nm, respectively. The highest quantum yield (QY) obtained was 60.7%. With the reported optical properties and biocompatibility, CDs can be looked at as a promising candidate for potential biosensing applications. Moreover, we employed a life cycle assessment (LCA) cradle-to-gate approach to study the environmental impacts of the synthesis strategy used for the fabrication of CDs. The results point out that citric acid is the main hotspot in CD synthesis, regarding environmental impacts in most categories. This justifies the introduction of biomass, which reduces the amount of citric acid, thus leading to a more sustainable synthesis strategy for fabricating CDs.

2. Nanoporous anodic alumina layers obtained from novel deep eutectic solvent formulations, Fernandes, PMV; Brincoveanu, O; Pantazi, A; Petica, A; Pereira, CM Silva, AF; Enachescu, M; Anicai, L in TRANSACTIONS OF THE INSTITUTE OF METAL FINISHING, 2023, ISSN: 0020-2967,  Volume: 101, 
Article,  Indexed in: crossref, scopus, unpaywall, wos  DOI: 10.1080/00202967.2022.2105571 P-00X-4NF
Abstract The possible fabrication of porous anodic oxide films on aluminium in ionic liquids based on choline dihydrogen citrate eutectic mixtures both with oxalic acid and isopropyl alcohol and ethylene glycol, has been investigated. The anodisation has been carried out in either potentiostatic or galvanostatic regime, at temperatures of 45-80 degrees C, for different process durations. Quite compact, uniform anodic alumina layers have been obtained. Based on AFM and SEM investigations, pore diameters between 50 and 80 nm and interpore distances in the range of 160-200 nm have been estimated, with values influenced by the electrolyte type and anodisation conditions. The highest anodisation rate of about 0.4 mu m min(-1) has been determined by applying operation temperatures of 60 degrees C. The recorded EIS spectra showed a pure capacitive behaviour and high anodic oxide resistances of 10(6)-10(7) omega cm(2) order.

3. Plasmonic genosensor for detecting hazelnut Cor a 14-encoding gene for food allergen monitoring, Moreira P.; Costa J.; Villa C.; Mafra I.; Brandão A.T.S.C.; Dias C.; Silva A.F.; Pereira C.M. Costa R. in ANALYTICA CHIMICA ACTA, 2023, ISSN: 0003-2670,  Volume: 1259, 
Article,  Indexed in: crossref, scopus, unpaywall, wos  DOI: 10.1016/j.aca.2023.341168 P-00Y-7RZ
Abstract A plasmonic nanostructure was constructed as a biorecognition element coupled to an optical sensing platform in sandwich format, targeting the hazelnut Cor a 14 allergen-encoding gene. The analytical performance of the genosensor presented a linear dynamic range between 100 amol L-1 and 1 nmol L-1 , a limit of detection (LOD) < 19.9 amol L-1 , and a sensitivity of 13.4 +/- 0.6 m.. The genosensor was successfully hybridized with hazelnut PCR products, tested with model foods, and further validated by real-time PCR. It reached a LOD <0.001% (10 mg kg(-1) ) of hazelnut in wheat material (corresponding to 1.6 mg kg(-1) of protein) and a sensitivity of 17.2 +/- 0.5 m. for a linear range of 0.001%-1%. Herein, a new genosensing approach is proposed as a highly sensitive and specific alternative tool with potential application in monitoring hazelnut as an allergenic food, protecting the health of sensitized/allergic individuals.

4. Microparticles as BDMDAC (Quaternary Ammonium Compound) Carriers for Water Disinfection: A Layer-by-Layer Approach without Biocide Release, Redondo, M; Pereira, A; Pereira, CM Melo, LF in NANOMATERIALS, 2023, ISSN: 2079-4991,  Volume: 13, 
Article,  Indexed in: crossref, scopus, wos  DOI: 10.3390/nano13233067 P-00Z-F3T
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.

5. Preparation, Characterization, and Environmental Safety Assessment of Dithiocarbazate Loaded Mesoporous Silica Nanoparticles, Menezes, T; Bouguerra, S; Andreani, T Pereira, R; Pereira, C in NANOMATERIALS, 2023, Volume: 13, 
Article,  Indexed in: crossref, scopus, wos  DOI: 10.3390/nano13020370 P-00X-R8J
Abstract Dithiocarbazates comprise an important class of Schiff bases with remarkable biological applications due to the imine group present in their structure. However, full exploitation of the biological activity of 3-methyl-5-phenyl-pyrazoline-1-(S-benzyldithiocarbazate) (DTC) is limited due to its easy degradation and poor solubility in aqueous solutions. The loading of DTC into mesoporous silica nanoparticles (MSiNPs) can be an excellent strategy to improve the solubility of DTC in the aqueous medium. Therefore, the main goal of the present work was to design MSiNP-DTC and to evaluate the success of the loading process by measuring its physicochemical properties and evaluating the environmental safety of the new DTC formulation using different aquatic organisms, such as the microalgae Raphidocelis subcapitata, the macrophyte Lemna minor, and the marine bacterium Aliivibrio fischeri. DTC, MSiNP, and MSiNP-DTC concentrations ranging from 8.8 to 150 mg L-1 were tested for all the species, showing low toxicity against aquatic organisms. Loading DTC into MSiNPs caused a slight increase in the toxicity at the concentrations tested, only allowing for the estimation of the effect concentration causing a 20% reduction in bioluminescence or growth rate (EC20). Therefore, despite the potential of MSiNPs as a drug delivery system (DDS), it is of utmost importance to assess its impact on the safety of the new formulations.