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Carbon nanotubes (CNTs) are receiving special attention due to their remarkable thermal, electrical, and mechanical properties. The present work reports an innovative synthesis procedure to decorate MWCNTs with silver nanoparticles (Ag-NPs) via pulsed reverse deposition technique using a deep eutectic solvent (DES) based on choline chloride and glycerol as an electrolyte at room temperature, not requiring any previous surface modification of MWCNTs. MWCNTs decorated with Ag-NPs disclose a significant enhancement of their electrochemical performance as demonstrated by the increase of electrode stability and specific capacitance. Electrochemical characterization of the composite material was performed using cyclic voltammetry and charge/discharge curves, achieving a specific capacitance up to 28.50 F. g−1, against 4.70 F. g−1 for the commercial MWCNTs in a three-electrode system. Retention of the specific capacitance up to 99% for the Ag-MWCNTs composites compared with a value of 78% for electrodes modified with commercial MWCNTs. The Ag-MWCNTs composites were characterized through SEM/EDX analysis, ultrahigh-resolution STEM, in which the Z – Contrast image was collected, and Raman analysis to prove the successful attachment of the Ag-NPs to the MWCNTs surface. AFM was performed to evaluate the conductivity of the composites.
Ana T.S.C. Brandão; Sabrina Rosoiu; Renata Costa; Oana Andreea Lazar; A. Fernando Silva; Liana Anicai; Carlos M. Pereira; Marius Enachescu. Characterization and electrochemical studies of MWCNTs decorated with Ag nanoparticles through pulse reversed current electrodeposition using a deep eutectic solvent for energy storage applications. Journal of Materials Research and Technology 2021, 15, 342 -359.
AMA StyleAna T.S.C. Brandão, Sabrina Rosoiu, Renata Costa, Oana Andreea Lazar, A. Fernando Silva, Liana Anicai, Carlos M. Pereira, Marius Enachescu. Characterization and electrochemical studies of MWCNTs decorated with Ag nanoparticles through pulse reversed current electrodeposition using a deep eutectic solvent for energy storage applications. Journal of Materials Research and Technology. 2021; 15 ():342-359.
Chicago/Turabian StyleAna T.S.C. Brandão; Sabrina Rosoiu; Renata Costa; Oana Andreea Lazar; A. Fernando Silva; Liana Anicai; Carlos M. Pereira; Marius Enachescu. 2021. "Characterization and electrochemical studies of MWCNTs decorated with Ag nanoparticles through pulse reversed current electrodeposition using a deep eutectic solvent for energy storage applications." Journal of Materials Research and Technology 15, no. : 342-359.
The design and synthesis of artificial receptors based on molecular imprinting (MI) technology for the development of a new MIP-based biosensor for detection of the stress biomarker α-amylase in human saliva in point-of-care (PoC) applications is described in this work. The portable electrochemical devices for monitoring α-amylase consists of cost-effective and disposable gold screen-printed electrodes (AuSPEs). To build the electrochemical device, the template biomolecule was firstly immobilized directly over the working area of the gold chip previously activated with a self-assembled monolayer (SAM) of cysteamine (CA). Then, pyrrole (Py) monomer was selected as building block of a polymeric network prepared by CV electropolymerization. After the electropolymerization process, the enzyme was removed from the polymer film in order to build the specific recognition sites for the target enzyme. The MIP biosensor showed a very wide linear concentration range (between 3.0 × 10−4 to 0.60 mg mL−1 in buffer solution and between 3.0 × 10−4 to 3.0 × 10−2 mg mL−1 in human saliva) and low detection levels were achieved (LOD < 3.0 × 10−4 mg mL−1) using square wave voltammetry (SWV) as the electroanalytical technique.
Tânia Rebelo; Inês Miranda; Ana Brandão; Laura Sousa; José Ribeiro; António Silva; Carlos Pereira. A Disposable Saliva Electrochemical MIP-Based Biosensor for Detection of the Stress Biomarker α-Amylase in Point-of-Care Applications. Electrochem 2021, 2, 427 -438.
AMA StyleTânia Rebelo, Inês Miranda, Ana Brandão, Laura Sousa, José Ribeiro, António Silva, Carlos Pereira. A Disposable Saliva Electrochemical MIP-Based Biosensor for Detection of the Stress Biomarker α-Amylase in Point-of-Care Applications. Electrochem. 2021; 2 (3):427-438.
Chicago/Turabian StyleTânia Rebelo; Inês Miranda; Ana Brandão; Laura Sousa; José Ribeiro; António Silva; Carlos Pereira. 2021. "A Disposable Saliva Electrochemical MIP-Based Biosensor for Detection of the Stress Biomarker α-Amylase in Point-of-Care Applications." Electrochem 2, no. 3: 427-438.
Here we report the rational development of a carbon dot (CDs)-based fluorescent pH nanosensor by employing an active surface preservation strategy. More specifically, citric acid, urea and fluorescein were subjected to a one-pot hydrothermal treatment, which preserved fluorescein-like structures on the surface of the CDs. The obtained CDs showed pH-sensitive green emission, which can be used to determine pH variations from 3.7 to 12.1 by fluorescence enhancement. Moreover, the obtained nanoparticles showed excellent selectivity toward pH, fluorescence reversibility in different pH values, photostability, while being compatible with human cell lines (even at high concentrations). Furthermore, their performance as pH sensors was comparable with reference pH determination procedures. Thus, an active surface preservation strategy was successfully employed to develop fluorescence pH nanosensors in a rational manner and without post-synthesis functionalization strategies, which show potential for future use in pH determination.
Ana Afonso; Ana Correia; Diana Duarte; Ana Brandão; Maria de Yuso; José Jiménez-Jiménez; Nuno Vale; Carlos Pereira; Manuel Algarra; Luís Pinto da Silva. An Active Surface Preservation Strategy for the Rational Development of Carbon Dots as pH-Responsive Fluorescent Nanosensors. Chemosensors 2021, 9, 191 .
AMA StyleAna Afonso, Ana Correia, Diana Duarte, Ana Brandão, Maria de Yuso, José Jiménez-Jiménez, Nuno Vale, Carlos Pereira, Manuel Algarra, Luís Pinto da Silva. An Active Surface Preservation Strategy for the Rational Development of Carbon Dots as pH-Responsive Fluorescent Nanosensors. Chemosensors. 2021; 9 (8):191.
Chicago/Turabian StyleAna Afonso; Ana Correia; Diana Duarte; Ana Brandão; Maria de Yuso; José Jiménez-Jiménez; Nuno Vale; Carlos Pereira; Manuel Algarra; Luís Pinto da Silva. 2021. "An Active Surface Preservation Strategy for the Rational Development of Carbon Dots as pH-Responsive Fluorescent Nanosensors." Chemosensors 9, no. 8: 191.
Metal and alloys electrodeposition from aqueous electrolytes is restricted due to the narrow electrochemical window and hydrogen evolution. To overcome these disadvantages, over the past years, ionic liquids (ILs) and deep eutectic solvents (DES) based on choline chloride have been successfully applied for the electrodeposition of different metals.Tin (Sn) layers applied to automotive or decorative plating are thought of as ecological alternatives to exchange lead and nickel/chromium coatings. Over the past few years, the attention drawn by metallic alloys and composites, namely Sn alloys (nickel, indium, copper, zinc…) and Sn-carbon materials composites, has increased due to the possibility of applying these materials as anodes for lithium-ion batteries.This review will highlight the leading research regarding the electrodeposition of Sn and several alloys and carbon composites, emphasizing the morphological changes of the alloy combinations using DESs as electrolytes.
Ana Teresa Silva Cardoso Brandão; Renata Costa; António Fernando Silva; Carlos Manuel De Melo Pereira. Nanostructured Tin-based Alloys Composites using Deep Eutectic Solvents as Electrolytes. U.Porto Journal of Engineering 2020, 6, 70 -85.
AMA StyleAna Teresa Silva Cardoso Brandão, Renata Costa, António Fernando Silva, Carlos Manuel De Melo Pereira. Nanostructured Tin-based Alloys Composites using Deep Eutectic Solvents as Electrolytes. U.Porto Journal of Engineering. 2020; 6 (2):70-85.
Chicago/Turabian StyleAna Teresa Silva Cardoso Brandão; Renata Costa; António Fernando Silva; Carlos Manuel De Melo Pereira. 2020. "Nanostructured Tin-based Alloys Composites using Deep Eutectic Solvents as Electrolytes." U.Porto Journal of Engineering 6, no. 2: 70-85.
Nano carbons, such as graphene and carbon nanotubes, show very interesting electrochemical properties and are becoming a focus of interest in many areas, including electrodeposition of carbon–metal composites for battery application. The aim of this study was to incorporate carbon materials (namely oxidized multi-walled carbon nanotubes (ox-MWCNT), pristine multi-walled carbon nanotubes (P-MWCNT), and reduced graphene oxide (rGO)) into a metallic tin matrix. Formation of the carbon–tin composite materials was achieved by electrodeposition from a choline chloride-based ionic solvent. The different structures and treatments of the carbon materials will create metallic composites with different characteristics. The electrochemical characterization of Sn and Sn composites was performed using chronoamperometry, potentiometry, electrochemical impedance, and cyclic voltammetry. The initial growth stages of Sn and Sn composites were characterized by a glassy-carbon (GC) electrode surface. Nucleation studies were carried out, and the effect of the carbon materials was characterized using the Scharifker and Hills (SH) and Scharifker and Mostany (SM) models. Through a non-linear fitting method, it was shown that the nucleation of Sn and Sn composites on a GC surface occurred through a 3D instantaneous process with growth controlled by diffusion. According to Raman and XRD analysis, carbon materials were successfully incorporated at the Sn matrix. AFM and SEM images showed that the carbon incorporation influences the coverage of the surface as well as the size and shape of the agglomerate. From the analysis of the corrosion tests, it is possible to say that Sn-composite films exhibit a comparable or slightly better corrosion performance as compared to pure Sn films.
Ana T. S. C. Brandão; Liana Anicai; Oana Andreea Lazar; Sabrina Rosoiu; Aida Pantazi; Renata Costa; Marius Enachescu; Carlos M. Pereira; A. Fernando Silva. Electrodeposition of Sn and Sn Composites with Carbon Materials Using Choline Chloride-Based Ionic Liquids. Coatings 2019, 9, 798 .
AMA StyleAna T. S. C. Brandão, Liana Anicai, Oana Andreea Lazar, Sabrina Rosoiu, Aida Pantazi, Renata Costa, Marius Enachescu, Carlos M. Pereira, A. Fernando Silva. Electrodeposition of Sn and Sn Composites with Carbon Materials Using Choline Chloride-Based Ionic Liquids. Coatings. 2019; 9 (12):798.
Chicago/Turabian StyleAna T. S. C. Brandão; Liana Anicai; Oana Andreea Lazar; Sabrina Rosoiu; Aida Pantazi; Renata Costa; Marius Enachescu; Carlos M. Pereira; A. Fernando Silva. 2019. "Electrodeposition of Sn and Sn Composites with Carbon Materials Using Choline Chloride-Based Ionic Liquids." Coatings 9, no. 12: 798.
Considering the high incidence level and mortality rate of ovarian cancer, particularly among the European female population, the carbohydrate antigen 125 (CA-125) was selected as the protein target for this study for the development of a MIP-based biosensor. This work presents the development of molecular imprinting polymers (MIPs) on gold electrode surface for CA-125 biomarker recognition. The preparation of the CA-125 imprinting was obtained by electropolymerization of pyrrole (Py) monomer in a gold electrode using cyclic voltammetry (CV) in order to obtain highly selective materials with great molecular recognition capability. The quantification of CA-125 biomarker was made through the comparison of two methods: electrochemical (square wave voltammetry -SWV) and optical transduction (surface plasmon resonance -SPR). SWV has been widely used in biological molecules analysis since it is a fast and sensitive technique. In turn, SPR is a non-destructive optical technique that provides high-quality analytical data of CA-125 biomarker interactions with MIP. Several analytical parameters, such as sensitivity, linear response interval, and detection limit were determined to proceed to the performance evaluation of the electrochemical and optical transduction used in the development of the CA-125 biosensor. The biosensor based in the electrochemical transduction was the one that presented the best analytical parameters, yielding a good selectivity and a detection limit (LOD) of 0.01 U/mL, providing a linear concentration range between 0.01 and 500 U/mL. This electrochemical biosensor was selected for the study and it was successfully applied in the CA-125 analysis in artificial serum samples with recovery rates ranging from 91 to 105% with an average relative error of 5.8%.
Tânia Rebelo; Renata Costa; Ana T.S.C. Brandão; A Fernando Silva; M. Goreti F. Sales; Carlos M. Pereira. Molecularly imprinted polymer SPE sensor for analysis of CA-125 on serum. Analytica Chimica Acta 2019, 1082, 126 -135.
AMA StyleTânia Rebelo, Renata Costa, Ana T.S.C. Brandão, A Fernando Silva, M. Goreti F. Sales, Carlos M. Pereira. Molecularly imprinted polymer SPE sensor for analysis of CA-125 on serum. Analytica Chimica Acta. 2019; 1082 ():126-135.
Chicago/Turabian StyleTânia Rebelo; Renata Costa; Ana T.S.C. Brandão; A Fernando Silva; M. Goreti F. Sales; Carlos M. Pereira. 2019. "Molecularly imprinted polymer SPE sensor for analysis of CA-125 on serum." Analytica Chimica Acta 1082, no. : 126-135.
Buckypapers prepared using CNTs with tailored surface chemistry showed better performance than the commercial PTFE in membrane distillation of salty water.
Sergio Morales-Torres; Tânia Luísa Santos Silva; Luisa M. Pastrana-Martínez; Ana T. S. C. Brandão; José Figueiredo; Adrián M. T. Silva. Modification of the surface chemistry of single- and multi-walled carbon nanotubes by HNO3 and H2SO4 hydrothermal oxidation for application in direct contact membrane distillation. Physical Chemistry Chemical Physics 2014, 16, 12237 -12250.
AMA StyleSergio Morales-Torres, Tânia Luísa Santos Silva, Luisa M. Pastrana-Martínez, Ana T. S. C. Brandão, José Figueiredo, Adrián M. T. Silva. Modification of the surface chemistry of single- and multi-walled carbon nanotubes by HNO3 and H2SO4 hydrothermal oxidation for application in direct contact membrane distillation. Physical Chemistry Chemical Physics. 2014; 16 (24):12237-12250.
Chicago/Turabian StyleSergio Morales-Torres; Tânia Luísa Santos Silva; Luisa M. Pastrana-Martínez; Ana T. S. C. Brandão; José Figueiredo; Adrián M. T. Silva. 2014. "Modification of the surface chemistry of single- and multi-walled carbon nanotubes by HNO3 and H2SO4 hydrothermal oxidation for application in direct contact membrane distillation." Physical Chemistry Chemical Physics 16, no. 24: 12237-12250.