Development of a graphite biodegradable composite based on NADES and soy wax association applied as a binder for carbon paste electrodes Thaís D. T. Santos, Beatriz A. Fernandes, Jonatha de Freitas, Suysia R. D.’A. Slusarenco, Rafael M. Buoro Journal of Solid State Electrochemistry, 2026 Natural deep eutectic solvents (NADES) have emerged as promising alternatives to conventional organic solvents, offering advantages such as low melting points and biodegradability, aligned with green chemistry principles. In this work, a hydrophobic NADES (hNADES) composed of menthol and decanoic acid (1:1 molar ratio) was combined with soy wax to formulate a biodegradable binder for carbon paste electrodes (CPE), serving as a substitute for mineral oil. The binder and its precursors were characterized by thermal analyses (TGA/DTG and DSC) and FTIR spectroscopy, which evidenced chemical interactions between soy wax and hNADES through marked shifts in functional groups associated with hydrogen-bond formation. A hydrophilic ternary NADES based on glucose, tartaric acid, and glycerol (tNADES (gly) ) was also incorporated to enhance conductivity by improving paste cohesion and promoting proton-coupled electron transfer (PCET) mechanisms, attributed to the presence of free carboxylic acid groups. Electrochemical performance was assessed via cyclic voltammetry, enabling optimization of composition and identification of CPE (50) /hNADES:wax(3:1)/20%tNADES (gly) as the most suitable formulation. Electrochemical impedance spectroscopy further confirmed a pronounced decrease in charge-transfer resistance for the sustainable composite when compared with mineral-oil-based CPE (bare CPE). The resulting electrode, composed exclusively of non-toxic and biodegradable components, was evaluated to detect ascorbic acid, paracetamol, and sulfamethoxazole using differential pulse voltammetry, demonstrating its potential as an environmentally friendly electrochemical sensor which application could be further investigated to detect pollutants in hydric resources, for instance. The most significant analytical response was observed for paracetamol oxidation, presenting higher peak current values and better concentration-current correlation than the bare CPE (mineral oil composition).
Electrochemical Investigation of Tartrazine and Brilliant Blue Interactions with Surface-Immobilized DNA on DES-Modified Carbon Paste Electrodes Beatriz A. Fernandes, Suysia R. D’ A. Slusarenco, Rafael M. Buoro Journal of the Electrochemical Society, 2026 We present a novel DNA electrochemical biosensor based on a carbon paste electrode modified with deep eutectic solvents as a binder to evaluate the interaction mechanisms between ds-DNA and the food colorants tartrazine and brilliant blue. The DES-modified CPE (CPE-DES) exhibited enhanced conductivity and charge-transfer rates for the oxidation of DNA residues, specifically the purine bases adenine and guanine, as evidenced by increased peak current values. The higher oxidation current observed for dGuo in the presence of a choline chloride-based deep eutectic solvent suggests greater exposure of the ds-DNA base moiety on the electrode surface, likely due to a stronger interaction between the choline ion and the dGuo residue. The interaction mechanisms between ds-DNA and the dyes were investigated using differential pulse voltammetry and electrochemical impedance spectroscopy. The results indicate that TZ interacts with ds-DNA primarily through groove binding, inducing conformational changes and strong DNA condensation. TheBB interacts with ds-DNA via electrostatic binding, causing the DNA helix to lengthen. For the TZ-BB mixture, the interactions likely involve both groove binding and electrostatic interaction. UV–vis and DC spectroscopy further supported these findings. Modifying CPE binders with DES demonstrates significant potential for evaluating interactions between ds-DNA and target molecules.
Insights into the Mechanism-Dependent Efficiency of the Electrocatalytic Oxygen Evolution Reaction on Octacarboxyphthalocyanine-Based Coordination Polymers Ítalo R. Machado, Raphael P. Bacil, Victor Vendruscolo, Rafael M. Buoro, Helton P. Nogueira, Robson R. Guimarães, Sergio H. Toma, Márcia C. A. Fantini, Josué M. Gonçalves, Koiti Araki ACS Applied Energy Materials, 2024 Cobalt and iron octacarboxyphthalocyanines based MaOcPc-Mb-type coordination polymers (where Ma = Fe2+ or Co2+, and Mb = Fe2+, Co2+, or Ni2+) were prepared and characterized and their oxygen evolution reaction electrocatalytic properties carefully evaluated using an experimental/theoretical approach. FeOcPc-Ni stands out among them as the electrocatalyst with the best performance, as confirmed by the low overpotential (η10 = 299 mV at ν = 0.020 V s–1) and Tafel slope (46.4 mV dec–1), results that were reinforced by additional parameters from Tafel, foot of the wave, turnover frequency, and electrochemical impedance spectroscopy analyses. The reaction mechanism was found to involve the formation of a peroxide intermediate where the rate-determining step can be either (a) the adsorption of the substrate (hydroxide ion or water) or (b) the regeneration of the catalyst at the end of the OER process in a competitive fashion. Turnover frequency analysis combined with foot of the wave analysis was shown to be a powerful tool, especially when associated with the analyses of the voltammetric and electrochemical impedance spectroscopy profiles, to evaluate the performance and mechanism of electrocatalytic materials. Both the bridging ligand and the macrocyclic ring-coordinated transition metal were shown to contribute synergic effects, boosting the electrocatalytic properties of the FeOcPc-Ni coordination polymer and increasing its potential as an oxidation electrocatalyst to close the circuit in reduction processes in aqueous media, such as hydrogen gas production by water splitting, nitrogen and CO2 reduction to ammonia, and processes involving low-molecular-weight hydrocarbons.
Binary and Ternary Deep Eutectic Solvents for Methylene Green Electropolymerization on Multiwalled Carbon Nanotubes: Optimization, Characterization and Application Joseany M. S. Almeida, Zeferino S. B. Pedro, Rafael M. Buoro, Christopher M. A. Brett Chemistry A European Journal, 2024 Choline chloride (ChCl) based binary and ternary deep eutectic solvents (DES) were evaluated for methylene green electropolymerization with oxalic acid (OA) and ethylene glycol (EG) as hydrogen bond donors. Binary DES ChCl : OA in molar ratios 1 : 1 and 2 : 1 and ChCl : EG 1 : 2 and ternary DES (tDES) in different molar ratios and percentages of water were evaluated. The highest polymer growth was in ChCl : OA : EG‐tDES with 13% added water, that had a lower viscosity and higher ionic conductivity when associated with HCl as dopant. This enhanced the formation of more cation radicals and, consequently, more polymer formation. The PMG/MWCNT/GCE‐tDES sensor was successfully applied to the simultaneous determination of 5‐aminosalicylic acid (5‐ASA) and acetaminophen (APAP) by differential pulse voltammetry in the concentration range 1 μM–200 μM, with detection limits of 0.37 μM and 0.49 μM for 5‐ASA and APAP, respectively. The sensor demonstrated good repeatability, reproducibility and stability, and was successfully applied in pharmaceutical formulations.
Cresyl violet electropolymerization on functionalized multiwalled carbon nanotubes in carboxylic acid based ternary deep eutectic solvents for hydroquinone sensing Rafael M. Buoro, Joseany M.S. Almeida, Christopher M.A. Brett Electrochimica Acta, 2024 The phenazine dye cresyl violet (CVio) has been evaluated as precursor for the preparation of a new electrochemical sensor based on poly(cresyl violet) deposited on multiwalled carbon nanotube (CNT) modified glassy carbon electrodes (GCE) in neutralized acid-doped ternary deep eutectic solvents (DES). DES with choline chloride as hydrogen bond acceptor and with different hydrogen bond donors (HBD), namely acetic acid, ethylene glycol and oxalic acid were evaluated for CVio electropolymerization by potential cycling. The best polymer films were obtained in ternary DES with the two HBD acetic acid plus ethylene glycol doped with H2SO4 and followed by NaOH neutralization. Electrochemical characterization (voltammetric and electrochemical impedance) showed the formation of anthraquinone groups during electropolymerization, which is initiated on the CNT by the formation of a cation radical. Anthraquinones in the polymer film led to an increased response at the modified electrode for the determination of hydroquinone (H2Q) with low LOD (0.25 µmol L−1) in a broad linear range (1-80 µmol L−1), with good reproducibility, repeatability, and stability. The sensor was successfully applied to the quantification of H2Q in dermatological creams with no matrix effect towards hydroquinone response.
Aptasensing of beta-amyloid (Aβ(1−42)) by a 3D-printed platform integrated with leaf-shaped gold nanodendrites Masoud Negahdary, William Barros Veloso, Raphael Prata Bacil, Rafael Martos Buoro, Ivano Gebhardt Rolf Gutz, Thiago Regis Longo Cesar Paixão, Claudimir Lucio do Lago, Solange Kazumi Sakata, Gabriel Negrão Meloni, Mesaque Carvalho França, Thawan Gomes de Oliveira, Wilson Akira Ameku, Michelangelo Durazzo, Lúcio Angnes Sensors and Actuators B Chemical, 2023
