Correction: An impedimetric immunosensor for diagnosis of Brazilian spotted fever in blood plasma.

Correction for 'An impedimetric immunosensor for diagnosis of Brazilian spotted fever in blood plasma' by Marx Osório Araújo Pereira et al., Anal. Methods, 2024, https://doi.org/10.1039/d3ay01308a.

A voltammetric peptide biosensor for Cu2+ metal ion quantification in coffee seeds.

A prion-derived copper(II)-binding peptide was assembled onto a gold electrode for the building of a voltammetric biosensor for measuring the Cu2+ metal ion in biological samples. The chosen sequence was H-CVNITKQHTVTTTT-NH2, with an appended cysteine residue for binding to the gold surface as a self-assembled monolayer and a histidine residue as the anchorage point for copper(II) complexation. The biosensor showed a linear range of 10-7 to 10-6 M with an 8.0 × 10-8 M detection limit and a 1.0 × 10-7 M quantification limit, with good precision, trueness, and absence of matrix effect. The quantification of Cu2+ was performed in the presence of other transition metal ions, such as Zn2+, Cd2+, Fe2+, or Ni2+, which indicates the excellent selectivity of the biosensor. When the modified electrode was applied for measuring copper(II) in calcined coffee seeds, a difference in copper amount was observed between two Coffea arabica cultivars that were submitted to a treatment with a copper-based antifungal, showing the applicability of the biosensor in the agricultural field.

An impedimetric immunosensor for diagnosis of Brazilian spotted fever in blood plasma.

Brazilian spotted fever (BSF) is a serious disease of medical importance due to its rapid evolution and high lethality. The effectiveness of the treatment mainly depends on the rapid diagnosis, which is currently performed by indirect immunofluorescence and PCR tests, which require high costs and laboratory structure. In order to propose an alternative methodology, we sought to develop an impedimetric immunosensor (IM) based on the immobilization of specific IgY antibodies for IgG anti Rickettsia rickettsii, using blood plasma from capybara (Hydrochoerus hydrochaeris), for characterization, validation and applications of the ready IM. IM selectivity was observed when comparing capybara reagent IgG (IgGcr) readings with non-reagent IgG (IgGnr). A reagent IgG calibration curve was obtained, from which the limits of detection (LOD) and quantification (LOQ) of 1.3 ng mL-1 and 4.4 ng mL-1 were calculated, respectively. The accuracy tests showed that different concentrations of IgGcr showed a maximum deviation of 20.0%, with CI between 90.00% and 95.00%. Intermediate precision tests showed a relative standard deviation of 2.09% for researcher 1 and 2.61% for researcher 2, and the F test showed no significant difference between the recovery values found between the two analysts, since Fcal 1.56 < 5.05 and P-value 0.48 > 0, 05. Therefore, an impedimetric immunosensor was developed to detect anti BSF IgG in capybara blood plasma, which greatly contributes to the improvement of diagnostic tests, cost reduction and ease of execution.

Novel matrix formulation for resin composite: Chemical and biomechanical characterization - Part 1.

OBJECTIVE: This study aimed to investigate the effects of adding cholesteryl methacrylate (CM) monomer to experimental composite resins and evaluate its impact on polymerization shrinkage force (PSF), Knoop microhardness (KHN), sorption and solubility (SS), vulnerability to spontaneous oxidation (VOE), porosity (BES), viscosity (V), and cross-link density (CLD). CM was synthesized, mixed with varying proportions of Bis-GMA, 70 wt% filler particles, and 40 % TEGDMA. The groups tested were: CM0 (60 % Bis-GMA), CM6 (54 % Bis-GMA/6 % CM), CM12 (48 % Bis-GMA/12 % CM), CM18 (42 % Bis-GMA/18 % CM) and CM24 (36 % Bis-GMA/24 % CM). The PSF was evaluated using a universal testing machine. KHN was measured with a 50 g load for 30 s. SS was determined according to ISO 4049:2009. VOE was measured with a three-electrode system in an electrochemical cell. BES images were obtained using an electron microscope to assess porosity. Viscosity was measured through rheological analysis. CLD was estimated from hardness readings before and after ethanol storage. RESULTS: CM6 (0.34 N) and CM12 (0.34 N) exhibited the lowest PSF values compared to CM0 (0.91 N). For KHN, CM6 (32.03) and CM12 (31.03) had higher values than CM0 (25.83) and were similar to CM18 (29.39) and CM24 (28.64). SS showed no significant differences among the groups. VOE indicated low vulnerability across all groups. CM12 had greater porosity compared to CM0 in BES images. CM0 had the lowest viscosity among the groups. No differences in CLD were observed among CM0, CM12, CM18, and CM24 regarding softening effects. SIGNIFICANCE: Adding CM to Bis-GMA/TEGDMA composite resins can reduce polymerization shrinkage force and increase the initial Knoop microhardness without affecting the other properties studied.

Characterization of experimental resin composites with cholesteryl methacrylate organic matrix - Part 2.

OBJECTIVE: The aim of this study was to evaluate the degree of conversion (%), flexural strength (MPa), elastic modulus (GPa), compressive strength (MPa), Knoop microhardness (KHN), post-gel shrinkage (%) and prediction of ideal concentration of cholesteryl methacrylate (CM) in experimental resins. METHODS: Four formulations were manipulated (F): F1, control group, (0 % CM); F2 (15 % CM); F3 (19.8 % CM) and F4 (30 % CM). Bis-GMA and CM percentages were determined using Statistica™ software. For the degree of conversion test, Raman spectroscopy was used. To testing flexural strength, elastic modulus and compressive strength, a universal testing machine was used. For the Knoop microhardness test five indentations were made in each sample. Post-gel shrinkage was determined using the strain gauge method. Statistica™ software processed all data obtained in this study. Results were submitted to one-way ANOVA and Tukey's post hoc tests (α = 0.05). RESULTS: Better performance was observed for F2 (15 % CM) and F3 (19,8 % CM) for degree of conversion, elastic modulus and post-gel shrinkage. For Knoop microhardness F2 (15 % CM), F3 (19,8 % CM) and F4 (30 % CM) showed higher values than F1 (0 % CM). For flexural strength F1 (0 % CM) and F3 (19,8 %) were similar and F4 showed the lowest values and for compressive strength F1 (0 % CM) showed the highest values. For mixture designs analysis data, concentrations ≤ 25 % of CM would provide better results. SIGNIFICANCE: Addition of CM at concentrations lower than 30 % contributed to a significant increase in the degree of conversion, microhardness values, elastic modulus and reduction of post-gel shrinkage.

Antioxidant and Vasodilatory Action of Grape Juices Produced in Different Regions of Brazil

Grapes and its derivatives (wines and juices) are rich in polyphenols that have high antioxidant and vasodilator capacity. These biological activities may vary in the juices marketed and produced in different regions of Brazil. Objectives: To determine the antioxidant and vasorelaxant effects of grape juice samples produced in different regions of Brazil. Methods: The content of phenolic compounds and antioxidant capacity were evaluated by the methods of Folin-Ciocalteau, DPPH, ABTS and a new electroanalytical approach (differential pulse voltammetry - DPV). Vasodilator effects were analyzed in isolated aorta from rats in an organ bath. Results: The samples from RJ and SP presented respectively the higher and lower phenolic content and also antioxidant capacity by the methods used (ABTS and DPPH). The results of the electrochemical index corroborate to the other tests, with the best results to RJ (21.69 ± 3.15 µA/V) and worse to the SP sample (11.30 ± 0.52 µA/V). In the vascular reactivity studies, the relaxation induced by each sample presented more distinct differences, following the order: RJ (87.9 ± 4.8%) > RS1 (71.6 ± 8.6%) > GO (56.2 ± 7.2%) > SP (39.9 ± 7.8%) > PR (39.4 ± 9.5%) > RS2 (19.5 ± 6.2%). Inhibition of endothelial NO practically abolished (p < 0.001) the relaxation for all samples, except one. Conclusion: The phenolic content and antioxidant capacity vary greatly among samples. The results obtained for the order of antioxidant activity were: RJ > RS1 > GO > RS2 > PR > SP. The juices were able to induce vascular relaxation at quite varied levels, and the RJ sample the most effective. The L-NAME practically blocked all samples except one (RS2)