Tuning the Chemical and Electrochemical Properties of Paper-Based Carbon Electrodes by Pyrolysis of Polydopamine.

Electrochemical paper-based analytical devices represent an important platform for portable, low-cost, affordable, and decentralized diagnostics. For this kind of application, chemical functionalization plays a pivotal role to ensure high clinical performance by tuning surface properties and the area of electrodes. However, controlling different surface properties of electrodes by using a single functionalization route is still challenging. In this work, we attempted to tune the wettability, chemical composition, and electroactive area of carbon-paper-based devices by thermally treating polydopamine (PDA) at different temperatures. PDA films were deposited onto pyrolyzed paper (PP) electrodes and thermally treated in the range of 300-1000 °C. After deposition of PDA, the surface is rich in nitrogen and oxygen, it is superhydrophilic, and it has a high electroactive area. As the temperature increases, the surface becomes hydrophobic, and the electroactive area decreases. The surface modifications were followed by Raman, X-ray photoelectron microscopy (XPS), laser scanning confocal microscopy (LSCM), contact angle, scanning electron microscopy (SEM-EDS), electrical measurements, transmission electron microscopy (TEM), and electrochemical experiments. In addition, the chemical composition of nitrogen species can be tuned on the surface. As a proof of concept, we employed PDA-treated surfaces to anchor [AuCl4]- ions. After electrochemical reduction, we observed that it is possible to control the size of the nanoparticles on the surface. Our route opens a new avenue to add versatility to electrochemical interfaces in the field of paper-based electrochemical biosensors.

Effect of 2-chloro-N-(4-fluoro-3-nitrophenyl)acetamide in combination with antibacterial drugs against Klebsiella pneumoniae.

Klebsiella pneumoniae is a species of Gram-negative bacteria related to a wide range of infections and high rates of drug resistance. The combined use of antibacterial agents is one of the strategies that has been analyzed in recent years as part of the alternatives in the treatment of drug-resistant infections. Recently, the antibacterial activity of of 2-chloro-N-(4-fluoro-3-nitrophenyl)acetamide has been demonstrated against K. pneumoniae, also indicating that this acetamide did not show significant cytotoxic potential in preliminary tests. Thus, it becomes an interesting substance for future studies that explore its antimicrobial capacity, including investigating its association with antibacterial drugs. Based on this, this research aimed to analyze the effects of the association of 2-chloro-N-(4-fluoro-3-nitrophenyl)acetamide (CFA) with ciprofloxacin, cefepime, ceftazidime, meropenem and imipenem against K. pneumoniae strains. The results showed additivity when the substance was combined with ciprofloxacin and cefepime, indifference when associated with ceftazidime and synergistic effect when combined with meropenem and imipenem. Thus, the acetamide was able to optimize the effects of antibacterial drugs, reducing the concentrations necessary to cause bacterial death. These data indicate a potential future clinical use of these combinations, and further studies are needed to analyze this viability.

Checklist of the fish fauna of the Munim River Basin, Maranhão, north-eastern Brazil.

Background: The Maranhão State harbours great fish diversity, but some areas are still undersampled or little known, such as the Munim River Basin in the northeast of the State. This lack of knowledge is critical when considering anthropogenic impacts on riverine systems especially in the face of major habitat destruction. These pressing threats mean that a comprehensive understanding of diversity is critical and fish checklists extremely relevant. Therefore, the present study provides a checklist of the fish species found in the Munim River Basin, Maranhão State, north-eastern Brazil, based on collected specimens. New information: A total of 123 species were recorded for the Munim River Basin, with only two non-native species, Oreochromisniloticus and Colossomamacropomum, showing that the fish assemblage has relatively high ecological integrity. In addition, 29 species could not be identified at the species level, indicating the presence of species that are probably new to science in the Basin. A predominance of species belonging to the fish orders Characiformes and Siluriformes, with Characidae being recovered as the most species-rich family (21 species) agrees with the general pattern for river basins in the Neotropical Region. The total fish diversity was estimated by extensive fieldwork, including several sampling gears, carried out in different seasons (dry and rainy) and exploring different environments with both daily and nocturnal sampling, from the Basin's source to its mouth. A total of 84 sites were sampled between 2010 and 2022, resulting in 12 years of fieldwork. Fish assemblages were distinct in the Estuary and Upper river basin sections and more similar in the Lower and Middle sections indicating environmental filtering processes. Species were weakly nested across basin sections, but unique species were found in each section (per Simpsons Index). High variability of species richness in the Middle river basin section is likely due to microhabitat heterogeneity supporting specialist fish communities.

Physical therapists and public perceptions of telerehabilitation: An online open survey on acceptability, preferences, and needs.

BACKGROUND: During the COVID-19 pandemic, telerehabilitation allowed the continuation of physical therapy care in parallel with public health measures to prevent the virus spread. However, in low- and middle-income countries including Brazil, telerehabilitation was unfamiliar to most of the population. OBJECTIVE: To investigate acceptability, preferences, and needs in telerehabilitation by Brazilian physical therapists and the general population. METHODS: We conducted an observational cross-sectional study with an online survey consisting of 13 multiple-choice items. Items were distributed among acceptability, preferences, and needs sections, and encompassed confidence in delivering or receiving telerehabilitation, its perceived efficacy and costs, and suitable content. RESULTS: A total of 1107 responses were registered, 717 from physical therapists. Half of them self-reported confidence in conducting telerehabilitation through the internet (synchronous or asynchronous). The same proportion disagreed that telerehabilitation is as effective as in-person interventions. Physical therapists agreed telerehabilitation should contain educational, self-management strategies, and exercises information, but the general population endorsed the provision of technical advice on exercise execution. The general population mostly reported that telerehabilitation could help their specific health condition (86%), but only 14% of respondents would pay the same as they pay for in-person consultations. Participants reported an overall preference for synchronous communication and concern about the lack of a hands-on approach. CONCLUSION: Physical therapists and the general population appear to demonstrate apprehension towards telerehabilitation. Insufficient preparation or inadequate knowledge might influence participants' acceptance, preferences, and needs.

Trans-fatty acids aggravate anabolic steroid-induced metabolic disturbances and differential gene expression in muscle, pancreas and adipose tissue.

AIMS: Although anabolic steroids (AS) and trans-fatty acids overload exerts systemic toxicity and are independent risk factors for metabolic and cardiovascular disorders, their interaction remains poorly understood. Thus, we investigated the impact of a diet rich in trans-fatty acids (HFD) combined with AS on glycemic control, lipid profile, adipose tissue, skeletal muscle and pancreas microstructure and expression of genes involved in energy metabolism. MAIN METHODS: Forty-eight C57BL/6 mice were randomized into 6 groups treated for 12 weeks with a standard diet (SD) or a diet rich in C18:1 trans-fatty isomers (HFD), alone or combined with 10 or 20 mg/kg testosterone cypionate (AS). KEY FINDINGS: Our results indicated that AS improved glycemic control, upregulated gene expression of Glut-4 and CPT-1 in skeletal muscle, FAS, ACC and UCP-1 in adipose tissue. AS also reduced total and LDL cholesterol in mice fed a SD. When combined with the HFD, AS was unable to induce microstructural adaptations in adipose tissue, pancreatic islets and ß-cells, but potentiated GCK and Glut-2 (pancreas) and Glut-4 and CPT-1 (skeletal muscle) upregulation. HFD plus AS also downregulated FAS and ACC gene expression in adipose tissue. Combined with HFD, AS increased triacylglycerol circulating levels, improved insulin sensitivity and glycemic control in mice. SIGNIFICANCE: Our findings indicated that HFD and AS can interact to modulates glycemic control and lipid profile by a mechanism potentially related with a reprogramming of genes expression in organs such as the pancreas, adipose tissue and skeletal muscle.

Enhanced mobility and controlled transparency in multilayered reduced graphene oxide quantum dots: a charge transport study.

Reduced graphene oxide (rGO) layers are known to be significantly conductive along the basal plane throughout delocalized sp2 domains. Defects present in rGO implies in disordered systems with numerous localized sites, resulting in a charge transport governed mainly by a 2D variable range hopping (VRH) mechanism. These characteristics are observed even in multilayered rGO since the through-plane conduction is expected to be insubstantial. Here, we report on the multilayer assembly of functionalized rGO quantum dots (GQDs) presenting 3D VRH transport that endows elevated charge carrier mobility, ca âˆ¼ 236 cm2 V-1 s-1. Polyelectrolyte-wrapped GQDs were assembled by layer-by-layer technique (LbL), ensuring molecular level thickness control for the formed nanostructures, along with the adjustment of the film transparency (up to 92% in the visible region). The small size and the random distribution of GQDs in the LbL structure are believed to overcome the translational disorder in multilayered films, contributing to a 3D interlayer conduction that enhances the electronic properties. Such high-mobility, transparency-tunable films assembled by a cost-effective method possess interesting features and wide applicability in optoelectronics.

Poole-Frenkel emission on functionalized, multilayered-packed reduced graphene oxide nanoplatelets.

The unique electronic, mechanical and optical properties of graphene make it a remarkable 2D material, widely explored in a plethora of applications. However, graphene zero-bandgap and the production of defect-free pristine graphene in large areas still limit some applications. To circumvent these issues, graphene-derived 2D materials have arisen as attractive candidates for low-dimensional systems, which requires a better comprehension of their properties. Here, we report a detailed investigation of the conduction mechanisms of two functionalized reduced graphene oxides (rGOs) nanoplatelets, named GPAH and GPSS. The functionalized rGO nanoplatelets were bottom-up assembled via the layer-by-layer technique, enabling molecular-level thickness control of nanostructures with well-defined composition and structure. For the reported multilayered GPAH/GPSS films the charge carriers followed Mott's law, presenting a typical conduction behavior of 2D systems described by the Poole-Frenkel model. The multilayered GPAH/GPSS nanostructure presented a conductivity of 10-4 S cm-1, optical bandgap of ∼3.3 eV and a relative dielectric permittivity (ε r) of 6.4. Temperature-dependent I-V measurements indicated a strong variation of ε r below the critical temperature (T C = 237 K), associated with a high dipole reorientation in the formed GPAH/GPSS nanostructure. All these characteristics make the GPAH/GPSS nanocomposite attractive for graphene-oriented applications, such as electronic devices.

Hybrid nanomembrane-based capacitors for the determination of the dielectric constant of semiconducting molecular ensembles.

Considerable advances in the field of molecular electronics have been achieved over the recent years. One persistent challenge, however, is the exploitation of the electronic properties of molecules fully integrated into devices. Typically, the molecular electronic properties are investigated using sophisticated techniques incompatible with a practical device technology, such as the scanning tunneling microscopy. The incorporation of molecular materials in devices is not a trivial task as the typical dimensions of electrical contacts are much larger than the molecular ones. To tackle this issue, we report on hybrid capacitors using mechanically-compliant nanomembranes to encapsulate ultrathin molecular ensembles for the investigation of molecular dielectric properties. As the prototype material, copper (II) phthalocyanine (CuPc) has been chosen as information on its dielectric constant (k CuPc) at the molecular scale is missing. Here, hybrid nanomembrane-based capacitors containing metallic nanomembranes, insulating Al2O3 layers, and the CuPc molecular ensembles have been fabricated and evaluated. The Al2O3 is used to prevent short circuits through the capacitor plates as the molecular layer is considerably thin (<30 nm). From the electrical measurements of devices with molecular layers of different thicknesses, the CuPc dielectric constant has been reliably determined (k CuPc = 4.5 ± 0.5). These values suggest a mild contribution of the molecular orientation on the CuPc dielectric properties. The reported nanomembrane-based capacitor is a viable strategy for the dielectric characterization of ultrathin molecular ensembles integrated into a practical, real device technology.

Charge carrier transport in defective reduced graphene oxide as quantum dots and nanoplatelets in multilayer films.

Graphene is a breakthrough 2D material due to its unique mechanical, electrical, and thermal properties, with considerable responsiveness in real applications. However, the coverage of large areas with pristine graphene is a challenge and graphene derivatives have been alternatively exploited to produce hybrid and composite materials that allow for new developments, considering also the handling of large areas using distinct methodologies. For electronic applications there is significant interest in the investigation of the electrical properties of graphene derivatives and related composites to determine whether the characteristic 2D charge transport of pristine graphene is preserved. Here, we report a systematic study of the charge transport mechanisms of reduced graphene oxide chemically functionalized with sodium polystyrene sulfonate (PSS), named as GPSS. GPSS was produced either as quantum dots (QDs) or nanoplatelets (NPLs), being further nanostructured with poly(diallyldimethylammonium chloride) through the layer-by-layer (LbL) assembly to produce graphene nanocomposites with molecular level control. Current-voltage (I-V) measurements indicated a meticulous growth of the LbL nanostructures onto gold interdigitated electrodes (IDEs), with a space-charge-limited current dominated by a Mott-variable range hopping mechanism. A 2D intra-planar conduction within the GPSS nanostructure was observed, which resulted in effective charge carrier mobility (µ) of 4.7 cm2 V-1 s-1 for the QDs and 34.7 cm2 V-1 s-1 for the NPLs. The LbL assemblies together with the dimension of the materials (QDs or NPLs) were favorably used for the fine tuning and control of the charge carrier mobility inside the LbL nanostructures. Such 2D charge conduction mechanism and high µ values inside an interlocked multilayered assembly containing graphene-based nanocomposites are of great interest for organic devices and functionalization of interfaces.

A simple capacitive method to evaluate ethanol fuel samples.

Ethanol is a biofuel used worldwide. However, the presence of excessive water either during the distillation process or by fraudulent adulteration is a major concern in the use of ethanol fuel. High water levels may cause engine malfunction, in addition to being considered illegal. Here, we describe the development of a simple, fast and accurate platform based on nanostructured sensors to evaluate ethanol samples. The device fabrication is facile, based on standard microfabrication and thin-film deposition methods. The sensor operation relies on capacitance measurements employing a parallel plate capacitor containing a conformational aluminum oxide (Al2O3) thin layer (15 nm). The sensor operates over the full range water concentration, i.e., from approximately 0% to 100% vol. of water in ethanol, with water traces being detectable down to 0.5% vol. These characteristics make the proposed device unique with respect to other platforms. Finally, the good agreement between the sensor response and analyses performed by gas chromatography of ethanol biofuel endorses the accuracy of the proposed method. Due to the full operation range, the reported sensor has the technological potential for use as a point-of-care analytical tool at gas stations or in the chemical, pharmaceutical, and beverage industries, to mention a few.

Multiscale sensing of antibody-antigen interactions by organic transistors and single-molecule force spectroscopy.

Antibody-antigen (Ab-Ag) recognition is the primary event at the basis of many biosensing platforms. In label-free biosensors, these events occurring at solid-liquid interfaces are complex and often difficult to control technologically across the smallest length scales down to the molecular scale. Here a molecular-scale technique, such as single-molecule force spectroscopy, is performed across areas of a real electrode functionalized for the immunodetection of an inflammatory cytokine, viz. interleukin-4 (IL4). The statistical analysis of force-distance curves allows us to quantify the probability, the characteristic length scales, the adhesion energy, and the time scales of specific recognition. These results enable us to rationalize the response of an electrolyte-gated organic field-effect transistor (EGOFET) operated as an IL4 immunosensor. Two different strategies for the immobilization of IL4 antibodies on the Au gate electrode have been compared: antibodies are bound to (i) a smooth film of His-tagged protein G (PG)/Au; (ii) a 6-aminohexanethiol (HSC6NH2) self-assembled monolayer on Au through glutaraldehyde. The most sensitive EGOFET (concentration minimum detection level down to 5 nM of IL4) is obtained with the first functionalization strategy. This result is correlated to the highest probability (30%) of specific binding events detected by force spectroscopy on Ab/PG/Au electrodes, compared to 10% probability on electrodes with the second functionalization. Specifically, this demonstrates that Ab/PG/Au yields the largest areal density of oriented antibodies available for recognition. More in general, this work shows that specific recognition events in multiscale biosensors can be assessed, quantified, and optimized by means of a nanoscale technique.

Pattern recognition techniques applied to the study of leishmanial glyceraldehyde-3-phosphate dehydrogenase inhibition.

Chemometric pattern recognition techniques were employed in order to obtain Structure-Activity Relationship (SAR) models relating the structures of a series of adenosine compounds to the affinity for glyceraldehyde 3-phosphate dehydrogenase of Leishmania mexicana (LmGAPDH). A training set of 49 compounds was used to build the models and the best ones were obtained with one geometrical and four electronic descriptors. Classification models were externally validated by predictions for a test set of 14 compounds not used in the model building process. Results of good quality were obtained, as verified by the correct classifications achieved. Moreover, the results are in good agreement with previous SAR studies on these molecules, to such an extent that we can suggest that these findings may help in further investigations on ligands of LmGAPDH capable of improving treatment of leishmaniasis.

T Cell Activation and Proinflammatory Cytokine Production in Clinically Cured Tuberculosis Are Time-Dependent and Accompanied by Upregulation of IL-10.

BACKGROUND: Th1 cytokines are essential for the control of M. tuberculosis infection. The role of IL-10 in tuberculosis is controversial and there is an increasing body of evidence suggesting that the relationship between Th1 cytokines and IL-10 is not as antagonistic as it was first believed, and that these cytokines may complement each other in infectious diseases. METHODS: The present study evaluated the activating capacity of CD4+ and CD8+ T cell repertoire in response to antigen stimulation through the expression of CD69 using Flow Cytometry, as well as the functionality of PBMCs by determining the cytokine profile in patients with active tuberculosis and in clinically cured patients after in vitro stimulation using ELISA. Treated patients were subdivided according to time after clinical cure (<12 months or >12 months post-treatment). RESULTS: We observed that T cell activation was higher in TB-treated patients, especially CD8+ T cell activation in TB-Treated >1 year. Th1 cytokines were significantly higher in TB-Treated, and the levels of IFN-γ and TNF-α increased continuously after clinical cure. Moreover, IL-10 production was significantly higher in cured patients and it was also enhanced in cured patients over time after treatment. Th17, Th2 and Th22 cytokines showed no statistically significant differences between Healthy Donors, Active-TB and TB-Treated. CONCLUSIONS: This study describes a scenario in which potentiation of CD4+ and CD8+ T cell activation and increased Th1 cytokine production are associated with the clinical cure of tuberculosis in the absence of significant changes in Th2 cytokine production and is accompanied by increased production of IL-10. In contrast to other infections with intracellular microorganisms, this response occurs later after the end of treatment.

Identification of electronic and structural descriptors of adenosine analogues related to inhibition of leishmanial glyceraldehyde-3-phosphate dehydrogenase.

Quantitative structure-activity relationship (QSAR) studies were performed in order to identify molecular features responsible for the antileishmanial activity of 61 adenosine analogues acting as inhibitors of the enzyme glyceraldehyde 3-phosphate dehydrogenase of Leishmania mexicana (LmGAPDH). Density functional theory (DFT) was employed to calculate quantum-chemical descriptors, while several structural descriptors were generated with Dragon 5.4. Variable selection was undertaken with the ordered predictor selection (OPS) algorithm, which provided a set with the most relevant descriptors to perform PLS, PCR and MLR regressions. Reliable and predictive models were obtained, as attested by their high correlation coefficients, as well as the agreement between predicted and experimental values for an external test set. Additional validation procedures were carried out, demonstrating that robust models were developed, providing helpful tools for the optimization of the antileishmanial activity of adenosine compounds.