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Wearable self-powered sensors represent a theme of interest in the literature due to the progress in the Internet of Things and implantable devices. The integration of different materials to harvest energy from body movement or the environment to power up sensors or act as an active component of the detection of analytes is a frontier to be explored. This review describes the most relevant studies of the integration of nanogenerators in wearables based on the interaction of piezoelectric and triboelectric devices into more efficient and low-cost harvesting systems to power up batteries or to use the generated power to identify multiple analytes in self-powered sensors and biosensors.

The required treatment and monitoring of contaminants in wastewater reinforces the development of low-cost adsorbents/chemosensors, introducing advantages relative to the detection/removal of toxic metals and dyes. Herein, it is reported a two-step process of fabrication of fluorescent carbon dots via the hydrothermal treatment of amino acids for the following encapsulation in electrospun fibers. The prominent anionic behavior of electrospun fibers of Eudragit L100 was explored for adsorption of cationic dyes (methylene blue and crystal violet)—with the prevailing electrostatic interaction of parts being favored by the formation of monolayers on the surface of adsorbents. On the other hand, the controlled release of carbon dots (CDs) from fibers to the reactor can be explored for a second application: the nitrogen ligands from released glycine-based carbon dots can be explored to indicate the presence of metal ions in aqueous solution. Our experiment resulted in a quenching in the fluorescence of the CDs in order of 90% in the emission of particles in the response of the presence of Fe3+ ions, characterizing a promising perspective for this experimental system.

The energy autonomy of self-powered wearable electronics depends on the adequate development of new technologies for energy harvesting and energy storage devices based on textile fibers to facilitate the integration with truly flexible and wearable devices. Silk fiber-based systems are attractive for the design of biomedical devices, lithium-ion batteries and flexible supercapacitors, due to their nitrogen-rich structure (for preparation of hierarchical carbon-based structures), and available surface for chemical modification reinforcing electroactive properties for use in batteries and supercapacitors. Herein, this paper reviews recent advances on silk fiber-based systems for harvesting and the storage of energy and the corresponding strategies to reinforce the physical and chemical properties of the resulting composites applied as electrodes and battery separators.

A biomass amino silica-functionalized material was successfully prepared by a simple sol–gel method. 3-Aminopropyltriethoxysilane (APTES) was added to a tannin-rich grape residue to improve its physicochemical properties and enhance the adsorption performance. The APTES functionalization led to significant changes in the material’s characteristics. The functionalized material was efficiently applied in the removal of methyl orange (MO) due to its unique characteristics, such as an abundance of functional groups on its surface. The adsorption process suggests that the electrostatic interactions were the main acting mechanism of the MO dye removal, although other interactions can also take place. The functionalized biomass achieved a very high MO dye maximum adsorption capacity (Qmax) of 361.8 mg g–1. The temperature positively affected the MO removal, and the thermodynamic studies indicated that the adsorption of MO onto APTES-functionalized biomass was spontaneous and endothermic, and enthalpy is driven in the physisorption mode. The regeneration performance revealed that the APTES-functionalized biomass material could be easily recycled and reused by maintaining very good performance even after five cycles. The adsorbent material was also employed to treat two simulated dye house effluents, which showed 48% removal. At last, the APTES biomass-based material may find significant applications as a multifunctional adsorbent and can be used further to separate pollutants from wastewater.

Our objectives were to identify genes of the multi-drug efflux system and to evaluate the antimicrobial activities of polypyrrole nanoparticles (PPy-NPs) and aqueous extract ofMoringa oleiferaagainstStaphylococcusspp. isolated from dairy farms in Northeast Brazil. Initially, 162Staphylococcusspp. isolates were subjected toin vitroantimicrobial sensitivity tests. Of these, 35 presented antimicrobial multi-drug resistance phenotypes. These 35 isolates were then referred for the detection ofnorA, norB, norC, msrA, mgrA, tet-38,andlmrSgenes, all of which feature in multi-drug efflux systems. In the isolates carrying the genes, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of PPy-NPs andMoringa oleiferaaqueous extract were determined. In the molecular analysis of the 35 isolatesnorA, norC, tet-38,andmsrAgenes were detected and for the other genesnorB, lmrSandmgrAthere was no amplification. Antimicrobial activity was verified of PPy-NPs and aqueous extract ofMoringa oleiferainStaphylococcusspp. carrying multi-drug efflux system genes. We concluded that there are multi-drug efflux system genes present in theStaphylococcusspp. from the agricultural environment in Northeast Brazil, and that aqueous extract ofMoringa oleiferaand PPy-NPs show bactericidal activity against these isolates.

Mastitis is one of the most important diseases in dairy milk systems. Molecular studies of the principal agents that are involved, as well as tests of bacterial sensitivity to plant extracts, are currently the most common forms of research related to this disease. The aim of the present study was to molecularly characterize isolates from cases of subclinical mastitis and to investigate the production of biofilm associated with extracts from Hymenaea martiana. The phytochemical screening of the crude ethanolic extract (CEE) confirmed the presence of phenolic substances, flavonoids, steroids and terpenoids. The antimicrobial susceptibility profile of the isolates that were assessed exhibited variations, with a notably high sensitivity to gentamicin. After the addition of the extract, 77.3, 81.8 and 86.3% of the isolates exhibited a reduction in biofilm production in the ethyl acetate, chloroform and hexane fractions, respectively. An extensive production of biofilm can be observed in the isolates that were not in contact with the natural extract. However, when in contact with the plant extract, there was a reduction in biofilm production, thereby demonstrating the therapeutic potential of the natural extract of H. martiana in mastitis caused by Staphylococcus spp. Key words: Mastitis, pathogens, resistance genes, sensitivity tests.

Some species of Lactobacillus (Gram-positive bacilli) are promising probiotics with positive physiological effects on the prevention and treatment of diseases. A critical drawback related to the action of these microorganisms refers to the sustainable viability of the cells at adverse conditions (under storage, packing and at gastrointestinal tract flux) - the high humidity conditions inhibit the prolonged viability of the cells. As a consequence, the encapsulation in oxygen-free or impermeable micro containers represents an additional protective procedure to preserve bioactive living cells, providing targeted release of microorganisms at specific parts of the organism. Herein, this mini-review investigates the alternative encapsulation of Lactobacillus spp. by polymeric electrospun fibers. The use of polymeric solutions as templates for electrospinning procedure may increase not only the stability of Lactobacillus spp. but also provide hydrophobic pockets that protect probiotics against adverse conditions. Besides, the electrospun fibers can control the release of species, favoring the therapeutic benefits of probiotics, increasing the viability and stability of Lactobacillus spp.

In this study, samples of pristine and chemically modified coconut shells are used as adsorbents for the removal of crystal violet from an aqueous solution. The modification based on NaOH treatment of coconut shell fibers was evaluated by scanning electron microscopy and Fourier transform infrared spectroscopy. The dye uptake efficiency was evaluated by determining the variation in dye concentration, pH, adsorbent mass, and reaction time. The equilibrium condition of the overall process was analyzed by standard methods (Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherms), while kinetics were evaluated using the pseudo-first-order/pseudo-second-order, Elovich, and intra-particle diffusion models.

The health benefits and sensing applications of curcumin-based systems depend on their prevailing photophysical and chemical properties at a specific environment—the characteristic low solubility of curcumin in water hinders high-dosage based applications. To circumvent this drawback, curcumin has been incorporated in hydrophobic environments in nanoscale. Herein, electrospun fibers of Eudragit L100 were loaded with curcumin and applied in fluorescence and antibacterial assays to evaluate prevailing physical and chemical properties in solid-state. The characteristic high loading degree of curcumin (250 mg/mL in Eudragit L100 solution) preserves not only the photophysical properties of molecules (such as the intrinsic fluorescence) but also the antibacterial activity of released molecules from electrospun fibers, characterizing an important strategy for improvement in the applicability potential of natural materials.

A new coronavirus appears in China in December 2019, subsequently threatening the world, it was identified as Covid-19. Its main symptomatic characteristic is directly linked to acute respiratory failure, however there are asymptomatic cases of the disease, mainly in the group not considered at risk. For the treatment of the disease a variety ofantiviral drugs have been tested, with conflicting results. The use of computer-assisted drugs is essential for the development of new therapeutic alternatives for various diseases, once they reduce the time consumed in the initial screening tests, in addition to determining the possible mechanisms of action and reducing toxicity. In our study, we evaluated the interaction of viral components of the coronavirus with potassium usnate, salt derived from lichenic origin and with proven antimicrobial and antitumor activities. Derived from ussic acid, potassium usnate showed low energy for complex formation, this interaction occurs between the usnate salt and the structures of proteinase 3CLpro and enzyme Mpro, all key parts of Covid-19. In addition, in order to prove in silico the use of potassium usnate, they were tested and compared with other approved drugs and candidates for clinical trials to combat the new coronavirus.

The green synthesis of silver nanoparticles represents an important strategy for production of alternative antibacterial agents. Herein, the reduction of silver nanoparticles is provided by the action of leaf extract of Ziziphus joazeiro. The as-synthesized material presented pH-dependent behavior that affects the kinetics of nanoparticles nucleation and the following aggregation. Alkaline and acidic environment favors the increasing polydispersity of nanoparticles providing the production of different distribution of particle size. At neutral condition (pH 7), particles with lower size and reduced aggregation degree are obtained and present antibacterial activity against S. aureus and E. coli. The number of viable cells for both systems (from initial culture containing 104 colonies) reached negligible counting after 5 h of interaction with silver nanoparticles prepared at neutral pH.

1,8-cineole is a monoterpene commonly used by the food, cosmetic, and pharmaceutical industries owing to its flavor and fragrances properties. In addition, this bioactive monoterpene has demonstrated bactericidal and fungicidal activities. However, such activities are limited due to its low aqueous solubility and stability. This study aimed to develop nanoemulsion containing cineole and assess its stability and antibacterial activity in this context. The spontaneous emulsification method was used to prepare nanoemulsion (NE) formulations (F1, F2, F3, F4, and F5). Following the development of NE formulations, we chose the F1 formulation that presented an average droplet size (in diameter) of about 100 nm with narrow size distribution (PdI0.2) and negative zeta potential (∼ - 35 mV). According to the analytical centrifugation method with photometric detection, F1 and F5 formulations were considered the most stable NE with lower droplet migration velocities. In addition, F1 formulation showed high incorporation efficiency (80 %) and TEM analyses demonstrated nanosized oil droplets with irregular spherical shapes and without any aggregation tendency. Antibacterial activity assessment showed that F1 NE was able to enhance the cineole action against Staphylococcus aureus, Enterococcus faecalis, and Streptococcus pyogenes. Therefore, using a simple and reproducible method of low energy emulsification we designed a stable nanoemulsion containing 1,8-cineole with improved antibacterial activity against Gram-positive strains.

Biobased carbon materials (BBC) obtained from Norway spruce (Picea abies Karst.) bark was produced by single-step chemical activation with ZnCl2 or KOH, and pyrolysis at 800 °C for one hour. The chemical activation reagent had a significant impact on the properties of the BBCs. KOH-biobased carbon material (KOH-BBC) had a higher specific surface area (SBET), equal to 1067 m2 g−1, larger pore volume (0.558 cm3 g−1), more mesopores, and a more hydrophilic surface than ZnCl2-BBC. However, the carbon yield for KOH-BBC was 63% lower than for ZnCl2-BBC. Batch adsorption experiments were performed to evaluate the ability of the two BBCs to remove two dyes, reactive orange 16 (RO-16) and reactive blue 4 (RB-4), and treat synthetic effluents. The general order model was most suitable for modeling the adsorption kinetics of both dyes and BBCs. The equilibrium parameters at 22 °C were calculated using the Liu model. Upon adsorption of RO-16, Qmax was 90.1 mg g−1 for ZnCl2-BBC and 354.8 mg g−1 for KOH-BBC. With RB-4, Qmax was 332.9 mg g−1 for ZnCl2-BBC and 582.5 mg g−1 for KOH-BBC. Based on characterization and experimental data, it was suggested that electrostatic interactions and hydrogen bonds between BBCs and RO-16 and RB-4 dyes played the most crucial role in the adsorption process. The biobased carbon materials showed high efficiency for removing RO-16 and RB-4, comparable to the best examples from the literature. Additionally, both the KOH- and ZnCl2-BBC showed a high ability to purify two synthetic effluents, but the KOH-BBC was superior.

The adhesion of pathogenic bacteria in medical implants and surfaces is a health-related problem that requires strong inhibition against bacterial growth and attachment. In this work, we have explored the enhancement in the antibacterial activity of metal free-based composites under external electric field. It affects the oxidation degree of polypyrrole-based electrodes and consequently the antibacterial activity of the material. A conductive layer of carbon nanotubes (graphite) was deposited on porous substrate of polyurethane (sandpaper) and covered by polypyrrole, providing highly conductive electrodes characterized by intrinsic antibacterial activity and reinforced by electro-enhanced effect due to the external electric field. The bacterial inhibition of composites was monitored from counting of viable cells at different voltage/time of treatment and determination of biofilm inhibition on electrodes and reactors. The external voltage on electrodes reduces the threshold time for complete bacterial inactivation of PPy-based composites to values in order of 30 min for Staphylococcus aureus and 60 min for Escherichia coli.

Plasmonically enhanced random lasing in eggshell biomembranes is reported using a hybrid metalorganic system comprised by Rhodamine 6G as gain medium and silver nanoparticles as the plasmonic metal. The scattering mechanism responsible for feedback in the random laser action arises from the submicron randomly arranged structure of the eggshell biomembrane. The measured spectral narrowing in the biomembranes without Ag is of the same order as of the Ag-infiltrated biomembrane, showing an emission linewidth reduction from ∼45 ± 2 nm below threshold to ∼5.0 ± 0.5 nm above threshold. On the other hand, the effect of the plasmon enhancement is clearly seen in the emitted random laser intensity, which is more efficient and with a lower threshold in the presence of the Ag nanoparticles. We also investigated the spatial behavior of the random laser emission, which shows hot spots with higher intensity in the presence of the Ag nanoparticles, arising from the plasmonic enhancement.

Background Bothropic venoms cause intense local damage, pain, edema, and myonecrosis. Morus nigra L. (Moraceae) has several uses in folk medicine and can be a promising candidate for the treatment of several inflammatory disorders. Hypothesis/Purpose The present study aims to evaluate the anti-inflammatory and antinociceptive effects of the ethanolic extract of Morus nigra L. (Mn-EtOH) on paw lesions induced by Bothrops jararacussu snake venom (BjcuV) in mice. Methods UV–vis absorption of BjcuV was evaluated. A phytochemical study was performed, which led to the isolation and characterization of three compounds. These compounds were identified using spectrometric methods, namely LC–MS and NMR (1D and 2D), followed by the validation of their spectra with the data available in the literature. Further, the flavonoids i.e. rutin and quercetin (chemical markers of M. nigra), Mn-EtOH or Mn-EtOH-encapsulated electrospun fibers of Eudragit L100 (FB/Mn-EtOH), and Mn-EtOH-encapsulated microparticles of Eudragit L100 (MP/Mn-EtOH) were evaluated, in paw edema test induced by BjcuV. Results UV–vis spectra showed the presence of phospholipases A2 as component of BjcuV. The chemical examination resulted in the isolation of β-sitosterol, quercetin-3-O-glucopyranoside, and kaempferol-3-O-glucopyranoside. Mn-EtOH, FB/Mn-EtOH, MP/Mn-EtOH, rutin, and quercetin reduced the local edema induced by BjcuV. The Mn-EtOH also prevented edema provoked by serotonin and bradykinin. Moreover, it reduced paw edema and peritoneal leukocyte infiltration induced by carrageenan, and decreased the mechanical hypernociception of BjcuV. Mn-EtOH exerted anti-inflammatory and antinociceptive effects, possibly by the inhibition of leukocyte migration and the modulation of serotonin and bradykinin actions. This anti-inflammatory activity was maintained even upon incorporation of the M. nigra extract into the drug delivery systems (i.e., Mn-EtOH-encapsulated FBs and MPs of Eudragit L100). Conclusion These results reinforce the therapeutic potential of M. nigra in the treatment of inflammatory conditions, in addition to, its role as a complementary treatment of snakebites.

RESUMO A atividade antibacteriana de nanopartículas metálicas (e em especial de prata) vem sendo explorada ao longo do tempo em diferentes formulações químicas para agentes biológicos livres de antibióticos. A produção dessas partículas por rotas ambientalmente responsáveis representa uma estratégia extremamente relevante por apresentar baixo custo, favorecer a escalabilidade e ter mínimos impactos ambientais. O uso de óleos essenciais como agentes redutores em síntese verde de nanopartículas de prata introduz a sinergia de um agente intrinsicamente antibacteriano e que favorece a nucleação/crescimento das nanopartículas. Esta revisão apresenta o estado da arte da síntese verde de nanopartículas de prata por óleos essenciais assim como discute os mecanismos mais relevantes desse processo de formação e ação antibacteriana. ABSTRACT The antibacterial activity of silver nanoparticles has been explored over time in different chemical formulations for antibiotic-free agents. The production of these particles by environmentally friendly routes represents an extremely relevant strategy for presenting low cost, favoring scalability and having minimal environmental impacts. The use of essential oils as reducing agents in green synthesis of silver nanoparticles introduces the synergy of an intrinsically antibacterial agent that favors the nucleation / growth of the nanoparticles. This review presents the state-of-the-art of green synthesis of silver nanoparticles by essential oils as well as discusses the most relevant mechanisms of formation process and antibacterial action.

Caseous lymphadenitis (CLA) is a chronic disease that affects small ruminants and causes economic losses in the associated breeding system. The causative agent of CLA is Corynebacterium pseudotuberculosis, a Gram-positive bacterium that exhibits tropism for external and internal lymph nodes and induces abscess formation in the host. Bacterial communities often produce a biofilm matrix that serves various functions, including protection against hostile environmental conditions, antibiotics, and the host immune response. Although biofilm formation has been reported for C. pseudotuberculosis, not all strains demonstrate this property in culture. In this work, we report the first comparative proteomic analysis of one biofilm-forming (CAPJ4) and one biofilm-non-forming strain (CAP3W) of C. pseudotuberculosis isolated from goats. Bacterial whole cell protein extracts were obtained for mass spectrometry analyses. Using LC-MS/MS, our studies reveal three and four proteins exclusively found in the CAPJ4 and CAP3W proteome, respectively. In addition, label-free quantitative analysis identified 40 proteins showing at-least 2-fold higher values in CAPJ4 compared CAP3W proteome Notably, CAPJ4 differentially synthesized the penicillin-binding protein, which participates in the formation of peptidoglycans. CAPJ4 also exhibited upregulation of N-acetylmuramoyl-L-alanine amidase and galactose-1-phosphate uridylyltransferase, which are involved in biofilm formation and exopolysaccharide biosynthesis. Here, we demonstrate that biofilm formation in C. pseudotuberculosis is likely associated with specific proteins, some of which were previously shown to be associated with virulence and biofilm formation in other organisms. Our findings may drive studies related to the bacterial mechanisms involved in the biofilm formation, in addition to providing targets for the treatment of CLA.

Wound dressings based on natural materials, such as fish skin, represent an important strategy for the treatment of burns. Despite their utility, contamination of these natural materials with bacteria (planktonic and biofilm forms) introduces significant risks to patients under treatment. This disadvantage can be overcome by modifying the material’s surface to prevent bacterial deposition through chemical or physical interactions. In this work, functional graphenic materials (FGM) with tunable surface charges were incorporated into tilapia (Oreochromis niloticus) fish skin as a part of a strategy to control the biofilm adhesion on surfaces. The antibiofilm activity was evaluated against S. aureus and K. pneumoniae due to the biofilm-forming properties of these bacterial strains. FGM-modified tilapia skin samples possess a strong capacity to reduce biofilm formation on the tilapia fish skin with a higher antibiofilm activity against Gram-positive bacteria, compared to Gram-negative bacteria. Negatively charged FGMs were more effective than positively charged FGMs in preventing biofilm formation on the impregnated tilapia skin xenografts: negatively charged Claisen graphene achieved an 88.8% reduction in biofilm formation on the tilapia skin. Overall, this study demonstrates the utility of FGM-impregnated tilapia skins as a treatment for burn wounds due to their ability to modulate bacterial adhesion.

The development of environmentally friendly prototypes for use as antibacterial agents and as alternatives to antibiotics is a necessary step toward the control of infections. With this in mind, the production of hybrid composites based on natural and synthetic materials has been successfully explored. Herein, the chemical polymerization of polyaniline on natural fibers of Calotropis procera was used to explore the combined available surface area of fibers with the intrinsic properties of the conductive layer of PANI. What resulted was a coating of conducting polymer on natural fibers with strong antibacterial activity against Staphylococcus aureus and Escherichia coli. The characteristic time for the complete elimination of colonies (kill time) observed in assays was in the region of 3–4 h of treatment, with an inhibition halo of 20 mm (against E. coli) and 24 mm (against S. aureus). In addition to the antibacterial activity against S. aureus and E. coli, the modified fibers exhibited antibiofilm activity against S. aureus, which was evidenced in the reduction in the degree of bacterial adhesion to the surface applied in treatment (with a 39.96% biofilm inhibition). The proposed method represents a simple, low-cost, and one-step method for the modification of natural fibers with relevant applications in antibacterial agents.

With an estimated increasing oil demand in the coming decades, the need to explore non-applicable areas is intensified, and associated with them, before the high exploration costs, the need to improve available technologies. In this sense, in the last decade, the application of nanoparticles to improve drilling fluids has been intensified. In this scenario, montmorillonite nanoclays and xanthan gums were little explored for the development of nanofluids. In this work, the influence of hydrophilic nanoclay on the rheological parameters of xanthan, sodium and calcium chlorides solutions was verified. For this, first, the clay was characterized by XRD, XRF and TGA. Then, maintaining constant the salt and xanthan concentrations, the influence of the variation in the concentration of nanoclay on the rheology of the solution was evaluated. Then, keeping the components concentrations constant, the influence of temperature was verified and then the hydration time on the rheology of the mixture. Finally, to assess the interaction of the mixture, it was verified the Electrical Conductivity and the Potential Zeta, varying the concentration of the nanoclay and the hydration time. It was concluded that: for certain nanoclay concentrations, there is an improvement in the rheology of xanthan solutions; an addition of nanoclay favors rheology in the mixture of xanthan with increased temperature; hydration time does not affect the rheology of the nanofluid; there is interaction between nanoclay and xanthan. Con el aumento estimado de la demanda de petróleo para las próximas décadas, la necesidad de exploración de áreas no convencionales se intensifica, y asociada con ellas, dados los altos costos de exploración, la necesidad de mejorar las tecnologías disponibles. En este sentido, en la última década, la aplicación de nanopartículas para la mejora de los fluidos de perforación se ha intensificado. En este escenario, las nanoarcillas de montmorillonita y las gomas de xantano se exploraron poco para el desarrollo de nanofluidos. En este trabajo, se verificó la influencia de la nanoarcilla hidrofílica de montmorillonita en los parámetros reológicos de las soluciones de cloruros de xantano, sodio y calcio. Para esto, primero, la arcilla se caracterizó por DRX, FRX y TGA. Luego, manteniendo constantes las concentraciones de sales y xantano, se evaluó la influencia de la variación en la concentración de nanoarcilla en la reología de la solución. Luego, manteniendo constantes las concentraciones de los componentes, se verificó la influencia de la temperatura y luego el tiempo de hidratación en la reología de la mezcla. Finalmente, para evaluar la interacción de las partículas en la mezcla, se verificó la conductividad eléctrica y el potencial Zeta, variando la concentración de nano arcilla y el tiempo de hidratación. Se concluyó que: para ciertas concentraciones de nanoarcilla, hay una mejora en la reología de las soluciones de xantano; la adición de nanoarcilla favorece la reología en la mezcla de xantano con el aumento de la temperatura; el tiempo de hidratación no afecta significativamente la reología del nanofluido; Existe una interacción entre nano-arcilla y xantano. Com a estimativa de aumento da demanda de petróleo para as próximas décadas, intensifica-se a necessidade de exploração de áreas não convencionais, e associada a elas, ante aos altos custos de exploração, a necessidade de aperfeiçoar as tecnologias disponíveis. Nesse sentido, na última década, intensificou-se a aplicação de nanopartículas para o aperfeiçoamento de fluidos de perfuração. Nesse cenário, as nanoargilas montmorilonitas e as gomas xantana foram pouco exploradas para o desenvolvimento de nanofluidos. Neste trabalho, verificou-se a influência da nanoargila montmorilonita hidrofílica sobre os parâmetros reológicos de soluções de xantana, cloretos de sódio e de cálcio. Para tal, primeiro, a argila foi caracterizada por DRX, FRX e TGA. Depois, mantendo constantes as concentrações dos sais e da xantana, avaliou-se a influência da variação de concentração de nanoargila sobre a reologia da solução. Em seguida, mantendo as concentrações dos componentes constantes, verificou-se a influência da temperatura e em seguida do tempo de hidratação sobre a reologia da mistura. Por fim, para avaliar a interação das partículas da mistura, verificou-se a Condutividade Elétrica e o Potencial Zeta, variando-se concentração de nanoargila e tempo de hidratação. Concluiu-se que: para certas concentrações de nanoargila, há melhoria da reologia das soluções de xantana; a adição de nanoargila favorece a reologia na mistura de xantana com o aumento da temperatura; o tempo de hidratação não afeta significativamente a reologia do nanofluido; há interação entre a nanoargila e a xantana.

Lichens are the symbiotic organisms formed by one species of fungus associated to one or more species of green algae and/or cyanobacteria. The relationship between these organisms results in a metabolism that culminates in a production of exclusive compounds, named lichen substances, also known as lichen compounds or lichen acids. These products are known to exhibit several biological properties, and can be effective against several diseases. Several species of lichens found in Brazil have been identified and characterized for their bioactives during the last few decades. Studies have shown that these species possess antimicrobial, antineoplastic, anti-inflammatory, anti-leishmanial, and many more such bioactivities. In most cases, the articles mention different mechanisms of action. In complement, biotechnological studies have been carried out to achieve a continuous production of bioactive compounds, for example, the use of small amounts of thallus, collected directly from the environment, bioconservation processes, nanotechnological assays, nano and microencapsulations for a controlled drug liberation, incorporation in polymer matrix for pharmacological uses, etc. The possibility of extensive use of lichen substances encourages for further studies in this field, including the Brazilian species.

RESUMO: Bactérias do gênero Aeromonas são patógenos altamente disseminados no ambiente aquático, responsáveis por grandes perdas econômicas na piscicultura de diversos países. São micro-organismos oportunistas e sua patogenicidade está ligada a alguns fatores de virulência, como a formação de biofilme. O estresse salino é um dos fatores que favorecem a formação dessas colônias e, consequentemente, o aumento de infecções. Essas infecções quando estão associadas ao biofilme são ainda mais resistentes aos antimicrobianos. Nesse contexto, o polipirrol destaca-se como uma alternativa antimicrobiana por possuir vários atributos terapêuticos e não apresentar toxicidade aos organismos. Dessa forma, o objetivo desse estudo foi avaliar o perfil de susceptibilidade e a capacidade de formação de biofilme dos isolados de Aeromonas spp. associados aos diferentes níveis de salinidade e polipirrol. Determinou-se a atividade antibacteriana dos isolados e ensaios de motilidade foram realizados com bactérias que carreavam o gene fla. Também verificou-se a capacidade do cloreto de sódio e polipirrol em interferir na formação do biofilme. Os resultados foram evidenciados com a microscopia eletrônica de varredura. As concentrações de 2 e 3% de NaCl inibiram a motilidade bacteriana. Na formação do biofilme, 83% dos isolados bacterianos induziram a produção na concentração de 0,25%. O polipirrol causou a morte de todos os isolados testados na concentração de 125μg/mL. Além disso, esse composto diminuiu a motilidade bacteriana nas concentrações de 0,25 a 3%, sendo que em relação à produção de biofilme, não houve interferência. Esses resultados evidenciam que os diferentes níveis de NaCl influenciam na formação do biofilme favorecendo a persistência da infecção. Este estudo também realçou a potencialidade do polipirrol como agente bactericida, sendo uma alternativa eficaz às drogas antimicrobianas para o tratamento das infecções causadas por Aeromonas spp.

Developing low-cost and efficient flexible supercapacitors is an important step towards the production of new energy storage systems for efficient wearable electronic devices. In this work, we report a simple and cost-effective approach to produce flexible electrodes for supercapacitors. The system consists of a complex ternary structure of hierarchical polyaniline (PAn) assembled on a polypyrrole (PPy) layer deposited on graphite pencil traces (Grt) in sandpaper. The proposed ternary composite PAn-PPy-Grt-Sp assembled in a device offered a maximal areal capacitance of 55.35 mF cm-2 at 0.3 mA cm−2, a higher value when compared to its counterparts of PAn-Grt-Sp (31.8 mF cm−2) and PPy-Grt-Sp (19.75 mF cm−2). The ternary composite also exhibited a higher energy (4.92 μWh cm−2) and power density (87.09 μW cm−2) at a current density of 0.3 mA cm−2 producing a more equilibrated supercapacitor device. The response to mechanical efforts returned negligible variation in electrochemical properties while cyclability remains as 80% of initial value after 3000 cycles.