Cellulose micro/nanomaterials (CMNM), comprising cellulose microfibrils (CMF), nanofibrils (CNF), and nanocrystals (CNC), are being recognized as promising bio-nanomaterials due to their natural and renewable source, attractive properties, and potential for applications with industrial and economical value. Thus, it is crucial to investigate their potential toxicity before starting their production at a larger scale. The present study aimed at evaluating the cell internalization and in vitro cytotoxicity and genotoxicity of CMNM as compared to two multi-walled carbon nanotubes (MWCNT), NM-401 and NM-402, in A549 cells. The exposure to all studied NM, with the exception of CNC, resulted in evident cellular uptake, as analyzed by transmission electron microscopy. However, none of the CMNM induced cytotoxic effects, in contrast to the cytotoxicity observed for the MWCNT. Furthermore, no genotoxicity was observed for CNF, CNC, and NM-402 (cytokinesis-block micronucleus assay), while CMF and NM-401 were able to significantly raise micronucleus frequency. Only NM-402 was able to induce ROS formation, although it did not induce micronuclei. Thus, it is unlikely that the observed CMF and NM-401 genotoxicity is mediated by oxidative DNA damage. More studies targeting other genotoxicity endpoints and cellular and molecular events are underway to allow for a more comprehensive safety assessment of these nanocelluloses.

Exoelectrogenic microorganisms are in the spotlight due to their unique respiratory mechanisms and potential applications in distinct biotechnological fields, including bioremediation, bioenergy production and microbial electrosynthesis. These applications rely on the capability of these microorganisms to perform extracellular electron transfer, a mechanism that allows the bacteria to transfer electrons to the cell’s exterior by establishing functional interfaces between different multiheme cytochromes at the inner membrane, periplasmic space, and outer membrane. The multiheme cytochrome CbcL from Geobacter sulfurreducens is associated to the inner membrane and plays an essential role in the transfer of electrons to final electron acceptors with a low redox potential, as Fe(III) oxides and electrodes poised at −100 mV. CbcL has a transmembranar di-heme b-type cytochrome domain with six helices, linked to a periplasmic cytochrome domain with nine c-type heme groups. The complementary usage of ultraviolet-visible, circular dichroism and nuclear magnetic resonance permitted the structural and functional characterization of CbcL’s periplasmic domain. The protein was found to have a high percentage of disordered regions and its nine hemes are low-spin and all coordinated by two histidine residues. The apparent midpoint reduction potential of the CbcL periplasmic domain was determined, suggesting a thermodynamically favorable transfer of electrons to the putative redox partner in the periplasm − the triheme cytochrome PpcA. The establishment of a redox complex between the two proteins was confirmed by probing the electron transfer reaction and the molecular interactions between CbcL and PpcA. The results obtained show for the first time how electrons are injected into the periplasm of Geobacter sulfurreducens for subsequent transfer to the cell’s exterior.

Iron is the most versatile of all biochemically active metals, with variability encompassing its electronic configuration, number of unpaired electrons, type of ligands and iron-complexes stability. The versatility of iron properties is transposed to the proteins it can be associated to, especially relevant in the case of heme proteins. In this Review, the structural and functional properties of heme proteins are revisited, with particular focus on c-type cytochromes. The genome of Geobacter bacteria encodes for an unusually high number of assorted c-type cytochromes and, for this reason, they are used in this Review as a showcase of the cytochrome diversity. In the last decades, a vast portfolio of cytochromes has been revealed in these bacteria, with most of them defining new classes, ranging from monoheme to the recently identified polymeric assembly of multiheme cytochromes that forms micrometer-long electrically conductive filaments. These discoveries were on pace with the development of modern NMR equipment and advances in protein isotopic labeling methods, which are also revisited in this Review. Finally, following the description of the current state of the art of Geobacter cytochromes, examples on how the available structural and functional information was explored to structurally map protein–protein and protein–ligand interacting regions in redox complexes, and hence elucidate Geobacter’s respiratory pathways, are presented.

(1) Background: Nanocellulose is an innovative engineered nanomaterial with an enormous potential for use in a wide array of industrial and biomedical applications and with fast growing economic value. The expanding production of nanocellulose is leading to an increased human exposure, raising concerns about their potential health effects. This study was aimed at assessing the potential toxic and genotoxic effects of different nanocelluloses in two mammalian cell lines; (2) Methods: Two micro/nanocelluloses, produced with a TEMPO oxidation pre-treatment (CNFs) and an enzymatic pre-treatment (CMFs), and cellulose nanocrystals (CNCs) were tested in osteoblastic-like human cells (MG-63) and Chinese hamster lung fibroblasts (V79) using the MTT and clonogenic assays to analyse cytotoxicity, and the micronucleus assay to test genotoxicity; (3) Results: cytotoxicity was observed by the clonogenic assay in V79 cells, particularly for CNCs, but not by the MTT assay; CNF induced micronuclei in both cell lines and nucleoplasmic bridges in MG-63 cells; CMF and CNC induced micronuclei and nucleoplasmic bridges in MG-63 cells, but not in V79 cells; (4) Conclusions: All nanocelluloses revealed cytotoxicity and genotoxicity, although at different concentrations, that may be related to their physicochemical differences and availability for cell uptake, and to differences in the DNA damage response of the cell model.

Electroactive Geobacter bacteria can perform extracellular electron transfer and present a wide metabolic versatility. These bacteria reduce organic, toxic and radioactive compounds, and produce electric current while interacting with electrodes, making them interesting targets for numerous biotechnological applications. Their global electrochemical responses rely on an efficient interface between the inside and the cell's exterior, which is driven by the highly abundant periplasmic triheme PpcA-family cytochromes. The functional features of these cytochromes have been studied in G. sulfurreducens and G. metallireducens, and although they share a high degree of structural homology and sequence identity, their properties are quite distinct. In this work, the heme axial ligand geometries and the magnetic properties of PpcF from G. metallireducens were determined. The data obtained constitute important constraints for the determination of its solution structure in the oxidized state and indicate that the (i) heme core architecture; (ii) axial ligands geometries and (iii) magnetic properties of the cytochrome are conserved compared to the other members of the PpcA-families. Furthermore, the results also indicate that the heme arrangement is crucial to maintain an intrinsic regulation of the protein's redox properties and hence its electron transfer efficiency and functionality.

Silk fibroin is a biobased material with excellent biocompatibility and mechanical properties, but its use in bioelectronics is hampered by the difficult dissolution and low intrinsic conductivity. Some ionic liquids are known to dissolve fibroin but removed after fibroin processing. However, ionic liquids and fibroin can cooperatively give rise to functional materials, and there are untapped opportunities in this combination. The dissolution of fibroin, followed by gelation, in designer ionic liquids from the imidazolium chloride family with varied alkyl chain lengths (2–10 carbons) is shown here. The alkyl chain length of the anion has a large impact on fibroin secondary structure which adopts unconventional arrangements, yielding robust gels with distinct hierarchical organization. Furthermore, and due to their remarkable air-stability and ionic conductivity, fibroin ionogels are exploited as active electrical gas sensors in an electronic nose revealing the unravelled possibilities of fibroin in soft and flexible electronics.

Abstract Relative humidity is simultaneously a sensing target and a contaminant in gas and volatile organic compound (VOC) sensing systems, where strategies to control humidity interference are required. An unmet challenge is the creation of gas-sensitive materials where the response to humidity is controlled by the material itself. Here, humidity effects are controlled through the design of gelatin formulations in ionic liquids without and with liquid crystals as electrical and optical sensors, respectively. In this design, the anions [DCA]− and [Cl]− of room temperature ionic liquids from the 1-butyl-3-methylimidazolium family tailor the response to humidity and, subsequently, sensing of VOCs in dry and humid conditions. Due to the combined effect of the materials formulations and sensing mechanisms, changing the anion from [DCA]− to the much more hygroscopic [Cl]−, leads to stronger electrical responses and much weaker optical responses to humidity. Thus, either humidity sensors or humidity-tolerant VOC sensors that do not require sample preconditioning or signal processing to correct humidity impact are obtained. With the wide spread of 3D- and 4D-printing and intelligent devices, the monitoring and tuning of humidity in sustainable biobased materials offers excellent opportunities in e-nose sensing arrays and wearable devices compatible with operation at room conditions.

{Over the past few years porous materials have become a topic of intense research. Porous poly(ionic liquid)s combine the porous architecture with intrinsic ionic liquids properties. In all research areas, the quest for new and improved materials has targeted functional materials with enhanced specificity and efficiency towards the final application. The application of porous materials ranges from sensing, protein separation, solid-phase extraction, catalysis, to CO2 capture and reuse. Recently, the design, synthesis, and porosity control of poly (ionic liquid)s have been attempted through strategies that include classic polymerization techniques as well as molecular imprinting and aerogels production. This review aims at providing the recent advances on porous poly (ionic liquid)s, giving a critical perspective about the works in which key requirements for porosity induction are discussed. Several applications that rely on molecular interactions between the porous material and target compounds are presented, focusing mainly on CO2 capture and reuse, along with some challenges that the scientific community in this field need to be aware of.}

{Aiming to rationalize the release profile of an incorporated pharmaceutical drug in terms of its mobility, driven by guest-host interactions, the poorly water-soluble ibuprofen drug was loaded in a mesoporous inorganic silica matrix with unmodified (MCM-41) and modified surface (MCM-41sil) by post-synthesis silylation, both having pore sizes similar to 3 nm. The single calorimetric detection of a broad glass transition step for both ibuprofen com-posites indicates full drug amorphization, confirmed by the only appearance of an amorphous halo in the powder XRD patterns. Moreover, a gradient profile is disclosed by the heat flux derivative plot in the glass transition, in coherence with the thermogravimetric profile that shows a multi-step decomposition trace for confined ibuprofen in these matrixes. While identical guest dynamics, as probed by dielectric relaxation spectroscopy, were found in both dehydrated composites, a significant molecular population with faster relaxation exists in the hydrated state for the drug inside the unmodified matrix. This was rationalized as the concurrence of true confinement effects, which manifest under nanometer dimensions, and greater water affinity of the unmodified matrix, forcing the drug molecules to be placed mostly in the pore core. Finite size effects are also felt in both dehydrated composites, however guest-host interactions give origin to a dominant population with slowed down mobility that governs the overall guest dynamics. In spite of an inferior number of active sites for drug adsorption in the silylated matrix, a faster ibuprofen delivery in phosphate buffer (pH = 6.8) was observed when the drug is released from unmodified MCM-41 in the hydrated state. Therefore, our results suggest that a relevant role is played by water molecules, which impair a strong guest adsorption in the host surface more efficiently than the limited surface modification, influence the higher ratio of a faster population in the pore core and facilitate the diffusion of the aqueous releasing media inside pores.}

{Understanding the behavior of a chemical compound at a molecular level is fundamental, not only to explain its macroscopic properties, but also to enable the control and optimization of these properties. The present work aims to characterize a set of systems based on the ionic liquids {[}Aliquat]{[}Cl] and {[}Aliquat]{[}FeCl4] and on mixtures of these with different concentrations of DMSO by means of H-1 NMR relaxometry, diffusometry and X-ray diffractometry. Without DMSO, the compounds reveal locally ordered domains, which are large enough to induce order fluctuation as a significant relaxation pathway, and present paramagnetic relaxation enhancement for the {[}Aliquat]{[}Cl] and {[}Aliquat]{[}FeCl4] mixture. The addition of DMSO provides a way of tuning both the local order of these systems and the relaxation enhancement produced by the tetrachloroferrate anion. Very small DMSO volume concentrations (at least up to 1%) lead to enhanced paramagnetic relaxation without compromising the locally ordered domains. Larger DMSO concentrations gradually destroy these domains and reduce the effect of paramagnetic relaxation, while solvating the ions present in the mixtures. The paramagnetic relaxation was explained as a correlated combination of inner and outer-sphere mechanisms, in line with the size and structure differences between cation and anion. This study presents a robust method of characterizing paramagnetic ionic systems and obtaining a consistent analysis for a large set of samples having different co-solvent concentrations.}

An innovative pilot installation and eddy current testing (ECT) inspection system for laser-brazed joints is presented. The proposed system detects both surface and sub-surface welding defects operating autonomously and integrated with a robotized arm. Customized eddy current probes were designed and experimentally validated detecting pore defects with 0.13 mm diameter and sub-surface defects buried 1 mm deep. The integration of the system and the manufacturing process towards an Industry 4.0 quality control paradigm is also discussed.

n/a

n/a

Automobile laser brazing remains a complex process whose results are affected by several process variables that may result in nonacceptable welds. A multisensory customized inspection system is proposed, with two distinct non-destructive techniques: the potential drop method and eddy current testing. New probes were designed, simulated, produced, and experimentally validated in automobile's laser-brazed weld beads with artificially introduced defects. The numerical simulations allowed the development of a new four-point probe configuration in a non-conventional orthogonal shape demonstrating a superior performance in both simulation and experimental validation. The dedicated inspection system allowed the detection of porosities, cracks, and lack of bonding defects, demonstrating the redundancy and complementarity these two techniques provide.

Ionogel are versatile materials, as they present the electrical properties of ionic liquids and also dimensional stability, since they are trapped in a solid matrix, allowing application in electronic devices such as gas sensors and electronic noses. In this work, ionogels were designed to act as a sensitive layer for the detection of volatiles in a custom-made electronic nose. Ionogels composed of gelatin and a single imidazolium ionic liquid were doped with bare and functionalized iron oxide nanoparticles, producing ionogels with adjustable target selectivity. After exposing an array of four ionogels to 12 distinct volatile organic compounds, the collected signals were analyzed by principal component analysis (PCA) and by several supervised classification methods, in order to assess the ability of the electronic nose to distinguish different volatiles, which showed accuracy above 98%.

A multigene polysaccharide utilization locus (PUL) encoding enzymes and surface carbohydrate (glycan)-binding proteins (SGBPs) was recently identified in prominent members of <i>Bacteroidetes</i> in the human gut and characterized in Bacteroides ovatus. This PUL-encoded system specifically targets mixed-linkage β1,3-1,4-glucans, a group of diet-derived carbohydrates that promote a healthy microbiota and have potential as prebiotics. The BoSGBP_MLG-A protein encoded by the <i>BACOVA_2743</i> gene is a SusD-like protein that plays a key role in the PUL's specificity and functionality. Here, we perform a detailed analysis of the molecular determinants underlying carbohydrate binding by BoSGBP_MLG-A, combining carbohydrate microarray technology with quantitative affinity studies and a high-resolution X-ray crystallography structure of the complex of BoSGBP_MLG-A with a β1,3-1,4-nonasaccharide. We demonstrate its unique binding specificity toward β1,3-1,4-gluco-oligosaccharides, with increasing binding affinities up to the octasaccharide and dependency on the number and position of β1,3 linkages. The interaction is defined by a 41-Å-long extended binding site that accommodates the oligosaccharide in a mode distinct from that of previously described bacterial β1,3-1,4-glucan-binding proteins. In addition to the shape complementarity mediated by CH-π interactions, a complex hydrogen bonding network complemented by a high number of key ordered water molecules establishes additional specific interactions with the oligosaccharide. These support the twisted conformation of the β-glucan backbone imposed by the β1,3 linkages and explain the dependency on the oligosaccharide chain length. We propose that the specificity of the PUL conferred by BoSGBP_MLG-A to import long β1,3-1,4-glucan oligosaccharides to the bacterial periplasm allows <i>Bacteroidetes</i> to outcompete bacteria that lack this PUL for utilization of β1,3-1,4-glucans. <b>IMPORTANCE</b> With the knowledge of bacterial gene systems encoding proteins that target dietary carbohydrates as a source of nutrients and their importance for human health, major efforts are being made to understand carbohydrate recognition by various commensal bacteria. Here, we describe an integrative strategy that combines carbohydrate microarray technology with structural studies to further elucidate the molecular determinants of carbohydrate recognition by BoSGBP_MLG-A, a key protein expressed at the surface of Bacteroides ovatus for utilization of mixed-linkage β1,3-1,4-glucans. We have mapped at high resolution interactions that occur at the binding site of BoSGBP_MLG-A and provide evidence for the role of key water-mediated interactions for fine specificity and affinity. Understanding at the molecular level how commensal bacteria, such as prominent members of <i>Bacteroidetes</i>, can differentially utilize dietary carbohydrates with potential prebiotic activities will shed light on possible ways to modulate the microbiome to promote human health.

The eucalyptus weevil, Gonipterus spp. Schoenherr, 1833 (Coleoptera, Curculionidae) is considered a major pest of eucalyptus plantations. In regions where control is achieved, success is usually brought by the action of the solitary egg parasitoid Anaphes nitens (Girault, 1928) (Hymenoptera, Mymaridae). Research was conducted to ascertain which cues might mediate female wasp host location and selection. In Petri dish arenas, females were attracted to Gonipterus platensis Marelli, 1927 egg capsules, to G. platensis mated female faeces and to leaves of Eucalyptus globulus Labillardiere, 1799. Gas chromatography-mass spectrometry electroantennographic detection analysis was conducted using extracts obtained from leaves of E. globulus, from G. platensis egg capsules, as well as from adults of both sexes and their faeces, in order to detect and identify compounds perceived by the wasp's olfactory system. The parasitoids were shown to detect a wide range of compounds emitted by each one of these sources, and for 31 compounds, antennal response was confirmed by dose-response tests. Further behavioural trials were conducted in Petri dishes in order to decode the effect, on parasitoid behaviour, of selected compounds emitted by E. globulus and of the pheromones, emitted by the weevils on parasitoid behaviour. Attraction was observed to two compounds emitted by E. globulus, namely 1,8-cineole and gamma-terpinene, and to the main component of the male sex/aggregation pheromone, cis-verbenol. To our knowledge, this is the first report of attraction of a parasitoid from the family Mymaridae to a component of its host's sexual/aggregation pheromone. Similarly, to other egg parasitoid species, A. nitens females are likely to use the host plant volatiles as long-range host location cues and to adopt the `infochemical detour' strategy in order to get in the vicinity of their hosts.