Molecular Physicochemical Properties of Selected Pesticides as Predictive Factors for Oxidative Stress and Apoptosis-Dependent Cell Death in Caco-2 and HepG2 Cells

In this work, three pesticides of different physicochemical properties: glyphosate (GLY, herbicide), imidacloprid (IMD, insecticide), and imazalil (IMZ, fungicide), were selected to assess their cytotoxicity against Caco-2 and HepG2 cells. Cell viability was assessed by the Alamar Blue assay, after 24 and 48 h exposure to different concentrations, and IC₅₀ values were calculated. The mechanisms underlying toxicity, namely cellular reactive oxygen species (ROS), glutathione (GSH) content, lipid peroxidation, loss of mitochondrial membrane potential (MMP), and apoptosis/necrosis induction were assessed by flow cytometry. Cytotoxic profiles were further correlated with the molecular physicochemical parameters of pesticides, namely: water solubility, partition coefficient in an n-octanol/water (Log P_ow) system, topological polar surface area (TPSA), the number of hydrogen-bonds (donor/acceptor), and rotatable bonds. In vitro outputs resulted in the following toxicity level: IMZ (Caco-2: IC₅₀ = 253.5 ± 3.37 μM, and HepG2: IC₅₀ = 94 ± 12 μM) > IMD (Caco-2: IC₅₀ > 1 mM and HepG2: IC₅₀ = 624 ± 24 μM) > GLY (IC₅₀ >>1 mM, both cell lines), after 24 h treatment, being toxicity time-dependent (lower IC₅₀ values at 48 h). Toxicity is explained by oxidative stress, as IMZ induced a higher intracellular ROS increase and lipid peroxidation, followed by IMD, while GLY did not change these markers. However, the three pesticides induced loss of MMP in HepG2 cells while in Caco-2 cells only IMZ produced significant MMP loss. Increased ROS and loss of MMP promoted apoptosis in Caco-2 cells subjected to IMZ, and in HepG2 cells exposed to IMD and IMZ, as assessed by Annexin-V/PI. The toxicity profile of pesticides is directly correlated with their Log P_ow, as affinity for the lipophilic environment favours interaction with cell membranes governs, and is inversely correlated with their TPSA; however, membrane permeation is favoured by lower TPSA. IMZ presents the best molecular properties for membrane interaction and cell permeation, i.e., higher Log P_ow, lower TPSA and lower hydrogen-bond (H-bond) donor/acceptor correlating with its higher toxicity. In conclusion, molecular physicochemical factors such as Log P_ow, TPSA, and H-bond are likely to be directly correlated with pesticide-induced toxicity, thus they are key factors to potentially predict the toxicity of other compounds.     

Effective GPS Jamming Techniques for UAVs Using Low-Cost SDR Platforms

Lately, a rising number of incidents between unmanned aerial vehicles (UAVs) and airplanes have been reported in airports and airfields. In order to help cope with the problem of unauthorized UAV operations, in this paper we evaluate the use of low cost SDR platforms (software defined radio) for the implementation of a jammer able to generate an effective interfering signal aimed at the GPS navigation system. Using a programmable BladeRF x40 platform from Nuand and the GNU radio software development toolkit, several interference techniques were studied and evaluated, considering the spectral efficiency, energy efficiency and complexity. It was shown that the tested approaches are capable of stopping the reliable reception of the radionavigation signal in real-life scenarios, neutralizing the capacity for autonomous operation of the vehicle.

     

Facile co-precipitated synthesis of NdFeO3 perovskite nanoparticles for lithium-ion battery anodes

In this report, NdFeO₃ perovskite nanoparticles were facilely prepared by co-precipitation of Nd³⁺ and Fe³⁺ cations in hot water, followed with the pyrolysis process in atmospheric conditions. Morphology and crystal structure of NdFeO₃ perovskite were determined with appropriate methods, revealing orthorhombic lattice with size distribution from 40 to 180 nm. Functioning as anode lithium-ion batteries (LIBs), NdFeO₃ exhibited great electrochemical performance such as high retention capacity, excellent cyclability, and high current rate. Such enhanced electrochemical efficiency was evidently ascribed to the perovskite structure of NdFeO₃ due to short lithium-ion diffusion pathway and volume expansion control of working material during lithiation/delithiation operation. By demonstrating a capacity value of 475 mAh g^?1 even through 450 cycles at 0.1 A g^?1, NdFeO₃ perovskite nanoparticles proved itself a competitive anode material for the coming generations of LIBs. In addition, this novel synthesis method is suitable for mass production of perovskite materials for long-life lithium-storage facilities.

     

Investigating metal‐inhibitor interaction with EQCM and SVET: 3‐amino‐1,2,4‐triazole on Au,Cu and Au–Cu galvanic coupling

This study reports a multiscale electrochemical investigation of the interaction between the organic compound 3‐amino‐1,2,4‐triazole (ATA), regarded as corrosion inhibitor, and two noble metals (Cu and Au), either separated or under galvanical coupling. Open circuit potential measurements show that Cu is not protected by the application of ATA, having its potential shifted towards more negative values, while on Au exhibits a slight inhibitive effect. The adsorption free energies were determined using the electrochemical quartz crystal microbalance (EQCM), with values that correspond to physisorption on either metal. The surface reactivity of the inhibitor‐modified metals in chloride‐containing aqueous solution was studied using the scanning vibrating electrode technique (SVET), showing high spontaneous activity, associated to electron transfer reactions in systems containing Cu and 3‐amino‐1,2,4‐triazole.     

Poly(lactide-co-glycolide)/silver nanoparticles: Synthesis,characterization, antimicrobial activity,cytotoxicity assessment and ROS-inducing potential

Silver nanoparticles (AgNps) were prepared by modified chemical reduction with poly (α, γ, l-glutamic acid) (PGA) as capping agent. These Ag/PGA nanoparticles (AgNpPGAs) were highly stable over long periods of time without signs of precipitation. In addition to obtaining stable AgNpPGAs, a further aim was to examine their encapsulation in the poly(L-lactide-co-glycolide) (PLGA) polymer matrix. The current interest of polymer-AgNps in biomedical applications is because a versatile system must have antimicrobial activity upon target contact, without the release of toxic biocides. The synthesis of these PLGA/AgNpPGAs used physicochemical methods with solvent/non-solvent systems. Degradation of these PLGA/AgNpPGAs and the release rate of their AgNPs were studied in physiological solution over three months. The antimicrobial activity of the samples was investigated towards six laboratory control strains from the American Type Culture Collection (ATCC) and one clinical isolate methicillin-resistant Staphylococcus aureus strain by the broth microdilution method and the results showed superior and extended activity of PLGA/AgNpPGAs. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay indicated good biocompatibility of these PLGA/AgNpPGAs. The formation of intracellular reactive oxygen species was measured spectrophotometrically using a fluorescent probe, which showed that these PLGA/AgNpPGAs are not inducers of such species. The samples were characterized by UV–VIS spectrometry, X-ray diffraction, zeta potential measurements, field-emission scanning electron microscopy, and transmission electron microscopy.     

Molecular Dynamics of Synthetic Flagelliform Silk Fiber Assembly

In order to better understand the relationship between flagelliform (Flag) spider silk molecular structural organization and the mechanisms of fiber assembly, the Nephilengys cruentata Flag spidroin analogue rNcFlag2222 is designed and produced. The recombinant proteins are composed by the elastic repetitive glycine-rich motifs (GPGGX/GGX) and the spacer region, rich in hydrophilic charged amino acids, present at the native silk spidroin. Using different approaches for nanomolecular protein analysis, the structural data of rNcFlag2222 recombinant proteins are compared in their fibrillar and fully solvated states. Based on the results, it is possible to identify the molecular structural dynamics of NcFlag2222 prior to and after fiber formation. Overall rNcFlag2222 shows a mixture of semiflexible and rigid conformations, characterized mostly by the presence of polyproline type II helix (PPII), β-turn, and β-sheet. These results agree with previous studies and bring insights about the molecular mechanisms that might drive Flag silk fibers assembly and elastomeric behavior.     

Development of poly(lactic acid) nanostructured membranes for the controlled delivery of progesterone to livestock animals

Solution blow spinning (SBS) is a novel technology feasible to produce nanostructured polymeric membranes loaded with active agents. In the present study, nanofibrous mats of poly(lactic acid) (PLA) loaded with progesterone (P4) were produced by SBS at different P4 concentrations. The spun membranes were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). The in vitro releasing of P4 was evaluated using high-performance liquid chromatography (HPLC). Interactions between progesterone and PLA were confirmed by rheological measurements of the PLA/P4 solutions and in the spun mats by microscopy (SEM), thermal (DSC) and spectral (FTIR) analyses. SEM micrographs provided evidences of a smooth and homogeneous structure for nanostructured membranes without progesterone crystals on fiber surface. FTIR spectroscopy indicated miscibility and interaction between the ester of PLA and the ketone groups of the P4 in the nanofibers. X-ray analysis indicated that the size of PLA crystallites increased with progesterone content. Finally, by in vitro release experiments it was possible to observe that the progesterone releasing follows nearly first-order kinetics, probably due to the diffusion of hormone into PLA nanofibers.     

Label‐Free Electrical Detection of DNA Hybridization on Graphene using Hall Effect Measurements: Revisiting the Sensing Mechanism

There is broad interest in using graphene or graphene oxide sheets as a transducer for label‐free and selective electrical detection of biomolecules such as DNA. However, it is still not well explored how the DNA molecules interact with and influence the properties of graphene during the detection. Here, Hall effect measurements based on the Van der Pauw method are used to perform single‐base sequence selective detection of DNA on graphene sheets, which are prepared by chemical vapor deposition. The sheet resistance increases and the mobility decreases with the addition of either complementary or one‐base mismatched DNA to the graphene device. The hole carrier concentration of the graphene devices increases significantly with the addition of complementary DNA but it is less affected by the one‐base mismatched DNA. It is concluded that the increase in hole carrier density, indicating p‐doping to graphene, is better correlated with the DNA hybridization compared to the commonly used parameters such as conductivity change. The different electrical observations of p‐doping from Hall effect measurements and n‐doping from electrolyte‐gated transistors can be explained by the characteristic morphology of partially hybridized DNA on graphene and the mismatch between DNA chain length and Debye length in electrolytes.     

Brazilian gamma-neutron dosemeter: response to 241AmBe and 252Cf neutron sources

With the aim of improving the monitoring of workers potentially exposed to neutron radiation in Brazil, the IPEN/CNEN-SP in association with PRO-RAD designed and developed a passive individual gamma-neutron mixed-field dosemeter calibrated to be used to (241)AmBe sources. To verify the dosimetry system response to different neutron spectra, prototypes were irradiated with a (252)Cf source and evaluated using the dose-calculation algorithm developed for (241)AmBe sources.