IF - Artigos publicados em periódicos

URI Permanente para esta coleçãohttp://200.137.215.59//handle/ri/1359

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Repurposing HIV protease inhibitors against west nile virus: insights from molecular docking and molecular dynamics simulations
(2026) Santos, Renato Douglas dos; Oliveira, Guilherme Colherinhas de; Cardoso, Wesley Bueno
West Nile virus (WNV) is a neurotropic flavivirus lacking approved antiviral therapies. Here, we evaluated the repurposing potential of ten HIV protease inhibitors as inhibitors of the WNV NS2B–NS3 protease using molecular docking followed by molecular dynamics simulations. Structural, energetic, and interaction analyses revealed substantial differences in binding stability under dynamic conditions. Indinavir and Atazanavir consistently showed strong and stable interactions, low structural and positional fluctuations, persistent hydrogen bonding, and favorable binding free energies. In contrast, several inhibitors displayed transient binding despite favorable docking scores. These findings emphasize the importance of molecular dynamics in drug repurposing studies and identify Indinavir and Atazanavir as promising candidates for further experimental evaluation against WNV.
Hydration and molar ratio effects in choline chloride-phenol deep eutectic solvents
(2026) Silva, Lucas de Sousa; Oliveira, Guilherme Colherinhas de
Deep eutectic solvents (DESs) based on choline chloride and phenol (CCPhe) have attracted increasing attention due to their tunable physicochemical properties and structural versatility. In this work, molecular dynamics (MD) simulations were performed for CCPhe systems at molar ratios of 1:2, 1:3, and 1:4 with water contents ranging from 0 to 30%. Energetic, hydrogen-bond, dielectric, transport, and structural analyses were combined to establish a multiscale description of hydration effects. Hydration promotes a progressive redistribution of stabilization from chloride-phenol and choline-chloride interactions toward chloride-water interactions, accompanied by increased watermediated hydrogen bonding and reduced hydrogen-bond lifetimes. The dielectric constant increases significantly with water content, reaching 15.93 for the 1:4 system at 30% hydration, while the infinite-system Kirkwood factor reveals enhanced cooperative dipolar correlations at high hydration levels. Diffusion coefficients increase by nearly an order of magnitude between dry and highly hydrated systems, indicating substantial mobility enhancement. Radial distribution functions show that hydration modifies the first solvation shell of choline through competitive coordination between chloride and water without altering the characteristic contact distance. These results demonstrate that controlled hydration acts as an effective tuning parameter in CCPhe systems, modulating energetic balance, hydrogen-bond connectivity, collective polarization, and molecular transport in a composition-dependent manner.
Mitigating water effects in humid [Pyr14][TFSI] at electrified surfaces via lithium-salt engineering
(2026) Oliveira, Leonardo Bruno Assis; Fonseca, Tertius Lima; Oliveira, Guilherme Colherinhas de
Ionic liquids (ILs) are attractive electrolytes for next-generation electrochemical devices; however, their hygroscopic nature leads to water uptake, which can reorganize the electrical double layer (EDL), promote interfacial water electrosorption, and contribute to the narrowing of the electrochemical stability window (ESW). In this work, we investigate lithium-salt engineering in humid 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Pyr14][TFSI]) using molecular dynamics (MD) simulations at fixed electrode surface charge densities. Corrected potential differences relative to the potential of zero charge (PZC), interaction energies, and number-density profiles of ions and water were systematically analyzed for dry, humid, and Li+-containing ILs. The simulations show that interfacial H2O interacts strongly with polarized electrodes and plays a central role in water-induced EDL restructuring. Upon Li+ addition, water molecules are increasingly coordinated by Li+, reducing the population of free water available for accumulation at electrified interfaces. At low surface charge densities, Li+ addition shifts the corrected potential differences toward those obtained for the dry IL, indicating partial mitigation of water-induced electrostatic screening. At higher polarizations and elevated Li+:H2O ratios, particularly 2:1, the calculated ΔδΦ values exceed those of the dry IL, suggesting an apparent overcompensation of water-screening effects within the classical MD framework. Importantly, the calculated potential differences are interpreted as electrostatic descriptors of EDL polarization and water-screening effects, rather than as direct measures of redox stability or absolute ESW. Overall, these results provide structural and electrostatic evidence that Li+ ions can sequester water and reduce free-water accumulation at electrified interfaces, suggesting that lithium-salt addition may help mitigate water-induced EDL perturbations in humid [Pyr14][TFSI]-based electrolytes
Nerolidol and a zwitterionic surfactant induce membrane rigidity in Leishmania amazonensis and infected macrophages
(2026) Borges, Ellyêssa do Nascimento; Silva, Kleber Santiago Freitas e; Cardoso, Éder Jéferson Souza; Gomes, Rodrigo Saar; Lima, Eliana Martins; Mendanha Neto, Sebastião Antônio; Alonso, Antonio
Spin-label electron paramagnetic resonance (EPR) spectroscopy revealed that the sesquiterpene nerolidol and the ionic surfactant N-hexadecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (HPS) induce membrane rigidity in Leishmania amazonensis after 24 h of exposure. These compounds exhibit antileishmanial activity with IC50 values of ∼74 µmol L-1 (nerolidol) and ∼10 µmol L-1 (HPS). At concentrations near 1-3 × their IC50 values, both agents caused pronounced membrane rigidity, attributed to lipid peroxidation and/or oxidation of membrane proteins driven by elevated ROS levels promoted by the compounds. Both compounds are active in the parasite's plasma membrane, causing a remarkable increase in fluidity immediately after treatment and throughout the 24h-incubation period of the antiproliferative activity assay, the effect reverts to rigidity. Notably, membrane stiffening was absent in uninfected J774A.1 macrophages, suggesting that nitric oxide production may mitigate oxidative damage. In contrast, rigidity was observed in membranes of Leishmania-infected macrophages, indicating compound-induced oxidative stress in infected host cells. These findings support a membrane-centered mechanism of action for both compounds. The early increase in membrane fluidity may promote ion leakage and depolarization of the parasite plasma membrane, leading to mitochondrial hyperpolarization and enhanced ROS generation, which triggers downstream events, including membrane oxidation and stiffening, which ultimately result in parasite death.
A green sol-gel route to Fe3O4@TiO2−CuO photocatalysts with structural stability, visible-light activity, and magnetic recoverability
(2026) Stelzer, Gabriel Bardella; Prescilio, Isabella Cristina; Vasconcelos, Leonardo Gomes de; Bakuzis, Andris Figueiroa; Jacinto, Marcos José
In this work, we present the synthesis of a multifunctional Fe3O4@TiO2−CuO photocatalyst, integrating Magonia pubescens plant extract and urea-assisted pH modulation. The as-prepared composite exhibits outstanding visible-light photocatalytic performance, achieving 75% degradation of rhodamine B (RhB, 15 ppm) after 5 h under 100 W LED irradiation and retaining more than 45% activity across four reuse cycles enabled by simple magnetic recovery. Notably, urea-assisted synthesis reduces iron leaching by ∼50%, preserving magnetic integrity and enabling efficient catalyst separation. Comprehensive structural, morphological, and surface analyses (TEM, XRD, XPS, XRF, VSM, ICP, GC−MS) confirm the formation of a robust, magnetically recoverable hybrid with a narrowed band gap of 1.65 eV and enhanced stability. GC−MS analysis revealed progressive mineralization of RhB into lowmolecular-weight intermediates.
Differential toxicities of manganese ferrite nanoparticles from two synthesis methods using developing zebrafish (Danio rerio): towards a biocompatible and safe magnetic nanoparticles
(2026) Jacintho, Jaqueline Cardoso Conrado; Sousa, Bianca Leite Carnib de; Sousa, Vitoria Gabriela Reis de; Araújo, Marcus Vinícius; Bakuzis, Andris Figueiroa; Rocha, Thiago Lopes
Manganese ferrite nanoparticles (MnFe2O4 NPs) have several environmental and biomedical applications. However, knowledge about their toxicity, as a function of the synthesis method, is still scarce. Thus, the current study aimed to evaluate whether the synthesis method (hydrothermal: HT NPs; coprecipitation: CP NPs) of citrate-coated MnFe2O4 NPs influences their potential toxicity in zebrafish embryos and larvae through multiple biomarker assessment. HT NPs were synthesized at high pressure and temperature, whereas CP NPs synthesis included a passivation step. Fe and Mn were detected in zebrafish chorion exposed to the higher concentration of HT and CP NPs, but they were not detected on the larvae’s body surface. The MnFe2O4 NPs did not induce mortality or inhibit hatching. HT NPs (5.0 and 10 mg L−1) and CP NPs (1.25 to 10 mg L−1) reduced the spontaneous contraction frequency in zebrafish embryos. HT NPs (5.0 and 10 mg L−1) induced tachycardia, CP NPs (2.5, 5.0, and 10 mg L−1) induced bradycardia in zebrafish embryos. Pericardial edemas were a transient effect, detected only in embryos exposed to HT NPs for 48 h. After 72 h of exposure, neither NP type induced significant morphological alterations, changes in ROS levels, effects on cell viability, or behavioral alterations. Overall, synthesis-dependent early developmental effects were observed, with no evidence of persistent post-hatching toxicity under the experimental conditions. Thus, the zebrafish is a suitable model system to compare NPs effects from different synthesis methods, contributing to the development of safer nanotechnologies.
Does electrode spacing truly control capacitance and energy density in graphene-based supercapacitors? A molecular simulation perspective
(2026) Guedes, Davi de Oliveira; Chagas, Henrique de Araujo; Voroshylova, Iuliia Volodymyrivna; Oliveira, Guilherme Colherinhas de
Electrode spacing is frequently considered a parameter in supercapacitor optimization, yet its intrinsic impact on capacitance and energy storage under nanoconfinement remains uncertain. In this study, classical molecular dynamics simulations were performed for graphene-based supercapacitors containing the ionic liquid [emim]- [ala] confined between planar electrodes separated by 4−12 nm. Electric potential profiles enabled the calculation of differential and total capacitances as well as stored energy densities. Mass density analyses show well-defined electric double layers (EDLs) at both electrodes. Strong overlap is observed at short separations, whereas a bulk-like central region is preserved at larger ones. Nevertheless, the total capacitance remains nearly constant (∼2.40−2.58 μF/cm2), and the differential capacitance at zero charge varies only slightly across all separations, indicating a surface-dominated storage mechanism. The integrated areal energy density up to 2.5 V is also essentially independent of spacing (∼7.4−7.7 μJ/cm2). In contrast, gravimetric and volumetric energy densities decrease with increasing separation due to mass and volume normalization effects. These results demonstrate that electrode spacing modulates EDL structure but only weakly affects intrinsic capacitive performance.
Nanoparticle-mediated hyperthermia for male cat neutering: disrupting fertility without surgery
(2026) Silva, Ana Bárbara Rocha; Brito, Juliana Lis Mendes; Souza, Rafaela Lopes Palmeiro de; Gontijo, Fernanda Souza Natividade; Barbosa, Wesley de Souza; Santana, Letícia Araújo de; Almeida, Júlia Palma Maia de; Almeida, Sara Alves; Moraes, Edynara Cruz de; Lima, Vanessa Nicolau de; Bakuzis, Andris Figueiroa
This study aimed to evaluate magnetic nanoparticle-mediated hyperthermia (MNH) as a potential method to induce infertility in male cats. The short- and long-term effects of the treatment on reproductive health parameters were assessed in 20 cats. Treatment consisted of a 150 μL intratesticular injection of a magnetic fluid composed of citrate-coated manganese ferrite (Ci-MnFe2O4) nanoparticles, followed by the application of an external magnetic field to raise and maintain testicular temperature at 45 °C for 15 min. Testicular MNH was found to be safe and well tolerated, with no signs of pain or clinical side-effects. Testicular volume increased significantly on Day 7 due to peritesticular inflammation, followed by a marked decrease on Day 180. Azoospermia was observed in 85 % of the treated animals, while 15 % were oligospermic. Histological analysis revealed substantial damage to seminiferous tubule architecture and epididymides. No hematological, biochemical or abdominal ultrasound abnormalities were observed in the treated animals. These findings demonstrated the strong potential of testicular magnetic hyperthermia mediated by Ci-MnFe2O4 nanoparticles as a non-surgical alternative method for male cat sterilization.
Unraveling the (1 × 1) and (1 × 2) reconstructed surface structures of SrTiO3(1 1 0) single crystal
(2026) Pancotti, Alexandre; Silva, Jenifer Jalowitzki; Castro, Mayron Silva; Siervo, Abner de; Landers, Richard; Nascente, Pedro Augusto de Paula
The surface composition and structure of a strontium titanate (1 1 0) single crystal were evaluated by x-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED), and x-ray photoelectron diffraction (XPD). The (1 × 1) and (1 × 2) reconstructions of the SrTiO3 (1 1 0) surface were characterized by XPD. The comparison between the experimental and theoretical XPD results that used multiple-scattering calculation of diffractions (MSCD) simulation combined with the genetic algorithm suggests that (1 × 2) reconstruction comprises a coexistence of 60.0 % TiO4+ and 40.0 % O24− terminations on the (1 × 1) reconstructed SrTiO3 (1 1 0) surface.
Bio-inspired peptide membranes for CO capture: a molecular dynamics study of A H and A R interface
(2026) Soares, Karinna Mendanha; Oliveira, Guilherme Colherinhas de
The increasing concentration of atmospheric CO2 demands the development of advanced and sustainable materials for carbon capture. Peptide-based nanostructures have emerged as promising candidates due to their tunable chemistry, biocompatibility, and ability to self-assemble into ordered supramolecular architectures. In this work, we investigate the adsorption behavior of CO2 on self-assembled A6H and A6R peptide membranes through classical molecular dynamics simulations. The A6H and A6R sequences consist of six alanine residues capped by a terminal histidine or arginine residue, respectively, and self-assemble into stable βsheet membrane structures whose surface charge distribution and hydration organization are governed by the nature of the terminal residue. After equilibrating the membranes in an aqueous medium, water molecules were removed, and CO2 was introduced into the simulation box to evaluate gas−surface interactions under idealized gas-phase contact conditions. The results reveal distinct adsorption mechanisms governed by headgroup chemistry: the imidazole-terminated A6H interface exhibits preferential electrostatic and hydrogen-bond-driven interactions with CO2, whereas the guanidinium-terminated A6R membrane, characterized by a higher surface charge density, promotes enhanced electrostatic attraction and a larger number of CO2 binding events. These findings highlight how the chemistry of peptide terminal residues modulates CO2 affinity at ordered, self-assembled membrane interfaces, underscoring the potential of bioinspired peptide membranes as tunable platforms for carbon capture. By focusing on experimentally validated supramolecular architectures rather than peptide aggregates or hybrid systems, this study provides molecular-level insights that can inform the rational design of peptide-based sorbent materials for sustainable CO2 sequestration.
Magnetic fluctuations in the Jupiter dusk magnetosheath: cassini observations
(2026) Echer, Ezequiel; Franco, Adriane Marques de Souza; Bolzan, M. J. A.
Magnetic field fluctuations in the Jupiter dusk magnetosheath during the Cassini crossing in 2000-2001 are studied in this work. The properties of the turbulence in this magnetosheath interval are compared with those observed during a background solar wind interval using wavelet, Fourier, kurtosis and multifractal techniques. It was found that the variance of the magnetic field is much higher in the magnetosheath than in the solar wind by factors of 6 to 36 times. The kurtosis parameter was enhanced and larger than 3.0 for the BT and BN components in the magnetosheath, contrasted to the solar wind, which showed a sub-Gaussian behaviour. The multifractal spectrum showed a quasi Gaussian behaviour for the solar wind magnetic field and the occurrence of tails in the magnetic field distributions for the magnetosheath interval. The wavelet analysis showed that there are comparable periods of about 5 to 15 h in the magnetosheath and in the solar wind but these periods are intermittent or present local occurrences in the magnetosheath while they are more continuously observed in the solar wind. Finally, the Fourier power spectrum results showed higher spectral power for the magnetosheath magnetic field components, a power break at 3 mHz for the magnetosheath and solar wind data, with higher power indices in the high frequency portion of the spectra for the magnetosheath (absolute spectral indices varying from 2.3 to 2.7 at high frequencies) than for the solar wind (power index about 2.1). These results show quantitatively that the plasma turbulence is higher in the jovian magnetosheath than in the background upstream solar wind, due to the fact that as the continuous solar wind is compressed and heated at the bow shock, it becomes disrupted and turbulent.
Room-temperature magnetic behavior of Bi-doped Co⁢0.6⁢Zn⁢0.4⁢Fe⁢2⁢O⁢4ferrite nanoparticles
(2026) Ribeiro, Ítalo Nuta; Macedo, Isabella Rocha de; Pessoa, Marcio Solino; Banerjee, Prasun; Franco Júnior, Adolfo
In this study, we examined the effect of Bi⁢3+ion substitution on the structural and magnetic properties of cobalt ferrite nanoparticles Co0.6Zn0.4Fe⁢2⁢−𝑥⁢Bi𝑥⁢O4 with nominal compositions of 𝑥= 0.0, 0.005, 0.008, 0.01, and 0.03 under applied magnetic fields of up to 6 T at room temperature. Hysteresis loop analysis reveals that the saturation magnetization (𝑀𝑠), coercive field (𝐻𝑐), and remanent magnetization (𝑀𝑟) exhibit significant variation with bismuth concentration. Notably, the coercivity shows a non-monotonic trend, increasing at low Bi contents and then decreasing at higher doping levels. The cubic magnetocrystalline anisotropy constant (𝐾1), derived from the “law of approach to saturation,” decreases from 2.32 × 106 erg/cm³ for x = 0 to 1.58 × 106 erg/cm³ for x = 0.03 at room temperature, indicating strong dependence on Bi substitution. Yafet–Kittel based analysis indicates the emergence and intensification of spin canting with increased Bi content, providing insight into the observed magnetic behavior. These results are discussed in relation to inter-particle interactions driven by thermal fluctuations during the synthesis process and the redistribution of Co⁢2+ ions between tetrahedral (𝐴) and octahedral (𝐵) sites induced by Bi⁢3+ doping. These results suggest that Bi-doped cobalt-zinc ferrite is a promising material for room-temperature applications, including magnetic sensors and actuators.
Cholesterol-driven optimization of liposomal systems for ivermectin capture: insights from experimental and molecular dynamics studies
(2026) Barros, Alexandre Có Mangoni; Pires, Jader; Sousa, Lucas Ribeiro de; Soares, Karinna Mendanha; Fontanezi, Bianca Bueno; Oliveira, Guilherme Colherinhas de; Botelho, Ana Flávia Machado; Mendanha Neto, Sebastião Antônio; Lima, Eliana Martins
This study investigates the interactions between ivermectin (IVM) and lipid membranes with varying cholesterol contents by using a combined molecular dynamics (MD) and experimental approach. DOPC bilayers containing 0, 10, 20, or 30% cholesterol were simulated, and SPC liposomes were employed for experimental validation. Mass density profiles indicated that the membrane thickness increased from 4.16 nm (0% cholesterol) to 4.60 nm (30% cholesterol), while ivermectin was most deeply embedded in membranes with 10% cholesterol with an average distance of 1.09 nm from the bilayer center. van der Waals interaction energies were most favorable at 10% cholesterol (−333.13 kJ/mol), correlating with an increased hydrogen-bond lifetime (2.10 ns) between IVM and lipid molecules. Mean square displacement (MSD) analysis revealed that ivermectin exhibited the lowest mobility (0.0019 × 10−5 cm2 /s) in membranes with 10% cholesterol. ESR spectroscopy of 5- DSA-labeled SPC liposomes demonstrated a progressive increase in 2A|| values with increasing cholesterol content, with additional increases following IVM incorporation. IVM capture experiments showed that liposomes containing 10% cholesterol achieved the highest drug association, consistent across saline and plasma environments. These findings provide a mechanistic basis for the rational design of liposomal systems with high ivermectin-binding capacity, with potential implications for future applications requiring the sequestration of this compound in biological environments.
Low-temperature magnetic anomalies in orthorhombic yttrium chromite nanoparticles: indications of magnetic frustration and glassy-like behavior
(2026) Ribeiro, Ítalo Nuta; Franco Júnior, Adolfo
In this study, we investigate the magnetic properties of Math input error nanoparticles synthesized via the combustion reaction method. Magnetic measurements performed over a wide temperature range (4–300 K) revealed two distinct magnetic regimes across the Néel temperatureMath input error, corresponding to a smooth and continuous transition from a canted antiferromagnetic to a paramagnetic state. The hysteresis loops exhibited pronounced asymmetry with respect to both the magnetic field and magnetization axes, indicating the presence of an exchange-bias-like effect. This behavior is attributed to interfacial coupling between coexisting magnetic phases or to competing spin structures, reflecting complex nanoscale magnetic interactions. Temperature-dependent magnetic susceptibility measurements yielded a negative Curie–Weiss temperature Math input error, confirming dominant antiferromagnetic correlations. Below Math input error, a significant divergence between field-cooled (FCC) and zero-field-cooled (ZFC) susceptibilities was observed, with magnetization exhibiting different saturation levels near 3 K. Furthermore, an irreversibility between the FCC and field-cooled warming (FCW) curves was detected below Math input error, suggesting the emergence of magnetic frustration or glassy-like behavior in the nanoparticles. Arrott plot analysis indicated that the magnetic transition is of second order.
Interplay between structural, electronic, and topological properties in low-dimensional tellurium
(2026) Araújo, Gabriel Elyas Gama; Rosa, Andréia Luisa da
We present a comprehensive first-principles investigation of the structural, electronic, vibrational, and topological properties of tellurium across its dimensional hierarchy, including bulk trigonal Te−I, two-dimensional tellurene polymorphs, and one-dimensional helical nanowires. Using density functional theory with full inclusion of spin−orbit coupling, we confirm that bulk Te−I is a narrow-gap semiconductor hosting Weyl nodes arising from broken inversion symmetry and degenerate phonon modes suggestive of chiral phonon behavior. In contrast, two-dimensional α- and β-tellurene are found to be topologically trivial ( = 0 2 ), with no spin−orbit-driven band inversion in the occupied manifold. Beyond these established phases, we find that buckled kagome and buckled square tellurene lattices exhibit a nontrivial two-dimensional = 1 2 topology of the occupied electronic bands, indicating incipient quantum spin Hall character in metallic systems. In contrast, one-sided hydrogen-passivated hexagonal tellurene realizes a fully gapped quantum spin Hall phase with a robust = 1 2 invariant, preserved under applied strain and chemical functionalization. In the one-dimensional limit, helical tellurium nanowires preserve chirality and host edgelocalized states accompanied by pronounced anisotropy in carrier effective masses. These results establish tellurium as a highly tunable platform for engineering topological phenomena across dimensionality, bridging three-dimensional Weyl physics, twodimensional quantum spin Hall and incipient 2 phases, and one-dimensional helical systems
Hydrogen bonding and membrane anchoring of the antimicrobial peptide NP-3a investigated through molecular dynamics
(2026) Aquino, Ana Clara Duarte; Soares, Karinna Mendanha; Oliveira, Guilherme Colherinhas de; Georg, Herbert de Castro
Antimicrobial peptides (AMPs) are emerging as critical alternatives to antibiotics in the fight against multidrug resistance. NP-3a, a rabbit defensin, combines structural stability with broad-spectrum activity, yet its molecular mechanism of membrane interaction remains unclear. Here, we employed atomistic molecular dynamics simulations to investigate NP-3a in vacuum, aqueous solution, and at a DOPC lipid bilayer interface. In solution, NP3a shifted from a compact β-sheet stabilized by ~23 intramolecular HBs to a dynamic state engaging extensively with water (~122 HBs, lifetime ~9.6 ps). At the membrane interface, NP-3a achieved stable anchoring with ~39% insertion, mediated by ~12 long-lived hydrogen bonds (~2.9 ns lifetime) with DOPC headgroups and a binding free energy of 24.3 kJ/mol. Residue-level analysis revealed Arg-7 to Arg-9 as dominant contributors through electrostatic anchoring to phosphate groups, reinforced by serine- and cysteine-mediated contacts. Notably, NP-3a remained localized at the membrane surface without penetrating the hydrophobic core, supporting a selective surface-associated mechanism of action. These findings provide atomistic insights into NP-3a’s interaction with eukaryotic-like membranes and highlight molecular determinants relevant for the rational design of next-generation AMPs.
Hydrogen adsorption on transition-metal dichalcogenide monolayers: energetics and desorption thermodynamics from first principles
(2026) Oliveira, Flávio Bento de; Araújo, Gabriel Elyas Gama; Rosa, Andreia Luisa da
Understanding how electronic structure, crystal phase, and lattice asymmetry control molecular hydrogen adsorption in two-dimensional materials is essential for designing reversible hydrogen-storage platforms. Here, we present a systematic first-principles investigation of H2 adsorption on 1T and 2H transition-metal dichalcogenides (MX2, M = Ni, Pd, Pt; X = S, Se) and their Janus counterparts (MSSe). Adsorption energies, coverage effects, ab initio molecular dynamics, and Arrhenius-based desorption kinetics are analyzed to identify the governing adsorption mechanisms and finite-temperature behavior. The calculations reveal three distinct adsorption regimes across the investigated monolayers. Ni- and Pd-based systems predominantly exhibit weak molecular physisorption characterized by small adsorption energies and high reversibility, whereas Pt-containing compounds display substantially stronger interactions and, in selected configurations, partial or complete hydrogen dissociation. The adsorption behavior is shown to depend not only on the density of metal d states near the Fermi level, but also on crystal phase, surface symmetry, molecular orientation, and local orbital hybridization. Janus monolayers introduce an additional polarity-driven asymmetry between the two surfaces, modifying the adsorption energetics and molecular confinement.Coverage-dependent calculations demonstrate that increasing hydrogen loading systematically weakens the average adsorption energy due to intermolecular repulsion and progressive saturation of favorable adsorption regions. Finite-temperature AIMD simulations further indicate that molecular adsorption remains dynamically stable at room temperature over the simulated timescale, with no evidence of irreversible surface degradation or spontaneous hydride formation.Among the investigated systems, Janus PdSSe exhibits adsorption energies and desorption kinetics compatible with reversible molecular hydrogen adsorption near ambient conditions while simultaneously achieving high gravimetric storage capacity at elevated coverage. These results provide insight into the interplay between electronic structure, structural asymmetry, and adsorption thermodynamics in transition-metal dichalcogenide monolayers and highlight Janus TMDs as promising platforms for tunable molecular hydrogen adsorption.
Electronic and optical properties of ultra-wide gap two-dimensional germanium dioxide
(2026) Reis, Rafael Franco Ribeiro; Araújo, Gabriel Elyas Gama; Kuritza, Danilo de Paula; Sousa, José Eduardo Padilha de; Dias, Alexandre Cavalheiro; Rosa, Andréia Luisa da; Pontes, Renato Borges
We employ first principles density-functional theory and the Bethe-Salpeter equation (BSE) in the framework of tight-binding based maximally localized Wannier functions model to investigate the electronic and optical properties of free-standing two-dimensional (2D) germanium dioxide phases. All investigated 2D GeO2polymorphs exhibit ultra-wide band gaps (3.6-5.3 eV) and strong excitonic effects, with valence bands tunable under strain. These features allow the design of materials with ultra large electronic gaps in low-dimensional systems, making these materials promising for devices operation at higher voltages and temperatures than conventional semiconductor materials.
Peptide-Carbon nanotube hybrids under confinement: structure and stability from atomistic simulations
(2026) Soares, Karinna Mendanha; Oliveira, Guilherme Colherinhas de
The interaction between peptides and carbon nanotubes (CNTs) represents a promising route for developing biofunctional nanomaterials that couple structural flexibility to superior electronic performance. In this work, we investigate the structural and energetic behavior of A6D peptides confined inside a single-walled CNT using classical molecular dynamics simulations. The system consists of a 2 nm-radius CNT containing 35 A6D peptides and an equivalent number of counterions, fully solvated in water. Analyses of hydrogen-bond dynamics, Coulombic and van der Waals energies, and Ramachandran distributions reveal that peptide−solvent interactions dominate peptide−peptide aggregation, maintaining high flexibility within the confined environment. The alanine residues exhibit strong hydrophobic attraction to the CNT surface, while aspartic acid residues form extensive hydrogen bonds with water, resulting in a balanced solvation−stabilization regime. The confined peptides preferentially adopt α-helical conformations compatible with the cylindrical geometry of the nanotube, suggesting the potential formation of an internal peptide-membrane-like structure. These findings provide molecular-level insights into how electrostatic (peptide−peptide) and dispersion forces (peptide− peptide and peptide−CNT) govern organization and stability under nanoscale confinement. The results highlight the potential of peptide-coated CNTs as building blocks for bioelectronic interfaces, selective molecular transport systems, and controlled-release nanocarriers, bridging biomolecular self-assembly with advanced carbon nanotechnology.
Unveiling the potential of natural deep eutectic solvents in electrochemical energy storage applications
(2026) Chagas, Henrique de Araujo; Oliveira, Guilherme Colherinhas de; Fileti, Eudes Eterno
Supercapacitors are key to sustainable energy storage due to their high power density and long lifespan, though their energy density remains limited. This study explores natural deep eutectic solvents (NADES) as alternative electrolytes for graphene-based supercapacitors via molecular dynamics simulations. Three NADES�composed of betaine chloride and the amino acids arginine, histidine, or lysine�are assessed for their biocompatibility, cost-effectiveness, and hydrogen-bonding capabilities. Simulations at 300 and 600 K reveal distinct physicochemical behaviors: histidine-based NADES shows the highest density and cohesive energy, attributed to imidazole-mediated interactions, while lysine-based NADES offers the greatest ionic mobility. In supercapacitor models, asymmetric electric double layers (EDLs) form, with amino acids dominating the positive EDL and betaine the negative. Interaction energy analyses underscore the stabilizing role of amino acids in the EDL structure. Capacitance values range from 2.2 to 2.8 μF/cm2, aligning with those of conventional electrolytes. These results highlight the promise of NADES as sustainable and tunable electrolytes, offering a viable route to enhance the performance of next-generation supercapacitors.

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