Search Results (770)

Poly(amidoamine) (PAMAM) dendrimers are widely recognized as versatile nanocarriers due to their tunable architecture and ability to associate with bioactive molecules. In this study, generation 3 PAMAM dendrimers functionalized with triphenylphosphonium (TPP) were employed to investigate the association of structurally related phenolic compounds—caffeic acid, p-coumaric acid, and cinnamic acid—through either covalent conjugation or non-covalent encapsulation. Physicochemical characterization by NMR, dynamic light scattering, and zeta potential measurements revealed the formation of supramolecular aggregates rather than isolated dendrimer units, with hydrodynamic diameters ranging from 127 to 260 nm and positive surface charge across all formulations. Encapsulation efficiencies determined by HPLC reached 93.8% for caffeic acid, 78.9% for p-coumaric acid, and 71% for cinnamic acid, indicating differential association behavior. Molecular dynamics simulations over 1 μs supported these findings, showing stronger and more stable interactions for polar antioxidants, particularly caffeic acid, driven by hydrogen bonding and electrostatic interactions, while cinnamic acid displayed preferential binding in more hydrophobic dendrimer regions. Radical scavenging assays (DPPH• and ABTS•+) demonstrated that all formulations retained antioxidant capacity, although dendrimer association modulated scavenging kinetics. In cellular assays under oxidative stress, free caffeic acid exhibited the strongest immediate reduction of intracellular reactive oxygen species, whereas dendrimer-associated systems showed reduced but significant activity, consistent with decreased solvent accessibility and slower release predicted by simulations. Overall, these results highlight a trade-off between molecular retention and immediate biological efficacy, demonstrating that the mode of association governs antioxidant accessibility and performance. This combined experimental and computational approach provides a mechanistic framework for the rational design of dendrimer-based delivery systems aimed at balancing stability and functional activity. Full article

Metal oxide nanoparticles dispersed in water are difficult to recover because of their small size and colloidal stability. In this study, the interfacial adsorption behavior of Fe₂O₃, CoO, and CuO nanoparticles at hydrophobic ionic liquid (IL)–water interfaces was investigated and compared with that at molecular solvent–water interfaces. When CuO nanoparticle dispersions were shaken with hydrophobic ILs, bis(trifluoromethanesulfonyl)imide ([NTf₂]⁻) salts of 1-butyl-3-methylimidazolium ([BMIm]⁺) and 1-octyl-3-methylimidazolium ([OMIm]⁺), the nanoparticles were removed from the aqueous phase and accumulated at the IL–water interface, while negligible Cu was detected in the bulk IL phase. The removal efficiency decreased with increasing ionic strength below 0.05 mol/dm³ and increased with pH, indicating that electrostatic interactions between charged nanoparticles and the IL–water interface contribute to adsorption. Adsorption isotherms were empirically fitted with the Langmuir equation to estimate the maximum adsorption capacity. For negatively charged Fe₂O₃ and CuO nanoparticles, the maximum adsorption capacities at IL–water interfaces exceeded those at molecular solvent–water interfaces and the theoretical monolayer capacity estimated from nanoparticle size, suggesting multilayer adsorption or aggregation at the interfaces. These results demonstrate the potential of hydrophobic IL–water interfaces for the separation and recovery of metal oxide nanoparticles from aqueous media. Full article

A series of Group 10 metal dithiocarbonate complexes [M(S₂COⁱPr)₂] (M = Ni 1, Pd 2, Pt 3) was prepared following procedures from the literature and cocrystallized with the ditopic σ/π-hole donor 1,4-diiodotetrafluorobenzene. Single-crystal X-ray diffraction revealed a consistent I···S halogen bonding motif alongside a remarkable diversity in metal-involving interactions across the Ni–Pd–Pt triad. While nickel(II) exhibits strong electrophilic M···S semicoordination, the palladium(II) center displays ambiphilic behavior, and platinum(II) acts exclusively as a nucleophile via π-hole···M bonding. Comprehensive density functional theory studies, including molecular electrostatic potential (MEP) mapping, quantum theory of atoms in molecules/noncovalent interaction plot analyses, and energy decomposition analysis, were used to quantify this competitive balance. The results demonstrate that the increasing nucleophilicity from Ni to Pt, supported by shifting MEP minima and stronger π-hole stabilization energies, dictates the preference for nucleophilic over electrophilic metal-centered contact. Full article

As an efficient dry separation technology, electrostatic separation exhibits significant potential for application in the sorting and recovery of carbon-rich resources from coal gasification fine slag (CGFS). The small particle size and high moisture content of CGFS particles are the main factors affecting the efficiency of separation. This study proposes a method integrating particle moisture reduction and charging promotion based on molecular sieves, with the aim of investigating its feasibility in improving the electrostatic separation efficiency of CGFS particles. The results indicate that molecular sieves can effectively adsorb moisture from the ambient humid air and the surface of particles, allowing for rapid drying of wet particles. The reduction in moisture content on the particle surfaces significantly promotes their charging capability, creating favorable conditions for electrostatic separation. After molecular-sieve-assisted charging enhancement, the carbon content in the ash-enriched positive plate product decreased by 4.96%, while the carbon content in the carbon-enriched negative plate product increased by 12.15%, indicating a significant improvement in carbon–ash separation efficiency. Correspondingly, the decarbonization efficiency of the positive plate and carbon recovery efficiency of the negative plate were increased by 21.30% and 52.17%, respectively. Furthermore, when the moisture content exceeds 10%, the phenomenon of inter-particle agglomeration can adversely affect the separation of carbon and ash particles. The most suitable operating conditions are a moisture content no higher than 10%, an electric field density of 30 kV/m, a filling molecular sieve of 400 g, and a gas velocity of 12 m/s (volumetric flow rate 84.78 m³/h). In practical industrial applications, it is advisable to consider pre-treating the particles for drying or employing secondary separation to enhance sorting accuracy. Full article

The molecular electrostatic surface potential (MESP) has become a key theoretical tool for probing reactivity in chemical systems. It reveals electrophilic and nucleophilic regions on molecular surfaces, underpinning the understanding of noncovalent interactions such as hydrogen, triel, tetrel, pnictogen, chalcogen, halogen, matere, and aerogen bonding, among many others. These interactions, driven by Coulombic attraction, govern aggregation in molecular and supramolecular systems across solid, liquid, and gas phases. MESP applications span crystal engineering, polymers, biology, catalysis, photovoltaics, and drug discovery. While limitations exist—such as the arbitrariness in defining isodensity surfaces—its impact on advancing both theoretical and applied chemical research is substantial. This review outlines the conceptual foundations of MESP and highlights its broad relevance across the chemical sciences. Full article

An efficient bacteriophage delivery system needs to be developed to overcome the challenges associated with phage instability, rapid diffusion, and loss of infectivity at the infection site. Hydrogels have been found to be potential carriers. Hydrogels have emerged as promising carriers due to their biocompatibility, tunable physicochemical properties and capacity for controlled release. However, the molecular factors that regulate phage–hydrogel interactions remain poorly understood. In this study, we employed an in silico framework combining molecular docking, molecular dynamics (MD) simulations, MM/PBSA binding energy calculations, machine learning-based adhesion prediction, and diffusion modeling to explore phage–hydrogel interactions at the molecular level. Surface-exposed bacteriophage proteins, such as capsid and tail proteins, were evaluated against eight different hydrogel polymers. Binding site analysis revealed the presence of multiple solvent-accessible pockets that can interact with the polymer. Docking studies showed favorable and stable interactions, with hyaluronic acid showing strong binding affinity to multiple phage proteins (−5.5 to −5.7 kcal/mol) and GelMA showing high affinity to the capsid gp10 protein (−5.6 kcal/mol). The integrity of the structural complexes was further confirmed by 100 ns MD simulations, stable RMSD and RMSF trajectories, compact structural conformations, and favorable MM/PBSA binding energies. Machine learning classification successfully differentiated high- and low-adhesion systems and identified hydrogen bonding and electrostatic interactions as key determinants of sustained yet reversible phage retention. Collectively, our findings suggest that the hydrogels enriched with charged and polar functional groups can facilitate stable but non-destructive phage binding, enabling controlled and sustained release. This study provides mechanistic insights into rational hydrogel design for phage delivery systems and highlights the potential of high-throughput computational strategies to accelerate the development of optimized phage therapeutics. Full article

As the demand for sustainable and bio-based alternatives to petroleum-derived membranes grows, polysaccharides have emerged as promising candidates. In this study, we fabricated free-standing membranes from konjac glucomannan (KGM), a neutral polysaccharide, using a simple base-induced insolubilization process. Fourier transform infrared spectroscopy revealed that the deacetylation of KGM chains promotes extensive intermolecular hydrogen bonding, creating a robust and stable three-dimensional network without the need for chemical cross-linkers. The resulting KGM free-standing membranes exhibited excellent mechanical properties, characterized by high tensile strength in the dry state and remarkable flexibility when hydrated. Furthermore, the membranes demonstrated superior chemical resistance to organic solvents such as acetone and n-hexane. Transport studies showed that the membranes possess a highly dense structure with no detectable pressure-driven pure-water permeation up to 0.25 MPa. Solute permeation experiments using eight model molecules (molecular weight = 144–14,600 Da) indicated that transport behavior is consistent with diffusion through a hydrated polymer network. The effective diffusion coefficient D_eff showed a strong correlation with molecular weight M, following the relationship D_eff ∝ M^−1.7. Furthermore, the permeation behavior remained stable across a wide pH range (2–12), and, within the investigated range of monovalent solutes, D_eff was insensitive to solute charge, indicating that mass transport is dominated by size-based diffusion rather than electrostatic interactions. These findings suggest that KGM free-standing membranes enable reliable molecular fractionation based on size-dependent diffusion within a stable, neutral matrix, offering significant potential for sustainable separation technologies and biomedical applications. Full article

For a protein to perform its biological functions, it must adopt a specific three-dimensional conformation. In addition, many proteins require the assistance of other protein complexes known as chaperonins to fold —i.e., to acquire such a specific conformation—, although the exact mechanisms whereby the chaperonins act and assist the folding process have not been completely determined. In this work, we characterize the physical environment at the interior of the chaperonin HSP60/HSP10 via Molecular Dynamics Simulations. We found that, inside the cavity of the chaperonin (within a region covering much of the cavity’s volume), the long-range electrostatic potential presents a structured pattern that, except for small fluctuations, does not change in time. The electrostatic potential generates an electric field that can be modeled, as a first approximation, as constant and unidirectional $(\mathit{E}/\left(\mathrm{V}·{\AA }^{-1}\right)\approx -0.0054\widehat{𝚤}+0.010\widehat{\mathit{𝚥}}-0.162\widehat{k}$, here the chaperonin’s main axis is aligned along $\widehat{k})$, which can produce large deformations in the structure of a heated protein (Rhodanese); the long-range approximated $\mathit{E}\left(\mathit{r}\right)$ can in fact unfold the Rhodanese, when applied as an external field. Finally, we discuss the possible implications of such an electric field for the protein folding problem, within the context of proteins whose folding is assisted by chaperones. The existence and effects of the electric field are consistent with several theories and experimental observations related to the protein folding problem, in particular with the foldon view. Full article

Zinc and iron are essential micronutrients in crop nutrition, and polymer-based nanogels have emerged as promising carriers to modulate their availability in sustainable agricultural systems. Here, a polymeric model receptor was designed to investigate how the nature and position of electron-donating (–NH₂) and electron-withdrawing (–NO₂) substituents control the recognition of Zn²⁺ and Fe²⁺ cations. Using a combination of density functional theory calculations, energy decomposition analysis with natural orbitals for chemical valence (EDA–NOCV), electrostatic potential (ESP) mapping, and quantum theory of atoms in molecules (QTAIM) method, the receptor–cation interactions are dissected into electrostatic, Pauli repulsion, orbital, and dispersion contributions. The results show that complex stability is governed mainly by orbital and electrostatic terms, with Fe²⁺ forming the most stable complex (−393.57 kcal mol⁻¹) with regard to a Zn²⁺ similar complex (−288.80 kcal mol⁻¹). Zn²⁺ complexes exhibit a broad tunability with substituent pattern. Electron-donating groups systematically strengthen both electrostatic and orbital components, whereas nitro substituents display a pronounced positional effect, ranging from strong destabilization to significant stabilization of Zn²⁺ binding. These findings establish molecular-level guidelines for engineering polymeric nanogels with tunable affinity and selectivity toward micronutrient cations in agricultural applications. Full article

In this study, a novel combination strategy of sodium trimetaphosphate (STMP) phosphorylation and dextran (DX) glycosylation was employed to modify soy protein isolate (SPI). The phosphorylated protein–dextran conjugate (TSPI-DX) was successfully prepared and then was used as an emulsifier to prepare the astaxanthin emulsion, with the aim to enhance the emulsion delivery performance. Structural analysis revealed that phosphorylation and glycosylation altered the microenvironment of the side chains, leading to changes in protein secondary structure, which consequently loosened the protein architecture and enhanced molecular flexibility. The functional properties of TSPI-DX, including its solubility, emulsifying activity (EAI) and emulsifying stability (ESI), were markedly enhanced. Furthermore, the concurrent modification through phosphorylation and the Maillard reaction yielded a synergistic effect, boosting the DPPH radical scavenging rate by 86.5% and increasing the ferric-ion reducing power nearly fourfold. The astaxanthin emulsion prepared by modified SPI also exhibited several advantages. The TSPI-DX emulsion exhibited a markedly smaller mean particle size and a larger absolute Zeta-potential value. Consequently, with the higher electrostatic repulsion and steric hindrance among the droplets, the astaxanthin emulsion prepared by TSPI-DX demonstrated superior encapsulation efficiency and stability across various conditions, including storage, oxidation, thermal, and pH challenges. Moreover, in vitro digestion experiments revealed that the modified SPI emulsion facilitated a higher extent of lipolysis and astaxanthin bioaccessibility. Therefore, this work proposes a novel strategy for constructing plant-protein emulsion systems with enhanced delivery and release capabilities. Full article

Acinetobacter baumannii (A. baumannii) represents a major threat because of its multidrug resistance, achieved through its ability to control virulence, and its mechanisms of drug efflux resistance. In this study, we used a combined experimental–computational approach to create and evaluate antimicrobial peptides that targeted the two essential pathogenic proteins, BfmR and AbaQ. The genomic analysis of a clinical isolate showed an extensive resistome and virulence profile, which matched high-risk global lineages. This study conducted molecular docking of an experimental AMP (cathelicidin KR-12 screened from the literature) and a rationally designed synthetic AMP (modified KR-12 analog) with pathogenic proteins, followed by 200 ns molecular dynamics simulations to evaluate both the binding stability and inhibitory potential of the compounds. The disk diffusion assay and microdilution assay were performed against A. baumannii. The study used comparative trajectory analyses, including RMSD, RMSF, radius of gyration, solvent-accessible surface area, principal component analysis, and MM-PBSA free energy calculations, to show that the synthetic AMP created stable electrostatic and hydrogen-bond networks, which caused conformational locking, and reached lower energy states than the experimental peptide. The synthetic AMP showed significant inhibition in validation in vitro. Contrastingly, the experimental AMP had transient interactions and no specificity. The study demonstrates that rationally designed AMPs have therapeutic potential, while the results create a reliable in silico framework to combat multidrug-resistant A. baumannii. Full article

In order to find green fungicides derived from natural products, 22 unreported anethole-based thiazolinone-hydrazone compounds were designed and synthesized, and their structures were characterized by FT-IR, ¹H NMR, ¹³C NMR, and HRMS. At a concentration of 50 mg/L, the preliminary antifungal activity of the target compounds against eight plant pathogens was evaluated. The results showed that 5q (R = m-OH C₆H₄) exhibited the best inhibitory activity against most of the tested plant pathogenic fungi, demonstrating that this compound had certain broad-spectrum antifungal activity. In addition, a reasonable and effective 3D-QSAR model (r² = 0.994, q² = 0.529) was established using the comparative molecular field analysis (CoMFA) method to study the relationship between the structures of the target compounds and their antifungal activity against Physalospora piricola. Meanwhile, the results of electrostatic potential calculation of the compounds indicated that the electronic effect caused by different substituents on the benzene ring might be one of the factors affecting antifungal activity. In addition, frontier molecular orbital calculations implied that the anethole moiety and the thiazolinone-hydrazone-benzene structure in the target compounds might play an important role in antifungal activity. The potential binding mode between the target compound 5q (R = m-OH C₆H₄) and the homology-modeled succinic dehydrogenase was explored by molecular docking. Full article

Streptococcus pneumoniae resists host defenses through multiple surface factors, yet their specific contribution to protection against antimicrobial peptides remains incompletely understood. We examined the role of pneumococcal surface protein A (PspA) and the polysaccharide capsule in protection against the human defensin HNP-1. PspA conferred increased resistance to HNP-1-induced killing, shown by a decreased killing in the presence of purified recombinant PspA and an increased sensitivity when PspA was deficient from the surface of strains of two different genetic backgrounds or when anti-PspA antibody was present. The capsule also conferred protection against HNP-1, which was serotype-dependent, with type 2 protecting better than type 4, and free polysaccharides acted as decoys by sequestering HNP-1. Removal of surface PspA from capsule-deficient mutants revealed additive contributions of both factors to survival. Molecular docking analysis suggests a potential electrostatic interaction between PspA and HNP-1. These findings highlight the independent and complementary roles of PspA and the capsule in pneumococcal resistance to HNP-1 and provide novel insights that may inform future vaccine design and antimicrobial strategies. Full article

This study explored the electronic and structural tunability of fullerene (C₆₀) derivatives via functionalization with heteroatoms (O, S, Se) in mono-, di-, and tri-bridged configurations, including covalently modeled dimers. Calculations were performed using density functional theory (DFT) at the B3LYP/6-31G(d,p) level. Electronic descriptors such as total dipole moments (TDMs), HOMO–LUMO energy gaps (ΔE), global reactivity descriptors, total density of states (TDOS), molecular electrostatic potential (MESP) and non-covalent interactions (NCIs) were analyzed to elucidate how functionalization alters reactivity and stability. Key findings indicate that TDM increases and ΔE decreases in all functionalized C₆₀; for example, the TDM increased from 0 Debye for C₆₀ to 2.156 Debye for C₆₀–O–S–Se, and ΔE decreased from 2.762 eV (C₆₀) to 2.532 eV (C₆₀–Se), indicating enhanced reactivity. This aligns with global reactivity descriptors such as reduced ionization energy and hardness. Mapped MESP surfaces showed activation around heteroatom sites. Quantum theory of atoms in molecules (QTAIM) and NCI analyses revealed that while mono-bridged structures retain covalent linkages, dimeric systems such as C₆₀–O–C₆₀ and C₆₀–S–C₆₀ relax into weak, van der Waals-type interactions. OPDOS (overlap population density of states) highlighted antibonding character between the fragments in the conduction region. These results demonstrate that heteroatom functionalization enhances the electronic properties of C₆₀, making it a promising candidate for optoelectronic, organic photovoltaic, and sensor applications. Full article

Atomic charges play a central role in the analysis of molecular electronic structure and are widely used in the development of computational models. We introduce a simple and computationally efficient extension of Hirshfeld’s 1977 stockholder partitioning method, called scaled Hirshfeld, in which neutral proatom densities are scaled to construct a promolecular density better adapted to the molecular electron density. We present a fixed-point iterative algorithm to compute the proatom scaling coefficients and show that this formulation is equivalent to the information-theoretic additive variational Hirshfeld method with a minimal basis. This equivalence establishes a rigorous mathematical foundation for the scaled Hirshfeld method and ensures size consistency as well as the existence of a unique solution. Numerical results demonstrate that the proposed approach yields charges larger than those obtained with the original Hirshfeld method, while retaining computational efficiency and providing an improved description of molecular dipole moments and electrostatic potentials. Full article