Search Results (121)

Siderophores are high-affinity iron-chelating metabolites that underpin microbial survival in iron-limited environments and play central roles in metal homeostasis, ecological competition, and pathogenesis. Traditionally viewed as dedicated Fe(III) scavengers, siderophores are now recognized as structurally and functionally versatile coordination agents whose donor-set architectures—particularly catecholate and α-hydroxycarboxylate motifs—permit conditional interactions beyond iron. In iron- and boron-rich niches, especially marine and mildly alkaline systems where borate availability increases, certain siderophores are chemically capable of forming reversible borate complexes through cis-diol coordination. Although Fe(III) exhibits substantially higher thermodynamic affinity and remains the primary biological target, boron binding represents a predictable secondary property arising from shared oxygen-donor chemistry. This dynamic interplay allows siderophores to cycle between iron-bound, boron-bound, and apo states depending on local redox conditions, pH, and metal availability. Here, we synthesize current knowledge on the structural classes of microbial siderophores, their transport and regulatory mechanisms, and emerging evidence for boron coordination within catecholate and carboxylate systems. By integrating coordination chemistry with microbial ecology, we propose an expanded model in which siderophores function not only as iron acquisition molecules but also as modulators of boron speciation and environmental sensing. This functional plasticity positions siderophores at the intersection of iron and boron biogeochemical cycles and highlights new directions for understanding microbial adaptation in complex metal-rich environments. Full article

Boron neutron capture therapy (BNCT) is a biologically targeted, high–linear energy transfer radiotherapy that selectively delivers cytotoxic α-particles to boron-loaded tumor cells and has re-emerged with the development of hospital-compatible accelerator neutron sources and improved boron carriers. We performed a structured literature review of PubMed, Embase, and the Cochrane Library through October 2025 to summarize the radiobiological rationale, boron delivery strategies, and clinical outcomes of BNCT in glioblastoma (GBM) and other high-grade central nervous system tumors. Eligible clinical and translational studies were screened independently, and data on patient populations, boron agents, neutron source technologies, dosimetry, survival, response, and toxicity were extracted. Contemporary series and phase II trials indicate that BNCT is technically feasible and generally well tolerated, with encouraging survival outcomes in selected newly diagnosed and recurrent GBM, meaningful activity in recurrent high-grade meningiomas, and acceptable safety in limited pediatric cohorts. Current practice relies primarily on second-generation carriers such as boronophenylalanine and sodium borocaptate, while third-generation molecular and nanocarrier platforms remain in preclinical development. Overall, BNCT represents a promising high-LET, pharmacologically targeted modality for heavily pretreated and radioresistant CNS tumors, and ongoing prospective studies are needed to define its comparative effectiveness and optimal integration into patient care. Full article

Siderophores are classically understood as microbial iron-acquisition metabolites: low-molecular-weight ligands secreted by bacteria to solubilize and transport Fe(III) under iron-limited conditions. In this review, we expand that paradigm by highlighting an emerging and underappreciated chemical axis—boron coordination by siderophores—that links terrestrial (soil/rhizosphere) and marine microbiomes. Across diverse bacterial taxa, siderophore production is widespread and central to competitive fitness because Fe(III) is poorly soluble and frequently sequestered in environmental or host matrices. Yet in boron-rich settings (seawater and borate-enriched soils), the same oxygen-donor architectures that support Fe(III) chelation can also engage boron chemistry. We synthesize evidence that carboxylate/α-hydroxyacid (dicitrate-type) and catecholate siderophores can form tetrahedral borate/boronate complexes, whereas hydroxamate siderophores generally lack the vicinal dianionic O,O motif required for stable boron binding. Structurally characterized examples—including vibrioferrin, rhizoferrin, and petrobactin—demonstrate that boron complexation is experimentally observable by ESI-MS and multinuclear NMR and can be modulated by pH and microenvironment. Integrating these findings with datasets on boron-tolerant bacteria, we propose that when iron is scarce and boron is available, boron–siderophore complexation becomes chemically feasible and may influence microbial physiology by altering ligand conformation, metal selectivity, and potentially extracellular signaling behavior—especially in marine systems where borate is abundant at oceanic pH. Overall, this review frames boron-binding siderophores as a cross-ecosystem phenomenon and a promising conceptual bridge between environmental boron geochemistry, microbial metal economy, and metalloid-mediated signaling. Full article

Background: Adult diffuse gliomas represent one of the most aggressive types of brain tumors. Proton therapy offers a minimally invasive treatment option whose biological effectiveness may be enhanced through nuclear reactions involving boron atoms, leading to the emission of high-LET α-particles. In this study, we investigated the potential enhancement of radiation-induced damage of a novel boron-conjugated, ATP-competitive SRC kinase inhibitor, in the U-87 MG glioma cell line and its isogenic cell line stably expressing the IDH1 R132H mutation. Methods: Glioma cells were exposed to either proton or X-ray irradiation to assess whether any enhancement associated with this boron-delivery strategy was specific to proton interactions. Cell survival assays and analyses of DNA damage responses were conducted in both cell lines. Results: While no significant synergistic effects were observed in survival endpoints, differences emerged at the level of early DNA damage effects, with IDH1-mutant glioma cells displaying an enhanced acute response following combined treatment with proton irradiation. Conclusions: These findings support further pharmacological development of boron-based SRC-targeted strategies and underscore the importance of tailoring therapeutic approaches to specific glioma molecular subtypes. Full article

While diverse previously fabricated pristine and hydrogenated borophene lattices have been characterized predominantly by their metallic nature, a recent experimental breakthrough has introduced α′–B₈H₄, a semiconducting hydrogenated borophene phase, opening new avenues for boron-based nanoelectronics. Spurred by this breakthrough, herein we utilize a comprehensive first-principles framework to investigate the critical properties of α′–B₈H₄ monolayer. Stability analyses confirm the considerable dynamical and thermal robustness of the α′–B₈H₄ monolayer. Calculations using hybrid functionals show that suspended single-layer α′–B₈H₄ exhibits an indirect semiconducting behavior, with band gaps of 2.06 eV and 2.45 eV predicted by HSE06 and PBE0, respectively. Optical response calculations reveal strong in-plane absorbance in the UV region, with the first notable peak at ~3.65 eV and the main peak occurring between 4.20 and 4.45 eV, both of which are clearly within the ultraviolet range. Mechanical analysis reveals that α′–B₈H₄ exhibits decent in-plane strength (>10 N/m), while phononic transport calculations yield a moderately low room-temperature lattice thermal conductivity of ~20 W/m·K, both displaying slight anisotropic behavior. These results provide a comprehensive first-principles characterization of the α′–B₈H₄ monolayer, highlighting the rare emergence of semiconducting behavior in borophene derivatives and underscoring its potential for UV optoelectronics and nanoscale device applications. Full article

Emerging mosquito-borne flaviviruses, such as Dengue virus (DENV) and Zika virus (ZIKV), pose major global public health threats due to their geographic expansion, climate change, and the absence of effective antiviral therapies. Antiviral development against these pathogens has primarily focused on two complementary strategies. On the one hand, the blocking of viral replication by directly inhibiting essential viral enzymes, and on the other, enhancing the host’s innate immune defenses via targeted activation of intracellular antiviral pathways. Among the viral proteins required for replication, the NS2B–NS3 protease complex is one of the most conserved and druggable targets, prompting extensive efforts to design both covalent and non-covalent inhibitors. Covalent inhibitors, such as boronic acids, aldehydes, trifluoromethyl ketones, phenoxymethylphenyl derivatives, and α-ketoamides, form irreversible or slowly reversible bonds with the catalytic serine residue (Ser 135), producing long-lasting and high-affinity suppression of protease activity. In parallel, several classes of non-covalent, particularly allosteric, inhibitors have emerged as promising alternatives with improved specificity and reduced off-target reactivity. A complementary antiviral strategy involves the use of agonists of key innate immune sensors such as TLRs, RIG-I, and the cGAS–STING axis, which mediate the release of interferons (IFNs). This review brings together current knowledge on these two mechanistically distinct yet convergent approaches, highlighting how both can ultimately restrict flavivirus replication. Future opportunities involving modified peptide scaffolds, advanced delivery systems, and drug-repurposing strategies are finally discussed for the development of next-generation therapeutics against DENV and ZIKV. Full article

In this study, boron carbide (B₄C), hexagonal boron nitride (hBN), holy super graphene (HSG), and hybrid (B₄C+hBN+HSG) nano-additives were added to SAE 15W-40 diesel engine oil at a range of 0.03–0.24 g per 30 mL of oil, and reciprocating tribological tests were conducted on a GG25 (EN-GJL-250) gray cast iron-based diesel piston surface in contact with an Al₂O₃ ball (Ø6 mm) at a load of 20 N, a sliding distance of 500 m, and a temperature of 75 °C. XRD analysis showed that the dominant phase on the piston surface was the α-Fe matrix and that no significant new phase had formed. The results obtained revealed that the nano-additive effect is strongly dependent on both the additive type and the additive level. At a low level (0.03 g/30 mL) of B₄C additive, the average COF decreased by approximately 19%, while at a low level (0.03 g/30 mL) of hBN additive, this decrease amounted to approximately 54%. In the HSG additive, at the highest level (0.24 g/30 mL), the coefficient of friction (COF) decreased to ≈0.032, achieving a friction reduction of approximately 75% compared to the base oil. In the hybrid oil series, COF values remained in the range of approximately 0.082–0.087 at all additive levels and were generally 25–28% lower than those of the base oil. SEM/EDS examinations showed that a tribofilm with high carbon content formed in the HSG-additive oils, while a tribofilm layer containing C, B, and N elements together formed in the hybrid-additive oils. Overall, it was concluded that selecting the appropriate additive type and level can reduce friction and wear losses at the piston interface, thereby contributing to engine efficiency by extending the life of engine components and limiting friction-induced energy losses. Full article

BNCT (Boron Neutron Capture Therapy) is a binary radiotherapeutic modality in which high LET (Linear Energy Transfer) particles are generated from ¹⁰B(n,α)⁷Li reaction, ideally within boron-loaded tumour cells, so the therapeutic outcome depends critically on the pharmacokinetics and biodistribution of boron carriers. In this review, boron-containing agents for BNCT, with a focus on ADMET (absorption, distribution, metabolism, excretion and toxicity) and model-informed design, were examined. Low-MW (low-molecular-weight) compounds, peptide conjugates, polymeric and nanostructured platforms and cell-based vectors were surveyed and how physicochemical properties, transporter engagement and nano–bio interactions govern tumour uptake, subcellular localisation and normal tissue exposure were discussed. A shift from maximising boron content towards optimising exposure profiles using PET (Positron Emission Tomography), PBK (physiologically based pharmacokinetic) modelling and in silico ADMET tools to define irradiation windows was also discussed. Classical agents such as BPA (Boronophenylalanine) and BSH (Sodium Borocaptate) are contrasted with newer polymeric and metallacarborane-based carriers, with attention to brain penetration, endosomal escape, linker stability, biodegradation and elimination routes, as well as platform-specific toxicities. Incontestably, further progress in BNCT will highly depend on integrating imaging-derived kinetics with PBPK-informed dose planning and engineering subcellularly precise yet degradable carriers, and that ADMET-guided design and spatiotemporal coordination are central to achieving reproducible clinical benefit from BNCT’s spatial selectivity. Full article

Background: Boron neutron capture therapy (BNCT) represents a highly selective therapeutic modality for recalcitrant cancers, leveraging the nuclear reaction initiated by thermal neutron capture in boron-10 (¹⁰B) to deliver high-linear energy transfer radiation (α-particles and ⁷Li ions) directly within tumor cell boundaries. However, the widespread clinical adoption of BNCT is critically hampered by the pharmacological challenge of achieving sufficiently high, tumor-selective intracellular ¹⁰B concentrations (20–50 μg of ¹⁰B/g tissue). Conventional small-molecule boron carriers often exhibit dose-limiting non-specificity, rapid systemic clearance, and poor cellular uptake kinetics. Methods: To overcome these delivery barriers, we synthesized and characterized a novel dual-modality nanoplatform based on highly biocompatible, functionalized graphene oxide (GO). This platform was structurally optimized via covalent conjugation with high-boron content carborane clusters (dodecacarborane derivatives) for enhanced BNCT efficacy. Crucially, the nanocarrier was further decorated with plasmonic gold nanostructures (AuNPs), endowing the system with intrinsic surface-enhanced Raman scattering (SERS) properties, enabling real-time, high-resolution intracellular tracking and quantification. Results: We evaluated the synthesized GO@Carborane@Au nanoplatforms for their stability, cytotoxicity, and internalization characteristics. Cytotoxicity assays demonstrated excellent biocompatibility against the non-malignant human keratinocyte line (HaCaT) while showing selective toxicity (upon irradiation, if tested) and high cellular uptake efficiency in the aggressive human glioblastoma tumor cell line (T98G). The integrated plasmonic component allowed for the successful, non-destructive monitoring of nanoplatform delivery and accumulation within both HaCaT and T98G cells using SERS microscopy, confirming the potential for pharmacokinetic and biodistribution studies in vivo. Conclusions: This work details the successful synthesis and preliminary in vitro validation of a unique graphene oxide-based dual-modality nanoplatform designed to address the critical delivery and monitoring challenges of BNCT. By combining highly efficient carborane delivery with an integrated photonic trace marker, this system establishes a robust paradigm for next-generation theranostic agents, significantly advancing the potential for precision, image-guided BNCT for difficult-to-treat cancers like glioblastoma. Full article

Hypoeutectic aluminum–silicon casting alloys in their unmodified state have a coarse-grained eutectic (α + β), which results in poor mechanical properties and brittleness. Microstructure refinement and improved mechanical properties are possible, among other things, by introducing various elements and chemical compounds. The literature presents numerous studies on the modification of hypoeutectic silumins, but there are no results confirming the effectiveness of the interaction of a master alloy containing titanium and boron with its main component, which may be aluminum, aluminum with silicon, or aluminum with silicon and magnesium. This paper presents the results of microstructure refinement using titanium or boron introduced into the Al, AlSi7, and AlSi7Mg master alloys. The introduction of titanium and boron into the aluminum-based master alloy resulted in microstructure refinement and improved mechanical properties. The results indicate that the most favorable results were obtained when titanium and boron were introduced into the AlSi7 master alloy. The addition of magnesium to the master alloy AlSi7 resulted in less effective microstructure refinement of the AlSi9 silumin, which resulted in lower mechanical properties than those obtained for the master alloy without Mg. Full article

To address the thermal management challenges in electronic devices, this study systematically investigates the effects of injection molding and compression molding on the microstructure and thermal conductivity of poly(vinylidene fluoride)/boron nitride nanosheet (PVDF/BNNs) composites. Using 10 μm diameter BNNs as thermal conductive fillers and PVDF as the matrix, the composites were characterized via scanning electron microscopy (SEM), thermal conductivity measurements, rheological analysis, X-ray diffraction (XRD), and mechanical tests. The results demonstrate that the strong shear stress in injection molding induces significant alignment of BNNs along the flow direction, leading to remarkable thermal conductivity anisotropy. At a PVDF/BNNs mass ratio of 90/10, the in-plane thermal conductivity of the injection-molded composite reaches 1.26 W/(m·K), while the through-plane conductivity is only 0.40 W/(m·K). In contrast, compression molding, which involves minimal shear, results in randomly dispersed BNNs and isotropic thermal conductivity, with both in-plane and through-plane values around 0.41 W/(m·K) at the same filler loading. Both processing methods preserve the coexistence of α- and β-crystalline phases in PVDF. However, injection molding enhances matrix crystallinity through stress-induced crystallization, yielding composites with higher density and superior tensile properties. Compression molding, due to slower cooling, leads to incomplete PVDF crystallization, as evidenced by a shoulder peak near 164 °C in differential scanning calorimetry (DSC) curves. This study elucidates the mechanism by which processing methods regulate the structure and properties of PVDF/BNNs composites, offering theoretical and practical guidance for designing high-performance thermally conductive materials. Full article

A non-standardized hypereutectic aluminum–silicon alloy, AlSi18Cu3CrMn, was developed. To refine the structure of the studied composition, a phosphorus modifier was used in an amount of 0.04 wt %, and a complex modifying treatment was applied by combining the chemical elements of phosphorus, titanium, boron and beryllium (P, 0.04 wt %; Ti, 0.2 wt %; B, 0.04 wt %; Be, 0.007 wt %). To improve the mechanical and operational properties of the alloy, it was heat-treated (T6) at a temperature of 510–515 °C before quenching, with artificial aging applied at a temperature of 210 °C for 16 h. Phosphorus-modified alloy AlSi18Cu3CrMn was quenched in water at 20 °C, and the combined modified alloy was quenched in water at temperatures of 20 °C and 50 °C. By conducting a microstructural analysis, the free Si crystals and silicon crystals in the composition of the eutectic in the alloy structure were characterized, and by conducting XRD, the presence and type of secondary phases were established. The hardness of the alloy was measured, as well as the microhardness of the α-solid solution. Static uniaxial tensile testing was carried out at normal and elevated temperatures (working temperatures of 200 °C, 250 °C and 300 °C). By using a gravimetric method, the corrosion rate of the alloy in 1 M NaCl and 1 M H₂SO₄ was calculated. The mass wear, wear intensity and wear resistance of the studied AlSi18Cu3CrMn alloy were determined during reversible reciprocating motion in the boundary-layer lubrication regime. Full article

Background: The synthesis and biological investigation of pyrrolidine (L-gulo) iminosugars bearing an organic boron pharmacophore in ortho and meta positions of an N-benzyl group is reported. This paper completes the structure–activity relationship data for this novel family of boron-bearing iminosugars. These can establish reversible intramolecular interactions via dative bonding from nucleophilic amino acid side chains to the empty p-orbital of the boron atom. Methods: Inhibitory activities against two panels of glycosidases and cancer cell lines were investigated to ascertain structure–activity relationship profiles for these novel iminosugar drug leads. Results: These iminosugars display selective, moderate-to-weak inhibitions (IC₅₀s = 116–617 μM) of β-D-galactosidase (bovine liver), and indications of inhibition of β-D-glucosidases (almond, bovine liver) (IC₅₀s = 633 and 710 μM) and α-D-glucosidases (rice, yeast, rat intestinal maltase) (IC₅₀s = 106–784 μM). The boronic acid group emerges as a useful pharmacophore for management of lysosomal storage disorders via the chaperone-mediated therapy approach. The cancer assays revealed that the A2780 ovarian carcinoma cell line is selectively inhibited by all compounds screened and the MIA-Pa-Ca2 pancreatic carcinoma cell line is selectively inhibited by most compounds. Growth inhibition and GI₅₀ values were most potent for the meta 7 side-product. Conclusions: Beyond the cancer cell line inhibition and dose-response capabilities, the real therapeutic potential of these borylated drugs lies in their switch on/switch off activation under boron neutron capture therapy (BNCT) radiotherapeutic conditions, thus providing an important area of application for borylated monosaccharides. Full article

Manganese complexes of the general formula [Mn(DAB)(CO)₃Br] featuring sterically demanding α-diimine ligands (DAB) were prepared, characterized, and found to be catalytically active in the hydroboration of ketones. The developed eco-friendly approach allowed straightforward formation of boronic esters in quantitative yields in mild and solvent-free conditions. Full article

The use of molybdenum-based alloys as materials for components operating under high temperatures and significant mechanical loads is widely recognized due to their excellent mechanical properties. However, their low high-temperature resistance remains a critical limitation, which can be effectively mitigated by applying protective coatings. In this study, we investigate the influence of a two-step coating process on the properties and performance of the TZM molybdenum alloy. In the first step, pack cementation was performed. Simultaneous surface saturation with aluminum and silicon, a process known as aluminosiliconizing, was conducted at 1000 °C for 6 h. The saturating mixture comprised powders of aluminum, silicon, aluminum oxide, and ammonium chloride. The second step involved the application of a pre-ceramic coating based on polyhydrosiloxane modified with silicon and boron. This treatment effectively eliminated pores and cracks within the coating. Thermodynamic calculations were carried out to evaluate the likelihood of aluminizing and siliconizing reactions under the applied conditions. Aluminosiliconizing of the TZM alloy resulted in the formation of a protective layer 20–30 µm thick. The multiphase structure of this layer included intermetallics (Al₆₃Mo₃₇, MoAl₃), nitrides (Mo₂N, AlN, Si₃N₄), oxide (Al₂O₃), and a solid solution α-Mo(Al). Subsequent treatment with silicon- and boron-modified polyhydrosiloxane led to the development of a thicker surface layer, 130–160 µm in thickness, composed of crystalline Si, amorphous SiO₂, and likely amorphous boron. A transitional oxide layer ((Al,Si)₂O₃) 5–7 µm thick was also observed. The resulting coating demonstrated excellent structural integrity and chemical inertness in an argon atmosphere at temperatures up to 1100 °C. High-temperature stability at 800 °C was observed for both coating types: aluminosiliconizing, and aluminosiliconizing followed by the pre-ceramic coating. Moreover, additional oxide layers of SiO₂ and B₂O₃ formed on the two-step coated TZM alloy during heating at 800 °C for 24 h. These layers acted as an effective barrier, preventing the evaporation of the substrate material. Full article