Search Results (784)

Low-molecular-weight gelators (LMWGs) have attracted growing attention as versatile alternatives to conventional polymeric thickeners and gelators, owing to their ability to form three-dimensional fibrillar networks through non-covalent self-assembly and to undergo reversible sol–gel transitions in response to external stimuli. Among the various stimuli that can be exploited, pH represents a particularly attractive trigger given its direct relevance to biological and physiological environments. This review focuses on three categories of pH-responsive LMWGs that have shown notable progress over the past decade yet remain relatively underexplored in the literature. First, N-oxide-type hydrogelators are discussed, with emphasis on amide amine oxide-based surfactants and pyridine-N-oxide frameworks. The pH-dependent protonation of the N-oxide moiety modulates intermolecular hydrogen bonding, thereby governing self-assembly and gel formation. The structural versatility of these gelators enables rational tuning of aggregate morphology and confers clear pH and temperature responsiveness. Second, recent advances in phenylboronic acid-based LMWGs are highlighted. Although boronic acid derivatives have long been studied as dynamic crosslinking units in polymeric hydrogels, 3-isobutoxyphenylboronic acid was recently identified as the first example of phenylboronic acid functioning as an LMWG, in which gelation is driven primarily by hydrogen bonding and pH responsiveness is exploited for stimuli-triggered gel disruption rather than gel formation. Third, pH-responsive orthogonal self-assembly systems are reviewed. Representative examples include multicomponent hybrid hydrogels combining pH-activated LMWGs with polymer gelators for controlled drug release, pH-triggered self-sorting of two LMWGs without any polymeric component, and bio-based orthogonal hydrogels composed of a glucolipid LMWG and cellulose nanocrystals. For each system, both advantages and remaining limitations are critically assessed. Collectively, this review aims to provide a timely overview of emerging trends in pH-responsive LMWG research and to offer perspectives on the rational design of next-generation stimuli-responsive soft materials. Full article

Developing effective metal-free electrocatalysts for acidic hydrogen evolution is challenging because both catalytic activity and electronic conductivity must be optimized simultaneously. Here, h-BN/carbon nano-onion (CNO) hybrid electrocatalysts were synthesized by integrating layered hexagonal boron nitride with conductive carbon nano-onions to generate accessible heterointerfaces for the hydrogen evolution reaction (HER). Structural characterization by XRD, SEM/TEM, and STEM-EDS confirmed intimate contact between h-BN sheets and quasi-spherical CNO domains. Similarly, XPS revealed B–N-rich frameworks with interfacial B–C/C–N surface environments and oxygen-associated defect sites. Among the prepared compositions, the h-BN/CNO20 eletrocatalyst exhibited the best apparent HER performance in 0.5 M H₂SO₄, delivering an overpotential of ~270 mV at 5 mA cm⁻² and a Tafel slope of 76 mV dec⁻¹, along with stable chronoamperometric behavior for 15 h. The improved electrocatalytic activity is due to the enhanced charge transport through the CNO network, suppression of h-BN restacking, increased exposure of interfacial sites, and charge redistribution across B–N/C heterojunctions. These findings identify h-BN/CNO20 as the optimum composition within this series and demonstrate that heterointerface engineering between boron nitride and curved graphitic nanocarbons is a promising strategy for developing metal-free HER electrocatalysts. However, further validation using a non-Pt counter electrode is necessary to confirm intrinsic catalytic activity. Full article

Radiotherapy is one of the conventional methods for the treatment of cancers. Boron neutron capture therapy (BNCT) has emerged as a promising and well-recognized modality for treating certain types of cancers. BNCT is a binary radiotherapy that largely depends on neutron beams and ¹⁰B carriers. Although an “ideal” boron carrier should fulfill multiple criteria, high tumor/normal tissue ratio (T/N > 5) and high tumor uptake of boron (>20 μg/g) are critically important. First-generation (boric acid and derivatives) and second-generation (BPA and BSH) boron carriers suffer from poor T/N and extremely high dose in clinical use (500 mg/kg and usually >30 g for each patient). Glucose transporter 1 (GLUT1) is overexpressed on the membrane surface of multiple tumors and is a potential target for third-generation boron carrier to achieve high T/N and high tumor uptake of boron. However, the boron-bearing sugar derivatives designed in the last few decades have suffered from suboptimal T/N values and significant cytotoxicity. In the present study, a total of two categories comprising 6 series (28 in total) of boron-bearing sugar derivatives were designed and synthesized and their cellular boron uptake, T/N, and cytotoxicity were evaluated. The structure–activity relationship (SAR) of these target compounds was analyzed, and one of the target compounds, B3, a phenyl C-mannoside with an o-carborane moiety, exhibited the best boron-carrying profile, which featured 10.6-fold higher boron uptake by the SCC-9 cell line and a largely improved T/N (3.3 for B3 vs. 1.4 for BPA) compared with the current clinical gold standard BPA. Therefore, the chemical structure of B3 represents a privileged candidate structure for the future design of “ideal” boron carriers for BNCT. Full article

GH3039 nickel-based alloy, as a key material for thermocouple protection tubes, is susceptible to wear and oxidation failure in high-temperature kiln environment. To address this, boronized, chromized and borochromized coatings were prepared on GH3039 substrate, and the friction-wear properties and high-temperature oxidation resistance of both the substrate and the coatings were systematically characterized. The results show that the borochromized coating, benefiting from the synergistic effect of its relatively high surface hardness and the boric acid lubricating film formed during the wear process, reduces the wear rate by 84.07% (to 1.44 × 10⁻⁵ mm³·N⁻¹·m⁻¹). Meanwhile, it exhibits the optimal oxidation resistance due to its dense Cr-rich layer, which can inhibit oxygen diffusion and supply chromium for protective Cr₂O₃ film. After 100 h of oxidation at 950 °C, its oxidation weight gain is reduced by 78.68% compared with the boronized sample (to 1.20 mg/cm²). Full article

This study aims to systematically investigate the influence of substituent effects on the strength of Lewis acid–base interactions in frustrated Lewis pairs (FLPs). Specifically, -C₆F₅ groups of the classical Lewis acid B(C₆F₅)₃ are sequentially replaced with -C₆Cl₅, -C₆Br₅, and -C₆I₅ groups, and the Lewis acids are paired with the Lewis base 1,3-disubstituted imidazol-2-ylidene (ItBu) to form FLPs. Further energy decomposition analysis (sobEDA), orbital analysis, and molecular fragment density difference (MFDD) analysis reveal the nature of the substituent effect on the interaction energy (∆Eint) of the FLPs. The research findings indicate that the ∆Eint of B(C₆F₅)3-ItBu, B(C₆F₅)_x(C₆Y₅)_3−x-ItBu (x = 0, 1, 2; Y = Cl, Br, I) originates mainly from the interaction between the outermost halogen atom of the Lewis acid and the central carbon (C) atom of the Lewis base, rather than from the interaction between the central atoms boron (B) and carbon (C). This mechanism ultimately leads to a ∆Eint for B(C₆F₅)₂(C₆Y₅)-ItBu (Y = Cl, Br, I) that is comparable to that of B(C₆F₅)₃-ItBu. This indicates that modified B(C₆F₅)₂(C₆Y₅) (Y = Cl, Br, I) exhibits greater potential for the construction of novel FLPs. Full article

Homeobox protein MEIS2 has been strongly implicated in colorectal cancer (CRC) progression and metastatic potential, making its targeted inhibition a promising therapeutic strategy. However, recently developed MEIS inhibitors are limited by poor aqueous solubility, instability under physiological conditions, and insufficient intracellular accumulation, which restrict their clinical applicability. To overcome these challenges, a multifunctional hybrid nanoemulsome system was developed by integrating boron–silane-doped carbon dots (CDs) with chitosan via glutaraldehyde crosslinking, followed by emulsification with oleic acid and non-ionic surfactants (Span 80 and Tween 20/80) in the presence of a MEIS inhibitor (MEISi-2). The resulting composite exhibited high structural stability, excellent biocompatibility, and a drug encapsulation efficiency of 96.2%. Fourier-transform infrared spectroscopy (FTIR) and dynamic light scattering (DLS) analyses confirmed successful hybridization and the formation of nanoemulsions with an average particle size of approximately 320 nm following drug loading. The system demonstrated controlled drug release under physiological conditions. In vitro studies using HCT116 CRC and HaCaT healthy keratinocytes revealed effective cellular uptake and selective cytotoxicity. The intrinsic fluorescence properties of CDs enabled real-time monitoring of intracellular drug delivery via DAPI-channel imaging. Overall, this hybrid nanoemulsome platform provides a stable and efficient delivery system for MEIS inhibitors and represents a promising strategy for the treatment of CRC. Furthermore, this approach may be extended to other poorly soluble amphiphilic therapeutic agents. Full article

By investigating the conditions for the C–C coupling reaction of p-terphenyls, we successfully synthesized C–C coupled dimeric p-terphenyls for the first time using a reaction system involving air, silica gel, and B(OH)₃. Additionally, we developed a novel method to synthesize furan-fused p-terphenyl dimers through solvent-free reactions by creatively applying rotary evaporation and heating. Compounds 6–12, 16, 20, and 22 demonstrated DPPH radical scavenging activity that was either stronger than or comparable to the positive control (vitamin C), with IC₅₀ values ranging from 0.14 to 4.61 μM. Compounds 4–22 also exhibited significant activity against α-glucosidase, with IC₅₀ values ranging from 0.37 to 17.9 μM, exceeding the efficacy of the positive control, acarbose. Moreover, compounds 6–14, 16–18, 21, and 22 demonstrated greater inhibitory activity against PTP1B compared with the positive control, oleanolic acid, with IC₅₀ values between 0.30 and 9.17 μM. These findings highlight their potential as promising leads or dietary supplements for the treatment and prevention of diabetes, as well as possible application as oxidative agents in food preservation. Full article

Our recent work has focused on red light-mediated photoreduction of p-benzoquinones and both o-, and p-naphthoquinones using methylene blue and the chlorophyll metabolite, pheophorbide A as photosensitizers. Photoreduction of biologically relevant quinones mimics photoreduction of plastoquinone by chlorophyll in photosynthesis. We examined photo-oxidation and photoreduction reactions of catechols because their oxidation to o-quinones by reactive oxygen species is implicated in protein damage in neurodegeneration. Photo-oxidation of catecholamines including dopamine, epinephrine and norepinephrine required red light, methylene blue or pheophorbide A, and molecular oxygen. Their cyclized oxidation products, aminochrome, adrenochrome and noradrenochrome, were detected by UV/visible spectroscopy. Hydrogen peroxide was generated during photo-oxidation by singlet oxygen-dependent oxidation of catecholamines. Inclusion of tertiary amine electron donors decreased cyclized products but did not affect hydrogen peroxide yield consistent with concurrent photo-oxidation followed by photoreduction of the o-quinone intermediate. Unreacted dopamine and norepinephrine were quantified using 3-hydroxyphenyl boronic acid following photochemical reactions. Dopamine and norepinephrine boronate esters absorb at 417 and 550 nm. Photo-oxidation of dihydroxycaffeic acid and dihydroxyphenyl acetic acid was also evaluated by detecting their boronate esters at 475 nm. We hypothesize that photoreduction of transient o-quinones by the combination of red light and dietary chlorophyll metabolites may be a path to limit protein damage and to recycle catechol antioxidants. Full article

Tissue adhesives offer a promising alternative to traditional sutures and staples, particularly in situations requiring rapid, minimally invasive wound closure. To address the limitations of commercially available cyanoacrylate-based adhesives, numerous hydrogel adhesives have been developed. This study presents the synthesis and characterisation of an alginate–aminophenylboronic acid (Alg-APBA) hydrogel adhesive, optimised for bioprinting as a method allowing us to control the thickness of the adhesive layer. The adhesive combines the biocompatibility of alginate with the pH-responsive bonding ability of boronic acid groups, eliminating the need for oxidative crosslinkers. Successful conjugation of APBA to alginate was confirmed via ¹H NMR, FTIR and UV-VIS spectroscopy, with a degree of substitution reaching approximately 46% or ~0.22 mol%. Rheological analysis demonstrated shear-thinning and self-healing properties suitable for bioprinting, achieving a high print fidelity (Pr ratio = 0.99 ± 0.08) and repeatability. Mechanical testing showed a shear strength of 19.0 ± 0.5 kPa and an interfacial toughness of 58.0 ± 2.11 J/m², exceeding those of commercial fibrin adhesives. Additionally, the adhesive joint remained stable after one week of incubation in an acidic environment. The material demonstrated biocompatibility during in vitro testing with keratinocytes and fibroblast cells. These results indicate that Alg-APBA is a strong, biocompatible and printable hydrogel adhesive with potential applications in soft tissue implant fixation. Full article

The global polymer waste burden has catalyzed a shift from linear “production–use–disposal” systems to circular models that prioritize recycling, reuse, and value retention. This article proposes an integrated, technology-ready roadmap for mechanical recycling and reuse of commodity and bio-based polymers via filament re-extrusion and Additive Manufacturing (AM). Building upon recent findings on performance envelopes of virgin vs. recycled Polylactic Acid (PLA) filaments processed by Fused Deposition Modeling (FDM), process parameter sensitivities (layer height, infill density) and their statistical optimization, and functional reinforcement routes (aluminum: Al, alumina: Al₂O₃, titanium: Ti, and Nano Boron Nitride: nano-BN), we articulate (1) a process–structure–property (PSP) mapping; (2) a low-defect, low-energy filament re-extrusion protocol; and (3) a graded-value strategy for upcycling mixed polymer streams. Across case analyses, we show that recycled PLA can achieve near-parity with virgin PLA when extrusion quality and printing parameters are controlled, and that ceramic/metal nanofillers enable thermal management and biocompatibility benefits crucial for durable reuse scenarios. Full article

This study presents the development of a highly sensitive and selective electrochemical method for the determination of etamsylate (ETM) using a Boron-Doped Diamond (BDD) electrode. Analytical conditions were optimized using Square Wave Voltammetry (SWV), establishing an orthophosphoric acid (V) solution as the ideal supporting electrolyte. Under optimized instrumental parameters, the sensor demonstrated a superior linear response with a correlation coefficient of 0.999. The calculated limit of detection (LOD) was 0.10 µmol L⁻¹ (0.026 mg L⁻¹), with very good repeatability, indicated by an RSD of 3.17%. The practical utility of the BDD electrode was confirmed through the analysis of pharmaceutical and spiked biological samples, yielding recovery values between 95% and 102%. The results indicate that this method serves as a robust, cost-effective, and efficient alternative for routine quality control, clinical diagnostics, and environmental monitoring of etamsylate. Full article

In acidic tea soil, boron (B) adsorption and desorption processes are dominated by the complex relationship between soil acidity, mineralogy, and organic matter. This study investigated B adsorption–desorption behavior in five acidic tea soils (pH 3.8–5.6) collected from the Eastern Black Sea region of Türkiye and evaluated the potential of machine learning (ML) algorithms to predict B desorption. Laboratory batch experiments were conducted using five initial B concentrations, and adsorption data were interpreted using the Langmuir isotherm model. Adsorption experiments indicated that B interacted with Fe/Al-oxide-containing clay minerals, which had low but favorable binding affinity, as indicated by Langmuir maximum adsorption capacities (Qmax) ranging from 46.5 to 181.8 mg kg⁻¹. Desorption experiments revealed a high degree of reversibility, particularly in soils with lower adsorption capacities, ensuring potential B leaching. To capture the governing B desorption, six machine learning (ML) algorithms—Extreme Gradient Boosting (XGBoost), Random Forest (RF), Support Vector Regression (SVR), Gaussian Process Regression (GP), Elastic Net Regression (EN), and Multivariate Adaptive Regression Splines (MARS)—were trained on 75 data points. Among the tested models, Elastic Net showed the highest predictive accuracy (R² = 0.735). This model does not replace adsorption experiments. It offers a within-assay determination of desorption given measured adsorption, which may reduce the requirement for separate desorption equilibration and analyses. Permutation importance analysis identified B_ads as the dominant predictor of B desorption, with smaller contributions from pH_ads and EC_ads. The results demonstrate that integrating laboratory experiments with machine learning provides an effective framework for predicting B mobility in acidic tea soils, offering a parameterized experimental framework for describing boron desorption behavior in acidic tea soils. 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

Neodymium–iron–boron (NdFeB) waste represents a valuable secondary source of rare earth elements (REEs). However, existing recovery technologies face several challenges, such as the difficulty of selectively recovering REEs, the generation of large volumes of secondary iron-rich slag, and an overall low level of comprehensive resource utilization. In this study, Aliquat 336 was applied for the selective extraction and separation of REEs and iron (Fe) from hydrochloric acid leachate derived from NdFeB waste. Experimental results showed that under optimized conditions—specifically, a 15% Aliquat 336 concentration, an organic-to-aqueous phase ratio of 1:2, and a 2 min extraction time—Fe extraction efficiency reached 99.93% after three-stage countercurrent extraction, while REEs were predominantly retained in the aqueous phase. Subsequent oxalic acid precipitation of the raffinate yielded RE₂(C₂O₄)₃·10H₂O with a purity of 99.60%. Moreover, under stripping conditions of 2 mol/L NaOH, a phase ratio of 2:1 (aqueous to organic), and a 2 min contact time, over 99.21% of Fe was stripped after three-stage countercurrent stripping, resulting in Fe(OH)₃ with a purity of 99.26%. The extraction mechanism followed an anion-exchange process: under high chloride ion concentrations, Fe³⁺ formed anionic FeCl₄⁻ complexes, which were exchanged with Cl⁻ ions in Aliquat 336 and transferred into the organic phase, whereas RE³⁺ cations remained in the aqueous phase, enabling efficient separation of Fe and REEs. These findings provide important insights for improving the comprehensive utilization of NdFeB waste and promoting the green and sustainable development of secondary rare earth resource recycling. Full article

For Co-N-C materials prepared under high-temperature calcination conditions, the formation of Co nanoparticles occurs when the metal loading exceeds 2%. Typically, CoNx is regarded as the primary active site of the catalyst, while Co nanoparticles are considered to possess limited catalytic activity. Consequently, within Co-N-C materials, Co nanoparticles are often likened to ‘ballast stone’ in a catalyst. In the model reaction of formic acid dehydrogenation, we incorporated boron into the precursor, thereby enhancing the electronic metal-support interactions (EMSI) between Co nanoparticles and carbon carriers. Consequently, this modification resulted in a catalytic performance of Co nanoparticles that was comparable to that of Co single-atom catalysts (SACs). Full article