Search Results (884)

The environmental challenges posed by heavy metal contamination in sludge leachate are becoming increasingly severe, necessitating the development of highly efficient remediation technologies. Among various treatment approaches, magnetic adsorbents have garnered significant attention as a promising solution due to their outstanding adsorption performance, convenient magnetic separation characteristics, and potential for regeneration. This paper systematically reviews the latest research progress on magnetic adsorbents designed for the complex system of sludge leachate, covering synthesis methods, surface functionalization, adsorption mechanisms, and performance evaluation. Key synthesis strategies are analyzed, including magnetic core preparation, inorganic coating, carbon composites, organic polymer grafting, functional molecule impregnation, and metal–organic framework (MOF) composites. The mechanisms by which these strategies influence material adsorption capacity, selectivity, and stability are elucidated. Despite significant achievements in laboratory studies, practical applications still face challenges such as large-scale synthesis, regeneration efficiency, cyclic stability, and adaptability to complex water bodies. Future research should focus on green synthetic pathways to advance the industrial application of structurally functional magnetic composite materials, providing systematic solutions from material design to process optimization for the sustainable remediation of heavy metal contamination in sludge leachate. Full article

A nanostructured sensing platform based on electrospun functionalized multi-walled carbon nanotubes/poly(3-aminobenzylamine) (FMWCNTs/P3ABA) was developed for the electrochemical detection of dopamine (DA) on fluorine-doped tin oxide (FTO) glass substrate. The electrochemical characteristics of the electrodes were investigated by chronocoulometry (CC) and cyclic voltammetry (CV) in phosphate-buffered saline solution containing K₃[Fe(CN)₆] as a redox mediator. The zeta potential analysis confirmed the presence of a stable surface charge that favors electrostatic interaction with DA molecules. The DA detection was performed in human urine by differential pulse voltammetry (DPV) over a potential of −0.2 to 0.8 V and at scan rate of 5 mV s⁻¹, where the FMWCNTs/P3ABA nanofiber electrode exhibited a high sensitivity of 1.502 µA cm⁻² nM⁻¹, a linear detection range of 10–500 nM (R² = 0.992), and a limit of detection of 1.753 nM. The sensor exhibited stable and reproducible responses, and the fibrous composite effectively discriminated DA from common electroactive interferents, including ascorbic acid, uric acid, creatinine, and glucose. Furthermore, reliable dopamine quantification in human urine samples demonstrates the strong potential of the electrospun FMWCNTs/P3ABA composite nanofiber platform for practical bioanalytical and non-invasive sensing applications in the future. Full article

The precise determination of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels is critical for understanding the photophysical and photochemical properties of carbon dots (C-dots), which directly govern their performance in optoelectronic, catalytic, and sensing applications. However, the lack of distinct redox peaks in cyclic voltammetry (CV) curves of C-dots poses a major challenge to conventional energy level calculation methods. Herein, we propose a novel strategy to calculate the HOMO–LUMO energy levels of C-dots by combining electron transfer (ET) kinetics with Marcus theory. A series of quinones (electron acceptors, EAs) and ferrocene derivatives (electron donors, EDs) were employed to quench the fluorescence of C-dots, and the ET rate constants (K) were derived from fluorescence lifetime measurements. The CV curves of EAs and EDs provided their respective oxidation and reduction potentials, which were used as reference energy levels. The UV–Vis absorption spectra confirmed that the fluorescence quenching mechanism was dominated by ET rather than energy transfer. Based on Marcus theory, the free energy change (ΔG) of ET reactions was correlated with K, and the HOMO and LUMO energy levels of C-dots were calculated to be −1.84 V (vs. SCE) and +1.60 V (vs. SCE), respectively. This study not only provides a reliable method for determining the energy levels of C-dots without distinct redox peaks but also deepens the understanding of ET mechanisms between C-dots and small molecules. The proposed strategy is expected to be extended to other fluorescent nanomaterials with similar CV limitations. Full article

Streptococcus parauberis is a major pathogen responsible for streptococcosis in both marine and freshwater fish species, causing substantial economic losses in aquaculture. The increasing prevalence of multidrug resistance has highlighted the urgent need for alternative disease control strategies. Interference with bacterial quorum sensing (QS) systems represents a promising approach. This study aimed to identify and biochemically characterize an Rgg-family transcriptional regulator and evaluate its potential as a target for quorum sensing-related regulatory interference in vitro. We hypothesized that this Rgg regulator may function as a quorum sensing-associated transcription factor capable of promoter binding and modulation by small molecules. Bioinformatic analyses were used to identify the rgg gene encoding an Rgg-family transcriptional regulator and predict its structural features. The gene was cloned, heterologously expressed, and purified. Promoter binding activity was examined using electrophoretic mobility shift assay (EMSA), and key amino acid residues were identified through site-directed mutagenesis. The inhibitory effect of the cyclic peptide cyclosporin A (CsA) on Rgg-promoter binding was further assessed. The rgg gene (864 bp) encoding a 287-amino-acid protein (34.1 kDa) was successfully identified and expressed. Purified Rgg specifically bound to its own promoter region in a concentration-dependent manner. Mutations at conserved arginine residues R12 and R15 within the helix-turn-helix DNA-binding domain abolished promoter binding activity. Furthermore, CsA disturbed Rgg-promoter binding in a dose-dependent manner. This study provides the first in vitro characterization of an Rgg-family transcriptional regulator in fish-derived S. parauberis. The findings expand current understanding of Rgg-family regulators potentially associated with quorum sensing in aquatic streptococci and provide a preliminary basis for further investigation of quorum sensing-related regulatory interference strategies for controlling streptococcal diseases in aquaculture. Full article

The safe and precise regulation of therapeutic gene expression remains a major challenge for mammalian synthetic biology and cell-based therapies. Many existing inducible systems rely on non-mammalian regulatory components or ligands with limited clinical compatibility. Designer receptors exclusively activated by designer drugs (DREADDs) offer a human G protein-coupled receptor (GPCR)-based framework for pharmacological control of intracellular signaling, yet their application as clinically relevant gene-regulation platforms remains underexplored. Here, we report a clozapine-responsive gene switch that couples a designer GPCR to signaling-dependent transcriptional control. By linking clozapine-activated receptors to cyclic adenosine monophosphate (cAMP)- or calcium-responsive synthetic promoters, receptor activation is converted into robust transgene expression across a broad dynamic range, with sensitivity to sub-nanomolar to low-nanomolar clozapine concentrations. In vivo, alginate-encapsulated reporter cells implanted in C57BL/6J mice responded to systemic or local clozapine administration with efficient secretion of a reporter protein, achieving robust induction at low daily doses (0.3 mg/kg) following either oral administration or local delivery. Together, these results establish a human GPCR-based clozapine-responsive gene switch that integrates regulation by a clinically used small molecule with modular transcriptional outputs, providing an additional approach for pharmacologically controllable gene expression in mammalian cells and in vivo. Full article

Photochromic molecules, capable of reversible isomerization under specific light irradiation, are pivotal for developing advanced photo-responsive materials. Azobenzene derivatives, in particular, are renowned for their significant conformational change, excellent reversibility, and high photostability. This study presents a novel cyclic diazo compound (CDTA) comprising two azobenzene units connected via flexible glycol chains. The photo-responsive behavior of CDTA doped into the liquid crystal 4-cyano-4′-octylbiphenyl (8CB) was systematically investigated. The composite exhibits a pronounced photo-induced phase transition from a liquid crystalline to an isotropic state under 365 nm UV irradiation, accompanied by a reversible change in light transmittance. The response kinetics were found to be highly dependent on temperature and dopant concentration. At 35 °C, the UV response time was accelerated to 6.8 s, attributed to the transition of the host 8CB from a smectic to a nematic phase. Furthermore, the composite demonstrated dual responsiveness: optical switching under UV light and electrical switching under an applied field in its nematic state. This work elucidates the interaction between molecular structure and photo-response in a liquid crystalline matrix, offering insights for designing next-generation smart windows and adaptive optical devices. Full article

Highly polar M-mol-X (M = alkali metal, mol = molecule, X = halogen) insertion complexes have been predicted to offer potential practical applications, including molecular interactions with light, ion-pair induced isomerization, etc. In the present work, the insertion complexes of the seven-membered, fused bicyclic norcaradiene and its monocyclic isomer trapped in Li-I, Na-I, and K-I counterion pairs were investigated using ab initio methods. The structures, stability, polarities, and simulated infrared spectra are analyzed and the effects of the insertion on the norcaradiene to cycloheptatriene isomerization process are examined. Furthermore, an uncommon bond between iodine and a fully substituted carbon atom is reported upon and hypothesized to be catalyzed by the presence of the cation in the insertion complexes. Full article

Molecularly imprinted polymers (MIPs) are widely employed for selective adsorption of target molecules in sensing and separation applications. The architecture of MIP films can influence adsorption behavior, interfacial stability, and reusability, yet systematic investigations of these effects are limited. This study aimed to evaluate how different polypyrrole (PPy) MIP film architectures affect the adsorption, stability, and regeneration characteristics of geraniol-imprinted layers on gold electrodes. Geraniol-imprinted and non-imprinted PPy films were electropolymerized onto quartz crystal microbalance (QCM) substrates. Two film architectures were compared: (i) a single-layer geraniol-imprinted PPy film, and (ii) a double-layer film consisting of a non-imprinted PPy underlayer followed by a geraniol-imprinted layer. Film characterization was performed using cyclic voltammetry (CV) and electrochemical quartz crystal microbalance (EQCM) measurements. Adsorption–desorption cycles were conducted to assess mass uptake, signal stability, and regeneration performance. EQCM analysis revealed that the double-layer architecture exhibited enhanced frequency signal stability during repeated adsorption–desorption cycles compared to single-layer films, suggesting a stabilizing effect of the underlying non-imprinted PPy layer at the electrode interface. Geraniol-imprinted films demonstrated significantly higher mass uptake than non-imprinted controls, confirming the sensitivity provided by molecular imprinting. Single-layer films showed more variability in signal response and less consistent regeneration performance. The architecture of MIP films significantly affects adsorption behavior, stability, and regeneration on electrode surfaces. Incorporating a non-imprinted PPy underlayer can improve signal reproducibility and enhance the robustness of MIP-based sensing interfaces. These findings provide guidance for the rational design of MIP coatings for electrochemical sensors and QCM-active platforms. Full article

The inorganic proton acid-doped polyaniline (H-PANI-X) is synthesized directly on a graphite carbon paper electrode. The polyaniline doped with hydrochloric acid (yielding H-PANI-Cl), sulfuric acid (yielding H-PANI-HSO₄), and nitric acid (yielding H-PANI-NO₃) is employed to construct both finite molecule and periodic molecule computational models. Theoretical calculation and experimental measurement of a polyaniline/graphite carbon paper electrode are adopted to reveal the doping effect of inorganic acid radical ions (Cl⁻, HSO₄⁻, NO₃⁻) on electrical and electrochemical properties of H-PANI-X. H-PANI-X shows a lower electronic band gap structure, indicating more feasible electron transfer than PANI. H-PANI-X shows a lower HOMO-LUMO orbital energy gap, indicating lower excitation energy than PANI. H-PANI-X also shows a higher electronic density of states level, indicating higher electrical conductivity than PANI. The charge density difference of H-PANI-X reveals a more delocalized electrostatic potential distribution, indicating an enhanced electrostatic interaction between protonated PANI and charge-balancing anions. Furthermore, H-PANI-HSO₄ and H-PANI-NO₃ exhibit hydrogen bonding between the protonated PANI and charge-balancing anions, resulting in reduced electronic band gaps and enhanced electronic density of states compared with H-PANI-Cl. H-PANI-NO₃ with higher electronic states at the Fermi level and higher anionic electronegativity exhibits higher electrical conductivity than H-PANI-Cl and H-PANI-HSO₄. The experimental measurement is conducted to investigate the electrochemical properties of H-PANI-X. The electrochemical impedance spectroscopy measurement indicates H-PANI-NO₃ maintains lower charge transfer resistance (0.357 Ω) than H-PANI-HSO₄ (3.003 Ω) and H-PANI-Cl (10.571 Ω). The cyclic voltammetry measurement indicates that H-PANI-NO₃ has much higher redox current and mean current density responses, accordingly exhibiting superior capacitance (208.0 mF cm⁻²) performance in comparison with H-PANI-Cl (129.5 mF cm⁻²) and H-PANI-HSO₄ (157.9 mF cm⁻²). Theoretical calculation and experimental investigation confirm H-PANI-NO₃ presents superior electroactivity to H-PANI-Cl and H-PANI-HSO₄ for promoting its electrochemical capacitance performance. Full article

Melanoma is a highly malignant neoplasm of the skin with early metastatic spread and increasing incidence worldwide. Although there are significant therapeutic advances in immunotherapy, especially with the checkpoint inhibitors targeting PD-1 and CTLA-4, challenges such as treatment-related toxicities, a heterogeneous response to therapy, and drug resistance continue to exist. There are unmet needs for novel therapeutic strategies and/or approaches to complement the existing treatment options. Potential targets for future melanoma treatment are the gap junction proteins, connexins, which show an altered pattern of regulation during melanoma progression. In this review, we highlight the regulation of gap junctions during melanoma progression and the characterization of gap junctions as tumor suppressors during early-stage tumor development and then the reversion to enhancers of tumor metastasis during late-stage melanoma progression. We provide a comprehensive overview of gap junctions in the skin and how the connexin proteins, which comprise gap junctions, are alternatively regulated in melanoma progression. Connexins are protein channels in the human body that consist of 21 isoforms. These isoforms form gap junctions that provide important intercellular signaling and permeability channels. Each connexin protein consists of four transmembrane domains and a C-terminal tail, which is an important part of its function and regulation. Permeants of gap junctions include signaling molecules such as cyclic AMP and inositol triphosphate which are linked to key cellular behaviors such as proliferation and migration, making them essential for several tumor-related processes. At least ten connexin isoforms are found in normal skin. Connexin 43 (Cx43) is classified as the most prevalent isoform while Connexin 26 (Cx26) has been reported to be more specialized with restricted expression patterns. Cx43 and Cx26 regulate the growth, differentiation, and repair of the epidermis after injury. Evidence suggests that connexins have a stage-related function in melanoma. Loss of connexin expression and gap junctional intercellular communication is linked to tumor suppression and loss of differentiation in early-stage melanoma, while re-expression or overexpression of specific connexins, notably Cx43, may promote metastasis through enhanced tumor–stromal interactions and increased motility in late-stage melanoma. Such opposing actions of connexins support their candidacy as biomarkers and therapeutic targets. Understanding the dual-stage related functions of connexins in melanoma development and progression may lead to less cytotoxic and more efficient future therapeutic approaches. Full article

The field of immunometabolism highlights the intricate interplay between immunity and metabolism. The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway is a central component of innate immunity that detects double-stranded DNA (dsDNA) from a range of sources, including pathogenic and host-derived DNA. It is now recognized that the cGAS-STING pathway has broad implications in a variety of human conditions including cancer, age-related diseases, and autoimmune disorders. Given the abundance and diversity of lipids across cellular compartments serving as structural components and signaling molecules, it is unsurprising that lipid metabolism influences the regulation of cGAS-STING signaling. Lipids can directly alter signaling protein dynamics through interactions within membrane compartments, while alterations in lipid metabolism can remodel multiple cell-intrinsic signaling cascades. Here, we summarize emerging concepts and recent discoveries that have advanced our understanding of how lipid metabolism and lipids regulate the cGAS-STING pathway. Full article

Aliphatic polyesters, widely used in biomedicine due to their biocompatibility and biodegradability, are typically synthesized via the ring-opening polymerization (ROP) of cyclic esters. Although traditional metal catalysts are highly active, their biological toxicity limits their applications. Organocatalysts, particularly natural organic molecules, offer safer alternatives. We explored the ROP mechanisms of cyclic esters (L-Lactide (L-LA), ε-caprolactone (ε-CL), and δ-valerolactone (δ-VL)) catalyzed by phosphonium carboxybetaines (PCBs, (PhR)₃P⁺(CH₂)₂COO⁻, R = H(PCB), F(PCB-F) and OMe(PCB-OMe)) through density functional theory (DFT) computations. The DFT results revealed that the ROP of cyclic esters follows a bifunctional–cooperative activation mechanism, wherein the phosphonium moiety (Ph₃P⁺(CH₂)₂) activates the monomer via an extensive hydrogen-bonding interaction network, and the carboxylate (COO⁻) serves as a proton acceptor to enhance the nucleophilicity of the initiator phenylpropanol (PPA). In contrast, unsubstituted PCB exhibited the lowest energy barrier, being consistent with the highest catalytic activity among PCB derivatives observed experimentally. Moreover, a series of novel PCB derivatives (Ph₃P⁺(CH₂)_nCOO⁻, n = 3–6 (PCB1-PCB4)) were designed by regulating the carbon spacer length, and their catalytic performances were computationally tested. The designed catalyst PCB2 (Ph₃P⁺(CH₂)₄COO⁻) exhibited higher activity for the ROP of L-LA, attributed to providing sufficient flexibility to minimize deformation while improving proton-accepting capability. Similarly, PCB2 also demonstrated superior catalytic activity for δ-VL and the more challenging ε-CL monomer. This work not only clarifies the intrinsic catalytic nature of these zwitterionic organocatalysts, but also provides an effective strategy for the rational design of high-performance, metal-free catalysts for the synthesis of sustainable polyesters. Full article

The electro-oxidation of eugenol (EUG) natural antioxidant was studied by cyclic voltammetry in phosphate buffer solutions (PBS) of different pH at electrochemically partially reduced graphene oxide (GCE/ePRGO). The voltammetric responses were mainly controlled by adsorption at this modified electrode. Current values were higher at pH 2.0 PBS, therefore, this pH was chosen to perform all experiments. DFT calculations of pKa’s and standard potentials defined the possible pathways of eugenol and its oxidation products. These pathways were evaluated through the comparison of voltammetric simulations of adsorbed species with experiments at pH 2.0, which also allowed for the estimation of the values of the kinetic parameters involved in electrochemistry. Our findings suggest a multi-step redox process in which Eugenol is first oxidized to the radical species and then to a cationic product. At this stage, the pathways branch into to methylenquinone and a 4-allyl-1,2-diquinone molecules. 4-allyl-1,2-diquinone is finally reduced in single or double reversible electrochemical step to the hydroquinone species. The present physicochemical work allows for a deeper understanding of the eugenol oxidation mechanism, which was only partially proposed in previous studies. Full article

Herein, (Nafion-treated) (30 wt%) NiO_x/graphene (GP) were prepared at 250 °C and 450 °C and investigated as materials for dopamine electrochemical detection. Initially, characterization of the samples was performed using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) techniques. Subsequently, they underwent electrochemical evaluation using cyclic voltammetry, linear sweep voltammetry (LSV), differential pulse voltammetry (DPV), and chronoamperometry (CA) techniques. All electrochemical measurements of the dopamine oxidation reaction (DOR) were performed in a 0.1 M phosphate buffer solution (PBS) at pH of 7.00 and at temperature of 36.6 °C. It was found that Nafion addition to the electrocatalysts surface facilitates access of the cationic dopamine molecule to their active centers being attributed to Nafion cation permeability. Nafion-NiO₂₅₀/GP exhibited higher activity towards the DOR reaction. The limit of detection (LOD) for the lower linear range of 0.5–10 μM was calculated to be 0.8 μM, with a sensitivity of 3.086 μA μM⁻¹cm⁻². Furthermore, the Nafion NiO₂₅₀/GP/GC electrode exhibited high selectivity towards DA, as well as good repeatability and reproducibility with an acceptable level of deviation, and excellent storage stability. The six electrodes produced from the Nafion-NiO₂₅₀/GP showed 8.28% reproducibility (RSD), indicating adequate behavior, while the same electrode after six measurements over a 30-day period showed an RSD of 5.50%, indicating a reliable electrode. Full article

B7-H3 (CD276), an immune checkpoint protein, is overexpressed in malignant tumors, while its expression in normal tissues is low, and several B7-H3-targeting therapies are under clinical evaluation. Radionuclide molecular imaging offers a non-invasive method for determining B7-H3 expression levels and may aid in improved patient selection. The feasibility of the use of Affibody molecules for the visualization of B7-H3 was demonstrated earlier. The selection of an approach for routine labeling providing high radiochemical yields and reproducibility is, however, critical for successful clinical translation. The optimal combination of a targeting protein, chelator/linker, and radionuclide should provide high-contrast visualization. In this study, we evaluated an acyclic chelator, tris(3,4-hydroxypyridinone) (THP), for labeling of the Affibody molecule Z_{B7-H3_2} with ⁶⁸Ga and compared its impact on radiolabeling efficiency and targeting properties with the impact of the cyclic chelator 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA). Maleimide derivatives of THP and NOTA were site-specifically coupled to the C-terminal cysteine of Z_{B7-H3_2}. THP-Z_{B7-H3_2} was successfully labeled with ⁶⁸Ga within 5 min of incubation at room temperature, achieving a 100% radiochemical yield. NOTA-Z_B7-H3 required heating at 60 °C for 10 min, and the radiochemical yield was lower. Both radioconjugates exhibited specific binding to B7-H3-expressing cells with similar binding strength, and both tracers demonstrated similar tumor uptake (p > 0.05) in a murine model. The biodistribution was similar, although [⁶⁸Ga]Ga-NOTA-Z_{B7-H3_2} provided slightly but significantly higher tumor-to-liver and tumor-to-spleen ratios. Nonetheless, the advantages of THP include rapid and mild radiolabeling with high efficiency, eliminating the need for heating and a post-purification step, which suggests a potential for streamlined clinical translation of Z_{B7-H3_2}. Full article