Search Results (150)

The competitive adsorption between phosphorus (V) and antimony (V) may influence the release of antimony from Sb-contaminated soils. The objectives of this study were to evaluate the effect of P(V) on the adsorption–desorption behavior and transport of Sb(V) in two typical soil types. Specifically, the simultaneous adsorption, competitive interactions, and miscible displacement dynamics of P(V) and Sb(V) in these soils were investigated. Results clearly indicated that the competitive effect of P(V) on Sb(V) adsorption is more pronounced in acidic red soil than in alkaline calcareous soil. The adsorption capacity of Sb(V) decreased with increasing solution pH, leading to greater mobility of Sb(V) in both soils. P(V) was preferentially adsorbed over Sb(V) in both soil types. Sb(V) adsorption isotherms fitting by Freundlich model yielded higher coefficients of determination (R²) compared to the Langmuir model, while the Langmuir model provided a good fit to the P(V) adsorption isotherms. The total released amounts of P(V) and Sb(V) accounted for 0% and 0.4%, respectively, in red soil and 2.7% and 48.6%, respectively, in calcareous soil, relative to their adsorption capacities. The red soil exhibited remarkably strong binding affinity, with only minimal amounts of P(V) and Sb(V) released after five consecutive desorption steps. Breakthrough curves (BTCs) revealed that the presence of P(V) can promote significant Sb(V) release from the soils, which persists over an extended duration. This study on the adsorption–desorption behavior of P(V) and Sb(V) in two typical soils enhances our understanding of their mobility, fate, and associated environmental risks. In conclusion, the assessment of environmental risks from antimony-contaminated soils should take into account the competitive adsorption–desorption interactions between Sb(V) and P(V). Full article

This study presents a comparative investigation of plasmonic sensing platforms based on colloidal gold nanoparticle (AuNP) suspensions and gold film over nanosphere (AuFoN) solid substrates for the detection of epidermal growth factor receptor (EGFR), an essential biomarker and therapeutic target in oncology. The strategy relies on fluorescence emission modulation of an Atto647N-labeled DNA oligomer competitively bound to an EGFR-specific aptamer. Our results demonstrate that the colloidal AuNPs can function as competitive binding sensors, leading to fluorescence quenching upon fluorophore attachment to the surface of the NPs and partial fluorescence recovery due to EGFR-induced displacement of the fluorophore–aptamer complex. This specificity was confirmed by reversed binding experiments. However, the system proved highly sensitive to the experimental design: excessive washing (centrifugation) led to unspecific aggregation and signal loss, while reduced washing steps improved signal retention and revealed EGFR-induced fluorophore displacement into the supernatant. On the contrary, film-based substrates exhibited strong initial fluorescence, but failed to retain the fluorophore–aptamer complex after washing, resulting in fluorescence decay independent of EGFR incubation. This indicates that AuFoN lacked the binding stability necessary for specific displacement-based sensing. These findings highlight that while colloidal AuNPs can support competitive binding detection, their reproducibility is limited by colloidal stability and protocol sensitivity, whereas AuFoN substrates require improved surface functionalization strategies. The study emphasizes the critical role of surface chemistry, aptamer–fluorophore affinity, and washing protocols in determining the success or failure of plasmon-enhanced aptamer-based biosensing systems and suggests opportunities for improving specificity and robustness in future designs. Full article

CB₁ agonist compounds may be potential drug candidates for the treatment of gliomas, as they have been shown to inhibit tumor cell proliferation, induce apoptosis, and reduce angiogenesis in various preclinical models. Their ability to modulate the endocannabinoid system suggests a promising therapeutic approach for targeting glioma growth and progression. Herein, we report the design, synthesis, biological studies, and bioinformatics assays of novel benzo[d]imidazole–naphthalen-arylmethanone regioisomers with affinity for the CB₁ receptor, as well as propose an indirect methodology to evaluate their presumed CB₁ agonist activity. Compounds that showed a propensity for binding to the CB₁ receptor were regioisomers 4d, 5b, 5e, 5f, and 5f′. Likewise, derivatives that displaced more than 50% of the radioligand [³H]CP-55940 at the CB₁ receptor were subjected to in vitro viability experiments. Compounds 4d, 5b, 5e, and 5f′ showed toxicity against U87MG cells (malignant glioma) in a considerable percentage. Notably, compound 5f′ showed CB₁ affinity, with a K_i of 2.12 µM, and was selectively toxic to U87MG cells, which highly express the CB₁ receptor, while exhibiting no toxicity toward the healthy HEK293 cell line, which expresses both cannabinoid receptors at negligible levels. Docking studies at the CB₁ orthosteric site indicate that 5f′ forms π-π interactions, a T-shaped interaction, and hydrogen bonding through the oxygen atom of the furan ring. Biologically, our experimental indirect model-based on a simple viability assay is supported by well-established evidence that activation of CB₁ and CB₂ receptors by agonists induces cell death and inhibits tumor cell growth. Structurally, we conclude that the presence of a furan ring at the 2-position of the benzo[d]imidazole core is beneficial for the development of new ligands with potential CB₁ agonist activity. Full article

BACH1 (BTB And CNC Homology 1) and NRF2 (Nuclear Factor Erythroid 2-related Factor 2) are transcription factors that regulate antioxidant and iron metabolism genes by competing for binding to cis-regulatory Maf-binding elements (CsMBEs) as heterodimers with small Maf proteins (sMafs). To dissect the mechanisms underlying this competition, we developed a chimeric tethering system where the DNA-binding domains of BACH1 or NRF2 were covalently linked to sMafG via a flexible, cleavable linker. This design enables efficient heterodimer formation on DNA and circumvents kinetic barriers to partner exchange in the solution. The site-specific fluorescent labelling of proteins allowed for the tracking of complex compositions by electrophoretic mobility shift assays. Both BACH1/sMafG and NRF2/sMafG heterodimers bind CsMBEs with similar affinities. Notably, DNA binding by BACH1 was impaired in a C574-dependent, redox-sensitive manner and promoted the exchange of heterodimer partners. Competition assays demonstrated that BACH1 and NRF2 can displace each other from preformed DNA-bound complexes, with greater efficiency when presented as preassembled heterodimers with sMafG. These findings reveal a redox-sensitive mechanism for regulating transcriptional switches at CsMBEs and highlight how preformed heterodimers facilitate the rapid displacement at target promoters. Full article

Epoxy asphalt is a superior polymer-modified asphalt material; however, significant differences in physicochemical properties, such as solubility parameters and dielectric constants, between epoxy resin and asphalt have led to compatibility issues that hinder its development. This study employed molecular dynamics simulations to investigate the effect of maleic anhydride-grafted styrene-butadiene-styrene (MAH-g-SBS) on the compatibility of epoxy asphalt. By analyzing parameters such as cohesive energy density, solubility parameters, energy distribution, interaction energy, radial distribution function, free volume fraction, and mean square displacement, the molecular mechanism underlying the enhanced compatibility was elucidated. The results indicate that the amphiphilic molecular structure of MAH-g-SBS significantly improves the thermodynamic compatibility between asphalt and epoxy resin, enhances interfacial affinity and stability, reduces the system’s total interaction and nonbonded energies, facilitates the dispersion and permeation of epoxy molecules into asphalt, and increases molecular mobility, thereby comprehensively enhancing the compatibility of the epoxy asphalt blend. Segregation tests and fluorescence microscopy further verified the simulation results, demonstrating that MAH-g-SBS improves the storage stability and phase uniformity of the epoxy asphalt system. Full article

The development of molecules that interact with G-quadruplex (G4) sequences requires effective evaluation methods. Several techniques are currently available, including nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography, surface plasmon resonance (SPR), isothermal titration calorimetry (ITC) and mass spectrometry (MS), fluorescence using FRET-melting, G4-fluorescent intercalator displacement assay (G4-FID) and affinity chromatography. Among these, CD spectroscopy is gaining prominence due to its lower material requirements, faster experimentation and quicker data processing. However, conventional CD methods have limitations, such as higher sample volume required and the inability to handle high-throughput analysis efficiently. The use of synchrotron radiation in high-throughput analysis methods (HT-SRCD) has further advanced the investigation of small-molecule interactions with DNA G4 structures in the presence of various monovalent cations. HT-SRCD offers the capability to analyze multiple samples simultaneously, overcoming the limitations of conventional CD methods. To validate this approach, three biologically relevant G4 sequences—HTelo1, G3T3 and T95-2T—were investigated. Their interactions with a library of small tetrazole-based molecules, synthesized via a four-component Ugi reaction, and with a peptide sequence deriving from RHAU helicases (Rhau25), were evaluated. The results demonstrate that this method not only effectively discriminates between different ligands but also provides valuable insights into the selectivity and the modes of interaction of these ligands with the G4 sequences. Full article

Incorporation of lanthanide (Ln) and actinide (An) ions into the human body poses significant chemotoxic and radiotoxic risks, necessitating effective decorporation strategies. This study investigates the displacement of biologically relevant ligands from trivalent ions of europium, Eu(III), and curium, Cm(III), in artificial biofluids by various complexing agents, i.e., ethylenediaminetetraacetic acid (EDTA), ethylene glycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid (EGTA), diethylenetriaminepentaacetic acid (DTPA), and spermine-based hydroxypyridonate chelator 3,4,3-LI(1,2-HOPO) (HOPO). Utilizing a modified unified bioaccessibility method (UBM) to simulate gastrointestinal conditions, we conducted concentration-dependent displacement experiments at both room and body temperatures. Time-resolved laser-induced fluorescence spectroscopy (TRLFS) supported by ²H nuclear magnetic resonance (NMR) spectroscopy and thermodynamic modelling revealed the complexation efficacy of the agents under physiological conditions. Results demonstrate that high affinity, governed by complex stability constants and ligand pK_a values, is critical to overcome cation and anion competition and leads to effective decorporation. Additionally, there is evidence that cyclic ligands are inferior to linear ligands for this application. HOPO and DTPA exhibited superior displacement efficacy, particularly in the complete gastrointestinal tract simulation. This study highlights the utility of in vitro workflows for evaluating decorporation agents and emphasizes the need for ligands with optimal binding characteristics for enhanced chelation therapies. Full article

Nucleolin (NCL), an RNA-binding protein which regulates critical cellular processes, is frequently dysregulated in human cancers, including breast cancer, making it an attractive therapeutic target. However, molecular details of the RNA-NCL interaction have not been investigated yet. A tRNA fragment named tRF3E, displaying tumor suppressor roles in breast cancer, was found to bind NCL with high affinity displacing NCL-controlled transcripts. Here, we investigated the determinants and cooperativity of tRF3E-NCL interaction by Electrophoretic Mobility Shift Assays and in silico docking analysis, using wild-type or mutated tRF3E. We found that NCL, through its RNA-binding domains (RBD1–2 and RBD3–4), binds simultaneously two tRF3E molecules, giving rise to an energetically favored complex. Instead, a mutant form of tRF3E (M19–24), in which the NCL recognition element in position 19–24 has been disrupted, contacts NCL exclusively at RBD3–4, causing the loss of cooperativity among RBDs. Importantly, when expressed in MCF7 breast cancer cells, tRF3E significantly reduced cell proliferation and colony formation, confirming its role as tumor suppressor, but tRF3E functional properties were lost when the 19–24 motif was mutated, suggesting that cooperativity among multiple domains is required for the NCL-mediated tRF3E antitumor function. This study sheds light on the dynamic of RNA-NCL interaction and lays the foundations for using tRF3E as a promising NCL-targeted biodrug candidate. Full article

Background: Alzheimer’s disease (AD) is a multifactorial neurodegenerative disorder characterised by the accumulation of neurotoxic substances in the brain, ultimately leading to progressive cognitive decline. The complex aetiology and involvement of multiple molecular targets in AD pathogenesis have made discovering effective therapeutic agents particularly challenging. Targeting multiple proteins simultaneously with a single therapeutic agent may offer a promising strategy to address the disease’s multifaceted nature. Methods: This study employed advanced computational methodologies to perform multitargeted molecular docking of FDA-approved drugs against four key AD-associated proteins implicated in disease progression. Among the screened compounds, Rebamipide—a drug conventionally used for treating gastrointestinal disorders—demonstrated notable binding affinities across all targets. Pharmacokinetic predictions, interaction fingerprinting, WaterMap analysis, density functional theory (DFT) calculations, and 100 ns MD simulations were performed for each protein–ligand complex to evaluate its multitarget potential. Results: Rebamipide bound effectively to the NR1 ligand-binding core, suggesting modulation of glutamatergic signalling while reducing β-secretase production and regulating neurotransmitter homeostasis through inhibiting monoamine oxidase-A. Furthermore, Rebamipide enhanced cholinergic neurotransmission by inhibiting human acetylcholinesterase, potentially improving cognitive function. Pharmacokinetic analyses confirmed favourable drug-like properties. Molecular interaction fingerprints revealed consistent hydrogen bonding, hydrophobic contacts, and π-π stacking interactions. WaterMap analysis indicated thermodynamically favourable water displacement upon binding, enhancing ligand affinity. DFT analysis of Rebamipide showed a 4.24 eV HOMO-LUMO gap, with ESP values ranging from −6.63 × 10⁻² to +6.63 × 10⁻² A.U., indicating reactive sites. TDDFT predicted strong UV absorption at 314 nm with a peak intensity of ~6500 L mol⁻¹ cm⁻¹. MD simulations over 100 ns demonstrated minimal structural deviations and stable ligand–protein complexes, reinforcing its multitarget efficacy. Conclusions: The comprehensive in silico investigation highlights Rebamipide as a promising multitargeted therapeutic candidate for Alzheimer’s disease. Its ability to modulate multiple pathogenic pathways simultaneously underscores its potential utility; however, these computational findings warrant further experimental validation to confirm its efficacy and therapeutic relevance in AD. Full article

The effects of magnesium and sodium on the interactions between aptamer, its specific ligand, and short complementary oligonucleotides (cDNAs) differing in affinity of their binding with the aptamer were studied. Aflatoxin B1 (AFB1) and AFB1-binding aptamer were used in the study. Dependencies for the aptamer binding with the fluorophore-labeled AFB1 under varied concentrations of the cations were obtained using fluorescence anisotropy measurements. The increase of the aptamer affinity to AFB1 in the presence of cations was demonstrated using fluorescence anisotropy and isothermal calorimetry. The collected data indicate that 300 mM Mg²⁺ (significantly more than the range commonly used in aptamer sensors) provides the best affinity (16.5 ± 2.2 nM) of the aptamer–AFB1 complexation. Sodium decreases the Mg²⁺-modulated affinity at some Na⁺/Mg²⁺ ratios. The aptamer affinity with cDNAs increases with concentration of cations, but not in the same way as for AFB1. Based on the characterized conditions for bimolecular interactions, the ligand-induced displacement of cDNAs was studied with the registration of the Forster fluorescence energy transfer (FRET). The most sensitive revealing of AFB1 (IC10% 3.2 ± 0.3 nM) in this three-compound FRET system was demonstrated for cDNA having an equilibrium constant of the aptamer binding close to the constant of the aptamer–AFB1 reaction. Full article

Dysregulated dopamine (DA) release in the mesocorticolimbic circuit is noted in Parkinson’s disease (PD) patients with impulsive and compulsive behaviors (ICBs). However, the effect of acute DA release on mood, the localization of this process, and the phenotypic differences in patients with ICB remain unknown. We applied a placebo-controlled dextro-amphetamine (dAMPH) study in 20 PD patients: 10 with ICBs (PD-ICB) and 10 without (PD-C). Subjective mood experiences were measured with well-described self-reported measures including the Positive and Negative Affect Scale (PANAS), Drug Effects Questionnaire (DEQ), and Amphetamine Interview Rating Scale (AIRS). D2-like receptor availability was measured as non-displaceable binding potential (BP_ND) using PET imaging with the high-affinity D2/3 receptor ligand [¹⁸F]-fallypride. Among all the subjects, dAMPH increased the PANAS positive, DEQ feel, DEQ high, and AIRS total scores. Increases in the PANAS positive and AIRS total scores were greater in the PD-ICB cohort. A mixed-effects model correlated these questionnaire changes with dAMPH-induced reductions in BP_ND in the ventral striatum (VS), caudate, amygdala, and caudo-medial orbitofrontal cortex. The baseline caudate, VS, and amygdala BP_ND positively correlated with lower on-dAMPH PANAS positive scores. Elevated mood symptoms of acute dAMPH administration in PD are linked to DA release in the mesocorticolimbic regions. Distinctions in behavioral effects among PD-ICB subjects emphasize that dysregulated striatal and extra-striatal DA-ergic networks alter mood responses to stimulated DA release and may also contribute to behavioral changes resulting from DA-targeting therapies in PD. Full article

Background/Objectives: High-performance affinity chromatography (HPAC) was used to investigate the binding affinity of a series of synthetic cannabinoids, a widely abused class of new psychoactive substances, to human serum albumin (HSA) and obtain insights into the binding sites. To better understand the recognition mechanisms, molecular docking studies were conducted. Methods: Binding affinity was assessed through zonal elution approach Additionally, displacement chromatography with site-specific probes provided insights into the HSA binding sites of five synthetic cannabinoids. Results: That these drugs exhibit extensive binding to HSA, with values ranging from 98.7% to 99.9%. Competition for site I was observed between warfarin and four synthetic cannabinoids (5F-AMB, AB-PINACA, AMB-FUBINACA, and AB-CHMINACA). Furthermore, AB-CHMINACA also competed with L-tryptophan for site II. The binding affinity of all synthetic cannabinoids increased in the presence of (S)-ibuprofen. Molecular docking studies supported the experimental findings, reinforcing the insights gained. Conclusions: The key novelty of this study lies in analyzing, for the first time, the binding affinity of synthetic cannabinoids to HSA through HPAC and molecular docking. These results may improve our understanding of their toxicokinetic behavior and help in predicting possible competitive interactions that could influence HSA binding and, consequently, their activity and toxicity. This study is the first to describe the binding affinity of synthetic cannabinoids to HSA, elucidate their recognition mechanisms, identify binding sites, and characterize their interactions with the protein. Full article

Biogas, one of the important controllable renewable energy sources, may be split into two streams: bio-CH₄ and bio-CO₂ using, among others, membrane processes. The proper optimization of such processes requires the knowledge of phenomena accompanying each specific CH₄–CO₂–membrane system (e.g., competitive sorption or swelling). The phenomena were analyzed for the polysulfone-based membrane used in a developed adsorptive–membrane system for biogas separation. The Dual Mode Sorption and partial immobilization models were used to describe the solubility and diffusion of CO₂, CH₄ and their mixtures in this material. The parameters of the models were determined based on pure-gas sorption isotherms measured gravimetrically and permeances of CO₂/CH₄ mixture components from our previous studies. It was found, among other things, that the membrane swelling caused by CO₂ was observed for pressures higher than 5 bar. The real selectivity (permselectivity) of CO₂ vs. CH₄ is significantly lower than the selectivity of pure gases (ideal selectivity), while the solubility selectivity of CO₂ vs. CH₄ in the mixture is higher than that of pure gases. This is due to the better affinity of CO₂ towards the tested polysulfone membrane, making CO₂ the dominant component in competitive sorption. The reduction in the permselectivity is mainly due to an approximately two-fold decrease in the CO₂ diffusion rate in the presence of CH₄. It was also found that the fraction of solubility in the fractional free volume (FFV) is dominant for both gases, pure and mixed, reaching 65–73% of the total solubility. Moreover, in CO₂/CH₄ mixtures, the mobility of methane in FFV disappears, which additionally confirms the displacement of methane by CO₂ from FFV. Full article

Ulcerous lesions can arise in primary skin cancers and upon infiltration of the skin by malignant cells originating from other organs. These malignant fungating wounds are difficult to treat, and they cause pain, itching and malodor. Distressing malodor imposes a major burden on patients. The carrion odor of decaying tissue is—at least in part—due to the bacterial breakdown products cadaverine and putrescine. Here, we examined the binding of cadaverine, histamine, putrescine, spermidine and spermine to the preparation of micronized purified clinoptilolite-tuff (PCT) by relying on three radiolabeled tracers ([³H]cadaverine, [³H]histamine and [³H]spermidine). Binding was rapid, stable and of high capacity. The binding affinities were in the low µM range. Displacement experiments indicated that the binding sites were non-equivalent. These three properties combined to support effective binding for any given ligand in the presence of the expected, submillimolar concentrations of competing ligands. This was further verified by measuring the binding of [³H]cadaverine in the presence of wound drainage fluids. [³H]Cadaverine was effectively adsorbed by a wound dressing, into which purified clinoptilolite-tuff had been incorporated: the observed binding capacity of this wound dressing was consistent with its content of purified clinoptilolite-tuff. Based on these findings, we propose that purified clinoptilolite-tuff be further investigated as a means to control malodor emanating from chronic wounds. Full article

Gene II Protein (Gp2/P2) is a nicking enzyme of the M13 bacteriophage that plays a role in the DNA replication of the viral genome. P2 recognizes a specific sequence at the f1 replication origin and nicks one of the strands and starts replication. This study was conducted to address the limitations of previous experiments, improve methodologies, and precisely determine the biochemical activity conditions of the P2 enzyme in vitro. For these purposes, the gene encoding P2 was cloned in Escherichia coli and expressed as a hybrid protein together with a green fluorescent protein (P2-GFP). P2-GFP was purified via metal affinity chromatography, and its nicking activity was determined by conversion of supercoiled DNA to open circular or linear forms. We discovered that, among the two loops of the f1 origin defined previously, P2 can recognize just the A1 loop. When a supercoiled plasmid containing the f1 origin was treated with P2-GFP, the plasmid was present in an open circular form, indicating that a nick was created on only one of the strands. However, when the A1 loop sequence was inserted into the 3′ ends of both strands by cloning a PCR product obtained by primers with the A1 loop sequence, the plasmid was linearized by treatment with P2-GFP, indicating that nicks were created on both strands. Certain infectious diseases are caused by single-stranded DNA viruses, and some of them have specific nicking enzymes that enable strand displacement and free 3′ end of a single strand that works as a primer for their replication mechanisms like M13 bacteriophages, such as parvovirus B19. Despite there being different host viruses such as bacteria and humans, their DNA replication mechanisms are very similar in this concept. Investigating the features of the P2-nicking enzyme may deepen the understanding of human pathogenic single-stranded viruses and facilitate the development of drugs that inhibit viral replication. Full article