Cation-π Interactions Research Articles

Adsorption of lead ions and methylene blue on acrylate-modified hydrochars

Hydrochars are promising sorbents for wastewater treatment. Herein, two acrylate-modified hydrochars (AMHC1 and AMHC2) were obtained by grafting acrylic acid on the surface of two hydrochars (MHC1 and MHC2 hydrothermally carbonized in water and acidic medium respectively) with free radical polymerization. Characterizations show that MHC2 is more prone to free radical polymerization than MHC1 does, and has higher carboxylate content after modification. The adsorption amounts of AMHC2 over methylene blue (MB) and Pb(II) are much higher than those of AMHC1. Pseudo-second-order kinetic and Langmuir isotherm equations well fit the Pb(II) and MB sorption data of AMHC2. The Pb(II) adsorptive mechanism is mainly inner-surface complexation accompanied by ion exchange and cation-π interaction. MB adsorption involves ion exchange, electrostatic interaction, H-bonding and π-π interaction. Hence, the one-step modification method of free radical polymerization under alkaline condition has great potential for preparing carboxylate-modified hydrochars to adsorb cationic pollutants.

Rationally designed a silent AIE oxidation platform based on pillar[5]arene for [formula omitted] and vitamin C (Vc) sensor

The benefits of Vc for the body's typical metabolism have received adequate attention. However, effective probes for analyzing specific Vc are currently lacking. To monitor Vc levels, we design and create a novel luminescence-silent oxidation AIE fluorescent probe (2BCP@Fe) by interacting between a coumarin dual-functionalized fluorescent pillar[5]arene derivative and Fe3+ to monitor largescale Vc. The morphological transformation was achieved by adding a certain amount of aqueous solution into the BCP DMF solution. A fluorescence ‘turn-on‘ phenomenon was observed, which was caused by restricting intramolecular rotation.Meanwhile, SEM measurements supported the importance of the cation-π interaction between Fe3+ and BCP in this supramolecular process. Additionally, the supramolecular system (2BCP@Fe) can monitor H2PO4- ions through competitive contact and can operate as a “turn-on” fluorescent probe for Vc detection through the process of redox reaction. As a result, such a novel fabrication strategy might offer a prospective strategy for preparing the metal-modified macrocyclic host functional materials for sensing, catalysis, and other fields.

Mussel-inspired cationic chitosan-based flocculants with floc enlarging capacity for efficient removal of anionic dye

Biomass-based flocculants have been widely studied and applied to wastewater treatment due to their environmental friendliness. However, these flocculants tend to generate flocs with small size and lead to difficult solid-liquid separation after the flocculation. The key to solving the floc size problem is enhancing intermolecular or intramolecular interaction forces by changing the molecular structure and functional groups of flocculants. Herein, we developed a mussel-inspired cationic biomass flocculant by functionalizing chitosan (CS) with cation component acryloyloxyethyltrimethyl ammonium chloride (DAC) and mussel-inspired monomer N-2-(3, 4-dihydroxyphenethyl) acrylamide (DAA) through free radical polymerization. The prepared flocculant could provide multiple interaction forces such as electrostatic interaction, cation-π interaction, π −π stacking, and hydrogen bonding to pollutants. As a result, the spent CS-g-p (DAC-co-DAA) flocculant generate dye-containing flocs with dramatically increased size when compared with its counterpart CS-g-pDAC without catechol groups and are capable to realize more than 95% removal efficiency towards organic dyes such as MB and CR over a broad pH range from 3 to 9. This study provides some insights in how to apply this mussel-inspired strategy to develop environmentally friendly biomass-derived flocculants with floc enlarging capacity to treat organic wastewaters in wide pH range.

Mechanistic Insights into the Binding of Different Positron Emission Tomography Tracers to Chronic Traumatic Encephalopathy Tau Protofibrils.

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with exposure to repetitive head impacts, and it is neuropathologically defined as the accumulation of abnormally hyperphosphorylated tau (p-tau). Early detection of p-tau in the brain is of great value in the prevention and treatment of CTE. Previous experimental studies reported that positron emission tomography (PET) technique using several tau tracers are available for imaging certain neurodegenerative diseases. However, few studies have focused on the development of CTE tau tracers. In this work, we performed conventional molecular docking and molecular dynamics simulations to address the binding properties and mechanisms of PET tracers (18F-PM-PBB3, 18F-CBD-2115, 18F-PI-2620, 18F-RO-948, 18F-MK-6240, and 18F-flortaucipir) to CTE tau protofibrils. The results show that the hydrophobic cavity and the top of the concave structure of CTE tau protofibrils are the preferred binding sites for the six tracers, and 18F-PM-PBB3 has the most competitive binding affinity to CTE tau protofibrils. Further investigation into the binding patterns of the six tracers to the CTE tau protofibrils showed that 18F-CBD-2115 and 18F-PM-PBB3 have a high number of H-bonds and hydrophobic contacts with tau protofibrils, resulting in strong hydrogen bonding and hydrophobic interactions; 18F-flortaucipir/18F-PI-2620 and 18F-PI-2620/18F-RO-948 form more intense π-π and cation-π interactions with tau protofibrils, respectively. Subsequently, we conducted a detailed analysis of the binding mechanism of 18F-PM-PBB3 to CTE tau protofibrils. The benzothiazole ring of 18F-PM-PBB3 exhibits stronger π-π stacking and cation-π interactions with tau protofibrils than the pyridine ring and forms a more concentrated T-shaped π-π stacking pattern. This study contributes to understanding the binding mechanism of PET tracers to CTE tau protofibrils and provides new insights into the design of potential novel tracers.

Effective diuretic drug uptake employing magnetic carbon nanotubes derivatives: Adsorption study and in vitro geno-cytotoxic assessment

In this study, furosemide (FUR) adsorption was performed employing magnetic carbon nanotubes (CNT‧Fe3O4) with different amounts of incorporated magnetite. The CNT and magnetic CNTs were synthesized by chemical vapor deposition (CVD) and co-precipitation methods, respectively. The nanoadsorbents were characterized by FTIR, XRD, Raman, SEM, and VSM techniques. The adsorption experiments revealed that the best performance was obtained by CNT‧Fe3O4 1:10, showing values of 82.39% and 83.5 mg g−1 of removal percentage and maximum adsorption capacity at pH 2.0, due to the improvement in π-π interactions, and the presence of iron nanoparticles enhanced the adsorption, suggesting that cation-π interactions control the process. The sorption process exhibited high dependence on pH, adsorbent dosage, and initial concentration of adsorbate. Sips and Elovich models showed the best adjustment for experimental data, suggesting that the process occurs on a heterogeneous surface and with different energy adsorption sites, respectively. The thermodynamic parameters indicated a spontaneous and exothermic process. The outcome of in vitro cytotoxicity assays revealed that the adsorbent/drug complex, after adsorption, exhibited lower toxic effects than the free drug. On the other hand, the genotoxicity assay showed that only the Fe3O4 caused damage at the DNA level. Magnetic carbon nanotubes prove to be efficient in the removal of furosemide from the aqueous solution. Also, the complex after adsorption showed good biocompatibility, allowing a promising application in the biological area and stimulating future studies in drug repositioning.

An electrochemical sensor based on synergistic enhancement effects between nitrogen-doped carbon nanotubes and copper ions for ultrasensitive determination of anti-diabetic metformin

Metformin (MET) is the primary medicine for type II diabetes, which produces carcinogenic byproducts during chlorine disinfection, so the detection of MET in aqueous environment is crucial. In this work, an electrochemical sensor based on nitrogen-doped carbon nanotubes (NCNT) has been constructed for ultrasensitive determination of MET in the presence of Cu(II) ions. The excellent conductivity and rich π-conjugated structure of NCNT facilitate the electron transfer rate of fabricated sensor and benefit the adsorption of cation ions. Cu(II) ions can chelate with MET to form MET-Cu(II) complex, which are easily accumulated on the surface of NCNT through cation-π interaction. Attributing to the synergistic enhancement effects of NCNT and Cu(II) ions, the fabricated sensor exhibits excellent analytical performances with a low detection limit of 9.6 nmol L−1, high sensitivity of 64.97 A mol−1 cm−2 and wide linear range of 0.3–10 μmol L−1. The sensing system has been successfully applied for rapid (20 s) and selective determination of MET in real water samples with satisfactory recoveries (90.2 %–108.8 %). This study provides a robust strategy for MET detection in aqueous environment and holds great promise for rapid risk assessment and early warning of MET.

Additive-Induced Synergies of Ion Migration Inhibition and Defect Passivation toward Sensitive Perovskite X-ray Detectors

Two-dimensional (2D) Ruddlesden-Popper (RP) metal halide perovskites have emerged as a promising material for X-ray detection. However, defects and ion migration generated nonradiative recombination and high dark current could cause severe performance degradation, which hinders their application. Herein, rubrene was added to the precursor solution of BA2MA3Pb4I13 to modulate the performance of the 2D RP perovskite X-ray detectors. The cation-π interaction between rubrene and perovskite could passivate the defects and inhibit the ion migration, resulting in improved performance and stability. The detectors made with rubrene exhibited a sensitivity of 354.30 μC·Gyair-1 cm-2 and a detection limit of 112.85 nGyair s-1. This work highlights the synergistic effect of rubrene in defect passivation and ion migration inhibition, providing a facile approach toward sensitive perovskite X-ray detectors.

Rational Exploration of Novel SDHI Fungicide through an Amide-β-ketonitrile Bioisosteric Replacement Strategy

The identification of succinate dehydrogenase inhibitor (SDHI) fungicides bearing a novel scaffold is of great importance to control pathogenic fungi. Difluoromethyl-pyrazole β-ketonitrile derivatives were rationally designed through an innovative amide-β-ketonitrile bioisosteric replacement strategy and evaluated for their antifungal activities. In preliminary fungicidal screening, our new β-ketonitrile compounds showed outstanding in vitro activity. Compounds A7 and A14 exhibited EC50 values of 0.116 and 0.165 μg/mL against Sclerotinia sclerotiorum, respectively, and A14 also displayed an EC50 of 0.0774 μg/mL against Rhizoctonia solani. Furthermore, A14 exhibited moderate in vivo protective activity against rice sheath blight on rice plants. Results from SDH enzymatic assays demonstrated that A14 possesses significant inhibitory effect toward porcine heart SDH, with an IC50 value of 0.183 μM, which was 20-fold more potent than that of fluxapyroxad (IC50 = 3.76 μM). A docking study indicated that H-bonds, cation-π interactions, and edge-to-face π-π interactions play key roles in the binding of A14 with R. solani SDH. The CoMSIA model guided the approach to further structural optimizations and indicated that hydrophobic and steric substituents on the benzene ring have decisive effects on the fungicidal activity against R. solani. The present work describes for the first time the successful bioisosteric replacement of the common SDHI amide moiety by a β-ketonitrile group and highlights the potential of β-ketonitriles as an innovative novel SDHI subclass.

Highly efficient remediation of Cu (II) from water by novel poly(o-phenylenediamine)/zinc oxide nanohybrids: Kinetic, equilibrium, and thermodynamic studies

Herein, novel nanohybrids of poly(o-phenylenediamine)/zinc oxide (POPD/ZnO) were synthesized using an ultrasound-assisted technique via a facile in situ polymerization method for the removal of Cu (II) ions from water. These nanohybrids were characterized using infrared spectra (FTIR), UV–Visible spectra, scanning electron microscopy (SEM), X-ray scattering (XRD), thermogravimetric analysis (TGA), and BET (Brunauer-Emmett-Teller surface area). Numerous parameters were optimized to see the performance of the adsorption process like effect of POPD loading, adsorbent dose, initial Cu (II) ion concentration, pH, contact time, and temperature. POPD/ZnO-13/87 was found the best adsorbent based on above analysis. Non-linear equilibrium isotherm (Langmuir and Freundlich), kinetics (pseudo-first and second order, intraparticle diffusion model), and thermodynamic studies were performed to analyze the adsorption process. Langmuir isotherm and pseudo-second-order kinetic model were found appropriate while thermodynamic parameters Gibbs free energy change (ΔG°), entropy change (ΔS°) (166.32 J mol−1 K−1), and enthalpy change (ΔH°) (34.03 kJ mol−1) were calculated showing an endothermic and spontaneous process for adsorption of Cu (II) ions. According to Langmuir isotherm, the maximum adsorption capacity was found at 2485 mg g−1 while experimental adsorption capacity was found 2360 mg g−1 at adsorbent doses = 0.4 g L−1, Cu (II) ion concentration = 1000 mg L−1, pH = 6.5, temperature = 25 °C in 90 min that was higher than that of other reported materials till date to the best of our knowledge. Mechanism studies suggested that the electrostatic interaction and cation-π interaction between nanohybrids and Cu (II) ions was the main driving force for the adsorption of Cu (II) ions.

Fabricating hydroxyapatite functionalized biochar composite using steel slag and Hami melon peel for Pb(II) and Cd(II) removal

With rising global concerns about the discharge of large volumes of waste materials derived from industrial manufacture and human life, methods for utilizing waste materials have been greatly developed. In this study, an ingenious hydroxyapatite (Hap) functionalized hierarchical porous biochar (HB) composite is fabricated using a filtrate rich in Ca2+ ions after steel slag reuse and spent Hami melon peel as raw materials. Microstructural analyses indicate that Hap nanoparticles are loaded on HB with hierarchical pores produced from a pyrolysis process of Hami melon peel. A series of HB-Hap materials by tuning HB addition amount (0.5, 1, and 2 g) can be obtained through a coprecipitation process. As a case study, HB-0.5Hap exhibits high specific surface area of 66.92 m2/g and high-efficiency removal performance for Pb(II) and Cd(II) ions in wastewater. The maximum adsorption capacities of HB-0.5Hap are 134.4 (Pb(II)) and 60.4 (Cd(II)) mg/g, which are 1.77 and 1.23 times higher than that of pure HB, respectively. It is attributed to a synergistic mechanism involving ion exchange, chemical precipitation, surface complexation, and cation-π interaction. According to a semi-quantitative calculation, ion exchange plays a major role in the removal of Pb(II) (78.61%, the relative contribution of ion exchange mechanism) and Cd(II) (77.77%). This study demonstrates a facile, economical, and sustainable strategy for the value-added utilization of steel slag and spent Hami melon peel, which can be critical in solving environmental problems.

Growth Reaction of Gold Nanorods in the Presence of Mutated Peptides and Amine-Modified Single-Stranded Nucleic Acids.

Conformation of biomolecules like DNA, peptides and amino acids play vital role during nanoparticle growth. Herein, we have experimentally explored the effect of different noncovalent interaction between a 5'-amine modified DNA sequence (NH2 -C6 H12 -5'-ACATCAGT-3', PMR) and arginine during the seed-mediated growth reaction of gold nanorods (GNRs). Amino acid-mediated growth reaction of GNRs results in a snowflake-like gold nanoarchitecture. However, in case of Arg, prior incubation of GNRs with PMR selectively produces sea urchin-like gold suprastructures, via strong hydrogen bonding and cation-π interaction between PMR and Arg. This distinctive structure formation strategy has been extended to study the structural modulation caused by two structurally close α-helical RRR (Ac-(AAAAR)3 A-NH2 ) peptide and the lysine mutated KKR (Ac-AAAAKAAAAKAAAARA-NH2 ) peptide with partial helix at the amino terminus. Simulation studies confirm that a greater number of hydrogen bonding and cation-π interaction between the Arg residues and PMR resulted in the gold sea urchin structure for RRR peptide against KKR peptide.

Cation-π Interaction Trigger Supramolecular Hydrogelation of Peptide Amphiphiles.

As an important noncovalent interaction, cation-π interaction plays an essential role in a broad area of biology and chemistry. Despite extensive studies in protein stability and molecular recognition, the utilization of cation-π interaction as a major driving force to construct supramolecular hydrogel remains uncharted. Here, a series of peptide amphiphiles are designed with cation-π interaction pairs that can self-assemble into supramolecular hydrogel under physiological condition. The influence of cation-π interaction is thoroughly investigated on peptide folding propensity, morphology, and rigidity of the resultant hydrogel. Computational and experimental results confirm that cation-π interaction could serve as a major driving force to trigger peptide folding, resultant β-hairpin peptide self-assembled into fibril-rich hydrogel. Furthermore, the designed peptides exhibit high efficacy on cytosolic protein delivery. As the first case of using cation-π interactions to trigger peptide self-assembly and hydrogelation, this work provides a novel strategy to generate supramolecular biomaterials.

Single-Molecule Force Spectroscopy Reveals Cation-π Interactions in Aqueous Media Are Highly Affected by Cation Dehydration.

Cation-π interactions underlie many important processes in biology and materials science. However, experimental investigations of cation-π interactions in aqueous media remain challenging. Here, we studied the cation-π binding strength and mechanism by pulling two hydrophobic polymers with distinct cation binding properties, i.e., poly-pentafluorostyrene and polystyrene, in aqueous media using single-molecule force spectroscopy and nuclear magnetic resonance measurement. We found that the interaction strengths linearly depend on the cation concentrations, following the order of Li^{+}<NH_{4}^{+}<Na^{+}<K^{+}. The binding energies are 0.03-0.23 kJ mol^{-1} M^{-1}. This order is distinct from the strength of cation-π interactions in gas phase and may be caused by the different dehydration ability of the cations. Taken together, our method provides a unique perspective to investigate cation-π interactions under physiologically relevant conditions.

Enhanced purification of kitchen-oil wastewater driven synergistically by surface microelectric fields and microorganisms

The stable structure and toxic effect of refractory organic pollutants in wastewater lead to the problem of high energy consumption in water treatment technology. Herein, we propose a synergistic purification of refractory wastewater driven by microorganisms and surface microelectric fields (SMEF) over a dual-reaction-center (DRC) catalyst HCLL-S8-M prepared by an in situ growth method of carbon nitride on the Cu-Al2O3 surface. Characterization techniques demonstrate the successful construction of SMEF with strong electrostatic force over HCLL-S8-M based on cation-π interactions between metal copper ions and carbon nitride rings. With the catalyst as the core filler, an innovative fixed bed bioreactor is constructed to purify the actual kitchen-oil wastewater. The removal efficiency of the wastewater even with a very low biodegradability (BOD5/COD = 0.33) can reach 60% after passing through this bioreactor. An innovative reaction mechanism is revealed for the first time that under the condition of a small amount of biodegradable organic matter, the SMEF induces the enrichment of electric active microorganisms (Desulfobulbus and Geobacter) in the wastewater, accelerates the interspecies electron transfer of intertrophic metabolism with the biodegradable bacteria through the extracellular electron transfer mechanism such as cytochrome C and self-secreted electron shuttle. The electrons of the refractory organic pollutants adsorbed on the surface of the catalyst are delocalized by the SMEF, which can be directly utilized by microorganisms through EPS conduction. The SMEF generated by electron polarization can maximize the utilization of pollutants and microorganisms in wastewater and further enhance degradation without adding any external energy, which is of great significance to the development of water self-purification technology.

Synthesis and fungicidal activity of 2-(methylthio)-4-methylpyrimidine carboxamides bearing a carbamate moiety

A series of 1-[2-(4-methyl-2-(methylthio)pyrimidine-5-carboxamido)phenyl]ethyl-substitutedphenyl carbamates (3a–3i) were designed and synthesized, using 4-methyl-2-(methylthio)pyrimidine-5-carboxylic acid, (2-aminophenyl)ethan-1-one, and substituted phenyl isocyanates as starting materials. Their structures were characterized by 1H NMR, 13C NMR, IR and HRMS. The in vitro fungicidal activities against Sclerotinia sclerotiorum were evaluated, and the result showed that some compounds displayed moderate antifungal activity with >60% inhibitory rates, among which 1-[2-(4-methyl-2-(methylthio)pyrimidine-5-carboxamido)phenyl] ethyl-(2- methyl phenyl)carbamate (3a) and 1-[2-(4-methyl-2-(methylthio)pyrimidine-5- carboxamido)phenyl] ethyl-(3-trifluoromethyl phenyl)carbamate (3g) held inhibitory rates of 69.5% and 70.3% at 100 mg/L, respectively. Molecular docking study showed that 3g can form two hydrogen bonds and a cation-π interaction with succinate dehydrogenase.

Development of axially chiral urazole scaffolds for antiplant virus applications against potato virus Y.

Potato virus Y (PVY) was first discovered by Smith in 1931 and is currently ranked as the fifth most significant plant virus. It can cause severe damage to plants from the family Solanaceae, which results in billions of dollars of economic loss worldwide every year. To discover new antiviral drugs, a class of multifunctional urazole derivatives bearing a stereogenic CN axis were synthesized with excellent optical purities for antiviral evaluations against PVY. The absolute configurations of the axially chiral compounds exhibited obvious distinctions in antiviral bioactivities, with several of these enantio-enriched axially chiral molecules showing excellent anti-PVY activities. In particular, compound (R)-9f exhibited remarkable curative activities against PVY with a 50% maximal effective concentration (EC50 ) of 224.9μg mL-1 , which was better than that of ningnanmycin (NNM), which had an EC50 of 234.0μg mL-1 . And the EC50 value of the protective activities of compound (R)-9fwas 462.2μg mL-1 , which was comparable to that of NNM (442.0μg mL-1 ). The mechanisms of two enantiomer of the axially chiral compounds 9fwere studied by both molecule docking and defensive enzyme activity tests. Mechanistic studies demonstrated that the axially chiral configurations of the compounds played significant roles in the molecule PVY-CP (PVY Coat Protein) interactions and could enhance the activities of the defense enzymes. The (S)-9f showed only one carbon-hydrogen bond and one π-cation interaction between the chiral molecule and the PVY-CP amino acid sites. In contrast, the (R)-enantiomer of 9f exhibited three hydrogen bonding interactions between the carbonyl groups and the PVY-CP active sites of ARG157 and GLN158. The current study provides significant information on the roles that axial chiralities play in plant protection against viruses, which will facilitate the development of novel green pesticides bearing axial chiralities with excellent optical purities. © 2023 Society of Chemical Industry.

3D-QSAR, design, docking and in silico ADME studies of indole-glyoxylamides and indolyl oxoacetamides as potential pancreatic lipase inhibitors

The versatility of indole heterocyclic led to the understanding of their structural requirements to develop new potential derivatives. The indole derivatives estimated to be active against pancreatic lipase have been chosen to develop 3D-QSAR field and atom-based models, validated using the Schrodinger suite. Designing of new agents through QSAR based predictions and performing docking on these compounds helped in defining the binding pattern and pharmacophoric features like π–π stacking interactions, hydrogen bonding, and π-cation interactions with the amino acid residues. The protein-ligand complex displayed good binding energies. In silico ADMET properties have been generated using the Quick-prop module of the Schrodinger suite. The 3D-QSAR model is found to be statistically significant and evaluated using various parameters like R2, R2CV, stability, F-value, P-value, RMSE, Q2, and Pearson-r by PLS factor of 4. The field fractions and contour maps along with their visualizations have helped in inferring the essential nature and type of substituent that should be incorporated for a compound to display potent pancreatic lipase inhibitory activity. These deductions and evaluations of the synthesized compounds through the generation of models could be further utilized for designing new molecules rationally.

Efficient and selective removal cesium from strong acidic medium by novel butenyl-calix [4]-crown 6 functionalized millimeter-sized mesoporous carbon spheres sorbent: Experimental and theoretical study

Eliminating the radioactive Cesium from high level waste (HLW) is crucial to avoid the radioactive pollution. Herein, a novel carbon-based recognizable material, butenyl-calix [4]-crown 6 functionalized millimeter-sized mesoporous carbon spheres (ButC[4]C6/MMCs), was prepared via “interpenetrating functionalization” strategy to remove Cs(I) from strongly acidic solution. ButC[4]C6 supramolecular was incorporated into the channels of MMCs and polymerized to form cross-linked IPN structure. The morphology and microstructure of the final product were characterized by SEM, NMR, FT-IR, TG-DSG and N2 adsorption–desorption isotherms. The adsorption behaviors of Cs(I) onto ButC[4]C6/MMCs were systematically investigated. ButC[4]C6/MMCs displayed an astonishing adsorption capacity (55.22 mg g−1), high selectivity and reusability at a low dose (2.0 g L-1) under 3.0 M HNO3 medium. Pseudo-second-order kinetic model, Brouers-Sotolongo model and thermodynamic study revealed that the adsorption process is a spontaneous endothermic chemical and heterogeneous adsorption process. Theoretical study revealed that the Cs(I) was tightly fixed in the calixarene cavity via cation-π interaction. This work proposes an effective approach to selectively remove Cs(I) from HLW by skillfully coupling supramolecular recognizer with millimeter-sized porous material to address radioactive pollution issue.

Designing adsorptive membranes for removing protein-bound uremic toxins via π-π and cation-π interaction

Protein-bound uremic toxins (PBUTs) are recently thought to critically influence overall organ dysfunction, morbidity, and mortality of chronic kidney disease (CKD) patients. However, traditional hemodialysis and/or hemoperfusion processes fail to remove PBUTs efficiently due to their strong affinity with albumins. Herein, we fabricated a novel adsorptive membrane incorporating amine/polyphenol/bimetal ions complexation in the polysulfone membrane substrate, which has a higher affinity with hippuric acid, p-cresol sulfate, and indoxyl sulfonate. The complexation is a synergy of polyelectrolyte (polyethyleneimine-tannic acid) and metal-phenolic (tannic acid/metals) networks. The adsorption behavior of those three uremic toxins on the optimized adsorptive membrane was investigated by kinetic and adsorption isotherm studies. From X-ray photoelectron spectroscopy analysis assisted by Fourier transform infrared reflection spectrum, we attribute the high adsorption capacity to π-π and/or cation-π interaction with aromatic ring groups of uremic toxins. The adsorptive membrane could effectively remove albumin bounded uremic toxins and water-soluble urea through a continuous dialysis process. Besides, the membrane showed excellent hemocompatibility and minimized immune responses by suppressing complement activation. The above results showed the potential clinical application of adsorptive membranes.

In Vitro and Silico Studies on the N-Doped Carbon Dots Potential in ACE2 Expression Modulation.

The alteration of ACE2 expression level, which has been studied in many diseases, makes the topic of ACE2 inducer potential crucial to be explored. The ACE2 inducer could further be designed to control the ACE2 expression level, which is appropriate to a specific case. An in vitro study of well-characterized carbon dots (CDs), made from citric acid and urea, was performed to determine their ability to modulate the ACE2 receptor. Gene expression of ACE2 was quantified using concentrations adjusted for IC50 results from CDs viability assays in HEK 293 and A549 cell lines. RT-qPCR was used to assess the expression of the ACE2 gene and its induction effect in normal cell lines (HEK-293A). According to the results of the tests, ACE2 is expressed in HEK-293A cell lines, and diminazene aceturate can increase ACE2 expression. The effect of CDs on ACE2 gene expression was further examined on the cell lines that had previously been induced with diminazene aceturate, which resulted in upregulation of the ACE2 expression level. An in silico study has been done by using a molecular docking approach. The molecular docking results show that CDs can make strong interactions with ACE2 amino acid residues through hydrophobic interaction, π-π interaction, π-cation interaction, and ionic interaction.