Zwitterionic Structure Research Articles

Negative-Ion Electron Capture Dissociation of MALDI-Generated Peptide Anions.

Negative-ion electron capture dissociation (niECD) is an anion MS/MS technique that provides fragmentation analogous to conventional ECD, including high peptide sequence coverage and retention of labile post-translational modifications (PTMs). niECD has been proposed to be the most efficient for salt-bridged zwitterionic precursor ion structures. Several important PTMs, e.g., sulfation and phosphorylation, are acidic and can, therefore, be challenging to characterize in the positive-ion mode. Furthermore, PTM-friendly techniques, such as ECD, require multiple precursor ion-positive charges. By contrast, singly charged ions, refractory to ECD, are most compatible with niECD. Because electrospray ionization (ESI) typically yields multiply charged ions, we sought to explore matrix-assisted laser desorption/ionization (MALDI) in combination with niECD. However, the requirement for zwitterionic gaseous structures may preclude efficient niECD of MALDI-generated anions. Unexpectedly, we found that niECD of anions from MALDI is not only possible but proceeds with similar or higher efficiency compared with ESI-generated anions. Matrix selection did not appear to have a major effect. With MALDI, niECD is demonstrated up to m/z ∼4300. For such larger analytes, multiple electron captures are observed, resulting in triply charged fragments from singly charged precursor ions. Such charge-increased fragments show improved detectability. Furthermore, significantly improved (∼20-fold signal-to-noise increase) niECD spectral quality is achieved with equivalent sample amounts from MALDI vs ESI. Overall, the reported combination with MALDI significantly boosts the analytical utility of niECD.

Aminolysis-Based Zwitterionic Immobilization on Polyethersulfone Membranes for Enhanced Hemocompatibility: Experimental, Computational, and Ex Vivo Investigations.

Dialysis membranes are not hemocompatible with human blood, as the patients are suffering from the blood-membrane interactions' side effects. Zwitterionic structures have shown improved hemocompatibility; however, their complicated synthesis hinders their commercialization. The goal of the study is to achieve fast functionalization for carboxybetaine and sulfobetaine zwitterionic immobilization on PES membranes while comparing the stability and the targeted hemocompatibility. The chemical modification approach is based on an aminolysis reaction. Characterization, computational simulations, and clinical analysis were conducted to study the modified membranes. Atomic force microscopy (AFM) patterns showed a lower mean roughness for carboxybetaine-modified (6.3 nm) and sulfobetaine-modified (7.7 nm) membranes compared to the neat membrane (52.61 nm). The pore size of the membranes was reduced from values above 50 nm for the neat PES to values between 2 and 50 nm for zwitterionized membranes, using Brunauer-Emmett-Teller (BET) analysis. More hydrophilic surfaces led to a growth equilibrium water content (EWC) of nearly 6% for carboxybetaine and 10% for sulfobetaine-modified membranes. Differential scanning calorimetry (DSC) measurements were 12% and 16% stable water for carboxybetaine- and sulfobetaine-modified membranes, respectively. Sulfobetaine membranes showed better compatibility with blood with respect to C5a, IL-1a, and IL-6 biomarkers. Aminolysis-based zwitterionization was found to be suitable for the improvement of hemodialysis membranes. The approach introduced in this paper could be used to modify the current dialysis membranes with minimal change in the production facilities.

Novel C3-Methylene-Bridged Indole Derivatives with and without Substituents at N1: The Influence of Substituents on Their Hemolytic, Cytoprotective, and Antimicrobial Activity.

Alkaloids are natural compounds useful as scaffolds for discovering new bioactive molecules. This study utilized alkaloid gramine to synthesize two groups of C3-substituted indole derivatives, which were either functionalized at N1 or not. The compounds were characterized by spectroscopic methods. The protective effects of the new compounds against in vitro oxidative hemolysis induced by standard oxidant 2,2'-azobis(2-amidinopropane dihydro chloride (AAPH) on human erythrocytes as a cell model were investigated. Additionally, the compounds were screened for antimicrobial activity. The results indicated that most of the indole derivatives devoid of the N1 substitution exhibited strong cytoprotective properties. The docking studies supported the affinities of selected indole-based ligands as potential antioxidants. Furthermore, the derivatives obtained exhibited potent fungicidal properties. The structures of the eight derivatives possessing indole moiety bridged to the imidazole-, benzimidazole-, thiazole-, benzothiazole-, and 5-methylbenzothiazoline-2-thiones were determined by X-ray diffraction. The C=S bond lengths in the thioamide fragment pointed to the involvement of zwitterionic structures of varying contribution. The predominance of zwitterionic mesomers may explain the lack of cytoprotective properties, while steric effects, which limit multiple the hydrogen-bond acceptor properties of a thione sulfur, seem to be responsible for the high hemolytic activity.

Co-Assembled Supramolecular Organohydrogels of Amphiphilic Zwitterion and Polyoxometalate with Controlled Microstructures.

The organization of modifiable and functional building components into various superstructures is of great interest due to their broad applications. Supramolecular self-assembly, based on rationally designed building blocks and appropriately utilized driving forces, is a promising and widely used strategy for constructing superstructures with well-defined nanostructures and diverse morphologies across multiple length scales. In this study, two homogeneous organohydrogels with distinct appearances were constructed by simply mixing polyoxometalate (phosphomolybdic acid, HPMo) and a double-tailed zwitterionic quaternary ammonium amphiphile in a binary solvent of water and dimethyl sulfoxide (DMSO). The delicate balance between electrostatic attraction and repulsion of anionic HPMo clusters and zwitterionic structures drove them to co-assemble into homogeneous organohydrogels with diverse microstructures. Notably, the morphologies of the organohydrogels, including unilamellar vesicles, onion-like vesicles, and spherical aggregates, can be controlled by adjusting the ionic interactions between the zwitterionic amphiphiles and phosphomolybdic acid clusters. Furthermore, we observed an organohydrogel fabricated with densely stacked onion-like structures (multilamellar vesicles) consisting of more than a dozen layers at certain proportions. Additionally, the relationships between the self-assembled architectures and the intermolecular interactions among the polyoxometalate, zwitterionic amphiphile, and solvent molecules were elucidated. This study offers valuable insights into the mechanisms of polyoxometalate-zwitterionic amphiphile co-assembly, which are essential for the development of materials with specific structures and emerging functionalities.

Salt-Bridged Peptide Anion Gaseous Structures Enable Efficient Negative Ion Electron Capture Dissociation.

We previously discovered that electron attachment to gaseous peptide anions can occur within a relatively narrow electron energy range. The resulting charge-increased radical ions undergo dissociation analogous to conventional cation electron capture/transfer dissociation (ECD/ETD), thus enabling a novel tandem mass spectrometry (MS/MS) technique that we termed negative ion electron capture dissociation (niECD). We proposed that gaseous zwitterionic structures are required for niECD with electron capture either occurring at or being directed by a positively charged site. Here, we further evaluate this zwitterion mechanism by performing niECD of peptides derivatized to alter their ability to form zwitterionic gaseous structures. Introduction of a fixed positive charge tag, a highly basic guanidino group, or a highly acidic sulfonate group to promote zwitterionic structures in singly charged anions, rescued the niECD ability of a peptide refractory to niECD in its unmodified form. We also performed a systematic study of five sets of synthetic peptides with decreasing zwitterion propensity and found that niECD efficiency decreased accordingly, further supporting the zwitterion mechanism. However, traveling-wave ion mobility-mass spectrometry experiments, performed to gain further insight into the gas-phase structures of peptides showing high niECD efficiency, exhibited an inverse correlation between the orientationally averaged collision cross sections and niECD efficiency. These results indicate that compact salt-bridged structures are also a requirement for effective niECD.

Hydrazine and its Derivatives: Role on Nitrogen Dioxide Hydrolysis and Ensuing Nucleation in the Atmosphere

AbstractHydrazine (HD) and mono‐methyl hydrazine (MMH), as the compositions of rocket fuels and corrosion inhibitor, have a significant impact on the atmospheric environment. The effects of them on the reaction between NO2 and H2O were investigated theoretically from mechanism and kinetics, and it is expected that they can promote the hydrolysis of NO2 due to their lower free energy barriers. For the subsequent reaction HNO3+HONO+HD/MMH, acid base complex and zwitterionic structure were produced through isomerization. When one or two water molecules were involved in the subsequent reaction, only zwitterionic structure can be found with the lower free energy barrier, and the products were more stable than those without water molecules. To study the atmospheric behavior of HD/MMH, the structures, thermodynamics, interaction forces and temperature dependence of the clusters, which were consisted with HNO3 and HONO with the base molecules including ammonia, amine and amide, were further calculated, and the results show that the hydrogen bond is the main interaction in the clusters. The global minima remained fixed when the temperature increases from 200 K to 325 K. The forming reactions of the clusters were spontaneous, suggesting that ammonia, amine and amide can promote the nucleation of HNO3 and HONO molecules.

A DFT Study on the Tautomerization of β‐Alanine

AbstractTautomerization paths of β‐alanine with explicit inclusion of water molecules, (H2O)n, were investigated by DFT calculations, wB97X‐D/6‐311+G(d,p) SCRF=PCM. Structures of zwitterions of the alanine of trans (t−) and gauche (g−) conformations with seven water molecules (n=7) were examined. On the basis of those geometries, elementary processes of the tautomerization were investigated. For the t‐conformer of β‐alanine, reaction models of n=8, 10, 14, 18 and 24 were scrutinized. While reaction processes are slightly modified with different number of water molecules, n=18 and 24 models afforded three elementary reactions, t‐alanine with cis‐COOH→t‐ion pair→t‐alanine with trans‐COOH→t‐zwitterion. The (H2O)4 hydrogen‐bonded chain participates in the reactions. For the g‐conformer, models of n=7, 10, 14 and 18 were investigated, and the tautomerization was found to take place concertedly via (H2O)2.

Design of new zwitterionic microparticles with intrinsic antibacterial activity

AbstractThe crosslinked porous microparticles based on glycidyl methacrylate, N‐vinylimidazole, and triethylene glycol dimethacrylate (molar ratio between monomers 40:30:30) obtained in the presence of three porogenic agents (toluene, n‐butyl acetate, and toluene:n‐butyl acetate mixture, 1:1, v/v) are used as precursors in the polymer analogous reactions with some betainizing agents (sodium monochloroacetate, acrylic acid, methacrylic acid and 1,3–propane sultone) in order to introduce the carboxybetaine/sulfobetaine groups to the tertiary nitrogen atom from the imidazole ring. ATR–FTIR spectroscopy is used to highlight the presence of carboxybetaine/sulfobetaine groups on the structure of the microparticles, but also to calculate the degree of betainization (55.91%–90.2%) The zwitterionic microparticles are characterized by scanning electron and atomic force microscopies, equilibrium swelling ratio as a function of pH values, swelling kinetics, ion exchange capacities and particle size distribution. Also, the parameters of porous structure (pore diameter, pore volume, porosity, and specific surface area) are determined by mercury porosimetry. The antibacterial properties of Gram‐positive (Enterococcus faecalis and Staphylococcus aureus) and Gram‐negative (Escherichia coli and Klebsiella pneumoniae) bacteria are evaluated. It is found that the zwitterionic structures containing a shorter length alkyl chain between ionic groups exhibit excellent antibacterial activity of about 80%–92%.

A Single Amino Acid Able to Promote High-Temperature Ring-Opening Polymerization by Dual Activation.

Amino acids are indispensable compounds in the body, performing several biological processes that enable proper functioning. In this work, it is demonstrated that a single amino acid, taurine, is also able to promote the ring-opening polymerization (ROP) of several cyclic monomers under industrially relevant conditions. It is shown that the unique zwitterionic structure of taurine, where the negatively charged sulfonic acid group and the protonated amine group are separated by two methylene groups, not only provides high thermal stability but also leads to a dual activation mechanism, which is corroborated by quantum mechanical calculations. This unique mechanism allows for the synthesis of polylactide of up to 50kDa in bulk at 180 °C with good end-group fidelity using a highly abundant catalyst. Furthermore, cytotoxicity tests confirm that PLLA synthesized with taurine is non-toxic. Moreover, it is demonstrated that the presence of taurine does not have any detrimental effect on the thermal stability of polylactide, and therefore polymers can be used directly without any post-polymerization purification. It is believed that the demonstration that a simple structure composed of a single amino acid can promote polymerization can bring a paradigm shift in the preparation of polymers.

Isomerization dynamics of a novel cis/trans‐only merocyanine

AbstractMerocyanines (MC) usually adopt ring opened zwitterionic structures that are interconvertible with their ring‐closed spiropyran photoisomers. By methylating the phenolate oxygen, and thereby blocking the ring‐closure reaction, a cis/trans‐only MC photoswitch was obtained, yielding a perfect candidate for a detailed examination of the cis/trans isomerization mechanism for this class of compounds. This photoswitch displays outstanding properties including excellent photoreaction quantum yields and photoswitching turnovers. Due to the central polymethine bridge of MC, in principle eight cis (C)/trans/(T) isomers are possible. Density Functional Theory (DFT) calculations revealed the CCT and TTT‐isomers of the studied compound as most stable cis and trans ground state isomers, respectively. UV/vis transient absorption studies combined with conical intersection computations with the complete active space self‐consistent field (CASSCF) method show that both trans/cis‐ and cis/trans‐photoisomerizations are initiated by a rotation of the central doubled bond fragment. A hot ground state species is then formed, which undergoes a second isomerization. Thus, the cis/trans reaction proceeds via a CCT‐CTT‐TTT sequence and the reverse reaction via TTT‐TCT‐CCT.

Synergistic resonant molecular passivator of various defects for high-performance perovskite solar cells

The defects and mismatched energy-level at interfaces of perovskite solar cells (PSCs) can weaken their performance and stability. In this paper, we introduce 3,8-dibromo-1,10-phenanthroline-5,6-dione (BPO) into PSCs to align perovskite energy levels and passivate defects. The theoretical and experimental results indicate that BPO molecules with zwitterionic resonance structure can accept electrons and change the charge state of perovskite surface to modify the energy-level. In addition, the multi-group passivation of BPO molecules, which contain “bipyridyl nitrogen” and bicarbonyl groups, can chelate the Pb defects such as Pb–I antisite (PbI) and iodine vacancy (VI). Notably, the BPO-doped PSCs achieve a power conversion efficiency of 23.18 % with enhanced efficiency retention ratio of 85 % (55 % for control sample) after 1000 h test at 65 % relative humidity. This study provides an effective choice for the exploration of novel additives for device performance improvement.

Effect of Zwitterionic Additives on Solvation and Transport of Sodium and Potassium Cations in (Ethylene Oxide)10: A Molecular Dynamics Simulation Study.

Sodium- (Na+) and potassium- (K+) ion batteries are cost-effective alternatives to lithium-ion (Li+) batteries due to the abundant sodium and potassium resources. Solid polymer electrolytes (SPEs) are essential for safer and more efficient Na+ and K+ batteries because they often exhibit low ionic conductivity at room temperature. While zwitterionic (ZW) materials enhance Li+ battery conductivity, their potential for Na+ and K+ transport in batteries remains unexplored. In this study, we investigated the effect of three ZW molecules (ChoPO4, i.e., 2-methacryloyloxyethyl phosphorylcholine, ImSO3, i.e., sulfobetaine ethylimidazole, and ImCO2, i.e., carboxybetaine ethylimidazole) on the dissociation of Na+ and K+ coordination with ethylene oxide (EO) chains in EO-based electrolytes through molecular dynamics simulations. Our results showed that ChoPO4 possessed the highest cation-EO10 dissociation ability, while ImSO3 exhibited the lowest. Such dissociation ability correlated with the cation-ZW molecule coordination strength: ChoPO4 and ImSO3 showed the strongest and the weakest coordination with cations. However, the cation-ZW molecule coordination could slow the cationic diffusion. The competition of these effects resulted in accelerating or decelerating cationic diffusion. Our simulated results showed that ImCO2 enhanced Na+ diffusion by 20%, while ChoPO4 and ImSO3 led to a 10% reduction. For K+, ChoPO4 reduced its diffusion by 40%, while ImCO2 and ImSO3 caused a similar decrease of 15%. These findings suggest that the ZW structure and the cationic size play an important role in the ionic dissociation effect of ZW materials.

Computational study of the dimerization of glyphosate: mechanism and effect of solvent.

A computational study on the structure and stability of different series of glyphosate (Glyph) dimers comprising nonionized (N) and zwitterionic structures (Z) for neutral monomers, followed by an analysis of energetics of Glyph dimerization process have been performed by means of quantum chemical calculations in different media. Optimized geometries for energy minima, as well as relative potential and free energies of the possible various conformers of each series of Glyph dimer were computed as a function of the medium at B3LYP-D3/6-311++G(2d,2p) level. The solvation model based on density (SMD) is employed for all solution phase computations. Non-ionized dimers (DN), anion-cation (AC) and either zwitterion-zwitterion (DZP and DZC) or non-ionized-phosphonate zwitterion (NZP) ionized neutral forms of Glyph dimer are predicted to exist in the gas phase and in solution in large contrast to Glyph monomers. The DZC dimer form exhibiting a centrosymmetric arrangement of two carboxylate zwitterion units was found to be the most stable dimer structure in all media. In aqueous solution, the DZP and AC dimer type structures are significantly stabilized by hydration. The tautomerisms between DZC, DZP and AC dimer type structures have been investigated in the gas phase and in solution. The DZC type structures are more prone to experience proton transfer in water than in the gas phase and in cyclohexane. The mechanism for the tautomerization process in neutral ionized Glyph dimers proceeds via two direct proton transfer paths: DZP ⇋ AC ⇋ DZC. Results show that solvents play a key role in modulating the energetics of the dimerization process of Glyph. Solvation in cyclohexane, favors the dimerization process however, hydration opposed it. In aqueous solution, the mechanism of the dimerization of Glyph from its phosphonate zwitterionic monomer form (ZP) could be described by a set of equilibria including direct proton transfer paths as follows: 2ZP ⇋ DZP ⇋ AC ⇋ DZC. According to our results, in aqueous solution, DZC Glyph dimers and their corresponding DZP and AC tautomers should be present in higher concentration than phosphonate zwitterionic Glyph monomers for high Glyph concentration, a fact that seems controversial in the literature.

Inhalable mucin-permeable nanomicelles deliver antibiotics for effective treatment of chronic pneumonia.

Pseudomonas aeruginosa (P. aeruginosa) pneumonia can have serious physiological consequences, particularly when P. aeruginosa biofilms are formed. Although inhaled therapy is preferred, inhaled drugs tend to get trapped by pulmonary mucus, which hinders efficient antibiotic permeability through mucus and biofilms. In this study, we prepare poly[2-(pentamethyleneimino)ethyl methacrylate]-block-poly[2-(N-oxide-pentamethyleneimino)ethyl methacrylate] (PPEMA-b-PPOEMA) micelles loaded with azithromycin (AZM) using reversible addition-fragmentation chain transfer (RAFT) polymerization to achieve effective treatment of P. aeruginosa pneumonia. The zwitterionic structure on the surface of the micelle facilitates the successful traversal of the mucus and optimal concentration within the biofilm. Furthermore, the protonation of piperidine in the polymer enables the micelles to exhibit a positive charge in the acidic environment of a bacterial infection, enhancing AZM's interaction with the bacterium. Both in vivo and in vitro experiments demonstrate that this transmucosal zwitterionic polymer, in combination with a charge reversal strategy, effectively promotes the enrichment of micelles at the site of bacterial infection, thereby increasing the number of antibiotics reaching the bacterial interior and demonstrating remarkable antibacterial synergy. Overall, this work offers a promising approach for trans-airway drug delivery in the treatment of pneumonia.

The influence of conversion creatine and guanidinoacetic acid from zwitterionic to cationic form on their solubility in water - a thermodynamic study

In this work, the solubility of creatine, creatinine, guanidinoacetic acid and their hydrochlorides in water at atmospheric pressure and in the temperature range T 293.15?313.15 K was determined by the gravimetric method. The thermodynamic parameters of dissolution in water for the mentioned compounds were calculated. The solubility increases significantly by converting the zwitterionic structures of creatine and guanidinoacetic acid into a cationic form, i.e., hydrochloride salt. The effect of increasing solubility is more pronounced for guanidinoacetic acid and decreases with temperature for both compounds. A simple process of transforming the electrically neutral zwitterionic structures into cations represents a good way to increase the solubility in water and bioavailability of biologically active compounds.

Electrochemical Approach for Studying Local Dynamic Heterogeneity of Ionic Liquids Applied to Neoteric Boroniums

Ionic liquids (ILs) are liquid salts (below ca. 100 °C) whose ions can be designed to impart unique physicochemical properties. An emergent class of ILs based on the boronium cation (BILs) can have unique zwitterionic structure within the cation that presents potential for electrochemical applications. In the present study we first show how broadband dielectric spectroscopy (BDS) can be used to evaluate local dynamic heterogeneity in imidazolium-based ionic liquid systems. We then apply this approach to a series of BILs (coupled with the bis(trifluoro-methanesulfonyl)imide ([Tf2N]–) anion), whose cationic structures show similar features, suggesting may have potential to promote more favorable ion transport for application in supercapacitors. Preliminary cyclic voltammetry and electrochemical impedance spectroscopy data will also be shown that evaluates the chemical stability of each BILs when combined with common electrode materials.

Synthesis and Characterization of Neoteric Boronium Ionic Liquids

Ionic liquids (ILs) are highly tailorable materials with unique physical and chemical properties that set them apart from conventional organic solvents. As the library of readily accessible ILs continues to grow, so too does their relevance in applications ranging from material processing to electrochemical energy storage as solvents capable of accessing new chemistries disallowed by traditional chemicals. While a great deal of interest has been directed towards imidazolium and quaternary ammonium based ionic liquids, there are other understudied classes of cations which have potentially favorable properties for energy related applications. One such class is that with boronium cations. These cations have a unique structure with a formally negative boron flanked by positive nitrogens. This inherently zwitterionic structure presents interesting possibilities for electrochemical applications. To date only a handful of boronium cation-based ionic liquids have been thoroughly characterized despite exhibiting impressive electrochemical stabilities (> 5.0 V). In the present study we synthesized a series of ILs with novel boronium cations coupled with the bis(trifluoro-methanesulfonyl)imide anion. We then characterized the electrochemical and physical properties of these boronium ionic liquids by techniques such as cyclic voltammetry, broadband dielectric spectroscopy, oscillatory shear rheology, and thermogravimetric analysis. We will discuss how systematic variations in boronium cation structure impacted electrochemical and physical properties.

New α-keto acid-derived hydrazone ligands and their reaction with the {Re(CO)3}+

Two hydrazone ligands derived of phenylglyoxylic acid (HL1) and 4-hydroxyphenylpyruvic acid (HL2) were synthesized and their zwitterionic structures were determined by X-ray diffraction. The rhenium(I) complexes of formula [ReCl(HLn)(CO)3] were obtained by reaction of the ligands with [ReCl(CH3CN)2(CO)3]. The formation of the hydazonate complexes were also achieved. In the case of HL1 the trimetic complex [Re3(L1)3(CO)9] was isolated by using a basic medium. On the other hand, from storage of a solution of the [ReCl(HL2)(CO)3] complex, crystals of the [Re2(L2)2(CO)6] dimer could be obtained for their structural analysis by X-ray diffraction. The study of the crystalline structures is included. The coordination geometry around rhenium(I) can be described as octahedral with three carbon atoms in fac configuration. In all complexes a five-membered chelate ring is formed including two nitrogen atoms from the hydrazone chain and the pyridine group. In the mononuclear complexes the carboxylic group does not participates in the coordination but acts as a bridge to form the polynuclear compounds. The coordination mode of the ligands in all the complexes could be corroborated by comparative studies of the experimental and calculated (DFT) IR spectra.

Pharmaceutical adsorption on NaOH-treated rice husk-based activated carbons: Kinetics, thermodynamics, and mechanisms

This study aims to explore the adsorption behavior of four pharmaceuticals: ciprofloxacin (CIP), sulfamethoxazole (SUL), diclofenac (DIC), and acetaminophen (ACE) on activated carbons produced from rice husk using different NaOH-based protocols at 800 °C. The main objective is to assess and compare the efficiency of activated carbons synthesized by solid-solid and wet treatment methods on pharmaceutical adsorption. All three activated carbons displayed strong affinity towards pharmaceutical adsorption, but the material produced with wet protocol after the carbonization process demonstrated the highest adsorption capacity and the lowest equilibrium time (15 min) due to its superior textural properties and higher surface area (1671 ± 31 m2 g−1). Further investigation of pharmaceutical adsorption in synthetic urine was carried out using the mentioned material. The results revealed that in both mono and multicomponent systems, CIP, SUL, and DIC did not exhibit any significant competition with each other or with the urine matrix. However, ACE showed competition for adsorption sites. For both CIP and ACE, the diffusion boundary layer and the adsorption process were identified as the velocity-limiting steps for adsorption in urine. To better understand the adsorption mechanism, both experimental and computational tools were employed. The results revealed that ACE exhibited typical Langmuir-like adsorption behavior with an exothermic nature on the mentioned material with an adsorption capacity of 209.6 ± 5.6 mg g−1. Regarding CIP, its adsorption displayed a non-typical endothermic nature, which was attributed to steric hindrance due to its zwitterionic structure and the porosity in the adsorbent. Analyzing the combination of Redlich-Peterson and Langmuir models with computational analysis supported this finding. However, the material exhibited an impressive adsorption capability of 584.4 ± 21.5 mg g−1. The parameter φ (cncreased cost associated with enhancing the adsorption process) revealed an augmentation in adsorption capacities of 45.1 and 125.6 mg USD−1 for ACE and CIP, respectively, compared to the raw rice husk. This research underscores the prospect of employing agricultural and industrial byproducts to create activated carbons capable of efficiently extracting pharmaceuticals from intricate mixtures, such as urine.

Influence of Dipole Orientation of Zwitterionic Materials on Hemodialysis Membrane Interactions with Human Serum Proteins

Hemodialysis is a lifesaving treatment for end-stage renal disease (ESRD) that exploits semipermeable membranes to remove fluids and uremic toxins from ESRD patients. Polyethersulfone (PES) is the most common membrane that is currently used in Canadian hospitals and represents 93% of the market. Nevertheless, PES membranes have limited hemocompatibility, which triggers blood activation cascades, as the rate of morbidity and mortality in ESRD patients is still unacceptably high. Surface modification with zwitterionic (ZW) materials, which are well known for their strong dipole–dipole interactions and exceptional antifouling properties, has recently received increased attention in improving PES characteristics like roughness, wettability, and biocompatibility, which are crucial factors in dialysis efficiency. The hydration structures, dynamics, and interactions of ZWs are significantly dependent on the backbone structures, such as differences in carbon space length [CSL], conformation, functional groups, pendant groups, and charge distributions, and even minor changes in ZW structure can drastically alter their behavior. However, a systematic investigation of the impact of dipole orientation of ZW on the hemocompatibility of the membranes has not yet been investigated. This study offers a comprehensive exploration of the interactions between hemodialysis membranes and human serum proteins, emphasizing the pivotal role of the zwitterion dipole orientation. We utilize molecular docking techniques to predict protein–ligand interactions, offering insights into the binding sites and binding energy of these complexes. The effect of dipole orientation on the hemocompatibility of various ZW-modified PES membranes compared to the pristine PES has been investigated using 2-methacryloyloxyethyl phosphorylcholine (MPC), 2-((2-(methacryloyloxy)ethyl)dimethylammonio)ethyl methyl phosphate (MMP), and butyl (2-((2-(methacryloyloxy)ethyl)dimethylammonio)ethyl) phosphate (MBP) zwitterions with opposite dipole orientations. Results showed that the protein–ligand interactions and affinity energies displayed by the reverse dipole moment structures are remarkably different. It was demonstrated that the MBP–PES ligand had the lowest affinity energy to interact with all examined human serum proteins compared to the structure, which had an opposite dipole moment. As a result, this membrane surface has better antifouling properties and, thus, higher hemocompatibility, which directly correlates with greater efficiency of hemodialysis in patients.