Quaternary Ammonium Research Articles

Removal of Diesel from Aqueous Solutions by a Combined Adsorption and Microbial Degradation Process

Diesel contamination in water bodies poses a significant environmental challenge due to the toxic effects of its water-soluble fraction (WSF) on aquatic ecosystems and human health. The aim of this work was the design of a new technological procedure for the purification of water contaminated with the WSF of diesel. The procedure is based on the adsorption of organic pollution on an organozeolite, after which the biodegradation of the adsorbed pollutant takes place. The material for obtaining organozeolite was a natural zeolite from the Zlatokop deposit (Vranje, Serbia). The zeolitic surface was modified with hexadecyltrimethylammonium bromide (HDTMA-Br), a cationic quaternary ammonium salt. The adsorption experiments, with initial WSF concentrations of 2.5–25 mg/L, at pH 6 and at 20 C, were performed in a batch system using organozeolite, and the results showed that more than 90% of the WSF of diesel was removed, reaching equilibrium after 1 h. The maximum adsorbed capacity of organozeolite for the removal of the WSF of diesel fuel from water under the tested conditions was 22.2 mg/g. Equilibrium data were well fitted by a linear isotherm model, while a pseudo-second-order equation well fitted the kinetic data. After adsorption, a 15-day biodegradation experiment was carried out under batch conditions. The results showed that the examined consortium of microorganisms degraded 80% of the adsorbed contaminant. Additional respirometric analyses showed that, in parallel with the degradation of the contaminant, the degradation of the long-chain HDTMA ions at the surface of the organozeolite also occurred. To the best of our knowledge, this is the first study combining adsorption and biodegradation to remove the WSF of diesel from water.

The effect of a magnetic field on the generation of free radicals in the interaction of quaternary ammonium compounds with hydroperoxides

The magnetic effects (ME) of a moderate magnetic field (MF, 600 mT) on the rate of radical generation (Wi) in mixed micellar systems of quaternary ammonium compounds with hydroperoxides (QAC-ROOH), measured by the inhibitor method, and the effect of magnetic field on the rate of radical polymerization initiated by radicals, generated from the surface by QAC chemisorbed on a solid carrier upon interaction with hydroperoxide dissolved in the monomer are compared. It has been established that in micellar solutions MF reduces Wi, ME ≈ –0.45. In the case of radical polymerization of styrene containing cumyl hydroperoxide on the surface of mica plates with a chemisorbed monolayer of QAC (CTAB or ACh), the polymerization rate increases in MF.

Pathologic Tissue Injury and Inflammation in Mice Immunized with Plasmid DNA-Encapsulated DOTAP-Based Lipid Nanoparticles.

Ionizable cationic lipids have been developed to mitigate the toxicity of quaternary ammonium lipids, such as DOTAP. Despite its toxicity, DOTAP can promote localization of lipid nanoparticles (LNPs) in target tissues, serving as one of the ionizable cationic helper lipids. Notably, DOTAP-based nanoadjuvants prepared via microfluidic methods showed a better T-cell response. Previous studies showed that DOTAP-based LNPs prepared by the lipid-film method resulted in obvious adverse events. Therefore, our research focused on evaluating the tissue localization and adverse toxicity of a DOTAP-based delivery system prepared through microfluidic techniques. We assessed the delivery efficacy, biodistribution, inflammatory response, and pathological injury in various tissues. In our study, the plasmid DNA encoding the receptor-binding domain (RBD) of SARS-CoV-2 was encapsulated using a mixture of lipids that included DOTAP, DOPE, cholesterol, and DMG-PEG2000 via microfluidic mixing. The LNP-RBDs were smaller than those prepared via the traditional lipid membrane system. We found that LNP-DNA complexes can be effectively delivered and expressed in muscle tissue, with specific antibodies in serum induced postimmunization. Initial distribution of the liposomes was observed in the muscle and liver. Interestingly, both LNPs and DNA showed sustained presence in the lungs and spleen in the group immunized with DNA-encapsulated DOTAP-based LNPs, whereas lower amounts of DNA were detected in the group immunized with dissociative DNA. We detected obvious inflammatory responses and pathological injuries in the muscle, heart, and liver, and the side effects decreased when the immunization dose decreased. These findings suggest that DOTAP-based LNPs have obvious advantages for targeting the lungs and spleen. Additionally, inflammatory responses and pathological injuries occur in a dose-dependent manner in the muscles, heart, and liver. In conclusion, these findings contribute to the development of an LNP delivery system with DOTAP, highlighting its potential to enhance tissue localization and promote high levels of expression when coordinated with ionizable lipids.

Impact of the COVID-19 Pandemic on the Use of Quaternary Ammonium Compound Disinfectants in Healthcare Facilities Within Selected States in the United States of America

Impact of the COVID-19 Pandemic on the Use of Quaternary Ammonium Compound Disinfectants in Healthcare Facilities Within Selected States in the United States of America

Transition Metal Chalcogenides/Nonconjugated Polymer Artificial Photosystems for Photoredox Catalysis.

Surface charge transfer doping (SCTD) has been established as an efficient strategy to achieve strong electronic coupling interactions between semiconductors and dopants, which lead to highly efficient electron transport over semiconductors. Herein, we report a facile, easily accessible, and effective SCTD strategy to exquisitely modulate the interfacial charge transfer over transition metal chalcogenides (TMCs: CdS, Zn0.5Cd0.5S, CdIn2S4, and ZnIn2S4) through surface modification with a nonconjugated polymer, poly(dimethyldiallylammonium chloride) (PDDA). We provide evidence that PDDA, as a surface electron transfer acceptor, can be used to enable rapid, directional, and tunable charge transfer along with an optimal charge lifetime over TMCs in photoredox catalysis because of the high-efficiency electron-trapping property of quaternary ammonium functional groups in the molecular structure of PDDA. The thus-assembled PDDA-encapsulated TMC composite artificial photosystems demonstrate significantly enhanced and versatile photoredox catalytic activities toward visible-light-responsive photocatalytic reduction of aromatic nitro compounds, photocatalytic oxidation of aromatic alcohols, and photocatalytic H2 production, wherein the ultrathin PDDA layer accelerates the interfacial charge transport and separation rate over TMC substrates. Moreover, it was evidenced that such an interface engineering strategy is general for a collection of TMCs. Our work will provide conceptual insights into nonconjugated polymer-based artificial photosystems for optimizing solar energy utilization.

Antimicrobial Biphasic Polymer Coatings Enabled by Fast Diffusion of Active Compounds.

The recent COVID-19 pandemic and the prospect of future global pandemics highlight the long-standing need to passively eliminate viruses and bacteria on surfaces. Conventional antimicrobial surfaces and coatings are typically constrained by a trade-off between antimicrobial efficacy and physical durability. A biphasic polyurethane coating has been developed that breaks this trade-off by incorporating a durability-imparting polycarbonate (PC) discrete phase with a continuous poly(ethylene glycol) (PEG) transport phase that absorbs, stores, and releases antimicrobial active compounds for extended microbial inactivation. The biphasic polymer was shown to absorb carboxylic acid and quaternary ammonium antimicrobial active compounds, maintained their levels after five years of simulated cleaning, and inactivated up to 99.99% of Human Coronavirus 229E and Influenza A H1N1. Furthermore, the levels of antimicrobial active compounds on the biphasic coating could be augmented by cleaning the substrate with a disinfectant. The practicality of biphasic coatings for automotive and commercial aerospace environments was demonstrated by showing control of hardness and stain resistance through biphasic composition, showing environmental durability through heat, humidity, and light exposure, and passing flammability protocols.

Engineering the Hydrophilic-Hydrophobic Interface of Polymeric Micelles by Cationic Blocks for Enhanced Chemotherapy.

The cationic surface charge critically influences the biological functions and therapeutic outcomes of the cancer nanomedicines. However, the basic correlation between the cationic group categories and their therapeutic efficacy has not been elucidated. In this study, cationic polymeric nanoparticles with amino groups (primary, tertiary, and quaternary amines) as the single variable were leveraged to investigate the various effects of amino species for enhanced antitumor chemotherapy. The nanoparticles were constructed from a series of triblock polymers with varying cationic repeating units at the hydrophilic-hydrophobic interface. Our results suggested that quaternary ammonium outperforms its primary and tertiary counterparts in destroying mitochondrial membranes to induce apoptosis, penetrating deep inside the tumor tissue, and damaging tumor vasculatures. As a result, we were able to effectively inhibit tumor growth in mice by a quaternary ammonium conjugate without causing significant toxicity. Our work demonstrated that the chemical structures played vital roles in regulating their biological functions and provided valuable information for designing cationic drug delivery systems.

Additives Capable of Stably Supplying Anions/Cations for Homogeneous Lithium Deposition/Stripping.

One of the important factors leading to lithium dendrites is a slow lithium-ion mass transport and imbalanced distribution of the Li+ concentration and nuclei sites on the anode surface. To achieve uniform lithium deposition during the charge and discharge process, we introduce a homemade new copolymer (with the quaternary ammonium group N3R+I- on its side chain as the main functional group), named P35, as a functional electrolyte additive to regulate the lithium deposition. Theoretical calculations show that under the strong coordinating interaction between I- and N3R+, P35 preferentially adsorbs onto the lithium foil surface, effectively countering the adsorption of lithium salt anions such as PF6-. Moreover, the positive charge carried by the quaternary ammonium salt group of P35 could interact with PF6- to limit their mobility. Consequently, the dipole interaction on lithium ions is diminished, leading to an enhancement in the transport rate and a decrease in the concentration gradient of lithium ions. Furthermore, a more efficient SEI was formed due to the dual charges electrostatic shield formed by N3R+I-. Li-Li symmetric cells and Li-LiFePO4 full cells assembled with electrolytes with P35 exhibit better rate performance, smaller polarization, and smoother deposition morphology in comparison to the cells without the P35 additive.

Toward the Electrostatic Catalysis of Nucleophilic Substitutions: A Surface Chemistry Study of the Menshutkin Reaction.

The catalysis of nonredox reactions by external electric fields is one of the most rapidly expanding areas of chemistry. The Menshutkin reaction, a classic example of bimolecular nucleophilic substitution (SN2), involves the conversion of a tertiary amine to a quaternary ammonium salt by coupling it with an alkyl halide. The reaction barrier of the Menshutkin reaction is theoretically predicted to be highly sensitive to the magnitude and direction of an external electric field experienced by the transition state. In this study, we investigate how near-surface electric fields can drive this prototypical nucleophilic substitution by examining the coupling of a diffusive redox-tagged tertiary amine with an electrode-tethered alkyl bromide under a variable external bias. Our findings reveal a competition between electrostatically assisted reactions, solvent effects, and electrochemically triggered side reactions involving radical intermediates. We estimate that only about 5% of the coupling events are attributable to the external field, while the majority of the reaction products originate from electrochemically generated radical intermediates.

Nature-inspired Novel Quaternary Ammonium Compounds: Synthesis, Antibacterial and Antibiofilm Activity.

Inspired by marine compounds isolated from sponges and the increased need for new effective antimicrobials, novel quaternary ammonium compounds with long alkyl chains (C8-C12) were designed and synthesized. Antibacterial and antibiofilm activity of new compounds was evaluated against six microbial strains (S. aureus, E. coli, and P. aeruginosa). All synthesized ammonium salts displayed antibacterial activity with MIC values ranging from 5.0 to 25.0 μg/mL. In addition, most compounds showed strong inhibition of biofilm formation of S. aureus ATCC 25923, P. aeruginosa PA01, and colistin-resistant P. aeruginosa (CRPA) at a concentration of 5.0 μg/mL. Ammonium salt 3 showed 100 % inhibitory activity against all tested bacterial biofilms except that of colistin-resistant S. aureus (CRSA).

Antibacterial carboxymethyl chitosan hydrogel loaded with antioxidant cascade enzymatic system for immunoregulating the diabetic wound microenvironment

Diabetic wound healing faces several complex challenges, such as hypoxia, oxidative stress, and bacterial infections, which severely inhibit the wound-healing process. Herein, a quaternary ammonium salt-crosslinked carboxymethyl chitosan hydrogel (TPC) with excellent antioxidant and antibacterial properties was developed to immunoregulate the diabetic wound microenvironment. The TPC hydrogel was prepared by first mixing carboxymethyl chitosan (CMCS) and protocatechualdehyde (PA), followed by the addition of a quaternary ammonium cross-linker (TSPBA) and a superoxide dismutase (SOD)–catalase (CAT) cascade system. The immobilized SOD and CAT retained their activity, continuously converting endogenous ·O2− and H2O2 to O2 and H2O. PA also provided the TPC hydrogel excellent oxygen and nitrogen radical scavenging capacity. The quaternary ammonium groups in TSPBA significantly enhanced the inherent antibacterial ability of CMCS-based hydrogels. In diabetic wound-healing experiments, this porous and adhesive TPC hydrogel effectively closed wounds and regenerated skin tissue, resulting in shorter wound edges, thicker granulation, and higher collagen deposition levels compared with other groups. The TPC hydrogel also promoted macrophage polarization toward the M2 phenotype, accelerating wound healing by upregulating IL-10 expression, downregulating IL-6 expression, and enhancing angiogenesis. These results demonstrate the great potential of TPC hydrogel as a promising therapeutic dressing for treating diabetic wounds.

Balancing hydrophobicity and surface potential in bio-based bisfuran-containing polyamide coatings for enhanced long-term antibacterial efficacy and endotoxin adsorption

To develop antimicrobial protective materials based on renewable polymers, we synthesized a series of bio-based bisfuran-based polyamide (bFPA) polymers with various functional groups, including allyl quaternary ammonium cations, decyl quaternary ammonium cations, and sulfonate betaine. These bFPA-based coating materials, featuring excellent thermal stability (>230 °C) and biocompatibility, were facilely fabricated on polyurethane (PU) substrates by blending and crosslinking with unsaturated aliphatic PU resin. By altering the combination of different functional groups in bFPA polymers, we controlled the hydrophilicity/hydrophobicity and surface charge properties of the bio-based coating. Compared to pure PU coatings, the bFPA-based coatings with moderate hydrophilicity/hydrophobicity and surface potential significantly reduced the adhesion of model protein and bacteria by approximately 70 % and >99 %, respectively, demonstrating outstanding anti-protein and anti-bacterial adhesion properties. Even after seven cycles of use, the coatings maintained the ability to kill ∼80 % and >99 % of Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria, respectively, indicating long-lasting antibacterial activity. Additionally, the optimized bFPA-based coatings effectively adsorbed ∼80 % of endotoxins from damaged Gram-negative bacteria through electrostatic interactions, thereby reducing the risk of inflammation and sepsis. The development of bio-based polyamide coatings with long-term antibacterial and endotoxin adsorption properties significantly advances their safe and reliable application of in the field of biomedical devices.

Synthesis of multifunctional di-cationic ionic liquids: Unveiling antibacterial activity across diverse strains

The increasing prevalence of antibiotic resistance poses a significant global risk to public health. Therefore, there is an urgent necessity to discover innovative antibacterial materials. In this study, we introduced a novel synthesis method that yielded 18 unique di-cationic ionic liquids (DILs), intricately crafted through a fusion of quaternization and metathesis reactions. These innovative compounds boasted imidazolium, pyridinium, and quaternary ammonium as their cationic constituents, accompanied by acetate and bisulfate ions as their anionic counterparts. The incorporation of spacer chains, specifically trans-1,4-dibromo-2-butene and α, α′-dibromo-p-xylene, facilitated the synthesis of these di-cations. Thorough characterization of the synthesized DILs was conducted using advanced spectroscopic techniques, including FTIR and nuclear magnetic resonance, ensuring a comprehensive understanding of their structural attributes. The central objective of this research was to assess the effectiveness of these DILs in combating a diverse spectrum of resilient bacterial strains commonly encountered in various environmental settings. This evaluation encompassed both gram-positive and gram-negative species.

Poly(isatin biphenylene) anion exchange membranes based on functionalization of long side chain N-spirocyclic

N-spirocyclic cations have high alkali resistance stability, but their poor mobility hinders the aggregation of cationic groups, which makes it difficult to form a good microphase-separated structure for OH− ion transport. In this work, two kinds of bicationic N-spirocyclic cations containing spacer side chains (BM-DSU and BM-DSD) were designed and synthesized, and a series of poly(isatin biphenylene) anion exchange membranes containing bicationic N-spirocyclic side chains were prepared by grafting different ratios of N-spirocyclic cations onto the poly(isatin biphenylene) polymer backbone. The bicationic N-spirocyclic quaternary ammonium salts containing spacer side chains increased the migration rate of the cationic groups and constructed a more continuous ion transport channel. The OH− ionic conductivities of BM-DSD-PIB-40 and BM-DSU-PIB-40 were 67.8 mS cm−1 and 63.4 mS cm−1 at 80 °C. After soaking at 80 °C in 1 M NaOH for 730 h, the residual conductivities of BM-DSD-PIB-30 and BM-DSU-PIB-30 were 73.19 % and 78.02 %, respectively.

Efficient one-pot tandem C-C formation reaction catalyzed by a multi-functionalized polyacrylonitrile fiber catalyst

A simple and straightforward method has been proposed in this work to construct a multi-functionalized polyacrylonitrile fiber catalyst containing carboxylic acid, tertiary amine, and quaternary ammonium salt to enable series one-pot C-C bond formation in water. The fiber catalyst was prepared from polyacrylonitrile fiber using a two-step method and characterized using various detection techniques. Furthermore, the activity of multi-functional synergistic catalysts can be controlled by adjusting the ratio of acid and base. It is noteworthy that the polyacrylonitrile fiber catalyst with an acid-base ratio of 3:1 (PANF-ABNCl3/1) exhibited superior catalytic activity and high yield in a variety of C-C generation reactions. Additionally, the PANF-ABNCl3/1 catalyst demonstrated exceptional recyclability (at least 10 times) and performed well in scale-up (7.4g, 96%) and continuous flow experiments (can be used continuously for 7 × 24h) using kettle and tubular fixed bed reactor respectively. These findings suggest that the PANF-ABNCl3/1 catalyst holds promise for industrialization.

Encapsulation of Antarctic krill peptide by polysaccharide-based nanoparticles: Preparation, characterization, evaluation of stability and hypoglycemic activity

The aim of this study was to construct a chitosan quaternary ammonium salt (HTCC)/sodium alginate (SA) nanoparticle delivery system for the encapsulation of Antarctic krill peptide (AKP), with the goal of enhancing its stability and post-digestive hypoglycemic activity. Additionally, the effect of the content and encapsulation sequence of HTCC/SA on the structure and properties of AKP-loaded nanoparticles (AKP-loaded NPs) was investigated. As the content of the outermost wall material (HTCC) increased, the particle size of nanoparticles initially increased and then decreased. Concurrently, the zeta potential showed a trend of increase, ranging from -38.77 to 46.07 mV. When SA was used as the outermost wall material, the nanoparticles exhibited a smaller particle size (240.1 nm) and better dispersibility. Electrostatic interaction and hydrogen bonding were the major forces involved in the formation of AKP-loaded NPs. X-ray diffraction revealed that AKP was successfully encapsulated in an amorphous state. Scanning electron microscopy showed that AKP-loaded NPs had an elliptical or blocky appearance. Moreover, AKP-loaded NPs demonstrated good storage and temperature stability, while nanoparticles with HTCC in the outermost layer (HTCC:SA=2:1) showed good pH and ionic stability. During simulated digestion, AKP-loaded NPs inhibited the release of AKP in gastric fluid. Consequently, the hypoglycemic activity of digested AKP-loaded NPs was remarkably higher than unencapsulated AKP. Notably, the nanoparticles with HTCC in the outermost layer provided superior hypoglycemic activity. In summary, the polysaccharide-based delivery system exhibited great potential to improve the stability and post-digestive hypoglycemic activity of AKP, broadening its applications in the food and pharmaceutical industries.

Antibacterial activity of polyethylene film by hyperthermal hydrogen induced cross-linking with chitosan quaternary ammonium salt

In this study, hyperthermal hydrogen-induced cross-linking (HHIC) technology was applied to construct a dense cross-linking layer of antibacterial chitosan quaternary ammonium salt (HTCC) to PE surface through the selective cleavage of CH bonds and subsequent cross-linking of the resulting carbon radicals. Before HHIC treatment, UV-Ozone was used to activate PE surface to facilitate HTCC adsorption. FT-IR and XPS analyses proved the successful cross-linking between PE and HTCC. From AFM analysis, the prepared PE cross-linked HTCC film (PE-c-HTCC) showed the rougher surface with average roughness (Ra) of 9.16 nm. The water vapor permeability (WVP) and oxygen permeability (OP) values of the film were decreased by about 83 % and 97 %, respectively. Additionally, the film exhibited strong antibacterial properties against E. coli and S. aureus. In terms of these properties, the shelf life of fresh beef could be extended for 2 days after packing with the PE-c-HTCC film.

Monomer in situ polymerization as topological sutures to achieve strong interfacial adhesion and long-term anti-mold of renewable adhesive

Integrated long-term anti-mold and high bonding capacity properties into renewable biomass adhesives hold significant importance for promoting the green and sustainable development of the wood industry, yet it remains an immense challenge. Drawing inspiration from the design of molecular suture materials, we successfully developed a series of innovative quaternary ammonium salt monomers (APM12) that polymerize in situ with glycidyl methacrylate (GMA) at the interface of bonded adherents. This process constructed molecular sutures on the molecular scale, forming a robust topological entanglement network between the adhesive and the wood substrate. Such a rational structure design allowed the modified soybean meal (SM) adhesive to present a boosted bonding strength and water resistance (2.08 and 1.05MPa). The stably riveting high-effect anti-germ platform imparted the protein adhesive with ultra-long mildew resistance of 150 days for liquid SM@GMA-APM12 adhesives, outperforming all the previously reported protein-based bio-adhesives. The implementation of the suture strategy through an in situ sutural interspersed crosslinking network provided a straightforward approach and offered a novel solution for creating renewable adhesives with multiple desirable properties. Moreover, this suture strategy can be applied to other interface strong adhesion and anti-bacterial materials comprised of polymer structure, such as hydrogel, organic coatings, and membrane, broadening its scope of applications.

Adsorption characteristics and mechanism of novel ink melanin composite modified chitosan for Cd(II) in water

In this study, chitosan (CS), carboxymethyl chitosan (CMCS), and chitosan quaternary ammonium salt (HACC) were successfully loaded with ink melanin (ME) as efficient adsorbents for Cd(II) removal. The results of batch adsorption experiments and structural characterization showed that the modified CS loaded with ME improved the adsorption capacity of the composites for Cd(II). The pseudo-second-order kinetic and Langmuir equations were better suited to describe the batch adsorption experiments. The adsorption of Cd(II) was chemisorption with desirable adsorption effect when the concentration of the three composites was 0.5 mg/mL and the pH value was neutral. Among them, HACC-ME demonstrated remarkable Cd(II) adsorption performance (107.18 mg/g) and sustained an 85 % efficiency in Cd(II) removal over five adsorption-desorption cycles. Ion exchange, complexation, electrostatic attraction, and hydrophobic interaction were the primary mechanisms for Cd(II) removal. Overall, HACC-ME could be employed as a low-cost and highly efficient new natural adsorbent material for the removal of Cd(II) ions from wastewater. These findings illuminate pathways for the development of efficient and novel natural adsorbent materials for environmental cleanup purposes.

Self-healing hydrogels loaded with Spatholobi Caulis alleviate disc degeneration by promoting autophagy in nucelus pulposus

Intervertebral disc degeneration (IDD) is a common degenerative disease of the spine that has a significant impact on both society and human health. Many studies have confirmed that there is a close relationship between IDD and senescence and apoptosis, and autophagy can combat apoptosis and senescence. Spatholobi caulis (SC) is an herb that contains various active compounds that are effective in tissue repair and regeneration, but it has not been explored in field of IDD. In this study, it was first found that SC can boost autophagy and reduce the apoptosis and senescence of Nucleus pulposus cell (NPCs). However, our animal studies revealed limited absorption of SC. To improve the bioavailability and efficacy of SC, we developed a hydrogel incorporating quaternary ammonium chitosan (QCS) and oxidized starch (OST) as carriers for SC. The QCS-OST/SC hydrogel exhibits excellent compatibility with cells, can be easily injected, and can release SC durably. At the cellular level, the QCS-OST/SC hydrogel enhances cell viability, initiates autophagy and release of the extracellular matrix (ECM), and inhibits cellular senescence and apoptosis. The injection of the QCS-OST/SC hydrogel via microneedles (MNs) into discs had successfully diminished disc degeneration in rats, which shows that this hydrogel has broad potential in the treatment of IDD.