Hyperbranched Polymer Induced Antibacterial Tree-Like Nanofibrous Membrane for High Effective Air Filtration

The air filtration materials with high efficiency, low resistance, and extra antibacterial property are crucial for personal health protection. Herein, a tree-like polyvinylidene fluoride (PVDF) nanofibrous membrane with hierarchical structure (trunk fiber of 447 nm, branched fiber of 24.7 nm) and high filtration capacity is demonstrated. Specifically, 2-hydroxypropyl trimethyl ammonium chloride terminated hyperbranched polymer (HBP-HTC) with near-spherical three-dimensional molecular structure and adjustable terminal positive groups is synthesized as an additive for PVDF electrospinning to enhance the jet splitting and promote the formation of branched ultrafine nanofibers, achieving a coverage rate of branched nanofibers over 90% that is superior than small molecular quaternary ammonium salts. The branched nanofibers network enhances mechanical properties and filtration efficiency (99.995% for 0.26 µm sodium chloride particles) of the PVDF/HBP-HTC membrane, which demonstrates reduced pressure drop (122.4 Pa) and a quality factor up to 0.083 Pa-1 on a 40 µm-thick sample. More importantly, the numerous quaternary ammonium salt groups of HBP-HTC deliver excellent antibacterial properties to the PVDF membranes. Bacterial inhibitive rate of 99.9% against both S. aureus and E. coli is demonstrated in a membrane with 3.0 wt% HBP-HTC. This work provides a new strategy for development of high-efficiency and antibacterial protection products.

Advances in the Synthesis of Biologically Active Quaternary Ammonium Compounds

This review provides a comprehensive overview of recent advancements in the design and synthesis of biologically active quaternary ammonium compounds (QACs). The covered scope extends beyond commonly reviewed antimicrobial derivatives to include synthetic agents with antifungal, anticancer, and antiviral properties. Additionally, this review highlights examples of quaternary ammonium compounds exhibiting activity against protozoa and herbicidal effects, as well as analgesic and anesthetic derivatives. The article also embraces the quaternary-ammonium-containing cholinesterase inhibitors and muscle relaxants. QACs, marked by their inherent permanent charge, also find widespread usage across diverse domains such as fabric softeners, hair conditioners, detergents, and disinfectants. The effectiveness of QACs hinges greatly on finding the right equilibrium between hydrophilicity and lipophilicity. The ideal length of the alkyl chain varies according to the unique structure of each QAC and its biological settings. It is expected that this review will provide comprehensive data for medicinal and industrial chemists to design and develop novel QAC-based products.

Polyelectrolyte-Surfactant Complex Nanofibrous Membranes for Antibacterial Applications

Polyelectrolyte-surfactant complexes (PESCs) have garnered significant attention due to their extensive range of biological and industrial applications. Most present applications are predominantly used in liquid or emulsion states, which limits their efficacy in solid material-based applications. Herein, pre-hydrolyzed polyacrylonitrile (HPAN) and quaternary ammonium salts (QAS) are employed to produce PESC electrospun membranes via electrospinning. The formation process of PESCs in a solution is observed. The results show that the degree of PAN hydrolysis and the varying alkyl chain lengths of surfactants affect the rate of PESC formation. Moreover, PESCs/PCL hybrid electrospun membranes are fabricated, and their antibacterial activities against both Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) are investigated. The resulting electrospun membranes exhibit high bactericidal efficacy, which enables them to serve as candidates for future biomedical and filtration applications.

Hydrogenation of Alkynes and Olefins Catalyzed by Quaternary Ammonium Salts

Catalytic hydrogenation of unsaturated hydrocarbons to alkenes and alkanes using molecular hydrogen is one of the most fundamental transformations in organic synthesis. While methodologies involving transition metals as catalysts in homogeneous and heterogeneous processes have been well developed, metal-free catalytic hydrogenation offers an ideal approach for future chemistry. Herein, the common and inexpensive quaternary ammonium salts are first introduced as catalysts in the catalytic hydrogenation system for the transformations from alkynes or olefins into the corresponding olefins or alkanes. Interestingly, the hydrogenation process of alkynes can be controlled to selectively produce alkenes or alkanes under different conditions. Moreover, the possible mechanism is discussed in new insights into the catalytic behavior of quaternary ammonium salts.

Low-Cytotoxicity, Broad-Spectrum Corn Starch-Based Antibacterial Particles that Inhibit Multidrug-Resistant Bacteria

Antimicrobial resistance is a serious problem in biomedical applications that seriously increases the risk of medical failure. Therefore, developing highly efficient antibacterial agents that inhibit the growth of multidrug-resistant bacteria is a long-standing research goal. In this report, a low-cytotoxicity and highly efficient alternative to antibiotics was designed and prepared using edible corn starch as the scaffold and 2-hydroxypropyl-trimethylammonium chloride chitosan (HTCC) as the antimicrobial agent. The HTCC/starch particles were found to have a positively charged surface over a wide pH range and to possess broad-spectrum and highly efficient antimicrobial properties. These particles inhibited the growth of standard Gram-positive and Gram-negative bacteria from the China Pharmacopoeia and a clinical multidrug-resistant bacterial strain. Moreover, after treating the HTCC/starch particles with simulated gastric fluid (SGF, pH 1.2) for 4 h, the growth of clinical multidrug-resistant Escherichia coli (NT 2036) was inhibited effectively, indicating that these particles tolerate a gastric acid environment. Although the mass of SGF-treated HTCC/starch particles required to achieve similar antibacterial activity was ∼20-fold that of chloramphenicol or ampicillin, antibiotic-containing products require considerable amounts of pharmaceutical excipients to prepare. Therefore, the HTCC/starch particles described herein are potentially cost-effective alternatives to antibiotics that resolve the antimicrobial resistance issue, especially for inhibiting the growth of pathogenic intestinal bacteria.

A Temperature and pH Dual-Sensitive Multifunctional Polyurethane with Bacteria-Triggered Antibacterial Activity

An effective and practical antibacterial strategy is to design multifunctional and stimuli-responsive materials that exhibit antibacterial activity in response to bacterial triggers. In this study, because the metabolism of Staphylococcus aureus (S. aureus) can acidify the surrounding environment and pH level can affect the lower critical solution temperature of temperature/pH dual-sensitive polymers, a monomer containing a temperature-sensitive N-isopropyl amide derivative and pH-sensitive tertiary amine groups is first synthesized. Then, the monomer is copolymerized with a polyurethane chain, and partial tertiary amine groups are quaternized to obtain bactericidal activity. The modified polyurethane exhibits temperature/pH sensitivity, antibacterial adhesion activity, bactericidal activity, and good cytocompatibility. An in situ investigation of bacterial behavior and pH changes in the bacterial suspension during the process confirms that the temperature/pH dual-sensitive polyurethane successfully achieves antibacterial activity though the metabolic activity of S. aureus without external intervention. This design concept provides a new perspective for antibacterial material design.

Efficient Demulsification Performance of Emulsified Condensate Oil by Hyperbranched Low-Temperature Demulsifiers

Focusing on the problem of poor demulsification performance of light crude oil emulsions in low-permeability oilfields at low temperatures, the composition of the emulsion samples, clay particle size distribution, and the viscosity-temperature relationship curve of samples were analyzed. Based on the results of emulsion composition analysis and characteristics, the bottle test method was used to analyze the demulsifying effect of different commercial types of demulsifiers, revealing the demulsification mechanism. The field tests confirm the demulsification capabilities of Polyoxyethylene polyoxypropylene quaternized polyoxyolefins surfactants (PR demulsifiers). The results reveal that PR demulsifiers combine the features of decreasing the interfacial tension between oil and water and adsorbing SiO2, allowing for quick demulsification and flocculation at low temperatures. This research serves as a theoretical and practical foundation for the study and advancement of low-temperature demulsification technology in oilfields.

Surface Activity, Wetting, and Aggregation of a Perfluoropolyether Quaternary Ammonium Salt Surfactant with a Hydroxyethyl Group

This paper reports the synthesis of a novel quaternary surfactant containing a hydroxyethyl group (PFPE-C) and the surface properties of its aqueous solution (investigated by comparisons with two structurally similar chemicals, dodecyl-(2-hydroxyethyl)-dimethylammonium chloride (DHDAC) and PFPE-A). The minimum surface tension (γCMC) and critical micelle concentration (CMC) of the PFPE-C aqueous solution were 17.35 mN/m and 0.024 mmol/L, respectively. This study confirms that surfactants containing hydroxyethyl groups efficiently reduce the surface tension of aqueous solutions, and fluorocarbon surfactants exhibit better surface activity than ordinary hydrocarbon surfactants with similar structures. The micellization, aggregation, air-water interfacial adsorption, and wettability of PFPE-C aqueous solutions have been systematically investigated. Highly concentrated PFPE-C aqueous solutions exhibit good wettability on PTFE and paraffin films. Moreover, the aggregates of PFPE-C in the aqueous solution were clearly seen as vesicles on Cryo-TEM micrographs. Primary biodegradation results indicate that 19% of PFPC-C can be degraded within one week.

Preparation of Volborthite by a Facile Synthetic Chemical Solvent Extraction Method

In this work, the extraction of vanadium (V) ions from an alkaline solution using a commercial quaternary ammonium salt and the production of metal vanadates through precipitation stripping were carried out. The crystallization of copper vanadates from the extracts was performed using a solution containing a copper(II) source in concentrated chloride media as a stripping agent. In an attempt to control growth, a stabilizing polymer (polyvinylpyrrolidone, PVP) was added to the stripping solution. The structural characteristics of the crystallized products, mainly copper pyrovanadate (volborthite, Cu₃V₂O₇(OH)₂·(H₂O)₂) nanoflakes and nanoflowers and the experimental parameter influencing the efficiency of the stripping process were studied. From the results, the synthesis of nanostructured vanadates is a simple and versatile method for the fabrication of valuable three-dimensional structures providing abundant active zones for energy and catalytic applications.

One-Step Synthesis of Self-Stratification Core-Shell Latex for Antimicrobial Coating

Herein, we describe a one-step method for synthesizing cationic acrylate-based core-shell latex (CACS latex), which is used to prepare architectural coatings with excellent antimicrobial properties. Firstly, a polymerizable water-soluble quaternary ammonium salt (QAS-BN) was synthesized using 2-(Dimethylamine) ethyl methacrylate (DMAEMA) and benzyl bromide by the Hoffman alkylation reaction. Then QAS-BN, butyl acrylate (BA), methyl methacrylate (MMA), and vinyltriethoxysilane (VTES) as reactants and 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AIBA) as a water-soluble initiator were used to synthesize the CACS latex. The effect of the QAS-BN dosage on the properties of the emulsion and latex film was systematically investigated. The TGA results showed that using QAS-BN reduced the latex film's initial degradation temperature but improved its thermal stability. In the transmission electron microscopy (TEM) photographs, the self-stratification of latex particles with a high dosage of QAS-BN was observed, forming a core-shell structure of latex particles. The DSC, TGA, XPS, SEM, and performance tests confirmed the core-shell structure of the latex particles. The relationship between the formation of the core-shell structure and the content of QAS-BN was proved. The formation of the core-shell structure was due to the preferential reaction of water-soluble monomers in the aqueous phase, which led to the aggregation of hydrophilic groups, resulting in the formation of soft-core and hard-shell latex particles. However, the water resistance of the films formed by CACS latex was greatly reduced. We introduced a p-chloromethyl styrene and n-hexane diamine (p-CMS/EDA) crosslinking system, effectively improving the water resistance in this study. Finally, the antimicrobial coating was prepared with a CACS emulsion of 7 wt.% QAS-BN and 2 wt.% p-CMS/EDA. The antibacterial activity rates of this antimicrobial coating against E. coli and S. aureus were 99.99%. The antiviral activity rates against H₃N₂, HCoV-229E, and EV71 were 99.4%, 99.2%, and 97.9%, respectively. This study provides a novel idea for the morphological design of latex particles. A new architectural coating with broad-spectrum antimicrobial properties was obtained, which has important public health and safety applications.

Quaternary ammonium salt-modified isabgol scaffold as an antibacterial dressing to improve wound healing

Chronic wounds require suitable treatment and management strategies for proper healing. Among other causes, infection delays the healing of wounds and increases the risk of wound-related complications. In this study, an inherently antibacterial and biocompatible wound dressing is developed to enhance the healing. Chemical modification of a natural polysaccharide, Isabgol with epoxypropyltrimethylammonium chloride, renders antibacterial activity to the material. This is the first report of such chemical modification of this polymer for biomedical applications. The modified material is freeze-dried to obtain porous scaffolds. ¹³C NMR and FTIR analysis confirmed the modification of the Isabgol polymer chains with EPTMAC. SEM analysis confirmed the porous structure of the scaffold that would allow the exchange of gases and nutrients through the matrix. The material can swell up to 17 times its initial weight, allowing it to absorb wound exudates and maintain a moist environment at the wound site. Thermogravimetric analysis and compression testing showed that the scaffold has suitable thermal and mechanical properties. The material is antibacterial and can potentially prevent infections at the wound site. In vitro studies have confirmed that these scaffolds are cytocompatible and hemocompatible. These properties indicate that the EPTMAC-modified Isabgol scaffolds would be suitable for wound dressing applications.

The Prolonged Treatment of Salmonella enterica Strains with Human Serum Effects in Phenotype Related to Virulence

Salmonella enterica as common pathogens of humans and animals are good model organisms to conduct research on bacterial biology. Because these bacteria can multiply in both the external environments and in the living hosts, they prove their wide adaptability. It has been previously demonstrated that prolonged exposition of Salmonella serotype O48 cells to normal human serum led to an increase in resistance to sera in connection with the synthesis of very long O-antigen. In this work, we have studied the phenotype connected to virulence of Salmonella enterica strains that were subjected to consecutive passages in 50% human serum from platelet-poor plasma (SPPP). We found that eight passages in SPPP may not be enough for the bacteria to become serum-resistant (S. Typhimurium ATCC 14028, S. Senftenberg). Moreover, C1q and C3c complement components bound to Salmonellae (S. Typhimurium ATCC 14028, S. Hammonia) membrane proteins, which composition has been changed after passaging in sera. Interestingly, passages in SPPP generated genetic changes within gene fljB, which translated to cells’ motility (S. Typhimurium ATCC 14028, S. Erlangen). One strain, S. Hammonia exposed to a serum developed a multi-drug resistance (MDR) phenotype and two S. Isaszeg and S. Erlangen tolerance to disinfectants containing quaternary ammonium salts (QAS). Furthermore, colonial morphotypes of the serum adaptants were similar to those produced by starter cultures. These observations suggest that overcoming stressful conditions is manifested on many levels. Despite great phenotypic diversity occurring after prolonged exposition to SPPP, morphotypes of colonies remained unchanged in basic media. This work is an example in which stable morphotypes distinguished by altered virulence can be confusing during laboratory work with life-threatening strains.

Efficient and Economic Heparin Recovery from Porcine Intestinal Mucosa Using Quaternary Ammonium-Functionalized Silica Gel

Heparin, usually isolated from porcine intestinal mucosa, is an active pharmaceutical ingredient of great material value. Traditionally, diverse types of commercial resins were employed as an adsorbent for heparin retrieval from biological samples. However, more recent years have encouraged the advent of new cost-effective adsorbents to achieve enhanced heparin retrieval. Inexpensive cationic ammonium-functionalized silica gels, monodispersed with larger surface area, porosity, and higher thermal stability, were chosen to evaluate the heparin recovery yield from porcine intestinal mucosa. We demonstrated that higher positively charged and less bulky quaternary modified silica gel (e.g., QDASi) could adsorb ~28% (14.7 mg g-1) heparin from the real samples. In addition, we also determined suitable surface conditions for the heparin molecule adsorption by mechanistic studies and optimized different variables, such as pH, temperature, etc., to improve the heparin adsorption. This is going to be the first reported study on the usage of quaternary amine-functionalized silica gel for HEP uptake.

Silver-Polymethylhydrosiloxane-Quaternary Ammonium Coating on Anodized Aluminum with Excellent Antibacterial Property

Multidrug-resistant bacteria are known to survive on high-touch surfaces for days, weeks, and months, contributing to the rise in nosocomial infections. Inducing antibacterial property in such surfaces can presumably reduce the overall microbial burden and subsequent nosocomial infections in hygiene critical environments. In the present study, a one-pot sol-gel process has been deployed to incorporate silver (Ag) and quaternary ammonium salt (QUAT) bactericides in a polymethylhydrosiloxane (PMHS) matrix. The Ag-PMHS-QUAT nanocomposite was coated on anodized aluminum (AAO/Al) by a simple ultrasound-assisted deposition process. The morphological features and chemical composition of the Ag-PMHS-QUAT nanocomposite have been characterized using SEM, XRD spectroscopy, and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) to confirm the formation of Ag-QUAT nanocomposites within the polymeric network of PMHS. The Ag-PMHS-QUAT nanocomposite coating on anodized aluminum oxide (AAO/Al) coupon exhibited superior antibacterial property with a 6-log bacterial reduction compared to the 5-log reduction for the commercially available antimicrobial copper coupon.

Improvement of Antibacterial and Antifouling Properties of a Cellulose Acetate Membrane by Surface Grafting Quaternary Ammonium Salt

Through etherification reaction, epoxy propyl dimethyl dodecyl ammonium chloride (EPDMDAC) was grafted onto the surface of a cellulose acetate (CA) membrane to prepare a stable nonleaching antibacterial antifouling membrane (QCA-X). The results showed that with the extension of grafting reaction time, the quaternary ammonium salt groups on the membrane surface increased and the hydrophilicity was enhanced. Compared with those of the CA membrane, the filtration capacity and antifouling performance of the QCA-X membrane are improved. When the grafting time is 4 h, the water permeability and flux recovery rate of the QCA-4 membrane are increased by 139 and 21.5%, respectively. The QCA-X membrane showed excellent antibacterial performance, and the sterilization rate against S. aureus and E. coli was more than 99.99%. After four repeated antibacterial cycles, the bactericidal rates against S. aureus and E. coli were maintained at about 99.69 ± 0.02 and 99.98 ± 0.02%, respectively, with good antibacterial persistence. Moreover, the QCA-X membrane can effectively inhibit bacterial adhesion. Mild and simple EPDMDAC grafting modifications improve the antibacterial, antifouling, and antibioadhesion properties of the CA membrane, showing its application potential in long-term water treatment, especially in biofouling water treatment.

Influence of PEG Subunit on the Biological Activity of Ionenes: Synthesis of Novel Polycations, Antimicrobial and Toxicity Studies

An alarming increase of antibiotic resistance among pathogens creates an urgent need to develop new antimicrobial agents. Many reported polycations show high antimicrobial activity along with low hemolytic activity. Unfortunately, most of those molecules remain highly cytotoxic against various mammalian cells. In this work, we present a systematic study on the impact of triethylene glycol monomethyl ether side groups (short PEG analog) on antimicrobial, hemolytic, and cytotoxic properties of novel amphiphilic ionenes. A detailed description of synthesis, leading to well-defined alternating polymers, which differ in structural elements responsible for hydrophilicity (PEG) and hydrophobicity (alkyl chain), is presented. Obtained results show that the PEG moiety and fine-tuned hydrophilic-lipophilic balance of ionenes synergistically lead to low-cytotoxic, low-hemolytic molecules with high activity against S. aureus, including methicillin-resistant strains (MRSA). Additionally, the results of mechanistic studies on bacterial cells and fluorescently labeled liposomes are also discussed. This article is protected by copyright. All rights reserved.

Polymerized naphthalimide derivatives as remarkable electron-transport layers for inverted organic solar cells

Two polymerized naphthalimide derivatives, named as N-TBHOB and N-DBH, have been prepared by quaternization, which exhibit excellent performance as electron-transport layers (ETLs) in inverted organic solar cells (i-OSCs). The results indicate N-TBHOB with a reticulated structure owns a superior performance on electron extraction, electron transport, thickness tolerance and less carrier recombination compared with N-DBH with linear structure. The i-OSCs based on N-TBHOB with PTB7-Th:PC₇₁ BM as the active layer achieve PCEs of 10.72% and 10.03% under the thickness of 11 and 48 nm respectively, which indicates N-TBHOB possesses better thickness tolerance than most of organic ETLs in i-OSCs. N-TBHOB also shows more competent performance than N-DBH and ZnO in non-fullerene i-OSCs for comprehensively improved J_sc , V_oc and FF values. Its i-OSC with PM6:Y6 blend presents a high PCE of 16.78%. The study provides an efficient strategy to prepare ETLs by combining conjugated and nonconjugated backbone with a reticulated structure for high-performance i-OSCs. This article is protected by copyright. All rights reserved.

Research Progress on Typical Quaternary Ammonium Salt Polymers

Quaternary ammonium salt polymers, a kind of polyelectrolyte with a quaternary ammonium group, are widely used in traditional and emerging industries due to their good water-solubility, adjustable cationicity and molecular weight, high efficiency and nontoxicity. In this paper, firstly, the properties and several synthesis methods of typical quaternary ammonium salt monomers were introduced. Secondly, the research progress on the synthesis of polymers was summarized from the perspective of obtaining products with high molecular weight, narrow molecular weight distribution and high monomer conversion, and special functional polymers. Thirdly, the relationships between the structures and properties of the polymer were analyzed from the perspectives of molecular weight, charge density, structural stability, and microstructural regulation of the polymer chain unit. Fourthly, typical examples of quaternary ammonium salt polymers in the application fields of water treatment, daily chemicals, petroleum exploitation, papermaking, and textile printing and dyeing were listed. Finally, constructive suggestions were put forward on developing quaternary ammonium salt polymers with high molecular weights, strengthening the research on the relationships between the structures and their properties and pinpointing relevant application fields.

Quaternary Ammonium Salts Anchored on Cross-Linked (R)-(+)-Lipoic Acid Nanoparticles for Drug-Resistant Tumor Therapy

A membrane-lytic mechanism-based nanodrug is developed for drug-resistant tumor therapy by anchoring the small-molecule quaternary ammonium salt (QAS) on cross-linked (R)-(+)-lipoic acid nanoparticles (cLANs). The anchoring of QAS on the nanoparticle avoids the direct attack of long alkyl chains to the cell membrane under physiological conditions, while after entering tumor cells, the QAS is released from the dissociated cLANs, migrates to the phospholipid bilayer via electrostatic interaction, and destroys the cell membrane by the puncture of long alkyl chains. Since the QAS is designed to finally be hydrolyzed to amino acid betaine and food additive cetanol and the cLANs degrade to dihydrolipoic acid (DHLA, reduced form of dietary antioxidant lipoic acid in cells), the QAS@cLANs hold superior biosafety. In addition to the drug-resistant tumors, the QAS@cLANs demonstrate significant inhibition of metastatic tumors. This work provides not only a general and clinic-promising treatment for the refractory tumors but also opens a door for the medicinal use of QAS.

Analysis of Fragmentation Pathways of Peptide Modified with Quaternary Ammonium and Phosphonium Group as Ionization Enhancers

Peptide modification by a quaternary ammonium group containing a permanent positive charge is a promising method of increasing the ionization efficiency of the analyzed compounds, making ultra-sensitive detection even at the attomolar level possible. Charge-derivatized peptides may undergo both charge remote (ChR) and charge-directed (ChD) fragmentation. A series of model peptide conjugates derivatized with N,N,N-triethyloammonium (TEA), 1-azoniabicyclo[2.2.2]octane (ABCO), 2,4,6-triphenylopyridinium (TPP) and tris(2,4,6-trimetoxyphenylo)phosphonium (TMPP) groups were analyzed by their fragmentation pathways both in collision-induced dissociation (CID) and electron-capture dissociation (ECD) mode. The effect of the fixed-charge tag type and peptide sequence on the fragmentation pathways was investigated. We found that the aspartic acid effect plays a crucial role in the CID fragmentation of TPP and TEA peptide conjugates whereas it was not resolved for the peptides derivatized with the phosphonium group. ECD spectra are mostly dominated by c_n ions. ECD fragmentation of TMPP-modified peptides results in the formation of intense fragments derived from this fixed-charge tag, which may serve as reporter ion.

Influence of New Compound Disinfectant From N-Dodecyl-2-(Piridin-1-Ium)Acetamide Chloride on Pathogenic Microorganisms in Poultry Houses

With the development of large-scale and intensive poultry farming, environmental disinfection has become particularly important, and the effectiveness of disinfection depends upon the performance of the disinfectants. Quaternate ammonium salt is a group of positively charged polyatomic ions with both antibacterial and antiviral activities. In order to prepare an ideal disinfectant for poultry farms, we combined a quaternate ammonium salt N-dodecyl-2-(piridin-1-ium)acetamide chloride with two other disinfectants (chlorhexidine acetate and glutaraldehyde), respectively. The antimicrobial activity, mutagenicity, and safety of the compound disinfectants were assessed by the European Standard methods using ATCC strains and clinical isolates. The results showed that both compound disinfectants meet the requirements of microbial reduction, and their effectiveness was not affected by organic matter. Quaternary ammonium disinfectant resistance genes were not detected in the strains tested indicating that bacteria are less likely to develop resistance to these compound disinfectants. Ames test showed that there was no detectable mutagenicity in the strains treated with the compound disinfectants. In vivo experiment showed that both compound disinfectants did not have significant pathological effect in mice. The bactericidal effect of the compound disinfectants was not significantly different among strains of different sources (p>0.05). Clinical tests showed that compound disinfectant had a good bactericidal effect on the air and ground of poultry farms. These results show that quaternary ammonium salts in combination with other compounds can enhance the bactericidal effect and can be used safely in poultry feedlots. This study provides a technical reference for the development of a new quaternate ammonium compound disinfectant with strong disinfection effect and low irritation.

Design, Synthesis, Antibacterial, and Antitumor Activity of Linear Polyisocyanide Quaternary Ammonium Salts with Different Structures and Chain Lengths

The development of organic polymer materials for disinfection and sterilization is thought of as one of the most promising avenues to solve the growth and spread of harmful microorganisms. Here, a series of linear polyisocyanide quaternary ammonium salts (L-PQASs) with different structures and chain lengths were designed and synthesized by polymerization of phenyl isocyanide monomer containing a 4-chloro-1-butyl side chain followed by quaternary amination salinization. The resultant compounds were characterized by 1H NMR and FT-IR. The antibacterial activity of L-PQASs with different structures and chain lengths against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was evaluated by determining the minimum inhibitory concentrations (MICs). The L-POcQAS-M50 has the strongest antimicrobial activity with MICs of 27 μg/mL against E. coli and 32 μg/mL against S. aureus. When the L-PQASs had the same polymerization degree, the order of the antibacterial activity of the L-PQASs was L-POcQAS-Mn > L-PBuQAS-Mn > L-PBnQAS-Mn > L-PDBQAS-Mn (linear, polyisocyanide quaternary ammonium salt, monomer, n = 50,100). However, when L-PQASs had the same side chain, the antibacterial activity reduced with the increase of the molecular weight of the main chain. These results demonstrated that the antibacterial activity of L-PQASs was dependent on the structure of the main chain and the length of the side chain. In addition, we also found that the L-POcQAS-M50 had a significant killing effect on MK-28 gastric cancer cells.

Rhodium-Catalyzed Oxidative Annulation of 2- or 7-Arylindoles with Alkenes/Alkynes Using Molecular Oxygen as the Sole Oxidant Enabled by Quaternary Ammonium Salt

Developing an efficient catalytic system using molecular oxygen as the oxidant for rhodium-catalyzed cross-dehydrogenative coupling remains highly desirable. Herein, rhodium-catalyzed oxidative annulation of 2- or 7-phenyl-1H-indoles with alkenes or alkynes to assemble valuable 6H-isoindolo[2,1-a]indoles, pyrrolo[3,2,1-de]phenanthridines, or indolo[2,1-a]isoquinolines using the atmospheric pressure of air as the sole oxidant enabled by quaternary ammonium salt has been accomplished. Mechanistic studies provided evidence for the fast intramolecular aza-Michael reaction and aerobic reoxidation of Rh(I)/Rh(III), facilitated by the addition of quaternary ammonium salt.

The Effect of Surfactant-Modified Montmorillonite on the Cross-Linking Efficiency of Polysiloxanes

Polymer–clay mineral composites are an important class of materials with various applications in the industry. Despite interesting properties of polysiloxanes, such matrices were rarely used in combination with clay minerals. Thus, for the first time, a systematic study was designed to investigate the cross-linking efficiency of polysiloxane networks in the presence of 2 wt % of organo-montmorillonite. Montmorillonite (Mt) was intercalated with six quaternary ammonium salts of the cation structure [(CH₃)₂R’NR]⁺, where R = C₁₂, C₁₄, C₁₆, and R’ = methyl or benzyl substituent. The intercalation efficiency was examined by X-ray diffraction, CHN elemental analysis, and Fourier transform infrared (FTIR) spectroscopy. Textural studies have shown that the application of freezing in liquid nitrogen and freeze-drying after the intercalation increases the specific surface area and the total pore volume of organo-Mt. The polymer matrix was a poly(methylhydrosiloxane) cross-linked with two linear vinylsiloxanes of different siloxane chain lengths between end functional groups. X-ray diffraction and transmission electron microscopy studies have shown that the increase in d-spacing of organo-Mt and the benzyl substituent influence the degree of nanofillers’ exfoliation in the nanocomposites. The increase in the degree of organo-Mt exfoliation reduces the efficiency of hydrosilylation reaction monitored by FTIR. This was due to physical hindrance induced by exfoliated Mt particles.

A Novel BODIPY Quaternary Ammonium Salt-Based Fluorescent Probe: Synthesis, Physical Properties, and Live-Cell Imaging

The development of biological fluorescent probes is of great significance to the field of cancer bio-imaging. However, most current probes within the bulky hydrophobic group have limited application in aqueous medium and restricted imaging under physiological conditions. Herein, we proposed two efficient molecules to study their physical properties and imaging work, and the absorption and fluorescence intensity were collected with varying ions attending in aqueous medium. We enhance the water solubility through the quaternization reaction and form a balance between hydrophilic and hydrophobicity with dipyrrome-theneboron difluoride (BODIPY) fluorophore. We introduced pyridine and dimethylaminopyridine (DMAP) by quaternization and connected the BODIPY fluorophore by ethylenediamine. The final synthesized probes have achieved ideal affinity with HeLa cells (human cervical carcinoma cell line) in live-cell imaging which could be observed by Confocal Microscope. The probes also have a good affinity with subcutaneous tumor cells in mice in in vivo imaging, which may make them candidates as oncology imaging probes.

Preparation of Alkaline Polyelectrolyte Membrane Based on Quaternary Ammonium Salt-Modified Cellulose and Its Application in Zn-Air Flexible Battery

In this study, a type of alkaline solid polyelectrolyte (ASPE) membrane was developed via the introduction of microcrystalline cellulose (MCC) and its modified product (QMCC) into the polyvinyl alcohol (PVA) matrix. In this process, green NaOH/urea-based solvent was used to achieve a good dispersion of MCC in the PVA matrix; meanwhile, the OH^- groups in the NaOH/urea-based solvent provided an alkaline environment for good ion conductivity. Compared to the MCC-incorporated ASPE, further improved conductivity was achieved when the MCC was modified with quantitative quaternary ammonium salt. TGA showed that the addition of QMCC improved the water retention of the matrix, which was beneficial to the OH^- conduction in the system. Compared to the control (50 mS cm^-1), a maximum conductivity of 238 mS cm^-1 was obtained after the incorporation of QMCC in the PVA matrix. Moreover, the tensile strength of the polymer electrolyte were also significantly increased with the addition of QMCC. Finally, this developed ASPE membrane was used in assembling a flexible Zn-air battery and showed a promising potential in the development of flexible electronic devices.

Antibacterial, Antifungal and Ecotoxic Effects of Ammonium and Imidazolium Ionic Liquids Synthesized in Microwaves

Ionic liquids are increasingly used for their superior properties. Four water-immiscible ionic liquids (butyltriethylammonium bis(trifluoromethylsulfonyl)imide, octyltriethylammonium bis(trifluoromethylsulfonyl)imide, dodecyltriethylammonium bis(trifluoromethylsulfonyl)imide, butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) and their water miscible precursors (bromides) were synthesized in a microwave reactor and by conventional heating. The best conditions for microwave-assisted synthesis concerning the yield and the purity of the product are proposed. The heating in the microwave reactor significantly shortened the reaction time. Biocide and ecotoxic effects of synthesized ionic liquids and their precursors were investigated. All tested compounds had at least a little effect on the growth or living of microorganisms (bacteria or mold). The precursor dodecyltriethylammonium bromide was found to be the strongest biocide, but posed a risk to the aquatic environment due to its relatively high EC₅₀ value in the test with Vibrio fischeri. We assumed that apart from the alkyl chain length, the solubility in water, duration of action, or type of anion can influence the final biocide and ecotoxic effect.

Surface Adsorption Properties and Layer Structures of Homogeneous Polyoxyethylene-Type Nonionic Surfactants in Quaternary-Ammonium-Salt-Type Amphiphilic Gemini Ionic Liquids with Oxygen- or Nitrogen-Containing Spacers

The amphiphilic ionic liquids containing an alkyl chain in molecules form nano-structure in the bulk, although they also show surface activity and form aggregates in aqueous solutions. Although insights into the layer structures of ionic liquids were obtained using X-ray and neutron scattering techniques, the nanostructures of ionic liquids remain unclear. Herein, the surface adsorption and bulk properties of homogeneous polyoxyethylene (EO)-type nonionic surfactants (C_xEO₆; x = 8, 12, or 16) were elucidated in quaternary-ammonium-salt-type amphiphilic gemini ionic liquids with oxygen or nitrogen-containing spacers [2C_n(Spacer) NTf₂; (Spacer) = (2-O-2), (2-O-2-O-2), (2-N-2), (2/2-N-2), (3), (5), or (6); n = 10, 12, or 14 for (2-O-2) and n = 12 for all other spacers] by surface tension, small- and wide-angle X-ray scattering, cryogenic transmission electron microscopy, and viscosity measurements. The surface tension of C₁₂EO₆ in 2C_n(Spacer) NTf₂ with oxygen-containing spacers increased with increasing concentration of C₁₂EO₆, becoming close to that of C₁₂EO₆ alone, indicating that the amphiphilic ionic liquid adsorbed at the interface was replaced with C_xEO₆. In contrast, both 2C_n(Spacer) NTf₂ with nitrogen-containing spacers and nonionic surfactants remained adsorbed at the interface at high concentrations. In the bulk, it was found that 2C_n(Spacer) NTf₂ formed layer structures, in which the spacing depended on the alkyl chain length of C_xEO₆. These insights are expected to advance the practical applications of amphiphilic ionic liquids such as ion permeation, drug solubilization, and energy delivery systems.

Effects of adsorbent carriers in modified ready biodegradability tests of quaternary ammonium salts

Standard ready biodegradability tests are conducted at unrealistically high test concentration and therefore cannot properly evaluate toxic substances to microorganisms. The present study evaluated the effects of four adsorbent carriers in modified ready biodegradability tests of four quaternary ammonium salts (QASs) demonstrating microbial toxicity according to the Organization for Economic Co-operation and Development Test Guideline 301F and cautions for using carriers were found. In the tests with silica gel, the concentration of all QASs in the test solutions decreased due to adsorption. The percentages of biodegradation of octadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, and benzyldimethyloctadecylammonium chloride, which have a linear alkyl chain, were 89.9%, 80.6%, and 70.1% on day 28, respectively; benzethonium chloride, with a branched alkyl chain, did not undergo biodegradation. In the tests with activated carbon, although the concentrations of QASs greatly decreased, no QASs underwent biodegradation. In the tests with sea sand or quartz sand, QASs were not adsorbed on the carriers and were not biodegraded. Using an adsorbent carrier for toxic substances will increase biodegradation, but it has no effect on highly persistent substances with specific chemical structures, e.g., branched carbons, which is very important because ready biodegradability is not overestimated. Carriers having moderate adsorbability should be selected.

Universal Antibacterial Surfaces Fabricated from Quaternary Ammonium Salt-Based PNIPAM Microgels

Because of the excellent film-forming ability of poly(N-isopropylacrylamide) (PNIPAM) microgel and high-efficient bactericidal property of quaternary ammonium salt (QAS), QAS-based PNIPAM (QAS-PNIPAM) microgels are synthesized and employed to modify the surface of a range of commonly used materials including metal, plastic, and elastomer. Bacterial culture is carried out on such QAS-PNIPAM microgel-modified surfaces to examine the viability of the attached bacteria. It is found that the bactericidal efficiency is nearly 100% on the modified surfaces of all the studied materials. We attribute the high-efficient bactericidal performance of QAS-PNIPAM microgel film to the QAS component rather than the topography of the microgel film itself. In addition, the microgel film is robust and shows great integrity even after culture of the bacteria and repeated rinses, and the cell experiment demonstrates that this microgel film is cyto-compatible. Therefore, such a simple, versatile method of preparing antibacterial films paves the way for future bactericidal applications.

Antimicrobial Efficiency and Surface Interactions of Quaternary Ammonium Compound Absorbed on Dielectric Barrier Discharge (DBD) Plasma Treated Fiber-Based Wiping Materials

The physicochemical interactions between alkyldimethylbenzylammonium chloride (ADBAC) as disinfectant and three commercial wiping materials made from 100% polyester (PET), 55%cellulose/45%PET (blend), and 100% cellulose were investigated after treatment with dielectric barrier discharge (DBD) plasma at atmospheric pressure. Wipe material type in terms of cellulose content, liquor ratio, and immersion time demonstrated a significant influence on the adsorption of ADBAC. The higher the content of cellulose in the material, the higher is the adsorption of ADBAC active ingredient. The antimicrobial tests confirm that the ADBAC adsorbed on pure cellulosic material is inactivated losing its bactericidal activity, while 100% PET and blend wipes showed good antimicrobial efficacy. XPS analysis demonstrates the strong interactions of ADBAC with the plasma-generated oxygen species in the polyester-containing wipes surface. Unexpectedly, plasma-treated blend wipe displays a reverse antimicrobial effect compared to untreated samples, performing better in Gram-negative bacteria. The best result was obtained in the plasma treated 100% polyester wipe showing an improvement of about 20% in Gram-positive bacteria and an excellent performance in Gram-negative ones. This method allows the unprecedented use of pure polyester as effective wiping material for surface disinfection eliminating the major drawback of pure polyester, its high hydrophobicity.

Crystal structures and hydrogen-bonding analysis of a series of solvated ammonium salts of molybdenum(II) chloride clusters

The crystal structures of four different ammonium salts of the molybdenum halide cluster anion, [Mo₆Cl₈Cl₆]²⁻, are reported. They display varying degrees of hydrogen bonding between ammonium ions and the respective solvent mol­ecules.

Charge-assisted hydrogen bonding plays a significant role in the crystal structures of solvates of ionic com­pounds, especially when the cation or cations are primary ammonium salts. We report the crystal structures of four ammonium salts of molybdenum halide cluster solvates where we observe significant hydrogen bonding between the solvent molecules and cations. The crystal structures of bis­(anilinium) octa-μ₃-chlorido-hexa­chlorido-octa­hedro-hexa­molybdate N,N-di­­methyl­formamide tetra­solvate, (C₆H₈N)₂[Mo₆Cl₈Cl₆]·4C₃H₇NO, (I), p-phenyl­enedi­ammonium octa-μ₃-chlorido-hexa­chlorido-octa­hedro-hexa­mol­yb­date N,N-di­methyl­formamide hexa­solvate, (C₆H₁₀N₂)[Mo₆Cl₈Cl₆]·6C₃H₇NO, (II), N,N′-(1,4-phenyl­ene)bis­(propan-2-iminium) octa-μ₃-chlorido-hexa­chlo­rido-octa­hedro-hexa­molybdate acetone tris­olvate, (C₁₂H₁₈N₂)[Mo₆Cl₈Cl₆]·3C₃H₆O, (III), and 1,1′-dimethyl-4,4′-bipyridinium octa-μ₃-chlo­rido-hexa­chlorido-octa­hedro-hexa­molybdate N,N-di­methyl­formamide tetra­solvate, (C₁₂H₁₄N₂)[Mo₆Cl₈Cl₆]·4C₃H₇NO, (IV), are reported and described. In (I), the anilinium cations and N,N-di­methyl­formamide (DMF) solvent mol­ecules form a cyclic R₄²(8) hydrogen-bonded motif centered on a crystallographic inversion center with an additional DMF mol­ecule forming a D(2) inter­action. The p-phenyl­enedi­ammonium cation in (II) forms three D(2) inter­actions between the three N—H bonds and three independent N,N-di­methyl­formamide mol­ecules. The dication in (III) is a protonated Schiff base solvated by acetone mol­ecules. Compound (IV) contains a methyl viologen dication with N,N-di­methyl­formamide mol­ecules forming close contacts with both aromatic and methyl H atoms.

Light-Induced Production of Reactive Oxygen Species by a Novel Water-Soluble Benzophenone Derivative Containing Quaternary Ammonium Groups and Its Assembly on the Protein Fiber Surface

Developing an efficient antimicrobial surface has important significance in the field of advanced biomaterials. A novel water-soluble benzophenone tetracarboxylamine derivative containing two quaternary ammonium groups, 3,3'-[4,4'-carbonyl-diphthalimide-]-bis(N-benzyl-N,N-dimethyl-N-propyl-1-aminium)dichloride (BPTCA-N), as a photoactive antibacterial agent was designed and synthesized. The ability of BPTCA-N to generate reactive oxygen species (ROS) in solution was investigated by light-induced activity. Its antibacterial activity in a dark environment or UV exposure was tested on Staphylococcus aureus and Escherichia coli. The influences of different solvents and the pH values on the ability of BPTCA-N to generate ROS were also discussed. BPTCA-N possessed high photoactivity and efficient ROS generation ability. The generation of hydroxyl radicals could be greatly affected by addition of other solvents and H⁺ or OH^-. For the BPTCA-N solution at a concentration of 0.2 mmol/L, the reduction of S. aureus and E. coli could all reach 99.99%. The BPTCA-N compound was assembled onto wool protein fibers. The modified protein fabrics also showed excellent photoactivity and antibacterial property against S. aureus and E. coli. For the wool fabric modified with 30 g/L of BPTCA-N, the reduction of S. aureus could reach 99.91% and that of E. coli was 91.23%. BPTCA-N had the synergistic antibacterial effect of quaternary ammonium salt and benzophenones. It has potential application in the biomedical field as highly effective antimicrobial agent or antimicrobial biomaterial.

Cellulose Nanocrystal Surface Cationization: A New Fungicide with High Activity against Phycomycetes capsici

At present, the management of Phytophthora capsici (P. capsici) mainly relies on chemical pesticides. However, along with the resistance generated by P. capsici to these chemical pesticides, the toxicity and non-degradability of this chemical molecule may also cause serious environmental problems. Herein, a new bio-based nano-antifungal material (CNC@CTAB) was made with coating hexadecyl trimethyl ammonium bromide (CTAB) on the surface of a cellulose nanocrystal (CNC). This material was then applied to the prevention of P. capcisi. This particle was facilely fabricated by mixing CTAB and sulfuric group modified CNC in an aqueous solvent. Compared to pure CTAB, the enrichment of CTAB on the CNC surface showed a better anti-oomycete activity both in vitro and in vivo. When CNC@CTAB was applied on P. capsici in vitro, the inhibition rate reached as high as 100%, while on the pepper leaf, the particle could also efficiently prevent the infection of P. capsici, and achieve a disease index as low as zero Thus, considering the high safety of CNC@CTAB in agricultural applications, and its high anti-oomycete activity against P. capsici, we believe that this CNC@CTAB has great application potential as a new green nano-fungicide in P. capsici management during the production of peppers or other vegetables.

Synthesis and characterization of new hydrolytic-resistant dental resin adhesive monomer HMTAF

Hydrolytic and enzymatic degradation of resin adhesives over time has been mainly attributed to secondary caries formation of methacrylate-based tooth-colored resin-based composite restorations. Ability of resin adhesive monomers to infiltrate into demineralized dentin forming stiff polymer matrix and potentially bonding to tooth structure is also a crucial property. The only commercially available antibacterial monomer, 12-methacryloyloxydodecyl pyridinium bromide (MDPB), is a quaternary ammonium methacrylate. This methacrylate monomer undergoes hydrolytic degradation, and could not bond to tooth structure. In this study, a new hydrolytic resistant monomer HMTAF was synthesized. It is methacrylamide-based monomer that, unlike methacrylate, is highly resistant to hydrolysis. Its molecular structure has particular functional groups; quaternary ammonium fluoride salt with potential antibacterial fluoride-releasing activity, hydroxyl and amide group with hydrogen bonding potential to dentin collagen. Hydroxyl group also increases monomer hydrophilicity for better penetration into water-saturated dentin and sufficient resin-dentin bond. The synthesized HMTAF and its polymer showed no hydrolytic degradation in acidic environment, while MDPB and its polymer were partially decomposed under this challenge. The conversion of monomer HMTAF to polymer was illustrated by FT-IR. The results indicated that HMTAF is highly resistant to hydrolysis, polymerizable and non-cytotoxic to Vero cell lines. It is a potential monomer to be incorporated into resin adhesives for improving hydrolytic and enzymatic resistance.

Preparation of chitin-amphipathic anion/quaternary ammonium salt ecofriendly dressing and its effect on wound healing in mice

Objective

This study aimed to prepare an eco-friendly dressing using a chitin-derived membrane with amphipathic anion/quaternary ammonium salt designed for antibacterial purposes.

Methods

Four dressings were prepared and group A was chitin, group B was chitin + amphiphilic ion, group C was chitin + quaternary ammonium salt, group D was chitin + amphiphilic ion + quaternary ammonium salt.

Results

In the group D material, precipitation of adherent composite ions was observed. The contact angle test showed that the material was hydrophilic. The drug loading rate in groups B, C, and D was 40-50 (ug:mg), the entrapment efficiency was 70%-75% (P>0.05), and the cumulative release percentages were 87.3%, 88.7%, and 90.2% after 72h for group B, C, and D, respectively. The anti-bacterial activity in vitro was in the order D>C>B>A> control (P>0.05). The anti-pollution activity in vitro was in the order D>B>C>A (P<0.05). The cell proliferation inhibition test showed slight proliferation inhibition (P<0.05) only on the seventh day for group D. Seven days after injury, the wound healing rate was in the order D>C> commercial chitin dressing >B>A> control (P<0.05), and the length of the neonatal epithelium also showed the same trend. Additionally, PCNA and CD31 expression indicated that cell proliferation and angiogenesis were enhanced when skin defects were covered with the D group material (P<0.05).

Conclusion

chitin-amphiphilic ion/quaternary ammonium salt dressing was successfully prepared. The antibacterial and antipollution effects of the prepared material (group D) were both very good, acting to promote wound healing.

pH-Sensitive Compounds for Selective Inhibition of Acid-Producing Bacteria

Stimuli-responsive compounds that provide on-site, controlled antimicrobial activity promise an effective approach to prevent infections, reducing the need for systemic antibiotics. We present a novel pH-sensitive quaternary pyridinium salt (QPS), whose antibacterial activity is boosted by low pH and controlled by adjusting the pH between 4 and 8. Particularly, this compound selectively inhibits growth of acid-producing bacteria within a multispecies community. The successful antibacterial action of this QPS maintains the environmental pH above 5.5, a threshold pH, below which demineralization/erosion takes place. The design, synthesis, and characterization of this QPS and its short-chain analogue are discussed. In addition, their pH-sensitive physicochemical properties in aqueous and organic solutions are evaluated by UV-vis spectroscopy, dynamic light scattering, and NMR spectroscopy. Furthermore, the mechanism of action reveals a switchable assembly that is triggered by acid-base interaction and formed by tightly stacked π-conjugated systems and base moieties. Finally, a model is proposed to recognize the correlated but different mechanisms of pH sensitivity and acid-induced, pH-controlled antibacterial efficacy. We anticipate that successful application of these QPSs and their derivatives will provide protections against infection and erosion through targeted treatments to acid-producing bacteria and modulation of environmental pH.

[Antibacterial dental adhesive containing nanoantibacterial inorganic fillers]

OBJECTIVE

This investigation aimed to develop a novel antibacterial dental adhesive containing nanoantibacterial inorganic fillers and measure the dentin bonding strength, mechanical properties, and antibacterial property of the novel adhesive in vitro.

METHODS

Novel nanoantibacterial inorganic fillers containing quaternary ammonium salt with long chain alkyl were synthesized on the basis of previous research. These novel nanoantibacterial inorganic fillers were added into the dental adhesive to prepare novel nanoantibacterial dental resin composite at mass fractions of 0%, 2.5%, 5.0%, 7.5%, and 10%; 0% was used as control. Dentin shear bonding test was used to evaluate the bonding strength. Flexural test was utilized to measure the novel resin composite flexural strength and elastic modulus. A dental plaque microcosm biofilm model with human saliva as inoculum was formed. Colony forming unit, lactic acid production, and live/dead assay of the biofilm on novel dental adhesive were calculated to assess the effect of novel dental adhesive on human dental plaque microcosm biofilm.

RESULTS

The dentin shear bond strength, flexural strength, and elastic modulus were 28.9 MPa, 86.6 MPa, and 4.2 GPa, respectively, when the nanoantibacterial inorganic filler mass fraction in the dental adhesive reached approximately 5.0%. Consequently, the dentin shear bond strength and mechanical properties significantly increased. Addition of 2.5% nanoantibacterial inorganic fillers into the dental adhesive exerted no adverse effect on the mechanical properties significantly (P>0.05). Dental adhesive containing 5% or more nanoantibacterial inorganic fillers inhibited the metabolic activity of the dental plaque microcosm biofilm significantly, thereby displaying a strong antibacterial potency (P<0.05).

CONCLUSIONS

This novel antibacterial dental adhesive, which contained 5.0% nanoantibacterial inorganic filler, exhibited promising bonding strength, mechanical property, and antibacterial ability. Hence, this adhesive can be potentially used in caries inhibition in dental application.

Quaternary ammonium salts substituted by 5-phenyl-1,3,4-oxadiazole-2-thiol as novel antibacterial agents with low cytotoxicity

Twenty-one novel 5-phenyl-1,3,4-oxadiazole-2-thiol (POT) substituted N-hydroxyethyl quaternary ammonium salts (6a-g, 7a-g, 8a-g) were prepared and characterized by FTIR, NMR, and elemental analysis. Compounds 6a, 6c, and 8a were confirmed by X-ray single-crystal diffraction. They display the unsurpassed antibacterial activity against Staphylococcus aureus, α-H-tococcus, Escherichia coli, P. aeruginosa, Proteus vulgaris, Canidia Albicans, especially 6g, 7g, 8g with dodecyl group. Compounds 8a-d with N,N-dihydroxyethyl and POT groups display unsurpassed antibacterial activity and non-toxicity. The structure-activity relationships indicate that POT and flexible dihydroxyethyl group in QAS are necessary for antibacterial activity and cytotoxicity. SEM and TEM images of E. coli morphologies of 8d show the antibacterial agents can adhere to membrane surfaces to inhibit bacterial growth by disrupting peptidoglycan formation and releasing bacterial cytoplasm from cell membranes.

Physicochemical properties and cytotoxicity of an experimental resin-based pulp capping material containing the quaternary ammonium salt and Portland cement

AIM

To evaluate in vitro the physicochemical properties, cytotoxicity and calcium phosphate nucleation of an experimental light-curable pulp capping material composed of a resin with antibacterial monomer (MAE-DB) and Portland cement (PC).

METHODOLOGY

The experimental material was prepared by mixing PC with a resin containing MAE-DB at a 2 : 1 ratio. Cured pure resin containing MAE-DB served as control resin. ProRoot MTA and Dycal served as commercial controls. The depth of cure, degree of monomer conversion, water absorption and solubility of dry samples, calcium release, alkalinizing activity, calcium phosphate nucleation and the cytotoxicity of materials were evaluated. Statistical analysis was carried out using anova followed by Tukey's HSD test (equal variance assumed) or Tamhane test (equal variance not assumed) and independent-samples t-tests.

RESULTS

The experimental material had a cure depth of 1.19 mm, and the mean degree of monomer conversion was 70.93% immediately post-cure and 88.75% at 24 h post-cure. The water absorption of the experimental material was between those of MTA and Dycal, and its solubility was significantly less (P < 0.05) than that of Dycal and higher than that of MTA. The experimental material exhibited continuous calcium release and an alkalinizing power between those of MTA and Dycal throughout the test period. Freshly set experimental material, control resin and all 24-h set materials had acceptable cytotoxicity. The experimental material, MTA and Dycal all exhibited the formation of apatite precipitates after immersion in phosphate-buffered saline.

CONCLUSIONS

The experimental material possessed adequate physicochemical properties, low cytotoxicity and good calcium phosphate nucleation.

Mutagenic activity of quaternary ammonium salt derivatives of carbohydrates

This paper presents a study on a series of quaternary ammonium salt (QAS) derivatives of glucopyranosides with an elongated hydrophobic hydrocarbon chain. The new N-[6-(β-D-glucopyranosyloxy)hexyl]ammonium bromides and their O-acetyl derivatives were analyzed via (1)H and (13)C NMR spectroscopy. The mutagenic activity of the newly synthesized QAS was investigated using two different techniques: The Vibrio harveyi luminescence assay and the Ames test. The obtained results support previous findings contesting QAS safety and indicate that QAS, specifically pyridinium derivatives, might be mutagenic.

Ionic Compatibilization of Cellulose Nanocrystals with Quaternary Ammonium Salt and Their Melt Extrusion with Polypropylene

On account to their high mechanical properties along with high reinforcing capacity, cellulose nanocrystals (CNCs) could be the ultimate choice for polymer nanocomposites as filler. Recently, different strategies have been investigated for the melt extrusion of CNC-based polymer nanocomposites because it is a solvent-free process and because this technique is more viable for commercial industrialization. However, most thermoplastic polymers are processed at high temperatures, and sulfuric acid preparation of CNC limits the processing because of surface sulfate groups degradation. In this study we profitably used these negatively charged groups, and quaternary ammonium salt was ionically adsorbed on CNC by a simple aqueous method. Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction were used to characterize adsorbed CNC, and changes in polarity were investigated by contact angle measurements. Modified CNC was extruded with polypropylene at 190 °C, and the ensuing composites were characterized in terms of mechanical (by dynamic mechanical analysis and tensile tests), thermal (by differential scanning calorimetry), and morphological (scanning electron microscopy) properties. The melt rheology of PP-based nanocomposites was also reported.

Quaternary ammonium salt of chitosan: preparation and antimicrobial property for paper

A series of 2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC) was prepared by the reaction of chitosan with glycidyl trimethyl ammonium chloride. Structure of HACC was characterized by FT IR and 1H NMR spectroscopies, and it was proved that substitution reaction mainly occurs on the N element. Antimicrobial activities of HACC was examined against S. aureus, E. coli, and A. niger. Results indicatd that the inhibitory effects of HACC solutions were varied with HACC concentration, quaternization degrees, pH values, metal ions, and heat treatment. The antimicrobial properties of handsheets prepared from HACC were studied by the inhibition zone method, and the sheets had good antimicrobial properties against S. aureus and E. coli, and low inhibition rate against A. niger.

[Dental plaque microcosm biofilm behavior on a resin composite incorporated with nano-antibacterial inorganic filler containing long-chain alkyl quaternary ammonium salt]

OBJECTIVE

To develop a resin composite incorporated with nano-antibacterial inorganic filler containing long-chain alkyl quaternary ammonium salt, and to measure its effect on human dental plaque microcosm biofilm.

METHODS

A novel nano-antibacterial inorganic filler containing long-chain alkyl quaternary ammonium salt was synthesized according to methods introduced in previous research. Samples of the novel nano-antibacterial inorganic fillers were modified by a coupling agent and then added into resin composite at 0%, 5%, 10%, 15% or 20% mass fractions; 0% composite was used as control. A flexural test was used to measure resin composite mechanical properties. Results showed that a dental plaque microcosm biofilm model with human saliva as inoculum was formed. Colony-forming unit (CFU) counts, lactic acid production, and live/dead assay of biofilm on the resin composite were calculated to test the effect of the resin composite on human dental plaque microcosm biofilm.

RESULTS

The incorporation of nano-antibacterial inorganic fillers with as much as 15% concentration into the resin composite showed no adverse effect on the mechanical properties of the resin composite (P > 0.05). Resin composite containing 5% or more nano-antibacterial inorganic fillers significantly inhibited the metabolic activity of dental plaque microcosm biofilm, suggesting its strong antibacterial potency (P < 0.05).

CONCLUSION

This novel resin composite exhibited a strong antibacterial property upon the addition of up to 5% nano-antibacterial inorganic fillers, thereby leading to effective caries inhibition in dental application.

[Dental plaque microcosm biofilm behavior on a resin composite incorporated with nano-antibacterial inorganic filler containing long-chain alkyl quaternary ammonium salt]

OBJECTIVE

To develop a resin composite incorporated with nano-antibacterial inorganic filler containing long-chain alkyl quaternary ammonium salt, and to measure its effect on human dental plaque microcosm biofilm.

METHODS

A novel nano-antibacterial inorganic filler containing long-chain alkyl quaternary ammonium salt was synthesized according to methods introduced in previous research. Samples of the novel nano-antibacterial inorganic fillers were modified by a coupling agent and then added into resin composite at 0%, 5%, 10%, 15% or 20% mass fractions; 0% composite was used as control. A flexural test was used to measure resin composite mechanical properties. Results showed that a dental plaque microcosm biofilm model with human saliva as inoculum was formed. Colony-forming unit (CFU) counts, lactic acid production, and live/dead assay of biofilm on the resin composite were calculated to test the effect of the resin composite on human dental plaque microcosm biofilm.

RESULTS

The incorporation of nano-antibacterial inorganic fillers with as much as 15% concentration into the resin composite showed no adverse effect on the mechanical properties of the resin composite (P > 0.05). Resin composite containing 5% or more nano-antibacterial inorganic fillers significantly inhibited the metabolic activity of dental plaque microcosm biofilm, suggesting its strong antibacterial potency (P < 0.05).

CONCLUSION

This novel resin composite exhibited a strong antibacterial property upon the addition of up to 5% nano-antibacterial inorganic fillers, thereby leading to effective caries inhibition in dental application.

Antimicrobial polymeric materials with quaternary ammonium and phosphonium salts

Polymeric materials containing quaternary ammonium and/or phosphonium salts have been extensively studied and applied to a variety of antimicrobial-relevant areas. With various architectures, polymeric quaternary ammonium/phosphonium salts were prepared using different approaches, exhibiting different antimicrobial activities and potential applications. This review focuses on the state of the art of antimicrobial polymers with quaternary ammonium/phosphonium salts. In particular, it discusses the structure and synthesis method, mechanisms of antimicrobial action, and the comparison of antimicrobial performance between these two kinds of polymers.

Synthesis, characterization and antibacterial properties of dihydroxy quaternary ammonium salts with long chain alkyl bromides

Five N-methyl-N-R-N,N-bis(2-hydroxyethyl) ammonium bromides (R = -benzyl (chloride, BNQAS), -dodecyl (C12QAS), -tetradecyl (C14QAS), -hexadecyl (C16QAS), -octadecyl (C18QAS)) were prepared based on N-methyldiethanolamine (MDEA) and halohydrocarbon. Five QAS were characterized by FTIR, NMR, and MS. BNQAS, C12QAS, C14QAS, and C16QAS were confirmed by X-ray single-crystal diffraction. Their antibacterial properties indicated good antibacterial abilities against E. coli, S. aureus, B. subtilis, especially C12QAS with the best antibacterial ability (100% to E. coli, 95.65% to S. aureus, and 91.41% to B. subtilis). In addition, C12QAS also displayed the best antifungal activities than BNQAS and C18QAS against Cytospora mandshurica, Botryosphaeria ribis, Physalospora piricola, and Glomerella cingulata with the ratio of full marks. The strategy provides a facile way to design and develop new types of antibacterial drugs for application in preventing the fruit rot, especially apple.

[Synthesis of a nano-antibacterial inorganic filler containing a quaternary ammonium salt with long chain alkyl and its effect on dental resin composites]

OBJECTIVE

This study aimed to synthesize a novel nano-antibacterial inorganic filler that contains a quaternary ammonium salt with long chain alkyl and to report the antibacterial property of dental resin composites.

METHODS

A novel nano-antibacterial inorganic filler that contains a quaternary ammonium salt with long chain alkyl was synthesized based on previous research. The antibacterial property of the filler was measured. The surface of the novel nano-antibacterial inorganic filler was modified by a coupling agent to achieve a good interfacial bonding between the filler and the resin matrix. Infrared spectrum analysis was carried out. The modified novel nano-antibacterial inorganic fillers were then incorporated into the dental resin matrix. The dispersion of the fillers was observed and compared with those incorporated into Tetric N-Ceram, a commercial resin composite, under a scanning electron microscope. Streptococcus mutans was used in testing the antibacterial property of the dental resin composites.

RESULTS

A quaternary ammonium salt with a long chain alkyl was successfully grafted onto the surface of nano-silica particles. The novel nano-antibacterial inorganic filler that contains quaternary ammonium salt with a long chain alkyl showed stronger antibacterial efficacy than the antibacterial inorganic filler that contains quaternary ammonium salt with a short chain alkyl. The modified novel antibacterial inorganic fillers displayed a homogeneous dispersion in the resin composite bulk and combined closely with the resin matrix, similar to the Tetric N-Ceram. The resin composites that contain novel antibacterial inorganic fillers showed stronger antibacterial effect on Streptococcus mutans compared with the control group.

CONCLUSION

The novel nano-antibacterial inorganic filler that contains a quaternary ammonium salt with long chain alkyl showed a strong antibacterial property. It also exhibited good compatibility with the dental resin matrix after undergoing coupling treatment.

[Synthesis of a nano-antibacterial inorganic filler containing a quaternary ammonium salt with long chain alkyl and its effect on dental resin composites]

OBJECTIVE

This study aimed to synthesize a novel nano-antibacterial inorganic filler that contains a quaternary ammonium salt with long chain alkyl and to report the antibacterial property of dental resin composites.

METHODS

A novel nano-antibacterial inorganic filler that contains a quaternary ammonium salt with long chain alkyl was synthesized based on previous research. The antibacterial property of the filler was measured. The surface of the novel nano-antibacterial inorganic filler was modified by a coupling agent to achieve a good interfacial bonding between the filler and the resin matrix. Infrared spectrum analysis was carried out. The modified novel nano-antibacterial inorganic fillers were then incorporated into the dental resin matrix. The dispersion of the fillers was observed and compared with those incorporated into Tetric N-Ceram, a commercial resin composite, under a scanning electron microscope. Streptococcus mutans was used in testing the antibacterial property of the dental resin composites.

RESULTS

A quaternary ammonium salt with a long chain alkyl was successfully grafted onto the surface of nano-silica particles. The novel nano-antibacterial inorganic filler that contains quaternary ammonium salt with a long chain alkyl showed stronger antibacterial efficacy than the antibacterial inorganic filler that contains quaternary ammonium salt with a short chain alkyl. The modified novel antibacterial inorganic fillers displayed a homogeneous dispersion in the resin composite bulk and combined closely with the resin matrix, similar to the Tetric N-Ceram. The resin composites that contain novel antibacterial inorganic fillers showed stronger antibacterial effect on Streptococcus mutans compared with the control group.

CONCLUSION

The novel nano-antibacterial inorganic filler that contains a quaternary ammonium salt with long chain alkyl showed a strong antibacterial property. It also exhibited good compatibility with the dental resin matrix after undergoing coupling treatment.

Selective detection of carbohydrates and their peptide conjugates by ESI-MS using synthetic quaternary ammonium salt derivatives of phenylboronic acids

We present new tags based on the derivatives of phenylboronic acid and apply them for the selective detection of sugars and peptide-sugar conjugates in mass spectrometry. We investigated the binding of phenylboronic acid and its quaternary ammonium salt (QAS) derivatives to carbohydrates and peptide-derived Amadori products by HR-MS and MS/MS experiments. The formation of complexes between sugar or sugar-peptide conjugates and synthetic tags was confirmed on the basis of the unique isotopic distribution resulting from the presence of boron atom. Moreover, incorporation of a quaternary ammonium salt dramatically improved the efficiency of ionization in mass spectrometry. It was found that the formation of a complex with phenylboronic acid stabilizes the sugar moiety in glycated peptides, resulting in simplification of the fragmentation pattern of peptide-derived Amadori products. The obtained results suggest that derivatization of phenylboronic acid as QAS is a promising method for sensitive ESI-MS detection of carbohydrates and their conjugates formed by non-enzymatic glycation or glycosylation.