Bioinspired nanoarchitectonics at the air-water interface to understand the interaction of lipids with a Europium-coordinated quinoline derivative

5SO3H-8-hydroxyquinoline coordinated to Europium (Eu-5SO3-HQ) was incorporated in biomembrane models using Langmuir monolayers. Dipalmitoyl phosphatidylcholine (DPPC) and dipalmitoyl phosphatidylserine (DPPS) were employed, representing mammalian cells and dioctadecyldimethylammonium bromide (DODAB) as a positively charged lipid to study the contrast with negatively charged lipids. Tensiometric, rheological and spectroscopic techniques were employed to characterize Eu-5SO3-HQ- lipid monolayer interactions. The complex condenses all the monolayer indicating interactions with the lipids' polar heads, but with distinctive effects on the mechanical and rheological properties. While the complex decreases the compression and elastic moduli of DPPC and DPPS monolayers, it increases for DODAB, also decreasing its lateral viscosity. Infrared spectroscopy shows that the interaction of Eu-5-SO3-HQ alters the ordering of the lipids' alkyl chains, impacting the monolayer's molecular packing. These results show that the interaction of Eu-5SO3-HQ with lipid monolayers at the air-water is modulated by the composition of the polar head, which can be supportive in the preparation of nanodevices for molecular probing.

Synthesis and evaluation of Fmoc-amino esters and amides bearing a substrate like quaternary ammonium group as selective butyrylcholinesterase inhibitors

The depletion of the neurotransmitter acetylcholine has been suggested to contribute to the reduced cognitive function observed in individuals suffering from neurodegenerative diseases such as Alzheimer's Disease (AD). For the two major cholinesterases, butyrylcholinesterase (BChE) and acetylcholinesterase (AChE), increased BChE activity observed in individuals with AD has been suggested to deplete acetylcholine levels. To reduce acetylcholine degradation and help restore the pool of the neurotransmitter, specific and potent BChE inhibitors are sought. Our previous findings have identified 9-fluorenylmethoxycarbonyl (Fmoc) amino acid-based inhibitors as effective BChE inhibitors. The amino acid-based compounds offered the opportunity to survey a range of structural features to enhance interactions with the enzyme active site. As enzymes interact with features of their substrates, incorporation of substrate-like features was predicted to lead to better inhibitors. Specifically, incorporation of a trimethylammonium moiety to mimic the cationic group of acetylcholine may lead to increased potency and selectivity. To test this model, a series of inhibitors bearing a cationic trimethylammonium group were synthesized, purified, and characterized. While the Fmoc-ester derivatives inhibited the enzyme, additional experiments showed the compounds acted as substrates and were enzymatically hydrolyzed. Inhibition studies with the Fmoc-amide derivatives showed that the compounds do not act as substrates and selectively inhibit BChE with IC50 values in the 0.06-10.0 µM range. Computational docking studies suggest that the inhibitors can interact with cholinyl binding site and peripheral site. Overall, the results suggest that introducing substrate-like characteristics within the Fmoc-amino acid-based background increases their potency. The versatile and ready access to amino acid-based compounds offers an attractive system to further our understanding of the relative importance of protein-small molecule interactions while guiding the development of better inhibitors.

The structure of biodegradable surfactants shaped the microbial community, antimicrobial resistance, and potential for horizontal gene transfer

While most household surfactants are biodegradable in aerobic conditions, their biodegradability may obscure their environmental risks. The presence of surfactants in a biological treatment process can lead to the proliferation of antimicrobial-resistance genes (ARG) in the biomass. Surfactants can be cationic, anionic, or zwitterionic, and these different classes may have different effects on the proliferation ARG. Cationic hexadecyltrimethyl-ammonium (CTAB), anionic sodium dodecyl sulfate (SDS), and zwitterionic 3-(decyldimethylammonio)-propanesulfonate inner salt (DAPS) were used to represent the three classes of surfactants in domestic household clean-up products. This study focused on the removal of these surfactants by the O₂-based Membrane Biofilm Reactor (O_2-MBfR) for hotspot scenarios (∼1 mM) and how the three classes of surfactants affected the microbial community's structure and ARG. Given sufficient O₂ delivery, the MBfR provided at least 98% surfactant removal. The presence and biodegradation for each surfactant uniquely shaped the biofilms' microbial communities and the presence of ARG. CTAB had by far the strongest impact and the higher ARG abundance. In particular, Pseudomonas and Stenotrophomonas, the two main genera in the biofilm treating CTAB, were highly correlated to the abundance of ARG for efflux pumps and antibiotic inactivation. CTAB also led to more functional genes relevant to the Type-IV secretion system and protection against oxidative stress, which also could encourage horizontal gene transfer. Our findings highlight that the biodegradation of quaternary ammonium surfactants, while beneficial, can pose public health concerns from its ability to promote the proliferation of ARG.

Quaternary Ammonium Compounds: A Chemical Class of Emerging Concern

Quaternary ammonium compounds (QACs), a large class of chemicals that includes high production volume substances, have been used for decades as antimicrobials, preservatives, and antistatic agents and for other functions in cleaning, disinfecting, personal care products, and durable consumer goods. QAC use has accelerated in response to the COVID-19 pandemic and the banning of 19 antimicrobials from several personal care products by the US Food and Drug Administration in 2016. Studies conducted before and after the onset of the pandemic indicate increased human exposure to QACs. Environmental releases of these chemicals have also increased. Emerging information on adverse environmental and human health impacts of QACs is motivating a reconsideration of the risks and benefits across the life cycle of their production, use, and disposal. This work presents a critical review of the literature and scientific perspective developed by a multidisciplinary, multi-institutional team of authors from academia, governmental, and nonprofit organizations. The review evaluates currently available information on the ecological and human health profile of QACs and identifies multiple areas of potential concern. Adverse ecological effects include acute and chronic toxicity to susceptible aquatic organisms, with concentrations of some QACs approaching levels of concern. Suspected or known adverse health outcomes include dermal and respiratory effects, developmental and reproductive toxicity, disruption of metabolic function such as lipid homeostasis, and impairment of mitochondrial function. QACs' role in antimicrobial resistance has also been demonstrated. In the US regulatory system, how a QAC is managed depends on how it is used, for example in pesticides or personal care products. This can result in the same QACs receiving different degrees of scrutiny depending on the use and the agency regulating it. Further, the US Environmental Protection Agency's current method of grouping QACs based on structure, first proposed in 1988, is insufficient to address the wide range of QAC chemistries, potential toxicities, and exposure scenarios. Consequently, exposures to common mixtures of QACs and from multiple sources remain largely unassessed. Some restrictions on the use of QACs have been implemented in the US and elsewhere, primarily focused on personal care products. Assessing the risks posed by QACs is hampered by their vast structural diversity and a lack of quantitative data on exposure and toxicity for the majority of these compounds. This review identifies important data gaps and provides research and policy recommendations for preserving the utility of QAC chemistries while also seeking to limit adverse environmental and human health effects.

Soft QPCs: Biscationic Quaternary Phosphonium Compounds as Soft Antimicrobial Agents

Quaternary ammonium compounds (QACs) serve as a first line of defense against infectious pathogens. As resistance to QACs emerges in the environment, the development of next-generation disinfectants is of utmost priority for human health. Balancing antibacterial potency with environmental considerations is required to effectively counter the development of bacterial resistance. To address this challenge, a series of 14 novel biscationic quaternary phosphonium compounds (bisQPCs) have been prepared as amphiphilic disinfectants through straightforward, high-yielding alkylation reactions. These compounds feature decomposable or "soft" amide moieties in their side chains, anticipated to promote decomposition under environmental conditions. Strong bioactivity against a panel of seven bacterial pathogens was observed, highlighted by single-digit micromolar activity for compounds P6P-12A,12A and P3P-12A,12A. Hydrolysis experiments in pure water and in buffers of varying pH revealed surprising decomposition of the soft QPCs under basic conditions at the phosphonium center, leading to inactive phosphine oxide products; QPC stability (>24 h) was maintained in neutral solutions. The results of this work unveil soft QPCs as a potent and environmentally conscious new class of bisQPC disinfectants.

DOTAP: Structure, hydration, and the counterion effect

The cationic lipid 1,2-dioleoyl-3-trimethylammonium propane (DOTAP) is one of the original synthetic cationic lipids used for the liposomal transfection of oligonucleotides in gene therapy. The key structural element of DOTAP is its quaternary ammonium headgroup that is responsible for interactions with both nucleic acids and target cell membranes. Because these interactions are fundamental to the design of a major class of transfection lipids, it is important to understand the structure of DOTAP and how it interacts with halide counterions. Here, we use x-ray and neutron diffraction techniques to examine the structure of DOTAP and how chloride (Cl-) and iodide (I-) counterions alter the hydration properties of the DOTAP headgroup. A problem of particular interest is the poor solubility of DOTAP/I- in water solutions. Our results show that the poor solubility results from very tight binding of the I- counterion to the headgroup and the consequent expulsion of water. The structural principles we report here are important for assessing the suitability of DOTAP and its quaternary ammonium derivatives for transfection.

The effect of 1,2-dioleoyl-3-trimethylammonium propane (DOTAP) Addition on the physical characteristics of β-ionone liposomes

β-ionone (ION) is a cyclic terpenoid compound that demonstrates considerable potential for the prevention and treatment of cancer. However, the water solubility of β-ionone is poor and the compound demonstrates low permeability. Liposomes have been reported as increasing both qualities. In this study, the development of β-ionone liposomes was initiated by adding 1,2-dioleoyl-3-trimethylammonium propane (DOTAP) to produce cationic liposomes as a means of enhancing binding to cancer cells. Liposomes composed of β-ionone, HSPC, cholesterol, and DSPE-mPEG2000 were prepared using the thin layer hydration method. Cellular uptake studies were carried out with HeLa cells incubated with β-ionone liposomes for two hours. The results indicated that the addition of DOTAP increased particle size and affected the spectroscopical and thermogram profiles of the liposomes, thereby confirming reduction in liposome crystallinity, while the zeta potential became positive. Moreover, the calcein release profile further showed that additional DOTAP increased both membrane fluidity and cellular uptake in HeLa cells In conclusion, adding DOTAP affected the physicochemical cationic properties of liposome and improved cellular uptake in HeLa cells.

Atom Economical QPCs: Phenyl-Free Biscationic Quaternary Phosphonium Compounds as Potent Disinfectants

Quaternary ammonium compounds (QACs) are vital disinfectants for the neutralization of pathogenic bacteria in clinical, domestic, and commercial settings. After decades of dependence on QACs, the emergence of antimicrobial resistance to this class of compounds threatens the ability of existing QAC products to effectively manage rising bacterial threats. The need for new disinfectants is therefore urgent, with quaternary phosphonium compounds (QPCs) emerging as a new class of promising antimicrobials that boast significant activity against highly resistant bacteria. Reported here is a series of twenty-one novel QPCs that replace phenyl substituents on the phosphorus center with alkyl groups yet allow for rapid synthetic routes in high yields. Within this series are structures containing methyl, ethyl, or cyclohexyl phosphonium substituents on bisphosphane scaffolds bearing ethyl linkers, affording atom economical structures and ones that represent exact analogs to nitrogenous amphiphiles. The resultant bisQPC structures display high antibacterial efficacy enjoyed by comparably constructed QACs, with three structures in the single-digit micromolar activity range despite structural simplification.

Design, Physical Characterizations, and Biocompatibility of Cationic Solid Lipid Nanoparticles in HCT-116 and 16-HBE Cells: A Preliminary Study

In this study, pEGFP-LUC was used as a model plasmid and three distinct cationic lipids (dioleyloxy-propyl-trimethylammonium chloride [DOTMA], dioleoyl trimethylammonium propane [DOTAP], and cetylpyridinium chloride [CPC]) were tested along with PEG 5000, as a nonionic surfactant, to prepare glyceryl monostearate (GMS)-based cationic solid lipid nanoparticles (cSLNs). Both the type and quantity of surfactant had an impact on the physicochemical characteristics of the cSLNs. Thermal analysis of the greater part of the endothermic peaks of the cSLNs revealed they were noticeably different from the individual pure compounds based on their zeta potential (ZP ranging from +17 to +56 mV) and particle size (PS ranging from 185 to 244 nm). The addition of cationic surfactants was required to produce nanoparticles (NPs) with a positive surface charge. This suggested that the surfactants and extensive entanglement of the lipid matrix GMS provided support for the behavioral diversity of the cSLNs and their capacity to interface with the plasmid DNA. Additionally, hemolytic assays were used to show that the cSLNs were biocompatible with the human colon cancer HCT-116 and human bronchial epithelial 16-HBE cell lines. The DOTMA 6-based cSLN was selected as the lead cSLN for further ex vivo and in vivo investigations. Taken together, these new findings might provide some guidance in selecting surfactants to prepare extremely efficient and non-toxic cSLN-based therapeutic delivery systems (e.g., gene therapy).

Photochemically Driven Polymeric Biocompatible and Antimicrobial Thiol-Acrylate Nanocomposite Suitable for Dental Restoration

The development a photochemically driven polymeric composite for dental restorative materials to restore tooth cavities with antibacterial, biocompatibility, and outstanding mechanical properties is an urgent need for clinical application in stomatology. Herein, a series of polyurethane acrylate (PUA) prepolymers and antibacterial polyurethane acrylate quaternary ammonium salts (PUAQASs) were synthesized, and their mechanical and biological properties were explored. The unique secondary mercaptan with a long shelf life and low odor was used to reduce oxygen inhibition and increase cross-linking density; meanwhile, modified photocurable nano zirconia (nano ZrO₂) enhances mechanical properties of the nanocomposites and possesses preeminent dispersion in the matrix. The results show that minimal inhibitory concentrations (MICs) of PUAQASs are 200 and 800 μg/mL for Staphylococcus aureus and Escherichia coli, respectively. The addition of secondary thiols significantly increases the photopolymerization rate and monomer conversion. The highest hardness and modulus reach 1.8 and 8.7 GPa compared to 1.8 and 8.3 GPa for commercial resin. The lap shear stress on the pig bone is 912 MPa, and that on commercial resin is 921 MPa. Most importantly, the photochemically driven polymeric composite has excellent biocompatibility and significantly better antimicrobial properties than commonly used commercial resins.

Highly Permeable Polylactic Acid Membrane Grafted with Quaternary Ammonium Salt for Effective and Durable Water Disinfection

Given the increasing usage of drinking water purifiers, highly permeable membranes with strong antimicrobial functions are desperately desirable for effective and durable water disinfection. Hereby, we prepared such antimicrobial membranes by chemical grafting of quaternary ammonium salt (QAS) molecules, 3-(trimethoxysilyl)propyldimethyloctadecyl ammonium chloride (TPMMC), onto air plasma pretreated biodegradable polylactic acid (PLA) substrates. The high chemical grafting density promoted very strong and positive zeta potential charge of the resulted PLA-QAS membrane, contributing to effective and broad-spectrum antimicrobial efficiencies (>99.99%) against different microbes, including fungi and conventional and drug-resistant bacteria. The solid grafting of QAS molecules produced a durable antimicrobial performance of the PLA-QAS membrane. In addition, the pleated filter (0.45 m²) of PLA-QAS membrane showed outstanding bacteria rejection properties (>99.99%) and excellent washing durability (up to 20 m³ water) even at very high water filtration rates (up to 4 L/min). The disinfection mechanism was clarified that negatively charged bacteria could be rapidly adsorbed to positively charged PLA-QAS spinnings, followed by devastating cell membrane damage to bacterial debris, leaving a clean environment without significant biofilm and biofouling formation.

A Water-Soluble Leggero Pillar[5]arene

The study of aqueous-phase molecular recognition of artificial receptors is one of the frontiers in supramolecular chemistry since most biochemical processes and reactions take place in an aqueous medium and heavily rely on it. In this work, a water-soluble version of leggero pillar[5]arene bearing eight positively charged pyridinium moieties (CWP[5]L) was designed and synthesized, which exhibited good binding affinities with certain aliphatic sulfonate species in aqueous solutions. Significantly, control experiments demonstrate that the guest binding performance of CWP[5]L is superior to its counterpart water-soluble macrocyclic receptor in traditional pillararenes.

Influence of cationic groups on the antibacterial behavior of cationic nano-sized hyperbranched polymers to enhance bacteria-infected wound healing

With the continuous emergence of drug-resistant pathogens, new strategies with high antibacterial efficacy are urgently needed. Herein, five cationic nano-sized hyperbranched polymers (CNHBPs) with cationic functional groups have been constructed, and their antibacterial mechanism has been studied in detail. CNHBPs bearing secondary ammonium salt groups and long alkyl chains (S₁₂-CNHBP) exhibited weak antibacterial and antibiofilm ability, while CNHBPs bearing quaternary ammonium salt groups and long alkyl chains (Q₁₂-CNHBP) showed the highest antimicrobial and strongest antibiofilm activities. ζ potential and isothermal titration microcalorimetry (ITC) results suggest that the negatively charged surfaces of bacterial cells provided Q₁₂-CNHBP with a higher intrinsic electrostatic driving force for bacterial killing than that with S₁₂-CNHBP. Fluorescent tracing and morphological observations indicate that the bacterial genome might be another antibacterial target for S₁₂-CNHBP in addition to the cell wall and membrane, which are mainly antibacterial targets for Q₁₂-CNHBP, making it less likely to induce bacterial resistance. Surprisingly, Q₁₂-CNHBP exhibited superior in vivo therapeutic efficacy in a mouse wound model of methicillin-resistant Staphylococcus aureus (MRSA) infection with low toxicity during treatment. These advantages and ease of preparation will undoubtedly distinguish Q₁₂-CNHBP as a new class of suitable candidates to combat multidrug-resistant pathogen infections. This study opens up a new avenue for exploiting antibacterial biomaterials to treat infections caused by drug-resistant bacteria.

The first detection of quaternary ammonium compounds in breast milk: Implications for early-life exposure

BACKGROUND

Quaternary ammonium compounds (QACs), commonly used in cleaning, disinfecting, and personal care products, have recently gained worldwide attention due to the massive use of disinfectants during the COVID-19 pandemic. However, despite extensive use of these chemicals, no studies have focused on the analysis of QACs in human milk, a major route of exposure for infants.

OBJECTIVE

Our objectives were to identify and measure QACs in breast milk and evaluate early-life exposure to this group of compounds for nursing infants.

METHODS

Eighteen QACs, including 6 benzylalkyldimethyl ammonium compounds (BACs, with alkyl chain lengths of C8-C18), 6 dialkyldimethyl ammonium compounds (DDACs, C8-C18), and 6 alkyltrimethyl ammonium compounds (ATMACs, C8-C18), were measured in breast milk samples collected from U.S. mothers. Daily lactational intake was estimated based on the determined concentrations for 0-12 month old nursing infants.

RESULTS

Thirteen of the 18 QACs were detected in breast milk and 7 of them were found in more than half of the samples. The total QAC concentrations (ΣQAC) ranged from 0.33 to 7.4 ng/mL (median 1.5 ng/mL). The most abundant QAC was C14-BAC with a median concentration of 0.45 ng/mL. The highest median ΣQAC estimated daily intake (EDI) was determined for <1-month old infants based on the average (using the median concentration) and high (using the 95th percentile concentration) exposure scenarios (230 and 750 ng/kg body weight/day, respectively).

SIGNIFICANCE

Our findings provide the first evidence of the detection of several QACs in breast milk and identify breastfeeding as an exposure pathway to QACs for nursing infants.

IMPACT STATEMENT

Our findings provide the first evidence of QAC occurrence in breast milk and identify breastfeeding as one of the exposure pathways to QACs for nursing infants.

Catalytic Transformation of Triglycerides to Biodiesel with SiO2-SO3H and Quaternary Ammonium Salts in Toluene or DMSO

SiO₂-SO₃H, with a surface area of 115 m²·g⁻¹, pore volumes of 0.38 cm³·g⁻¹ and 1.32 mmol H⁺/g, was used as a transesterification catalyst. Triglycerides of waste cooking oil reacted with methanol in refluxing toluene to yield mixtures of diglycerides, monoglycerides and fatty acid methyl esters (FAMEs) in the presence of 20% (w/w) catalyst/oil using the hydrophilic sulfonated silica (SiO₂-SO₃H) catalyst alone or with the addition of 10% (w/w) co-catalyst/oil [(Buⁿ₄N)(BF₄) or Aliquat 336]. The addition of the ammonium salts to the catalyst lead to a decrease in the amounts of diglycerides in the products, but the concentrations of monoglycerides increased. Mixtures of (Buⁿ₄N)(BF₄)/catalyst were superior to catalyst alone or Aliquat 336/catalyst for promoting the production of mixtures with high concentrations of FAMEs. The same experiments were repeated using DMSO as the solvent. The use of the more polar solvent resulted in excellent conversion of the triglycerides to FAME esters with all three-catalyst media. A simplified mechanism is presented to account for the experimental results.

Antimicrobial and Antioxidant Activities of N-2-Hydroxypropyltrimethyl Ammonium Chitosan Derivatives Bearing Amino Acid Schiff Bases

N-2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC), a cationic quaternary ammonium salt polymer exhibiting good solubility in water, is widely used because of its low toxicity and good biocompatibility. Herein, through ion exchange reaction, we prepared N-2-hydroxypropyltrimethyl ammonium chitosan derivatives bearing amino acid Schiff bases with good biological activities. The accuracy of the structures was verified by FT-IR and ¹H NMR. The antibacterial activity, antifungal activity, and scavenging ability of DPPH radical and superoxide radical of HACC derivatives were significantly improved compared with that of HACC. In particular, HACGM (HACC-potassium 2-((2-hydroxy-3-methoxybenzylidene)amino)acetate) and HACGB (HACC-potassium 2-((5-bromo-2-hydroxybenzylidene)amino)acetate) showed good inhibitory effect on bacteria and fungi, including Staphylococcus aureus, Escherichia coli, Botrytis cinerea, and Fusarium oxysporum f. sp. cubense. The inhibition rate of HACGB on Staphylococcus aureus and Escherichia coli could reach 100% at the concentration of 0.1 mg/mL, and the inhibition rate of HACGM and HACGB on Botrytis cinerea and Fusarium oxysporum f. sp. cubense could also reach 100% at the concentration of 0.5 mg/mL. Improving antimicrobial and antioxidant activities of HACC could provide ideas and experiences for the development and utilization of chitosan derivatives.

On-DNA Transfer Hydrogenolysis and Hydrogenation for the Synthesis of DNA-Encoded Chemical Libraries

DNA-encoded libraries (DELs) are an increasingly popular approach to finding small molecule ligands for proteins. Many DEL synthesis protocols hinge on sequential additions of monomers using split-pool combinatorial methods. Therefore, compatible protecting group strategies that allow the unmasking of reactive functionality (e. g. amines and alcohols) prior to monomer coupling, or the removal of less desirable functionality (e. g., alkenes and alkynes) are highly desirable. Hydrogenation/hydrogenolysis procedures would achieve these ends but have not been amenable to DEL chemistry. We report a catalytic hydrogen transfer reaction using Pd/C, HCONH4 and the micelle-forming surfactant, TPGS-750-M, which gives highly efficient conversions for hydrogenolysis of Cbz-protected amines and benzyl protected alcohols and hydrogenation of nitros, halides, nitriles, aldehydes, alkenes and alkynes. Application to multicycle synthesis of an encoded compound was fully compatible with DNA-amplification and sequencing, demonstrating its applicability to DEL synthesis. This method will enable synthetic DEL sequences using orthogonal protecting groups.

Sensitive Micro-Breathing Sensing and Highly-Effective Photothermal Antibacterial Cinnamomum camphora Bark Micro-Structural Cotton Fabric via Electrostatic Self-Assembly of MXene/HACC

Natural fabrics are gradually becoming the ideal substrate for flexible smart wearable devices due to their excellent moisture absorption, softness, and skin-friendliness. However, the bonding fastness of the conductive layer and the corresponding durability during service have not yet been well satisfied. In this report, we successfully prepared a smart wearable multifunctional protective cotton fabric with microbreathing monitoring and rapid-photothermal antibacterial abilities of Cinnamomum camphora bark microstructure, by combining chitosan quaternary ammonium salt (HACC) with MXene nanosheets through electrostatic self-assembly. Impressively, MXene nanosheets and HACC established a strong interaction using the electrostatic attraction, endowing the fiber surface with ordered nanosheets. Meanwhile, the fabric decorated with MXene/HACC retains its original characteristics of outstanding breathability and softness, and its conductivity exhibits noticeable stability in terms of resistances to oxidation, washing, various solvents, and long-term bending cycles. On the basis of the principle of adsorption and release of water molecules in the MXene multilayer structures, the MXene/HACC fabric could accurately monitor the physiological health activities of users according to their breathing frequency and depth. Benefiting from the local surface plasmon resonance (LSPR) effect, the MXene/HACC shows encouraging photothermal conversion ability, photothermal stability under long time irradiation, washing resistance, and cycle stability. In addition, the fabric achieved an antibacterial efficiency of nearly 100% against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus within 5 min under an irradiation intensity of 400 mW/cm². More importantly, after 10 washes, the antibacterial efficiency against the two bacteria could still reach 99.975% and 99.98%, respectively. This multifunctional protective MXene/HACC cotton fabric is expected to play a unique role in the new generation of smart wearable microbreathing sensing and against to bacterial attack, and shows a broad application prospect.

Surfactant Effect on the Physicochemical Characteristics of Solid Lipid Nanoparticles Based on Pillar[5]arenes

Novel monosubstituted pillar[5]arenes containing both amide and carboxyl functional groups were synthesized. Solid lipid nanoparticles based on the synthesized macrocycles were obtained. Formation of spherical particles with an average hydrodynamic diameter of 250 nm was shown for pillar[5]arenes containing N-(amidoalkyl)amide fragments regardless of their concentration. It was established that pillar[5]arene containing N-alkylamide fragments can form spherical particles with two different sizes (88 and 223 nm) depending on its concentration. Mixed solid lipid nanoparticles based on monosubstituted pillar[5]arenes and surfactant (dodecyltrimethylammonium chloride) were obtained for the first time. The surfactant made it possible to level the effect of the macrocycle concentration. It was found that various types of aggregates are formed depending on the macrocycle/surfactant ratio. Changing the macrocycle/surfactant ratio allows to control the charge of the particles surface. This controlled property will lead to the creation of molecular-scale porous materials that selectively interact with various types of substrates, including biopolymers.

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.

Montmorillonite clay and quaternary ammonium silane-reinforced pullulan/agar-based nanocomposites and their properties for packaging applications

Synergistic combinations of pullulan, agar, montmorillonite (MMT) clay, and quaternary ammonium silane (QAS)-based (Pullulan/agar/MMT clay/QAS) active nanocomposites were prepared by a simple, cost-effective method. The Pullulan/agar/MMT clay/QAS nanocomposites were studied via Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray diffraction analyses. The concentration of MMT clay played a very important role in the properties of the nanocomposites. However, the transparency of the composite was not significantly affected by the addition of MMT clay. The ultraviolet (UV) transmittance of Pullulan/agar/MMT clay/QAS was in the range of 91.4-79.8 at 600 nm. The thermal and mechanical properties were significantly improved by the MMT clay. The tensile strength and elongation at break of the composites were in the range of 23.8-39.7 MPa and 37.2-26.9%, respectively. The long alkyl chain in QAS significantly improved the hydrophobic nature of the Pullulan/agar/MMT clay nanocomposites, impacting the contact angle (66.2-71.2°), water vapor permeability (3.17-2.20 × 10^-9 g/m² Pa·s), and swelling ratio (1837-836%). The combination of Pullulan/agar/MMT clay/QAS had a synergistic effect on the rheological properties. MMT clay and QAS significantly increased the viscosity, storage, and loss modulus of the hydrogel composites. With the addition of QAS, the Pullulan/agar/MMT clay nanocomposites showed good antimicrobial activity against gram-positive and gram-negative pathogens.

Intracellular signaling pathway in dendritic cells and antigen transport pathway in vivo mediated by an OVA@DDAB/PLGA nano-vaccine

BACKGROUND

Poly(D, L-lactic-co-glycolic acid) (PLGA) nanoparticles have potential applications as a vaccine adjuvant and delivery system due to its unique advantages as biodegradability and biocompatibility.

EXPERIMENTAL

We fabricated cationic solid lipid nanoparticles using PLGA and dimethyl-dioctadecyl-ammonium bromide (DDAB), followed by loading of model antigen OVA (antigen ovalbumin, OVA257-264) to form an OVA@DDAB/PLGA nano-vaccine. And we investigated the intracellular signaling pathway in dendritic cells in vitro and antigen transport pathway and immune response in vivo mediated by an OVA@DDAB/PLGA nano-vaccine.

RESULTS

In vitro experiments revealed that the antigen uptake of BMDCs after nanovaccine incubation was two times higher than pure OVA or OVA@Al at 12 h. The BMDCs were well activated by p38 MAPK signaling pathway. Furthermore, the nano-vaccine induced antigen escape from lysosome into cytoplasm with 10 times increased cross-presentation activity than those of OVA or OVA@Al. Regarding the transport of antigen into draining lymph nodes (LNs), the nano-vaccine could rapidly transfer antigen to LNs by passive lymphatic drainage and active DC transport. The antigen+ cells in inguinal/popliteal LNs for the nano-vaccine were increased over two folds comparing to OVA@Al and OVA at 12 h. Moreover, the antigen of nano-vaccine stayed in LNs for over 7 days, germinal center formation over two folds higher than those of OVA@Al and OVA. After immunization, the nano-vaccine induced a much higher ratio of IgG2c/IgG1 than OVA@Al. It also effectively activated CD4+ T, CD8+ T and B cells for immune memory with a strong cellular response.

CONCLUSION

These results indicated that DDAB/PLGA NP was a potent platform to improve vaccine immunogenicity by p38 signaling pathway in BMDCs, enhancing transport of antigens to LNs, and higher immunity response.

Design, Synthesis and Tumour-Selective Toxicity of Novel 1-[3-{3,5-Bis(benzylidene)-4-oxo-1-piperidino}-3-oxopropyl]-4-piperidone Oximes and Related Quaternary Ammonium Salts

A novel series of 1-[3-{3,5-bis(benzylidene)-4-oxo-1-piperidino}-3-oxopropyl]-4-piperidone oximes 3a-h and related quaternary ammonium salts 4a-h were prepared as candidate antineoplastic agents. Evaluation against neoplastic Ca9-22, HSC-2 and HSC-4 cells revealed the compounds in series 3 and 4 to be potent cytotoxins with submicromolar CC50 values in virtually all cases. In contrast, the compounds were less cytocidal towards HGF, HPLF and HPC non-malignant cells revealing their tumour-selective toxicity. Quantitative structure-activity relationships revealed that, in general, both cytotoxic potency and selectivity index figures increased as the magnitude of the Hammett sigma values rose. In addition, 3a-h are cytotoxic towards a number of leukemic and colon cancer cells. 4b,c lowered the mitochondrial membrane potential in CEM cells, and 4d induced transient G2/M accumulation in Ca9-22 cells. Five compounds, namely 3c,d and 4c-e, were identified as lead molecules that have drug-like properties.

Near-Infrared Fluorescence Imaging of Carotid Plaques in an Atherosclerotic Murine Model

Successful imaging of atherosclerosis, one of the leading global causes of death, is crucial for diagnosis and intervention. Near-infrared fluorescence (NIRF) imaging has been widely adopted along with multimodal/hybrid imaging systems for plaque detection. We evaluate two macrophage-targeting fluorescent tracers for NIRF imaging (TLR4-ZW800-1C and Feraheme-Alexa Fluor 750) in an atherosclerotic murine cohort, where the left carotid artery (LCA) is ligated to cause stenosis, and the right carotid artery (RCA) is used as a control. Imaging performed on dissected tissues revealed that both tracers had high uptake in the diseased vessel compared to the control, which was readily visible even at short exposure times. In addition, ZW800-1C's renal clearance ability and Feraheme's FDA approval puts these two tracers in line with other NIRF tracers such as ICG. Continued investigation with these tracers using intravascular NIRF imaging and larger animal models is warranted for clinical translation.

Synthesis of Purine-Based Ionic Liquids and Their Applications

Bio-based ionic liquids (ILs) are being increasingly sought after, as they are more sustainable and eco-friendly. Purines are the most widely distributed, naturally occurring N-heterocycles, but their low water-solubility limits their application. In this work, four purines (theobromine, theophylline, xanthine, and uric acid) were combined with the cation tetrabutylammonium to synthesize bio-based ILs. The physico-chemical properties of the purine-based ILs were characterized, including their melting and decomposition temperatures and water-solubility. The ecotoxicity against the microalgae Raphidocelis subcapitata was also determined. The ILs show good thermal stability (>457 K) and an aqueous solubility enhancement ranging from 53- to 870-fold, in comparison to their respective purine percursors, unlocking new prospects for their application where aqueous solutions are demanded. The ecotoxicity of these ILs seems to be dominated by the cation, and it is similar to chloride-based IL, emphasizing that the use of natural anions does not necessarily translate to more benign ILs. The application of the novel ILs in the formation of aqueous biphasic systems (ABS), and as solubility enhancers, was also evaluated. The ILs were able to form ABS with sodium sulfate and tripotassium citrate salts. The development of thermoresponsive ABS, using sodium sulfate as a salting-out agent, was accomplished, with the ILs having different thermosensitivities. In addition, the purine-based ILs acted as solubility enhancers of ferulic acid in aqueous solution.