Dodecyl Chains Research Articles

Disrupting J‐Aggregation in Triazatruxene Dimers to Develop Responsive Luminescent Inks for Anti‐Counterfeiting Applications

AbstractThe fight against counterfeiting is a crucial concern for economies around the world, underscoring the urgent need for effective measures to ensure the legitimacy of products and documents. Luminescent security inks have emerged as effective tools in this battle. The third generation of these inks, incorporating stimuli‐responsive organic materials, enables unique efficiency. In this work, the stimuli‐responsive behavior of three trialkylated triazatruxene dimers (TRI1, TRI2, and TRI3), endowed with N‐alkyl chains of different length is investigated. Among them, TRI3, with three flexible dodecyl chains, shows remarkable stimuli‐responsive fluorescence that is attributed to thermally or shear‐induced phase transitions between a tetragonal columnar phase and a discotic‐nematic liquid crystal phase. Such transformation involves the breakdown of highly emissive J‐aggregates with a strong influence on the resulting emissive color. Interestingly, these stimuli‐triggered transformations are spontaneously reversed, which renders this compound very interesting in the search of third‐generation security inks.

Effects of Secondary Amine and Molecular Weight on the Biological Activities of Cationic Amphipathic Antimicrobial Macromolecules.

Cationic amphipathic antimicrobial agents inspired by antimicrobial peptides (AMPs) have shown potential in combating multidrug-resistant bacteria because of minimal resistance development. Here, this study focuses on the development of novel cationic amphipathic macromolecules in the form of dendrons and polymers with different molecular weights that employ secondary amine piperidine derivative as the cationic moiety. Generally, secondary amine compounds, especially at low molecular weights, have stronger bacteriostatic, bactericidal, and inner membrane disruption abilities than those of their primary amine counterparts. Low molecular weight D2 dendrons with two cationic centers and one hydrophobic dodecyl chain produce outstanding synergistic activity with the antibiotic rifampicin against Escherichia coli, where one-eighth of the standalone dose of D2 dendrons could reduce the concentration of rifampicin required by up to 4000-fold. The low molecular weight compounds are also less toxic and therefore have higher therapeutic index values compared to compounds with larger molecular weights. This study thus reveals key information that may inform the design of future synthetic AMPs and mimics, specifically, the design of low-molecular-weight compounds with secondary amine as the cationic center to achieve high antimicrobial potency and biocompatibility.

Role of gemini surfactants with biodegradable spacer as efficient capping agents of silver nanoparticles

Since the last decade, silver nanoparticles (AgNPs) continue to attract interest of both academia and industry due to their peculiar physical, chemical, and optical properties. In the field of pharmaceutical applications, they are efficient carriers in the processes of controlled drug release, improve the drug's bioavailability, act as efficient antimicrobial agents and provide other biological functions conveyed at the nanometric scale. The known issue hampering further development of applications of AgNPs is their instability in aqueous environment. The present study utilizes two series of cationic bisammonium gemini surfactants with two dodecyl chains and a biodegradable spacer containing two amide or ester groups for the stabilization of AgNPs. The presence of nanosilver in the dispersions was confirmed by UV–VIS plasmon resonance spectra. Stability of AgNPs was characterized by zeta potential measurements proving that amide and ester gemini surfactant series are able to effectively stabilize AgNPs. The particles size analysis utilizing dynamic light scattering and scanning electron microscopy showed that AgNPs stabilized with flexible ester-based gemini surfactants have their size smaller than those capped with amide-containing gemini surfactants. Antimicrobial and anti-inflammatory activity determination as well as cytotoxicity experiments with gemini surfactant stabilized AgNPs showed a complex dependence of biological activity of AgNPs on the molecular structure of stabilizing agents.

A Minimalist Pathogen-Like Sugar Nanovaccine for Enhanced Cancer Immunotherapy.

Pathogen-mimicking nanoparticles have emerged at the forefront of vaccine delivery technology, offering potent immune activation and excellent biocompatibility. Among these innovative carriers, mannan, a critical component of yeast cell walls, shows promise as an exemplary vaccine carrier. Nevertheless, it faces challenges like unpredictable immunogenicity, rapid elimination, and limited antigen loading due to high water solubility. Herein, mannan with varying carbon chain ratios is innovatively modified, yielding a series of dodecyl chains modified mannan (Mann-C12). Through meticulous screening, a mannan variant with a 40% grafting ratio is pinpointed as the optimal vaccine carrier. Further RNA sequencing confirms that Mann-C12 exhibits desired immunostimulatory characteristics. Coupled with antigen peptides, Mann-C12/OVA257-280 nanovaccine initiates the maturation of antigen-presenting cells by activating the TLR4 and Dectin-2 pathways, significantly boosting antigen utilization and sparking antigen-specific immune responses. In vivo, experiments utilizing the B16-OVA tumor model underscore the exceptional preventive capabilities of Mann-C12/OVA257-280. Notably, when combined with immune checkpoint blockade therapy, it displays a profound synergistic effect, leading to marked inhibition of tumor growth. Thus, the work has yielded a pathogen-like nanovaccine that is both simple to prepare and highly effective, underscoring the vast potential of mannan-modified nanovaccines in the realm of cancer immunotherapy.

Novel AIE liquid crystals with high CPL-active bearing multiple dodecyl/cholesterol-decorated R-BINOL-cyanostilbene

The well-structured circularly polarized luminescence (CPL) active liquid crystal materials (R-BINC-Al and R-BINC-Ch) were synthesized through Suzuki coupling of the R-binaphthyl-cyanostilbene unit, followed by modification with dodecyl chains or cholesterol groups. The influence of chiral sources on the liquid crystal behavior, optical properties, and chiroptical response of R-BINC-Al and R-BINC-Ch was thoroughly investigated. Such results revealed that both molecules exhibited typical aggregation-induced emission (AIE) properties and strong solid-state fluorescence. Concretely, the quantum efficiency (ΦF) values of samples with multiple chiral sources increased from 46 % to 51 % by forming liquid crystals in the smectic C and cholesteric phases, the chirality can be transferred to the cyanostilbene unit through ordered self-assembly in the mesophase, resulting in a significant CPL signal across the molecules. Rightfully, the dissymmetry factor (glum) was increased from -7.92 × 10–3 to -1.53 × 10–2 with the introduction of chiral cholesteryl groups. our work elucidated the relationship between multiple chiral sources and CPL behavior, offering a systematic approach to designing chiral luminescent materials in the liquid-crystal phase with high ΦF and substantial glum values, providing a theoretical framework for potential applications in optoelectronic devices.

Solid-phase synthesis of amphiphilic cyclic peptides as a surfactin mimetic

The cyclic lipopeptide surfactin, an anionic biosurfactant, has received increased interest owing to its unique characteristics and promising applications. Although surfactin is known to exhibit distinctive surface activities and self-assembly ability, the role of the cyclic peptide moiety in its physico-chemical properties requires further investigation. Here, we report the solid-phase peptide synthesis of surfactin mimics such as cyclic heptapeptides with the same amino acid sequence as surfactin (CSF) and cyclic octapeptides with dodecyl chains (CSF12). The structure–property relationships of the cyclic peptides were then examined. The acidic forms of CSF and CSF12 were poorly soluble in water, but the addition of 1.5 or 2.0 equiv. of NaOH increased their solubility in aqueous solutions. The disodium salt of CSF (CSF-2Na) reduced the surface tension of water to 39.0 mN/m despite its absence of a long alkyl chain, indicating that the cyclic peptide moiety plays a crucial role in the surface activity of the surfactin mimic. In the case of the disodium salt of CSF12 (CSF12–2Na), the introduction of a dodecyl chain to the cyclic peptide moiety led to an increase in molecular orientation such that saturation at the air–water interface was observed. Thus, a long alkyl chain enhances the molecular assembly of the cyclic peptide at the air–water interface. The introduction of a long alkyl chain also enhanced the solubilisation of phospholipids. For instance, CSF12–1.5Na induced the solubilisation of L-α-dimyristoylphosphatidylcholine (DMPC) multilamellar vesicles in phosphate-buffered saline (PBS). These findings greatly contribute to the fundamental understanding of the broad spectrum of physico-chemical properties and biological activities of bio-derived cyclic peptides. Furthermore, these insights can also be helping design libraries for developing cyclic peptides for challenging therapeutics in skin disease or as cosmeceuticals to enhance skin appearance.

Liquid crystalline behaviour of symmetrical thermotropic Schiff base compounds

A series of new symmetrical liquid crystal compounds with Schiff base as a linking unit attached to different terminal alkyl chains were synthesized and characterized. The intermediates of 4-(decyloxy)benzaldehyde, 4-(dodecyloxy)benzaldehyde, and 4-(tetradecyloxy)benzaldehyde were synthesized through alkylation reaction between 4-hydroxybenzaldehyde with three series of bromoalkanes. Next, it further reacted with 1,4-phenylenediamine through condensation reaction to produce symmetrical Schiff base linkage with different terminal group chain which indicated as N-(substitutedbenxylidene)benzene-1,4-diamine. The compounds were characterized using Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR) and CHN elemental analysis. The Schiff base linkages are detectable in the FTIR spectra within the range of 1601–1604 cm⁻¹ and in the NMR spectra at δ 8.47–8.48 ppm. The mesophase transition phase of this compounds were determined using polarized optical microscope (POM) and further confirmed using differential scanning calorimetry (DSC). The Schiff base compounds were found to be mesogenic with smectic C and nematic transitions phases. These compounds attached to decyl, dodecyl, and tetradecyl terminal chains were found to exhibit smectic C phase at 142.47, 135.60, and 131.90 °C and nematic phase at 199.62, 197.11, and 188.76 °C, respectively. The incorporation of a Schiff base linking unit with a symmetrical alkyl chain induces the mesogenic effect in the molecules. A long alkyl chain allows the compounds to adopt a lamellar packing, facilitating the formation of a smectic phase. Incorporating the Schiff base into the molecules maintains an appropriate permanent dipole moment, which enables the homologs to arrange in a parallel orientational order, thereby adopting a nematogenic character.

Zincophilic and hydrophobic groups of surfactant-type electrolyte additive enabled stable anode/electrolyte interface toward long-lifespan aqueous zinc ion batteries

Rechargeable aqueous zinc-ion batteries, while promising in terms of safety, cost-effectiveness, and eco-friendliness, face challenges such as zinc dendrite growth and parasitic reactions at the anode/electrolyte interface. Herein, a low-cost cationic surfactant, dodecyltrimethyl ammonium chloride (DTAC) is deployed as a competitive additive in traditional ZnSO4 electrolyte to stabilize the zinc anode. Firstly, the DTAC additive disrupts the hydrogen bonding network and regulates the solvation structure. Secondly, the DTA+ cations preferentially adsorb onto the anode surface vertically, forming a dodecyl chain hydrophobic layer that suppresses the side reactions. Thirdly, the hydrophobic layer not only elevates the nucleation overpotential of Zn2+ ions but also limits their 2D diffusion at the anode surface, triggering oriented deposition of metal zinc and inhibiting dendrite growth. Leveraging these triple-regulation effects, the Zn//Zn symmetric cell with DTAC additives achieves an ultra-long cycle life of 2000 h at a current density of 1 mA cm−2 with 1 mAh cm−2. Furthermore, the Zn//MnO2 full cell with DTAC additive demonstrates promising performance, delivering an initial capacity of 149.44 mAh g−1 at 5 A g−1 and retaining 83.02 % of its capacity after 2000 cycles. These results underscore the potential of DTAC additives in advancing the industrialization of AZIBs.

Phase behavior of lyotropic alkyl thioglycolipid surfactants: Effects of sugar headgroup and alkyl tail length

AbstractThe lyotropic properties of alkyl thioglycosides with varying sugar headgroup (lactose, cellobiose, maltose, galactose, or glucose) and alkyl chain length (octyl, decyl, or dodecyl chains) are investigated by surface tensiometry, visual observation, and fluorescence spectroscopy. The results substantiate that the glycosidic S‐linkage confers considerably different solution aggregation behavior on these surfactants relative to their O‐linked counterparts, where the properties of the latter are known. The materials properties of the aggregated structures from the alkyl thioglycosides vary considerably. Micelles are formed by octyl thiocellobioside and all alkyl thiomaltosides. Turbid aggregate solutions are formed by the alkyl thioglucosides and octyl thiogalactoside, whereas the longer chain alkyl thiogalactosides are minimally soluble. Fluorescence spectroscopy of these systems confirms their aggregation in lamellar‐like structures. The alkyl thiocellobiosides and alkyl thiolactosides form hydrogels from these low‐molecular weight materials at concentrations almost an order of magnitude lower than gels using other low‐molecular weight materials. Here, hydrogels form at concentrations <0.3 wt% with some forming hydrogels at concentrations as low as 0.03 wt% from alkyl thiocellobiosides and thiolactosides, with hydrogel properties differing significantly with this slight change in the sugar headgroup. Alkyl thiocellobiosides form a nanofiber network and alkyl thiolactosides form globular hydrogels. Overall, these results clearly document materials properties that can readily be controlled and designed depending on molecular structure.

Transcriptomic changes in barley leaves induced by alcohol ethoxylates indicate potential pathways of surfactant detoxification

Hardly anything is known regarding the detoxification of surfactants in crop plants, although they are frequently treated with agrochemical formulations. Therefore, we studied transcriptomic changes in barley leaves induced in response to spraying leaf surfaces with two alcohol ethoxylates (AEs). As model surfactants, we selected the monodisperse tetraethylene glycol monododecyl (C12E4) ether and the polydisperse BrijL4. Barley plants were harvested 8 h after spraying with a 0.1% surfactant solution and changes in gene expression were analysed by RNA-sequencing (RNA-Seq). Gene expression was significantly altered in response to both surfactants. With BrijL4 more genes (9724) were differentially expressed compared to C12E4 (6197). Gene families showing pronounced up-regulation were cytochrome P450 enzymes, monooxygenases, ABC-transporters, acetyl- and methyl- transferases, glutathione-S-transferases and glycosyltransferases. These specific changes in gene expression and the postulated function of the corresponding enzymes allowed hypothesizing three potential metabolic pathways of AE detoxification in barley leaves. (i) Up-regulation of P450 cytochrome oxidoreductases suggested a degradation of the lipophilic alkyl residue (dodecyl chain) of the AEs by ω- and β- oxidation. (ii) Alternatively, the polar PEG-chain of AEs could be degraded. (iii) Instead of surfactant degradation, a further pathway of detoxification could be the sequestration of AEs into the vacuole or the apoplast (cell wall). Thus, our results show that AEs lead to pronounced changes in the expression of genes coding for proteins potentially being involved in the detoxification of surfactants.

Self-assembly properties of zinc(ii) complexes with azo ligands grafted with dodecyl chains: towards supramolecular materials driven by coordination and hydrophobic effect

Crystallographic and theoretical insight into the self-assembly of two zinc(ii) complexes is provided through analyzing an interplay of coordination and hydrophobic effects resulting from the interdigitation of the long alkyl chains of the ligands.

Crystalline bilayer formation in homoleptic low-spin Fe(II) compounds with alkyl chain substituents.

A series of asymmetric, homoleptic Fe(II) compounds based on the facially-binding tridentate ligand N-methyl-1,1-di(pyridin-2-yl)Cn-amine (LCn) (Cn = butyl, hexyl, octyl, decyl, dodecyl, tetradecyl and hexadecyl alkyl chains) with formula [FeII(LCn)2](X)2·solvate, where n = 4, 14 and X = BF4 (1C4 and 1C14) or n = 6, 8, 10, 12, 16 and X = CF3SO3 (1C6-1C12 and 1C16), are reported. Complexes 1C6 to 1C16 pack in crystalline bilayers in the solid state, forming hydrophobic and hydrophilic regions between adjacent layers of complexes. The combination of short Fe-N bond distances (∼2.00 Å) and SQUID magnetic susceptibility measurements show that the complexes are in the low-spin state across all measured temperature ranges. Differential scanning calorimetry confirmed phase transitions occur in compounds 1C6, 1C12, 1C14 and 1C16 upon heating from room temperature. The lack of any spin transitions and thermal stability conferred by thermogravimetric analysis over this temperature range suggest that these transitions are crystallographic in nature. 1H NMR studies show that the low-spin Fe(II) centres undergo partial conversion to paramagnetic species in solution. UV-vis spectroscopy in a range of common organic solvents show that the central Fe ions remain in the +2 oxidation state, suggesting that the increase in magnetic susceptibility in solution is likely due to partial spin-crossover, or due to speciation, in which a proportion of the compounds are high-spin Fe(II) complexes.

Optimization of thin-film formation of naphthalene tetracarboxylic diimide derivatives with head and tail structure and application to transistors

Herein, we characterized vacuum-evaporated thin-films of several new naphthalene tetracarboxylic diimide derivatives (C12-NTCDI-R) as n-type organic thin-film transistor (TFT) materials. They have head and tail structure with dodecyl chain and phenylalkyl (benzyl or phenylethyl) groups. By introducing fluorine groups into the phenylalkyl groups, the electron transport properties were enhanced. In addition, modifying the substrate surfaces with a fluorine-rich polymer material and annealing at the appropriate temperature allowed the TFT devices with C12-NTCDI-F2Bn (R = 3,5-difluorobenzyl) to reach a maximum electron mobility (μ e) of 0.11 cm2 V−1 s−1. Furthermore, the alteration of the number of methylene carbons in the side chain of phenylalkyl groups in C12-NTCDI-R (namely, phenylethyl was used as R) affected the thermal behavior of their molecules during the thin-film formation. For the TFT device with C12-NTCDI-PhEt (R = phenylethyl), the μ e reached the maximum value of 0.16 cm2 V−1 s−1 by just surface modification, without annealing.

Smectic behaviour of α,ω-alkanediol diesters of a partially fluorinated 4-dodecyloxybenzoic acid: the odd-even effect

ABSTRACT Synthesis of a new series of mesogenic dimers and investigation of their liquid crystalline properties with thermal, optical and XRD methods is reported. Unlike dimeric mesogens studied to date, the presently reported dimers are derived from a single-ring mesogen containing a partially fluorinated dodecyl chain, which effects nanosegregation and formation of a lamellar phase. The reported four diesters with the odd-membered connecting alkyl chain exhibit a SmA phase. In contrast, two even-membered analogues have higher melting points and do not exhibit mesogenic behaviour.

Silicon nanoparticles functionalized with 1-dodecene/alkyne-terminated conjugated groups and its properties

A series of alkyne-terminated conjugated groups were synthesized and characterized, which enrich the surface species of silicon nanoparticles (SiNPs). Subsequently, the alkyne-terminated conjugated groups were lithiated, and capped the surface of the SiNPs. After modification, both the alkyne-terminated conjugated group and the dodecyl chain can be successfully immobilized confirmed by FTIR and TGA. From the photoluminescence spectrum, the wavelength range is further broadened, and the redshift was not lost even with further 1-dodecane capping. These inspiring results shed light on the potential applications of functionalized silicon nanoparticles in multiple fields, including but not limited to electronic devices, biomarkers, etc.

Self-Assembled Monolayers of Gemini-Type Amphiphilic Hexabenzocoronenes on Gold: Contribution of Their Triethylene Glycol Side Chains to Self-Assembly Formation.

We report on a two-dimensional self-assembled structure of a supramolecule with hydrophilic oligoethylene glycol (EG) units, which are capable of stronger electrostatic interactions than van der Waals (vdW) interactions between alkyl chains. For this purpose, hexabenzocoronene (HBC) with two hydrophobic dodecyl chains on one side of the HBC core and two hydrophilic triethylene glycol (TEG) chains on the other side of the HBC core (HBCGemini) and HBCGemini with a trinitrofluorenone (TNF) added to the end of one TEG chain (HBCTNFGemini) were employed. Scanning tunneling microscopy (STM) revealed the presence of multiple two-dimensional self-assembled structures in each of HBCGemini and HBCTNFGemini deposited on the gold substrate in vacuum. The role of polar functional groups in these observations is discussed based on semiempirical molecular orbital simulations. Two types of 2D organized structures of HBC-TEG were observed: one with rectangular and relatively dense unit cells and the other with nearly square and relatively sparse unit cells. In both organized structures, the phenyl group TEG units and alkyl chains were considered to be the main molecular interactions with each other. On the other hand, in HBCTNFGemini, three types of organized structures were observed, which could be explained by the mechanism of interdigitation of the TEG-containing side-chain moieties to form a dimeric core. The EG units are more flexible than the alkyl chains and thus can interact flexibly with the hydrophobic HBC core, and the glycol side chains facilitate the intermolecular interactions as well as the alkyl chains.

Covalent functionalization of activated MoS2 via using alkyl sulfide and their utilization in polymeric composites with mechanical and thermal property enhancements

AbstractRecently developed covalent functionalization of chemically exfoliated MoS2 (typically in alkyl lithium) allows the formation of chalcogenide‐carbon bonds by reacting with organohalides and aryl diazonium salts. We herein develop a novel method for the covalent functionalization of MoS2 to yield dodecylated MoS2 via reductive activation in a strongly reducing sodium‐naphthalene solution and using alkyl sulfide as an electrophile. Dodecylated MoS2/polystyrene (PS) composites fabricated by solution casting method. Dodecyl chains are grafted successfully onto MoS2 nanosheets, which gives rise to the exfoliation level of few‐layer thickness and matched compatibility with the host polymeric matrix. The inclusion of dodecylated MoS2 at a concentration of 1.0 wt% yields a substantial improvement in both Young's modulus and tensile strength, with a 106.7% increase and a 67% enhancement, respectively, as compared to the performance of pure PS. The enhanced mechanical characteristics can be credited to the uniform dispersion of dodecylated MoS2 within the PS matrix and enhanced interfacial interaction between the PS material and the filler. The composites demonstrate a significant increase in their glass transition temperature (Tg). Notably, the dodecylated MoS2/PS (1.0 wt%) composite exhibits a 59.8% elevation in storage modulus when compared to pure PS. The coke yield of dodecylated MoS2/PS (1.0 wt%) reaches 2.7%, much larger than the value (only 0.2%) for pure PS. The novel functionalization might expedite the applications of molybdenum disulfide in diverse fields.Highlights A novel method for the covalent functionalization of MoS2. Dodecylated MoS2/PS composites were fabricated via solution casting method. Ultrathin structure of MoS2 nanosheets was obtained after functionalization. Composites improvement in Young's modulus and tensile strength compared to PS. The composites show significant enhancements in Tg.

An amphiphilic near-infrared Mn,O-chelated metallo-azadipyrromethene dye: Synthesis, acid-responsive properties, and aggregation pathway control

A new amphiphilic Mn,O-chelated azadipyrromethene dye 1 bearing dodecyl chains at the 1,7-phenyls and oligo(ethylene glycol) chains at the 3,5-phenyls was synthesized and characterized. The dye 1 exhibited an absorption maximum in NIR at 823 nm, which is largely bathochromically shifted as compared with the known aza-BODIPY as well as the B,O-chelated aza-BODIPY dyes. Meanwhile, the electrochemical studies of this dye indicated a lower HOMO-LUMO gap in comparison with the boron-chelated analogues. This dye also displayed the acid-responsive properties, as indicated by the hypsochromical shift of ca. 94 nm of the absorption band as well as the occurrence of fluorescence emission at 751 nm upon adding trifluoroacetic acid (TFA) into the dye 1 solution. Moreover, in highly polar solvent MeOH the amphiphilic dye 1 self-assembled into H-type aggregates, which exhibited a fibrous morphology in AFM studies. Further temperature-dependent UV/Vis absorption spectroscopic studies revealed a cooperative aggregation mechanism of dye 1 in MeOH. Based on the acid-responsive properties of 1, a method of control of the aggregation pathway of dye 1 by using acid and base was proposed and demonstrated by UV/Vis spectroscopic studies.

Thiourea-based low molecular-mass organogelators from (+)-dehydroabietylamine

Three new thiourea-based thermo-reversible, low molecular weight organogelators (LMOGs) 3-5 have been synthesized using (+)-Dehydroabietylamine (DAA, a tricyclic diterpene) employing DLS (Diterpene-Linker-spacer) strategy. (+) DAA was converted into isothiocynates through a cascade of reactions and cross-coupled with primary amines to furnish thiourea 3-5 with respective spacers. The structures of gelators 3-5 were confirmed through 1H-NMR and 13C-NMR spectroscopy, high-resolution electron spray ionization mass spectrometry (HRESI–MS, positive mode) and FTIR spectroscopy. Gelation potential of gelators 3-5 was investigated through inverted test tube method and sol–gel transition measured by ball-dropping method. The results revealed that unbranched alkyl groups furnish gelation and their gelation ability increases with increasing spacer length. Gelator 5 with dodecyl chain found to be excellent gelator that can gelate hexane (spontaneously), toluene, methanol, ethanol, petrol, and diesel. Morphology of gels was studied though scanning electron microscopy exhibiting fibrillar to lamellar structure with a thickness in the range of 9.5 nm to 5.0 μm with increasing length of spacer.

A Comparison of the Antibacterial Efficacy of Carbohydrate Lipid-like (Thio)Ether, Sulfone, and Ester Derivatives against Paenibacillus larvae.

Paenibacillus larvae is the causative agent of American foulbrood (AFB), the most serious bacterial disease affecting developing honeybee larvae and pupas. In this study, a library of 24 (thio)glycosides, glycosyl sulfones, 6-O-esters, and ethers derived from d-mannose, d-glucose, and d-galactose having C10 or C12 alkyl chain were evaluated for their antibacterial efficacy against two P. larvae strains. The efficacy of the tested compounds determined as minimal inhibitory concentrations (MICs) varied greatly. Generally, dodecyl derivatives were found to be more potent than their decylated analogs. Thioglycosides were more efficient than glycosides and sulfones. The activity of the 6-O-ether derivatives was higher than that of their ester counterparts. Seven derivatives with dodecyl chain linked (thio)glycosidically or etherically at C-6 showed high efficacy against both P. larvae strains (MICs ranged from 12.5 μM to 50 μM). Their efficacies were similar or much higher than those of selected reference compounds known to be active against P. larvae-lauric acid, monolaurin, and honeybee larval food components, 10-hydroxy-2-decenoic acid, and sebacic acid (MICs ranged from 25 μM to 6400 μM). The high efficacies of these seven derivatives suggest that they could increase the anti-P. larvae activity of larval food and improve the resistance of larvae to AFB disease through their application to honeybee colonies.