Aggregation behavior and antimicrobial activity of ester-functionalized imidazolium- and pyridinium-based ionic liquids in aqueous solution

Two series of long chain imidazolium- and pyridinium-based ionic liquids containing an ester functional group in the alkyl side chain, 3-methyl-1-alkyloxycarbonylmethylimidazolium bromides (CnEMeImBr) and 1-alkyloxycarbonylmethylpyridinium bromides (CnEPyrBr), were synthesized and their thermal stability, aggregation behavior in aqueous medium, and antimicrobial activity investigated. The introduction of an ester group decreased the thermal stability of the functionalized ILs compared to simple alkyl chain containing ILs (1-alkyl-3-methylimidazolium bromides and 1-alkylpyridinium bromides). Tensiometry, conductimetry, and spectrofluorimetry were applied to study the self-aggregation of the amphiphilic ILs in aqueous solution. The ILs investigated displayed surface activity and the characteristic chain length dependence of the micellization process of surfactants. As compared to simple alkyl chain containing ILs bearing the same hydrocarbon chain, ester-functionalized ILs possess higher adsorption efficiency (pC 20) and significantly lower critical micelle concentration (cmc) and surface tension at the cmc (γcmc), indicating that the incorporation of an ester group promotes adsorption at the air/water interface and micelle formation. The antimicrobial activity was evaluated against Gram-negative and Gram-positive bacteria and fungi. ILs containing more than eight carbon atoms in the alkyl chain showed antimicrobial activity. Their efficiency as antimicrobial agents increased with the hydrophobicity of the amphiphilic cation being the C12 homologous the most active compounds. The incorporation of an ester group particularly increased the biological activity against fungi.We thank the Spanish Ministry of Economia y Competitividad (CTQ2010-17990/PPQ and CTQ2010-21183/PPQ) and the Generalitat de Catalunya (SGR2009-1331) for financial support.Peer reviewe

Self-assembly and antimicrobial activity of long-chain amide-functionalized ionic liquids in aqueous solution

Surface active amide-functionalized ionic liquids (ILs) consisting of a long alkyl chain (C6C14) connected to a polar head group (methylimidazolium or pyridinium cation) via an amide functional group were synthesized and their thermal stability, micellar properties and antimicrobial activity in aqueous solution investigated. The incorporation of an amide group increased the thermal stability of the functionalized ionic liquids compared to simple alkyl chain substituted ionic liquids. The surface activity and aggregation behaviour in aqueous solution of amide-functionalized ionic liquids were examined by tensiometry, conductivity and spectrofluorimetry. Amide-functionalized ILs displayed surface activity and their critical micelle concentration (cmc) in aqueous media decreased with the elongation of the alkyl side chain as occurs for typical surfactants. Compared to non-functionalized ILs bearing the same alkyl chain, ionic liquids with an amide moiety possess higher surface activity (pC20) and lower cmc values. The introduction of an amide group in the hydrophobic chain close to the polar head enhances adsorption at the air/water interface and micellization which could be attributed to the H-bonding in the headgroup region. The antimicrobial activity was evaluated against a panel of representative Gram-negative and Gram-positive bacteria and fungi. Amide-functionalized ILs with more than eight carbon atoms in the side chain showed broad antimicrobial activity. Antibacterial activities were found to increase with the alkyl chain length being the C12 homologous the most effective antimicrobial agents. The introduction of an amide group enhanced significantly the antifungal activity as compared to non-functionalized ILs.We thank the Spanish Ministry of Economia y Competitividad (CTQ2013-41514-P) for financial support.Peer reviewe

Micellization and antimicrobial properties of surface active ionic liquids containing cleavable carbonate linkages

Imidazolium-based ionic liquids (ILs) containing cleavable carbonate linkages, 1-alkyloxycarbonyloxyethyl-3-methylimidazolium chlorides with alkyl chains of 10, 12, and 14 carbon atoms, were synthesized, and their self-assembly behavior and antimicrobial activity were investigated. Differential scanning calorimetry and polarized optical microscopy studies reveal that carbonate-functionalized ILs form stable thermotropic smectic liquid-crystalline phases over a wide range of temperature. The surface activity and aggregation behavior of these new ILs were investigated by tensiometry, conductometry, potentiometry, and spectrofluorimetry. The size of aggregates was examined by dynamic light scattering (DLS). Carbonate-functionalized ILs display a higher adsorption efficiency and a lower critical micelle concentration (cmc) than simple alkyl-chain-substituted ILs. The insertion of a carbonate ester moiety in the alkyl side chain favors adsorption at the air-water interface and micellization in the bulk solution when compared to nonfunctionalized ILs. DLS measurements show that small micellelike aggregates are spontaneously formed above the cmc. Furthermore, carbonate-functionalized ILs were examined for their antimicrobial activity against a panel of clinically relevant microorganisms. Biological activity was found to increase with hydrophobicity. The presence of a carbonate ester moiety significantly enhances the antimicrobial efficiency as compared to nonfunctionalized ILs, with the susceptibility of Staphylococcus sp. toward the action of these compounds being particularly remarkable. It has been demonstrated that the functionalization of the alkyl side chain of the imidazolium salts can not only modify the aggregation behavior but also lead to differences in both efficiency and the spectrum of antimicrobial activity of amphiphilic ILs

Hexadecyltrimethylammonium bromide (CTA-Br) and 1-butyl-3-methylimidazolium tetrafluoroborate (bmim-BF4) in aqueous solution: An ephemeral binary system

Hypothesis Mixtures of the cationic surfactant hexadecyltrimethylammonium bromide (CTA-Br) and the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (bmim-BF4) in aqueous solutions are expected to behave as typical binary cationic surfactant system taking into account the surface activity displayed by the ionic liquid, instead of considering the IL as a water cosolvent. Experiments Surface tension and conductivity measurements have been conducted as a function of the total concentration of the mixtures at different surfactant mole fraction (αCTA-Br) to investigate the surface active properties. Findings Turbidity immediately appearing when the compounds are mixed in water suggests the spontaneous formation of the low soluble compound hexadecyltrimethylammonium tetrafluoroborate (CTA-BF4), together with the salt formed by the respective counterions bmim+and Br− in solution. For αCTA-Br ≠ 0.5, furthermore of the mentioned compounds, the spare bmim-BF4 (for αCTA-Br 0.5), are also present in the aqueous solution. Systems containing excess of bmim-BF4 show a low critical aggregate concentration (cac), but an unexpected high surface tension at cac (γcac ≈ 53–56 mN/m), as pure CTA-BF4. For systems containing excess of CTA-Br, cac increases but γcac decreases up to 36 mN/m. Mixtures of pure CTA-BF4 and bmim-BF4 or CTA-Br behave as typical binary surfactant systems.The authors thank the Spanish Ministry of Economia y Competitividad (CTQ2013-41514-P) for financial support.Peer reviewe

Different pattern of CSF glial markers between dementia with Lewy bodies and Alzheimer's disease

The role of innate immunity in dementia with Lewy bodies (DLB) has been little studied. We investigated the levels in cerebrospinal fluid (CSF) of glial proteinsYKL-40, soluble TREM2 (sTREM2) and progranulin in DLB and their relationship with Alzheimer's disease (AD) biomarkers. We included patients with DLB (n = 37), prodromal DLB (prodDLB, n= 23), AD dementia (n = 50), prodromal AD (prodAD, n= 53), and cognitively normal subjects (CN, n= 44).We measured levels ofYKL-40, sTREM2, progranulin, A beta(1-42), total tau (t-tau) and phosphorylated tau (p-tau) in CSF. We stratified the group DLB according to the ratio t-tau/A beta(1-42 ) (>= 0.52, indicative of AD pathology) and the A/T classification. YKL-40, sTREM2 and progranulin levels did not differ between DLB groups and CN.YKL-40 levels were higher in AD and prodAD compared to CN and to DLB and prodDLB. Patients with DLB with a CSF profile suggestive of AD copathology had higher levels of YKL-40, but not sTREM2 or PGRN, than those without. T+ DLB patients had also higherYKL-40 levels than T-. Of these glial markers, onlyYKL-40 correlated with t-tau and p-tau in DLB and in prodDLB. In contrast, in prodAD, sTREM2 and PGRN also correlated with t-tau and p-tau. In conclusion, sTREM2 and PGRN are not increased in the CSF of DLB patients. YKL-40 is only increased in DLB patients with an AD biomarker profile, suggesting that the increase is driven by AD-related neurodegeneration. These data suggest a differential glial activation between DLB and AD

Cerebral Amyloid Angiopathy in Down Syndrome and Sporadic and Autosomal-Dominant Alzheimer\u27s Disease

Introduction—We aimed to investigate if cerebral amyloid angiopathy (CAA) is more frequent in genetically determined than in sporadic early-onset forms of Alzheimer\u27s disease (AD) (early-onset AD [EOAD]). Methods—Neuroimaging features of CAA, APOE, and cerebrospinal fluid-Aβ40 levels were studied in subjects with Down syndrome (DS, n = 117), autosomal-dominant AD (ADAD, n = 29), sporadic EOAD (n = 42), and healthy controls (n = 68). Results—CAA was present in 31%, 38%, and 12% of cognitively impaired DS, symptomatic ADAD, and sporadic EOAD subjects and in 13% and 4% of cognitively unimpaired DS individuals and healthy controls, respectively. APOE-ε4 genotype was borderline significantly associated with CAA in sporadic EOAD (p = .06) but not with DS or ADAD. There were no differences in Aβ040 levels between groups or between subjects with and without CAA. Discussion—CAA is more frequently found in genetically determined AD than in sporadic EOAD. Cerebrospinal fluid-Aβ40 levels are not a useful biomarker for CAA in AD

The Sant Pau Initiative on Neurodegeneration (SPIN) cohort : A data set for biomarker discovery and validation in neurodegenerative disorders

Altres ajuts: The SPIN cohort has received funding from CIBERNED; Instituto de Salud Carlos III; jointly funded by Fondo Europeo de Desarrollo Regional (FEDER), Unión Europea, "Una manera de hacer Europa"; Generalitat de Catalunya; Fundació "La Marató TV3" Fundació Bancària Obra Social La Caixa; Fundación BBVA; Fundación Española para el Fomento de la Investigación de la Esclerosis Lateral Amiotrófica (FUNDELA); Global Brain Health Institute; Fundació Catalana Síndrome de Down; and Fundació Víctor Grífols i Lucas. These funding sources had no role in study design; in the collection, analysis, and interpretation of data; in the writing of the report; or in the decision to submit the article for publication.The SPIN (Sant Pau Initiative on Neurodegeneration) cohort is a multimodal biomarker platform designed for neurodegenerative disease research following an integrative approach. Participants of the SPIN cohort provide informed consent to donate blood and cerebrospinal fluid samples, receive detailed neurological and neuropsychological evaluations, and undergo a structural 3T brain MRI scan. A subset also undergoes other functional or imaging studies (video-polysomnogram, 18 F-fluorodeoxyglucose PET, amyloid PET, Tau PET). Participants are followed annually for a minimum of 4 years, with repeated cerebrospinal fluid collection and imaging studies performed every other year, and brain donation is encouraged. The integration of clinical, neuropsychological, genetic, biochemical, imaging, and neuropathological information and the harmonization of protocols under the same umbrella allows the discovery and validation of key biomarkers across several neurodegenerative diseases. We describe our particular 10-year experience and how different research projects were unified under an umbrella biomarker program, which might be of help to other research teams pursuing similar approaches

Catanionic surfactant formation from the interaction of the cationic surfactant hexadecyltrimethylammonium bromide (CTAB) and the ionic liquid 1-butyl-3-methylimidazolium octyl sulfate (bmim-octyl SO4) in aqueous solution

The interaction between the cationic surfactant Hexadecyltrimethylammonium bromide (CTAB) and the ionic liquid 1-butyl-3-methylimidazolium octyl sulfate (bmim-octylSO4) in aqueous solution has been investigated at two total concentrations (0.5 and 10mM) and different CTAB mole fractions (αCTAB). Samples of different physical appearance were obtained depending on αCTAB suggesting different kind of aggregates. Bluish solutions (αCTAB from 0.1 to 0.6) were assigned to vesicles of the catanionic surfactant formed (CTA-octylSO4), whereas clear and isotropic solutions (αCTAB>0.6) corresponded to mixed micelles. Surface tension, electrical conductivity, absorbance and dynamic light scattering (DLS) measurements were performed with the aim of correlating properties changes with the aggregation structures. The critical aggregation concentration (cac) and the surface tension value at the cac (γcac) were much lower for the mixtures than for the individual components. This finding reveals the exceptional surface activity of these mixtures, attributable to the formation of the CTA-octylSO4 catanionic surfactant. Once the catanionic surfactant is formed it makes no sense to consider anymore the initial CTAB/bmim-octylSO4 binary system but a new one composed by CTA-octylSO4 and the excess of bmim-octylSO4 or CTAB. On the basis of this consideration the surface activity parameters have been recalculated.The authors thank the Spanish Ministry of Economia and Competitividad (CTQ2013-41514-P) for financial support.Peer reviewe

Biodegradability and ecotoxicity of amine oxide based surfactants

5 pages, 2 figures.-- PMID: 17631946 [PubMed].Printed version published Nov 2007.The aerobic and anaerobic biodegradability as well as the aquatic toxicity of two fatty amine oxides and one fatty amido amine oxide were investigated. Aerobic biodegradation was evaluated using the CO2 headspace test (ISO 14593) and biodegradation under anaerobic conditions was assessed employing a standardised batch test. The three amine oxide based surfactants tested were readily biodegradable under aerobic conditions but only the alkyl amido amine oxide was found to be easily biodegradable under anaerobic conditions. Toxicity to Photobacterium phosphoreum and Daphnia magna was evaluated. Bacteria (EC50 from 0.11 to 11 mg l-1) proved to be more sensitive to the toxic effects of the amine oxide based surfactants than crustacea (IC50 from 6.8 to 45 mg l-1). The fatty amido amine oxide showed the lowest aquatic toxicity.This research was supported by the Spanish Ministerio de Ciencia y Tecnología (MCYT) Fondo Europeo de Desarrollo Regional (FEDER), project PPQ2001-2322.Peer reviewe

Surface activity, self-aggregation and antimicrobial activity of catanionic mixtures of surface active imidazolium- or pyridinium-based ionic liquids and sodium bis(2-ethylhexyl) sulfosuccionate

The surface activity and spontaneous formation of vesicles in aqueous solution of catanionic mixtures composed of different surface active ionic liquids (SAILs), methylimidazolium- or pyridinium-based, non-functionalized or bearing an ester or amide group in the alkyl chain, and the anionic surfactant sodium bis(2-ethyl-1-hexyl) sulfosuccinate (Na-AOT) have been studied. Furthermore, the antimicrobial activity of these catanionic mixtures against bacteria and fungi has been investigated. Catanionic mixtures were prepared by mixing aqueous solutions of SAIL-Br and Na-AOT in equimolar ratio. The resulting SAIL-AOT catanionic surfactant mixtures aggregate in vesicles and display high surface activity, enhanced interfacial adsorption and low critical aggregation concentration (cac) as compared to the individual components. The critical aggregation concentration decreases with the elongation of the alkyl chain of the ionic liquid and, for the same chain length, the cac values of SAIL-AOT mixtures follow the order, non-functionalized > amide functionalized > ester functionalized. The zeta-potential of SAIL-AOT vesicles increases from negative to positive values with the alkyl chain lengthening, consistently with the composition of the aggregates determined by the Regular Solution Theory. The vesicle formation in SAIL-AOT catanionic mixtures affects the intrinsic antimicrobial activity of individual amphiphilic components. The catanionic mixtures investigated exhibit high antimicrobial activity against fungi and most Gram-positive bacteria and low toxicity to Gram-negative microorganisms.The authors thank the Spanish Ministry of Economia y Competitividad (CTQ2017-88948-P) for financial support.Peer reviewe