The chiral bile salt sodium cholate has been covalently linked to tetra-aryl-porphyrins, conferring them an extrinsic chirality and obtaining new molecules with high tendency to aggregate in ...solution. The chirality transfer from the molecular to the nano- and meso-scale has been investigated by promoting the self-assembly of the conjugates balancing the ratio of aqueous/organic solvent mixtures and allowing a fine control of the dimensions and morphology of the final supramolecular architectures. The shift from elongated structures with helical ribbon features to monodisperse tubules or from tightly packed rolled sheets to wrapped scrolls was enabled by changing the solvent composition, with the possibility of forming tubular structures with a hollow cavity. From UV–Vis and Circular Dichroism (CD) spectroscopy the ability to self-assemble into J-type aggregates with a strong induction of supramolecular chirality was revealed, shedding light on a two-step process, with a fast monomer nucleation followed by a slow second step of further stereospecific chiral evolution. The results as a whole promote the new porphyrin-cholate conjugates as promising smart and easily tunable chiral materials for the design of stereoselective sensing devices.
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Steroidal surfactants like bile salts have a rigid amphiphilic structure significantly different from the typical head–tail one. As a result, these molecules show peculiar features in their ...self-assembly behavior and solubilization and permeation abilities. Bile salts are widely used as starting materials in the preparation of synthetic derivatives by changing their amphiphilic structure and by introducing specific functionalities. Due to the steroid rigidity and the peculiar distribution of hydrophobic and hydrophilic domains, these molecules self-organize in ordered supramolecular assemblies and are particularly attractive for the bottom up construction of complex nanostructures. They often self-assemble in 1D structures such as tubes or fibers and show low molecular weight gelator features. Their tubular nanoscale structures have cross section diameters spanning a wide range of values (inner diameter 3–450nm) and are sometimes formed through appealing pH or temperature responsive aggregations. Moreover, mixtures of these surfactants allow in some cases the preparation of mixed tubes with tunable composition and related features such as charge and sizes. The unconventional amphiphilic molecular structure of BSs dictates also remarkable abilities as carriers across tissues and membranes of many compounds (e.g. drugs, carbohydrates and ions). Therefore they are often employed as encapsulators, dispersants and transporters in complex systems. Chemical modifications can also be used to provide derivatives with improved performances.
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•Bile salts are biological rigid amphiphiles often modified into synthetic derivatives.•Natural and modified molecules form appealing ordered 1D nanostructures.•They form gels or tubes with cross section in the range of 3–450nm.•Tubes are pH and/or temperature responsive or tunable in composition, charge and size.•Bile salts and derivatives are used as encapsulators, dispersants and transporters.
Sodium lauryl ether sulfates (SLES) are a class of surfactants, among the most used in the formulations of healthcare products. Although largely used in industry, literature studies are hereto ...completely missing of the characterization of some species, as sodium lauryl triether sulfates (E3S), and of the effect of several assembly parameters, as temperature. Moreover, drastic disparity of assembly performance subsists among laboratory synthesized and industrial raw SLES, generating problems in the real-world applications of formulations design.
We report on the self-assembly analysis of industrial grade sodium lauryl monoether sulfate (E1S), sodium lauryl diether sulfate (E2S) and laboratory synthesized E3S. The surfactants were studied in a large range of NaCl concentrations (0.1–1 M NaCl) and as function of the temperature by crossing Surface Tension, Small-Angle X-ray Scattering and Dynamic Light Scattering measurements.
Such analysis enabled to establish systematic relationship between the molecular structure and assembly properties of the surfactants and to define size and morphologies variations of the aggregates. We observed that i) core-shell spherical aggregates evolve towards elongated core-shell structures upon addition of NaCl, ii) the elongation is higher the lower the number of the ether groups iii) E3S is greatly stable in the analyzed temperature range (20 °C - 60 °C), iv) the industrial grade SLES exhibit a minimum of the surface tension and an anticipated self-assembly as a function of concentration, probably due to the presence of hydrophobic impurities. Impurities are also detected by DLS in unfiltered samples of the industrial grade SLES as large particles.
Moreover, a case of industrial interest was investigated: the instability of formulations comprising of E3S and 3,4,5-trimethoxybenzoic acid.
Such information enriches the quite small literature on pure SLES self-assembly, rationalizing new and literature data within a unified framework.
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•Bile salts affect monoolein phase behavior.•Oleic acid tunes the curvature of the system, giving rise to vesicles or hexosomes.•Taurocholate provides the most stable ...formulations.•Catechin can be encapsulated in taurocholate-loaded hexosomes.•Bile salts enhances the penetration properties of the nanoparticles on pig skin.
The delivery of bio-active molecules through the skin is challenging given the complex structure of its outer layer, the stratum corneum. Here we explore the possibility to encapsulate natural compounds into nanocarriers containing permeation enhancers that can affect the fluidity of the stratum corneum lipids. This approach is expected to facilitate dermal or transdermal release. For this purpose, the application of bile salts, which are natural surfactants involved in vivo in lipid digestion, was exploited.
Bile salts were added to lipid liquid crystalline nanoparticles (NPs) made of monoolein for antioxidant topical delivery. Monoolein self-assembly behaviour in water was affected by the presence of bile salts molecules, giving a transition from a bicontinuous cubic to unilamellar vesicles dispersion. By adding oleic acid (OA), the change of curvature in the system led to a reverse hexagonal phase. The morphology, structure and size of the nanocarriers was investigated before the nanoparticles were loaded with catechin, a natural antioxidant occurring in plants and food. The encapsulation did not affect significantly the formulation phase behaviour. The formulation loaded with bile salts and catechin was thereafter tested in vitro on the skin from new-born pig. The results for two different lipid formulations without bile salts were compared under the same experimental conditions and with the same antioxidant. The formulation with bile salts showed the best performance, allowing a superior permeation of catechin in the different skin layers in comparison with formulations without bile salt.
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The self-association equilibria of doxorubicin hydrochloride (DX), at high drug and NaCl concentrations, are studied by temperature scan fluorescence spectroscopy, with the support of ...molecular dynamics (MD) calculations.
Even though all anthracyclines show dimerization equilibria, DX only can further associate into long polymeric chains according to DXmon ⇄ DXdim ⇄ DXpol.
This is reflected not only in the mechanical properties of DXpol solutions (behaving as thixotropic gels) but also in their spectroscopic behaviour. Fluorescence, in particular, is the technique of election to study this complex set of equilibria. Upon increasing the temperature, DXpol melts into DXdim, which in turn is in equilibrium with DXmon. Since DXdim is non fluorescent, with a fluorescence temperature scan experiment the DXpol⇄ DXmon equilibrium is probed. However, also information on the DX dimerization equilibrium can be derived together with the relevant thermodynamic parameters ruling the dimerization process (ΔHdim°= -56 kJ mol-1; ΔSdim°= -97 J mol-1 K-1). The residence time of DX molecules in the dimer (74.7 μs), as well as the monomers mutual orientation in the dimer, are characterized by means of theoretical and computational modelling.
This study investigates the performance of two non-ionic sugar-based surfactants, belonging to the families of synthetic alkylpoliglucosides and biological rhamnolipids, for enhancing the ...solubilization and mass transfer of strongly adsorbed hydrophobic organic compounds (HOCs) in porous media. Using toluene and perchloroethylene (PCE) as reference pollutants, a continuous configuration test (column experiment) was performed to simulate a soil flushing process under controlled laboratory conditions. The potential applicability of the selected surfactants in remediation processes was evaluated within the context of Surfactant Enhanced Aquifer Remediation (SEAR) technology. Experimental results showed that both surfactants effectively increased the solubilization of contaminants adsorbed on porous media. Compared to H2O flushing, synthetic surfactant increased the solubilization of toluene by 52% and the solubilization of PCE by 81%, while biosurfactant increased solubilization ability by 73% and 92% for toluene and PCE, respectively. Biosurfactant exhibited the greatest solubilization ability, with 92% of adsorbed toluene and 98% of adsorbed PCE solubilized. This research highlights the potential of green surfactants as efficient candidates for remediation processes due to their excellent solubilization ability and environmentally friendly nature.
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•Non-ionic sugar-based green surfactants for contaminants solubilization.•Simulation of soil flushing process in bench scale through laboratory column test.•Solubilization abilities of selected surfactants are evaluated.•Solubilizing performances of synthetic surfactants and biosurfactants are compared.
Anthracyclines self‐assemble in water into dimers. In the presence of sufficiently high salt (NaCl) concentrations, solutions of the antibiotic doxorubicin, but not those of the closely related ...molecules daunomycin and epirubicin, turn into gels barely compatible with the presence of small oligomers. The use of spectroscopic, scattering, imaging and computational techniques, allowed light to be shed on the self‐assembly process that triggered doxorubicin gelification. A complex picture emerged, with doxorubicin molecules assembled into long, highly chiral, supramolecular aggregates made of hundreds of units, showing redshifted fluorescence spectra, very short fluorescence lifetimes and small‐angle X‐ray scattering profiles compatible with long cylinders. The involvement of specific chemical groups and the need for a specific stereochemistry of the monomers in the formation of a hydrogen‐bond network to stabilise the supramolecular aggregates was supported by molecular dynamics calculations. A salt‐induced, temperature‐dependent, cooperative nucleation–elongation supramolecular polymerisation of the doxorubicin molecules is deduced.
Translation
Le antracicline si autoassociano in acqua a formare dimeri. In presenza di concentrazioni saline (NaCl) sufficientemente elevate, le soluzioni dell'antibiotico doxorubicina, ma non quelle delle molecole strettamente correlate daunomicina ed epirubicina, si trasformano in gel difficilmente compatibili con la presenza di piccoli oligomeri. L'uso di tecniche spettroscopiche, di scattering, di imaging e computazionali, ha consentito di far luce sul processo di auto‐assemblaggio che porta alla formazione dei gel di doxorubicina. Il quadro che ne deriva è complesso, con le molecole di doxorubicina organizzate a formare lunghi aggregati sopramolecolari, altamente chirali, costituiti da centinaia di unità, i cui spettri di fluorescenza sono spostati nel rosso e con tempi di vita di fluorescenza molto brevi e profili SAXS compatibili con lunghi cilindri. È stato messo in evidenza, anche col supporto della dinamica molecolare, il coinvolgimento di specifici gruppi chimici nonché la necessità di una specifica stereochimica dei monomeri per consentire la formazione della rete di legami idrogeno che stabilizza gli aggregati sopramolecolari. Il modello d'associazione ricavato per la doxorubicina è quello di una polimerizzazione sopramolecolare indotta dalla forza ionica, caratterizzata da un processo di nucleazione‐allungamento T‐dipendente.
So near and yet so far: The stereochemistry of just one carbon atom makes the difference between a gel and non‐gel. The self‐aggregation behaviour of anthracyclines in salt solutions has been revealed.
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•We studied lecithin/water/bile salt mixtures in cyclohexane.•Addition of water and/or bile salt promotes growth of lecithin reverse worms.•At low additive/lecithin molar ratios ...stable wormlike micelles dispersions form.•Addition of bile salt to lecithin/water mixtures induces formation of branches.•Primers complementarily interact with lecithin and switch micelle elongation.
Knowing the ability of water and bile salts to promote the reverse wormlike micelle growth in lecithin/water or lecithin/bile salt mixtures in oil, this work was aimed at elucidating the association properties of the three solutes lecithin, water and the bile salt (BS) sodium deoxycholate in cyclohexane. By systematically changing the fraction of the two additives (i.e.: water and BS) we could identify a region at low additive/lecithin molar ratios where stable wormlike micelle dispersions were formed. Small angle X-ray scattering and oscillatory rheology measurements demonstrated that the ability of bile salt and water to transform the originally spherical lecithin reverse micelles into wormlike micelles and thereby impart to the sample viscoelastic properties is preserved in the three-solute mixture. The results suggest that reverse micelle including both bile salt and water are formed in this system. Reasonably the two primers interact with the same region of the lecithin headgroups and are complementary in altering the packing parameter of the amphiphile to values suitable for the formation of cylindrical aggregates.
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Doxorubicin hydrochloride (DX) is one of the most powerful anticancer agents though its clinical use is impaired by severe undesired side effects. DX encapsulation in nanocarrier ...systems has been introduced as a mean to reduce its toxicity. Micelles of the nonionic triblock copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) (PEO-PPO-PEO), are very promising carrier systems. The positive charge of DX confines the drug to the hydrophilic corona region of the micelles. The use of mixed micelles of PEO-PPO-PEO copolymers and a negatively charged bile salt should favour the solubilization of DX in the apolar core region of the micelles.
We studied the DX uptake in the micellar systems formed by sodium cholate (NaC) and the PEO100PPO65PEO100 (F127) copolymer, prepared with different mole ratios (MR = nNaC/nF127) in the range 0 ÷ 1. The systems were characterized by small angle X-ray scattering (SAXS) and dynamic light scattering (DLS); DX encapsulation was followed by steady-state and time-resolved fluorescence spectroscopy.
The successful solubilization of DX in the host micellar systems did not affect their structure, as evidenced by both SAXS and DLS data. In the presence of NaC, DX experiences a more apolar environment as indicated by its characteristic fluorescent behaviour. The almost complete uptake of the drug occurred shortly after the sample preparation; however, time resolved fluorescence revealed a slow partition of DX between corona and core regions of the micelles. DX degradation in the mixed micellar systems was markedly reduced relative to aqueous DX solutions.
Liposomes functionalized on their surface with carbohydrates (glycoliposomes) represent an optimal approach for targeting of drugs to diseased tissues in vivo, thanks to biocompatibility, low ...toxicity and easy manufacturing of these lipid nanoparticles. Here we report on the study of liposomes including a novel glycosylated amphiphile and on the comparison of their features with those of glycosylated analogues described previously. Further, the capability of the different glucosylated formulations to interact with three breast cancer cell lines was investigated. Our results show that the hydrophobic portion of the lipid bilayer strongly influences both the properties and the internalization of glycosylated liposomes.
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•Liposomes containing conventional and twin glucosylated surfactants were studied.•Also the length of the hydrophilic spacer of the glucosylated surfactants differ.•The interaction of liposomes with three breast cancer cell lines was investigated.•The hydrophobic portion of the bilayer is crucial for liposomes internalization.
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