Polyoxyethylene Spacer Research Articles

An imidazole modified lipid confers enhanced mRNA-LNP stability and strong immunization properties in mice and non-human primates

The mRNA vaccine technology has promising applications to fight infectious diseases as demonstrated by the licensing of two mRNA-based vaccines, Comirnaty® (Pfizer/BioNtech) and Spikevax® (Moderna), in the context of the Covid-19 crisis. Safe and effective delivery systems are essential to the performance of these vaccines and lipid nanoparticles (LNPs) able to entrap, protect and deliver the mRNA in vivo are considered by many as the current “best in class”. Nevertheless, current mRNA/LNP vaccine technology has still some limitations, one of them being thermostability, as evidenced by the ultracold distribution chain required for the licensed vaccines. We found that the thermostability of mRNA/LNP, could be improved by a novel imidazole modified lipid, DOG-IM4, in combination with standard helper lipids. DOG-IM4 comprises an ionizable head group consisting of imidazole, a dioleoyl lipid tail and a short flexible polyoxyethylene spacer between the head and tail. Here we describe the synthesis of DOG-IM4 and show that DOG-IM4 LNPs confer strong immunization properties to influenza HA mRNA in mice and macaques and a remarkable stability to the encapsulated mRNA when stored liquid in phosphate buffered saline at 4 °C. We speculate the increased stability to result from some specific attributes of the lipid's imidazole head group.

Transgene expression in mice of the Opa1 mitochondrial transmembrane protein through bicontinuous cubic lipoplexes containing gemini imidazolium surfactants

BackgroundLipoplexes are non-viral vectors based on cationic lipids used to deliver DNA into cells, also known as lipofection. The positively charge of the hydrophilic head-group provides the cationic lipids the ability to condensate the negatively charged DNA into structured complexes. The polar head can carry a large variety of chemical groups including amines as well as guanidino or imidazole groups. In particular, gemini cationic lipids consist of two positive polar heads linked by a spacer with different length. As for the hydrophobic aliphatic chains, they can be unsaturated or saturated and are connected to the polar head-groups. Many other chemical components can be included in the formulation of lipoplexes to improve their transfection efficiency, which often relies on their structural features. Varying these components can drastically change the arrangement of DNA molecules within the lamellar, hexagonal or cubic phases that are provided by the lipid matrix. Lipofection is widely used to deliver genetic material in cell culture experiments but the simpler formulations exhibit major drawbacks related to low transfection, low specificity, low circulation half-life and toxicity when scaled up to in vivo experiments.ResultsSo far, we have explored in cell cultures the transfection ability of lipoplexes based on gemini cationic lipids that consist of two C16 alkyl chains and two imidazolium polar head-groups linked with a polyoxyethylene spacer, (C16Im)2(C4O). Here, PEGylated lipids have been introduced to the lipoplex formulation and the transgene expression of the Opa1 mitochondrial transmembrane protein in mice was assessed. The addition of PEG on the surface of the lipid mixed resulted in the formation of Ia3d bicontinuous cubic phases as determined by small angle X-ray scattering. After a single intramuscular administration, the cubic lipoplexes were accumulated in tissues with tight endothelial barriers such as brain, heart, and lungs for at least 48 h. The transgene expression of Opa1 in those organs was identified by western blotting or RNA expression analysis through quantitative polymerase chain reaction.ConclusionsThe expression reported here is sufficient in magnitude, duration and toxicity to consolidate the bicontinuous cubic structures formed by (C16Im)2(C4O)-based lipoplexes as valuable therapeutic agents in the field of gene delivery.Graphical

Dynamic surface dilational properties of anionic Gemini surfactants with polyoxyethylene spacers

Abstract The dynamic interfacial dilational properties of anionic Gemini surfactants (oligooxa)-α,ω-bis( m -octylbenzene sulfonate) (C 8 E 4 C 8 and C 8 E 8 C 8 ) with polyoxyethylene spacers at the water–air interface were investigated by means of oscillating the drop profile method. The influences of temperature and salt on dilational properties were explored. The experimental results show that the special structure of surfactant C 8 E 8 C 8 is a principal factor to control the nature of interfacial adsorption film. The distinct two peak values appear in dilational modulus vs. time curves for surfactant C 8 E 8 C 8 , which is different from that of traditional surfactants with low molecular weight. The first peak is believed to be related to the molecular diffusion-exchange process between the bulk and interface, and the second peak may be due to the formation and collapse of interfacial sublayer by ethylene oxide groups. In addition, the temperature has obviously effect on the second peak value of dilatioanl modulus. However, there is nearly no effect on the value of the second peak by addition of NaCl. The mechanisms responsible for unique interfacial behaviors mentioned above have been provided schematically.

Cationic gemini lipids containing polyoxyethylene spacers as improved transfecting agents of plasmid DNA in cancer cells.

Lipoplex nano-aggregates have been analyzed through biophysical characterization (electrostatics, structure, size and morphology), and biological studies (transfection efficiency and cell viability) in five cancer cell lines. Lipoplexes were prepared from pEGFP-C3 plasmid DNA (pDNA) and mixed liposomes, constituted by a zwitterionic lipid (DOPE) and a gemini cationic lipid (GCL) synthesized in this work, [bis(hexadecyl dimethyl ammonium) oxyethylene], referred to as (C16Am)2(C2O)n, (where n is the oxyethylene spacer length, n = 1, 2 or 3, between the ammonium heads). Cryo-TEM micrographs show nano-aggregates with two multilamellar structures, a cluster-type (at low-to-medium GCL composition) and a fingerprint-type that coexists with the cluster-type at medium GCL composition and appears alone at high GCL composition. SAXS diffractograms show that these lipoplexes present three lamellar structures, two of them coexisting at low and high GCL composition. The optimized transfection efficiency (TE) of pDNA was higher for lipoplexes containing GCLs with a longer (n = 3) or shorter (n = 1) polyoxyethylene spacer, at high GCL composition (α = 0.7) with low charge ratio (ρeff = 2). In the all cancer cell lines studied, the TE of the optimized formulations was much better than those of both lipofectamine 2000 and lipoplexes with GCLs of the bis(hexadecyl dimethyl ammonium) alkane series recently reported. Probably, (a) the coexistence of two lamellar structures at high GCL composition synergizes the TE of these lipid vectors, (b) the orientation of the polyoxyethylene region in (C16Am)2(C2O)3/DOPE may occur in such a way that the spacing between two cationic heads becomes smaller than that in (C16Am)2(C2O)2/DOPE which is poor in terms of TE, and (c) the synergistic interactions between serum proteins and (C16Am)2(C2O)n/DOPE-pDNA lipoplexes containing a polyoxyethylene spacer improve TE, especially at high GCL content. Lipoplexes studied here show very low levels of toxicity, which confirm them as improved vectors of pDNA in gene therapy.

Dilational Viscoelasticity of the Zwitterionic Gemini Surfactants with Polyoxyethylene Spacers at the Interfaces

The dilational viscoelasticity of zwitterionic gemini surfactants C8ExNC12 with polyoxyethylene spacers at the water-air and water-decane interfaces were investigated by oscillating barriers method. The experiments were carried out at different concentrations with an accessible frequency range of 0.005 to 0.1 Hz. Interfacial tension relaxation method was employed to obtain dilational parameters in a reasonably broad frequency range. Experimental results show that the values of dilational elasticity and viscosity of C8ExNC12 are larger than those of common nonionic surfactants, such as T × 100, and the dilational viscoelasticity at the water-decane is close to that at the water-air interface on the whole. The results may be attributed to Coulombic attraction, and the possible schematic diagrams of adsorbed molecules with different polyoxyethylene spacers at the water-air and water-decane interfaces are proposed. We also analyzed C8ExNC12 from the results of relaxation experiments and Cole-Cole plots.

Synthesis of Highly Selective Indole-Based Sensors for Mercuric Ion

Two indole-based fluorescent chemosensors 1 and 2 were prepared and investigated characteristic features with transition metal ions. Sensors 1 and 2 were selective for Hg(2+) ion, among a series of metal ions, in aqueous ethanol (H(2)O-EtOH, 1:2, v/v) with association constants of 5.74 × 10(3) and 4.46 × 10(3) M(-1) and detection limits of 7.4 and 6.8 μM, respectively. Computational results revealed that sensor 1 or 2 with Hg(2+) ion formed 1:1 complex with a central, sandwich-coordinated Hg(2+) ion. Computational calculations provided evidence that a sandwich-coordinated Hg(2+) ion center was formed and the polyoxyethylene spacer acted as a scaffold for bringing functional ligands into a suitable geometry.

Dilational Properties of Anionic Gemini Surfactants with Polyoxyethylene Spacers at Water−Air and Water−Decane Interfaces

The dilational properties of anionic gemini surfactants (oligooxa)-alpha,omega-bis(m-octylbenzene sulfonate) (C(8)E(x)C(8)) with polyoxyethylene spacers at the water-air and water-decane interfaces were investigated via the oscillating barriers method. The influences of oscillating frequency and bulk concentration on dilational properties were explored. The interfacial tension relaxation method was employed to obtain dilational parameters in a reasonably broad frequency range. The experimental results show that the number of ethylene oxide groups is one of the principal factors to control the nature of the interfacial film. With an increase of ethylene oxide groups, the dilational modulus of C(8)E(8)C(8) shows two maxima with the increasing concentration. Furthermore, the dilational moduli at the water-decane interface are remarkably lower than those at the water-air interface for C(8)E(1)C(8) and C(8)E(4)C(8), while the dilational modulus at the water-decane interface is close to that at the water-air interface for C(8)E(8)C(8), which indicates that the structure of the adsorption sublayer plays a more important role. Possible schematic diagrams of adsorbed molecules with different polyoxyethylene spacers at the water-air and water-decane interfaces are proposed. The results of relaxation experiments and Cole-Cole plots can support our provided mechanism strongly.

Synthesis and properties of a novel class of anionic gemini surfactants with polyoxyethylene spacers

A series of anionic gemini surfactants called (oligooxa)-α,ω-bis( m-alkylbenzene sulfonate) with different length in spacer and in hydrophobic chain, C 8E x C 8 ( x = 1, 2, 3, 4, 8) and C n E 4C n ( n = 8, 10, 12), have been synthesized from 4- n-alkylphenol and their basic physicochemical properties are investigated. The results indicate that they are different from cationic gemini surfactants called (oligooxa)alkanediyl-α,ω-bis(dimethyl-dodecylammonium bromide), 12-CH 2CH 2(EO) s -12, in the literature. As the number of oxyethylene segments increases, the cmc (critical micelle concentration) decreases initially and then increases, and the surface area per molecule decreases initially and then tends to a constant value of approximate 1.30 nm 2. Both of the breakpoints appear at number 4 of oxyethylene segments in the spacer. It is confirmed that the hydrophilic spacer with oxyethylene moieties is not fully extended at the air–water interface. With increasing spacer length, the spacer becomes sufficiently flexible to adopt a particular conformation with a loop at the water side of the air–water interface. The fluorescence data show that the micropolarity increases little from C 8E 1C 8 to C 8E 4C 8 and decreases obviously when x changes from 4 to 8. In addition, the plot of the logarithm of the cmc against the alkyl chain length for C n E 4C n shows a linear decrease with the increase in chain length. The micropolarity of the gemini surfactants (C n E 4C n ) decreases with an increase in the alkyl chain length ( n from 8 to 12).

Synthesis of ABA Triblock Copolymers via Ring Opening Metathesis Polymerization Using a Bimetallic Initiator: Influence of a Flexible Spacer in the Side Chain Liquid Crystalline Block

A series of monomers with side chain liquid crystals (SCLCs) were synthesized for ring opening metathesis polymerization (ROMP). The liquid crystals (LCs) used were 4-hydroxybenzoic acid 4-methoxyphenyl ester (MPOB-H), which is known to exhibit a nematic liquid crystalline phase, and biphenyl-4-carboxylic acid 4-(1-butoxycarbonylethoxy)phenyl ester (BPP4-H), which is known to exhibit a smectic phase. The side chains differed in spacer length, spacer type, and the nature of the LC. Monomers were polymerized using a bimetallic ROMP initiator [Mo(NAr)(OCMe3)2CH]2C6H4 (where Ar = 2,6-diisopropyl phenyl); both homopolymers and ABA type triblock copolymers, where the B block is the LC functional monomer, and A is methyltetracyclodocene (MTD) were prepared. The polymers gave unimodal peak distributions with polydispersities <1.22. Incorporation of a polyoxyethylene spacer decreased the glass transition temperature of the polymer block to −25 from +20 °C, the Tg when an alkyl spacer was used. Although no distinct LC phase was observed with the polyoxyethylene spacer when MPOB was used, when BPP4 was attached via a polyoxyethylene spacer, a distinct liquid crystalline transition was observed. Polymers with an alkyl spacer exhibited liquid crystalline behavior and good phase segregation on the basis of differential scanning calorimetry and small-angle X-ray scattering studies.

Hairpin helicates: a missing link between double-helicates and trefoil knots

We have prepared a novel ligand in which two qpy metal-binding domains are linked by a polyoxyethylene spacer. The new ligand reacts with copper(ii) salts to form dinuclear double helicates with a hairpin structure. The hairpin complex and a model complex have been structurally characterised. The hairpin structure is formed regioselectively as the head-to-tail (HT) stereoisomer. Detailed electrochemical and spectroelectrochemical studies of the complexes are reported.

Characterization of alkyl polyglycosides by both reversed-phase and normal-phase modes of high-performance liquid chromatography

Alkyl polyglycosides today represent the most important sugar surfactant. Nonionic sugar surfactants produced via different synthetic routes are mixtures of alkyl homologues, oligomers, anomers and isomers. Alkyl homologues and oligomers of alkyl mono- and diglucosides were separated by reversed-phase high-performance liquid chromatography (HPLC) with methanol–water as the mobile phase using a gradient elution. The gradient was optimized in respect to a simultaneous separation of alkyl glycosides according to their alkyl chain length and alkyl polyoxyethylene glucosides with regard to their length of the polyoxyethylene spacer. The separation of alkyl glycosides into α- and β-anomers was carried out by normal-phase HPLC with isooctane–ethyl acetate (60:40, v/v)–2-propanol in the gradient mode. Light scattering detection was used. Matrix-assisted laser desorption ionization time-of-flight mass spectra of alkyl glucosides and dodecyl glucosides with oxyethylene spacer groups are presented.

Molecular design and synthesis of a calix[6]crown-based lithium-selective ionophore

Several 1,4-bridged calix[6]arene tetraesters were prepared from 1,4- p-tert-calix[6]crown-4’s by etherifying with ethyl bromoacetate. It was found that the 1,4- p-tert-calix[6]crown-4 tetraethylester ( 3a) and the 1,4- p-tert-calix[6]benzocrown-4 tetramethylester ( 4b) exhibit very high selectivity toward lithium and sodium ions, respectively. The ion selectivity is very sensitive to the structure of polyoxyethylene spacer and the R in the ester moiety.

Synthesis and X-ray crystal structure of novel trans-syn thymine photodimers: effect of a polyoxyethylene spacer chain on photodimer stereochemistry

X-ray crystal structures have been determined for the trans-syn photodimers 1 and 2 which are the exclusive products upon photodimerization of bis-thymines.

Configurational characteristics and nematic order of semiflexible thermotropic polymers

The stability and the molecular order of nematic states of thermotropic polymers comprising rigid groups connected by flexible spacers are found to be dominated primarily by the characteristics (configurational partition function) of highly extended conformers, which are favoured for packing. Moreover, both the macroscopic consideration of the enthalpies and the entropies of isotropic–nematic transitions and the microscopic probe by deuterium n.m.r. of labelled chains lead to the conclusion that the highly extended conformers are selected preferentially in polymeric nematogens. A number of unique results exhibited by polymer liquid crystals, i.e. strong effects of even–odd character of polymethylene spacers, abnormalities associated with —C(O)O— links [compared with —O— and —OC(O)— links] between rigid (phenylene) groups and polymethylenes and drastic differences between polymethylene and polyoxyethylene spacers, can all be attributed quantitatively to this conformational ordering, which is the most prominent feature distinguishing polymer liquid crystals from their monomeric counterparts. The orientational order parameters of a nematic polymer measured from both D and H n.m.r. spectra of labelled chains are found to be quite high, ca. 0.8 throughout the nematic region. These findings on conformational order and orientational order of polymer liquid crystals are compared with theoretical predictions based on ideal lattice chains and worm-like chains.