New amphiphilic glycopolymers by click functionalization of random copolymers - application to the colloidal stabilisation of polymer nanoparticles and their interaction with concanavalin A lectin.

Glycopolymers with mannose units were readily prepared by click chemistry of an azido mannopyranoside derivative and a poly(propargyl acrylate-co-N-vinyl pyrrolidone). These glycopolymers were used as polymer surfactants, in order to obtain glycosylated polycaprolactone nanoparticles. Optimum stabilization for long time storage was achieved by using a mixture of glycopolymers and the non-ionic triblock copolymer Pluronic® F-68.

Two-dimensional supramolecular assemblies involving neoglycoplipids: Self-organization and insertion properties into Langmuir monolayers.

In nature, interfacial molecular recognition and chirality are of fundamental significance for the construction of biological assemblies. Lipid monolayers at liquid interface can be used as biomimetic models for studying molecular interactions in such assemblies. In this article, we will focus on the use of Langmuir monolayers for studying self-organization and insertion properties of several neoglycolipids.

Synthesis of biotinylated α-D-mannoside or N-acetyl β-D-glucosaminoside decorated gold nanoparticles: study of their biomolecular recognition with Con A and WGA Lectins.

Gold nanoparticles (NPs) functionalized with a mixed shell of well-defined biotinylated glycopolymers and polyethylene glycol (PEG) provide an effective platform for the biomolecular recognition of proteins both in solution and on surfaces. Well-defined biotinylated glycopolymers were first synthesized by the reversible addition-fragmentation chain transfer (RAFT) process. They contain two types of carbohydrate residues either N-acetyl β-D-glucosaminopyranoside (GlcNAc) or α-D-mannopyranoside (Man) as pendent groups.

Hyaluronidase binds differently DPPC, DPPS or GlcNAc-bearing glycolipid biomimetic monolayers.

Bovine testis hyaluronidase (btHyal) had been shown to have direct effects on cancer cells and to be a useful adjuvant in several medicines. Furthermore this enzyme had been found to be membrane-associated. Thus, in this work, the interactions between btHyal and membranes were analyzed by using lipid monolayers at the air-water interface as a biomimetic membrane system.

Validation of lipolysis product extraction from aqueous/biological samples, separation and quantification by thin-layer chromatography with flame ionization detection analysis using O-cholesteryl ethylene glycol as a new internal standard.

A general and easily accessible method for the extraction followed by the simultaneous separation and quantitative determination of triacylglycerols, diacylglycerols, monoacylglycerols and free fatty acids has been improved and optimized based on existing protocols using liquid-phase extraction and thin-layer chromatography coupled to flame ionization detection (TLC/FID Iatroscan). After lipid extraction in the presence of a suitable new synthetic internal standard, namely CholE1, a single elution step using n-heptane/diethyl ether/formic acid (55:45:1, v/v/v) was applied. This method was validated in line with international bioanalytical method validation guidelines using two different matrix systems: purified water and human gastro-intestinal fluid.

Self-organization of synthetic cholesteryl oligoethyleneglycol glycosides in water.

Lectin-sugar recognition systems are of interest in the pharmaceutical field, especially for the development of drug carriers, tailored for selective delivery. This paper deals with the anhydrous and aqueous self-organization properties of a synthetic cholesteryl oligoethyleneglycol glycoside with the aim of their incorporation in liposomes. Successive phases (lamellar, R3m, Im3m, micelles) have been described depending on water content and temperature.

Continuous measurement of galactolipid hydrolysis by pancreatic lipolytic enzymes using the pH-stat technique and a medium chain monogalactosyl diglyceride as substrate.

Galactolipids are the main lipids from plants and galactolipases play a major role in their metabolism. These enzymes were however poorly studied so far and only few assays have been developed. A specific and continuous galactolipase assay using synthetic medium chain monogalactosyl diacylglycerol (MGDG) as substrate was developed using the pH-stat technique and recombinant human (rHPLRP2) and guinea pig (rGPLRP2) pancreatic lipase-related protein 2 as model enzymes.

Glycosylated liposomes against Helicobacter pylori: behavior in acidic conditions.

Helicobacter pylori was isolated in 1982 and confirmed as a gastric pathogenic agent at the end of the 1980s. The present work deals with liposomes formulations in which are incorporated cholesteryl tetraethylene glycol oside as model ligands for H. pylori adhesins.

Pre-formulation of liposomes against Helicobacter pylori: characterization and interaction with the bacteria.

This paper deals with the formulation of targeted liposome against Helicobacter pylori. We describe the characterization of liposomes loaded with antimicrobial agents (ampicillin and metronidazole) and the quantification of the interactions between such formulations and bacteria. If the encapsulation rate of ampicillin seems not strongly affected by the change of phospholipidic composition, the encapsulation of metronidazole drastically decreased in epikuron 170 liposomes compared to DPPC ones.

One-step immobilization of alkanethiol/glycolipid vesicles onto gold electrode: amperometric detection of Concanavalin A.

Functionalized vesicles composed of glycolipid and alkanethiol lipids have been immobilized onto gold surface through one-step self-assembly to construct an electrochemical biosensor for Concanavalin A (Con A) detection. Incorporation of alkanethiol lipid molecules into the vesicles allows for firm attachment of the vesicles onto a gold surface to form a sensing interface. At the same time, the introduction of alkanethiol lipid avoids cumbersome organic syntheses of sulfur-containing compound, making the biosensor greater applied prospect.

Preparation of biotinylated glyconanoparticles via a photochemical process and study of their bioconjugation to streptavidin.

We report here the preparation of novel biotinylated glyconanoparticles from well-defined biotinylated glycopolymers and poly(N-isopropylacrylamide) (PNIPAAm) synthesized via the reversible addition fragmentation chain transfer (RAFT) polymerization process. The in situ reduction of the biotinylated glycopolymers, PNIPAAm, poly(ethylene glycol), and HAuCl4 via a photochemical process resulted in the formation of biotinylated gold nanoparticles. The multifunctional biotinylated glyconanoparticles were then evaluated for their bioconjugation toward streptavidin using UV-vis spectroscopy and surface plasmon resonance (SPR).

Glycolipid patterns supported by human serum albumin for E. coli recognition.

We demonstrated that human serum albumin (HSA) patterns constructed in a solid substrate by using micro-contact printing (muCP) technique supported the deposition of phospholipid bilayer containing glycolipid, 10-tetradecyloxymethy-3,6,9,12-tetraoxahexacosyl 2-acetamido-2-deoxy-beta-D-glucopyranoside (PB1124). It is observed by confocal laser scanning microscopy (CLSM) that the obtained glycolipid patterns are well-defined, stable and can be used to recognize and immobilize Escherichia coli (E. coli).

Further biochemical characterization of human pancreatic lipase-related protein 2 expressed in yeast cells.

Recombinant human pancreatic lipase-related protein 2 (rHPLRP2) was produced in the protease A-deficient yeast Pichia pastoris. A major protein with a molecular mass of 50 kDa was purified from the culture medium using SP-Sepharose and Mono Q chromatography. The protein was found to be highly sensitive to the proteolytic cleavage of a peptide bond in the lid domain.

Synthesis and liquid crystalline properties of mono-, di- and tri-O-alkyl pentaerythritol derivatives bearing tri-, di- or monogalactosyl heads: the effects of curvature of molecular packing on mesophase formation.

Self-organisation and self-assembly are critical to the stability of synthetic and biological membranes. Of particular importance is consideration of the packing arrangements of the various molecular species. Both phospho- and glycolipids can pack in ways in which curvature can be introduced into self-organised or self-assembled systems.

Establishment of mass spectrometric fingerprints of novel synthetic cholesteryl neoglycolipids: the presence of a unique C-glycoside species during electrospray ionization and during collision-induced dissociation tandem mass spectrometry.

In this study we evaluated the fragmentation pattern of 16 novel amphiphilic neoglycolipid cholesteryl derivatives that can be efficiently used to increase cationic liposomal stability and to enhance gene transfer ability. These neoglycolipids bear different sugar moieties, such as D-glucosamine, N-acetyl-D-glucosamine, N-trideuterioacetyl-D-glucosamine, N-acetyllactosamine, L-fucose, N-allyloxycarbonyl-D-glucosamine, and some of their per-O-acetylated derivatives. Regardless of the structure of the tested neoglycolipid, QqToF-MS analysis using electrospray ionization (ESI) source showed abundant protonated [M+H]+ species.

Highly sensitive gold nanoparticles biosensor chips modified with a self-assembled bilayer for detection of Con A.

In this paper, an improved method for detection of Concanavalin A (Con A) with label-free optical biosensors is reported. 1-Dodecanethiol (DDT) was self-assembled onto gold nanoparticles which were deposited on glass slides, and then glycolipid molecules were inserted into dodecanethiol by physical interactions only. The recognition between Con A and carbohydrate was observed by UV-vis spectrophotometry.

Size effect of polydiacetylene vesicles functionalized with glycolipids on their colorimetric detection ability.

In this paper, the size effect of the polydiacetylene vesicles functionalized with glycolipids on their colorimetric detection ability has been studied. Polydiacetylene vesicles in which were incorporated glycolipids acted as a model system for the affinochromatic property. Visible color changes from blue to red could be observed to the naked eye owing to Con A binding to the sugar moiety and be detected quantitatively by the visible absorption spectrum.

Syntheses of alpha-D-galactosamine neoglycolipids.

Several N-acetyl-alpha-d-galactosamine neoglycolipids, as well as hydrophobized T and T(N) antigen analogues, were prepared for embedment onto liposomes. Three different lipidic structures were used for the anchoring, that is cholesterol, 1,3-bis(undecyloxy)propan-2-ol and 1,3-bis(3,7,11,15-tetramethylhexadecyloxy)propan-2-ol. Oligoethyleneglycol spacers were used to link the carbohydrate and the hydrophobic moieties; their lengths were varied in order to obtain model compounds for the selective recognition by sialyl transferases involved in cancer processes.

Syntheses of an alpha-D-Gal-(1-->6)-beta-D-Gal diglyceride, as lipase substrate.

Two different routes were explored to afford 3-O-(6-O-alpha-D-galactopyranosyl-beta-D-galactopyranosyl)-1,2-di-O-dodecanoyl-sn-glycerol. In the first one, the key step was the glycosylation of the 3-O-(2,3,4-tri-O-benzyl-beta-D-galactopyranosyl)-1,2-O-isopropylidene-sn-glycerol acceptor with 2-pyridyl 2,3,4,6-tetra-O-benzyl-1-thio-beta-D-galactopyranoside as the donor. In the second one, the key step was the coupling of 2,3,4-tri-O-acetyl-6-O-(2,3,4,6-tetra-O-benzyl-alpha-D-galactopyranosyl)-D-galactopyranosyl trichloroacetimidate donor with 1,2-O-isopropylidene-sn-glycerol.

An alternative high yielding and highly stereoselective method for preparing an alpha-Neu5NAc-(2,6)-D-GalN3 building block suitable for further glycosylation.

This paper deals with new approaches to alpha-Neu5NAc-(2,6)-D-GalN3 building blocks, suitable as glycosylation donors. The major improvement, by comparison with the results of the literature, lies in the glycosylation step of a new d-galactosamine acceptor (tert-butyldimethylsilyl 3-O-acetyl-2-azido-2-deoxy-beta-D-galactopyranoside) with O-methyl-S-[methyl(5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-alpha-D-galacto-non-2-ulopyranosyl)onate] dithiocarbonate as the N-acetylneuraminic acid donor. The reaction affords the expected disaccharide in high yield (85%) and a complete alpha-Neu5NAc stereoselectivity.

In situ formation of C-glycosides during electrospray ionization tandem mass spectrometry of a series of synthetic amphiphilic cholesteryl polyethoxy neoglycolipids containing N-acetyl-D-glucosamine.

In this communication, the structural analysis of six synthetic O-Linked amphiphilic cholesteryl polyethoxy neoglycolipids containing N-acetyl-D-glucosamine was performed by electrospray ionization mass spectrometry in the positive ion mode, with a QqTOF-MS/MS hybrid instrument. The MS/MS analyses provided evidence for the "in situ" formation, in the collision cell of the tandem mass spectrometer, of an unexpected and unique [C-glycoside]+ product ion, resulting from an ion-molecule reaction between the N-acetyl-D-glucosamine oxonium ion and the neutral cholesta-3,5-diene molecule. Quasi MS3 analysis of this ion resulted in the dissociation of the precursor [C-glycoside]+ ion, which produced the expected third generation N-acetyl-D-glucosamine oxonium and the protonated cholesta-3,5-diene product ions.

Cholesteryl oligoethyleneglycol glycosides: fluidizing effect of their embedment into phospholipid bilayers.

Glycosides of cholesteryl oligoethyleneglycols have been synthesized and embedded in liposome bilayers. Several methods as steady-state fluorescence polarization, differential scanning calorimetry, zeta potential, and agglutination have been used to describe the physicochemical outcome of the incorporation of these synthetic glycolipids within phospholipid layers. From calorimetry and fluorescence experiments, it is apparent that the glycolipids decrease the transition temperature of the bilayers in a more important extent than cholesterol.

Kinetics study of Bungarus fasciatus venom acetylcholinesterase immobilised on a Langmuir-Blodgett proteo-glycolipidic bilayer.

This study deals with the kinetics properties of an enzyme immobilised in a defined orientation in a biomimetic environment. For this purpose, acetylcholinesterase (AChE) was captured at the surface of a nanostructured proteo-glycolipidic Langmuir-Blodgett film through specific recognition by a noninhibitor monoclonal antibody (IgG) inserted in a neoglycolipid bilayer. Modelling of this molecular assembly provided a plausible interpretation of the functional orientation of the enzyme.

Human pancreatic lipase-related protein 2 is a galactolipase.

Human pancreatic lipase-related protein 2 (HPLRP2) was found to be expressed in the pancreas, but its biochemical properties were not investigated in detail. A recombinant HPLRP2 was produced in insect cells and the yeast Pichia pastoris and purified by cation exchange chromatography. Its substrate specificity was investigated using pH-stat and monomolecular film techniques and various lipid substrates (triglycerides, diglycerides, phospholipids, and galactolipids).

Synthesis of amphiphilic phenylazophenyl glycosides and a study of their liquid crystal properties.

Several 4-(4'-N,N-didodecylaminophenylazo)phenyl 1,2-trans glycosides 5a-e with various carbohydrate heads (beta-D-gluco, beta-D-galacto, beta-lacto, beta-D-xylo, and alpha-D-manno) have been synthesized. The key step was the formation of phenyldiazonium tetrafluoroborates 2a-e from the per-O-acetylated 4-aminophenyl glycosides 1a-e. These salts were condensed with N,N-didodecylaniline under phase transfer conditions and the per-O-acetylated 4-(4'-N,N-didodecylaminophenylazo)phenyl 1,2-trans glycosides 4a-e were fully de-O-acetylated by the Zemplén method.