Christophe Tribet

Ecole Normale Supérieure de Paris | ENS · Département de Chimie

Hypothesis: A key question in the kinetics of surfactant self-assembly is whether exchange of unimers or fusion/fission of entire micelles is the dominant pathway. In this study, an isomerizable surfactant is used to explore fundamental out-of-equilibrium kinetics and mechanisms for growth and dissolution of micelles. Experiments: The kinetics o...

One of the biggest challenges in membrane protein (MP) research is to secure physiologically relevant structural and functional information after extracting MPs from their native membrane. Amphipathic polymers represent attractive alternatives to detergents for stabilizing MPs in aqueous solutions. The predominant polymers used in MP biochemistry a...

Gold nanoparticles (AuNPs) are increasingly used for their thermoplasmonic properties, i.e. their ability to convert light into heat upon plasmon resonance. However, measuring temperature gradients generated at the microscale by assemblies of AuNPs remains challenging, especially when they are randomly distributed in three dimensions. Here, we intr...

The encapsulation of fragile biomacromolecules is crucial in many biotechnological applications but remains challenging. Interfacial complexation (IC) in water-in-oil emulsions proves to be an efficient process for the formation of protective polymer layers at the surface of capsule-precursor water droplets. In this work, the enhancement of convent...

Hypothesis Photoswitchable surfactants are used in the design of many light-responsive colloids and/or self-assemblies. Photo-isomerization enables to control molecular equilibrium, and triggers transient reorganizations with possibly out-of-equilibrium intermediate states that have been overlooked. Here, we address this question by an in depth str...

The encapsulation of fragile biomacromolecules is crucial for many biotechnological applications but remains challenging. Interfacial complexation (IC) in water-in-oil emulsions turned out to be an efficient process for the formation of protective polymer layers at the surface of capsule-precursor water droplets. We propose to further enhance this...

Membrane remodeling and phospholipid biosynthesis are normally tightly regulated to maintain the shape and function of cells. Indeed, different physiological mechanisms ensure a precise coordination between de novo phospholipid biosynthesis and modulation of membrane morphology. Interestingly, the overproduction of certain membrane proteins hijack...

Membrane proteins need to be extracted from biological membranes and purified in their native state for most structural and functional in vitro investigations. Amphiphilic copolymers, such as amphipols (APols), have emerged as very useful alternatives to detergents for keeping membrane proteins water-soluble under their native form. However, classi...

Membrane remodeling and phospholipid biosynthesis are normally tightly regulated to maintain the shape and function of cells. Indeed, different physiological mechanisms ensure a precise coordination between de novo phospholipid biosynthesis and modulation of membrane morphology. Interestingly, the overproduction of certain membrane proteins hijack...

Effects of green tea tannin epigallocatechin-gallate (EGCG) on thermal-stress-induced amyloid fibril formation of reduced carboxymethylated bovine milk protein κ-casein were studied by dynamical light scattering and small angle X-ray scattering (SAXS). Two populations of aggregates, micelles, and fibrils dominated the time evolution of light scatte...

Structural features of lysine-conjugated antibody-drug conjugate (ADC) from humanized IgG1 were studied by small-angle X-ray scattering (SAXS). As the physicochemical properties of the cytotoxic drug (payload) and linker may impact the conformational and colloidal stability of the conjugated mAb, it is essential to characterize how the conjugation...

Effects of green tea tannin epigallocatechin-gallate (EGCG) on thermal-stress-induced amyloid fibril formation of reduced carboxymethylated bovine milk protein $\kappa$-casein (RCMK) were studied by dynamical light scattering (DLS) and small angle x-rays scattering (SAXS). Two populations of aggregates, micelles and fibrils, dominated the time evol...

Spontaneous adsorption of poly(lysine)-g-poly(ethyleneglycol) comb-like copolymers (PLL-g-PEG) is a versatile mean to coat substrates with polymer layers that resist cell adhesion. We prepared redox cleavable PLL-g-PEG to switch adhesion on demand. Redox sensitivity was obtained by introducing disulfide linkers between the PLL backbone and PEG stra...

Soft adhesion to a horizontal flat substrate of micron-sized colloids coated by a controlled molar fraction f of PLL-g-PNIPAM is tuned and triggered by controlling the temperature of the sample. This mechanism is possible because PNIPAM is a thermo-responsive polymer, which undergoes a phase transition at a LCST (lower critical solution temperature...

Despite growing research efforts on the preparation of (bio)functional liposomes, synthetic capsules cannot reach the densities of protein loading and the control over peptide display that is achieved by natural vesicles. Here we present a microbial platform for high yield production of lipidic nanovesicles, with clickable thiol moieties in their o...

Despite growing research efforts on the preparation of (bio)functional liposomes, synthetic capsules cannot reach the densities of protein loading and the control over peptide display that is achieved by natural vesicles. Here we present a microbial platform for high yield production of lipidic nanovesicles, with clickable thiol moieties in their o...

Immediately before adsorption to a horizontal substrate, sinking polymer-coated colloids can undergo a complex sequence of landing, jumping, crawling, and rolling events. Using video tracking, we studied the soft adhesion to a horizontal flat plate of micron-size colloids coated by a controlled molar fraction f of the poly(lysine)-grafted-poly(N-is...

uploading link: http://pubs.acs.org/articlesonrequest/AOR-ckDvHKVU2nPyIfekiQpj Dynamic guidance of living cells is achieved by fine tuning and spatiotemporal modulation on artificial polymer layers enabling reversible peptide display. Adjustment of surface composition and interactions is obtained by coadsorption of mixed poly(lysine) derivatives, g...

Colloids with aggregation and adhesion properties reversibly tunable by shift of pH, T, light etc. can be designed by deposition of stimuli-responsive polymer chains on the particle surface. The aim of this work was to investigate how to control the strength of temperature-triggered attraction by analyzing self-aggregation kinetics and soft adhesio...

Back Cover: Aggregation-prone antibody single-chain variable fragments (scFv) are refolded from urea solutions in the presence of amphiphilic derivatives of poly(sodium acrylate) playing the role of artificial chaperons. Weak noncovalent interactions with the polymers impart solubility to partly-folded scFv intermediates, resulting in recovery of t...

ScFv antibody fragments are a promising alternative to full-length antibodies for both therapeutic and diagnosis applications. They can be overexpressed in bacteria, which enables easy large scale production. Since scFv are artificial constructs, they are poorly soluble and prone to aggregation, which makes them difficult to manipulate and to refol...

Coupling a hydrophobic drug onto monoclonal antibodies via lysine residues is a common route to prepare antibody drug conjugates (ADC), a promising class of biotherapeutics. But a few chemical modifications on protein surface often increase aggregation propensity, without a clear understanding of the aggregation mechanisms at stake (loss of colloid...

http://pubsdc3.acs.org/articlesonrequest/AOR-QKu4x8kDdWM98BVjzX5F Adlayers of poly(lysine)-g-PEG comblike copolymer are extensively used to prepare cell-repellant and protein-repellent surfaces by a straightforward coulomb-driven adsorption that is compatible with diverse substrates (glass, petri-dish, etc). To endow surfaces with functional proper...

The kinetics of micelles involving photosensitive surfactants is still not well understood. In this work, we unravel the mechanistic pathways involved in the micelle formation and dissolution of photocontrollable micelles. Here we focus on the fast self-assembly processes of a photosensitive cationic azobenzene-containing surfactants (AzoTMA) that...

We report a simple and versatile method to functionalize anionic colloid particles and control particle solubility. Poly(lysine)-based copolymers (PLL) grafted with polyethylene oxide (PLL-g-PEG) or poly(N-isopropylacrylamide) (PLL-g-PNIPAM) spontaneously adsorb on bare beads dispersed in aqueous solutions of the copolymers. The final composition o...

http://pubs.acs.org/articlesonrequest/AOR-t6Zmw5Qs3buc46VjV9sG Prevention of aggregation during renaturation of urea-denatured carbonic anhydrase B (CAB) via hydrophobic and Coulomb association with anionic polymers was studied in mixed solutions of CAB and amphiphilic poly(acrylate) copolymers. The polymers were derivatives of a parent poly(acryli...

Complexes formed between poly(acrylates) and polyclonal immunoglobulin G (IgG) in its native conformation and after heat stress were characterized using asymmetric flow field-flow fractionation (AF4) coupled with on-line UV-Vis spectroscopy and multi-angle light-scattering detection (MALS). Mixtures of IgG and poly(acrylates) of increasing structur...

http://pubs.acs.org/articlesonrequest/AOR-puacrHXbc2kk5pG3BUsa Prevention of thermal aggregation of antibodies in aqueous solutions was achieved by noncovalent association with hydrophobically modified poly(acrylate) copolymers. Using a polyclonal immunoglobin G (IgG) as a model system for antibodies, we have studied the mechanisms by which this mu...

Antimicrobial and cell-penetrating peptides have inspired developments of abiotic membrane-active polymers that can coat, penetrate, or break lipid bilayers in model systems. Application to cell cultures is more recent, but remarkable bioactivities are already reported. Synthetic polymer chains were tailored to achieve (i) high biocide efficiencies...

http://pubs.acs.org/articlesonrequest/AOR-Ubi7GdAjSQF6nbW5AdD9 To remotely control ionization of polymer assemblies, we tailored amphiphilic diblock polyacrylates with varying hydrophilic and hydrophobic block lengths and containing pendant 2-hydroxyazobenzene photoswitchable groups in the hydrophilic block. Formation in water of rodlike polymer m...

Our goal is to control the stability of liquid interfaces using a photoswitchable azobenzen surfactant which can change shape and hydrophobicity under UV or blue light. We have studied experimentally and theoretically the influence of light on the adsorption and desorption fluxes of these surfactants at the scale of a single air-water interface. We...

There's an APP for that: cell-repellent APP (azido-[polylysine-g-PEG]) is used to create substrates for spatially controlled dynamic cell adhesion. The simple addition of a functional peptide to the culture medium rapidly triggers cell adhesion. This highly accessible yet powerful technique allows diverse applications, demonstrated through tissue m...

http://pubs.acs.org/articlesonrequest/AOR-tiUusCsRFVScQHdVi3Mg

In water, cloud points are usually increased upon making the chain more polar in response to light exposure of photochrome side groups. We show here that a reverse response to light is obtained in azobenzene-modified amphiphilic polymers because of the fonnation of self-assemblies. We propose a model to calculate the cloud point accounting for the...

The thermal stability of immunoglobulin G (IgG) in water was monitored by differential scanning calorimetry, dynamic light scattering, and fluorescence correlation spectroscopy in the presence of an amphiphilic polymer (amphipol). The polymer was shown to decrease significantly the enthalpy of IgG unfolding. IgG did not aggregate upon heating up to...

Here we present a readily accessible strategy for creating protein-resistant surfaces that contain azides, based on the spontaneous adsorption of a comb-like copolymer. Using a strain-promoted azide alkyne cycloaddition, we illustrate the single-step conjugation of various representatives of important applications, being the labelling with small or...

The response to light of macromolecules in aqueous media is a significant concern for the design of complex fluids, and (bio)materials imparted with stimuli-triggered properties. It is common knowledge that polymer chains containing photochrome groups can be tailored to undergo a transition between poor and good solvent conditions upon exposure to...

Amphipols (APols) are short amphiphilic polymers designed to handle membrane proteins (MPs) in aqueous solutions as an alternative to small surfactants (detergents). APols adsorb onto the transmembrane, hydrophobic surface of MPs, forming small, water-soluble complexes, in which the protein is biochemically stabilized. At variance with MP/detergent...

Light opens: Photocontrolled transmembrane passage of soluble dyes and delivery of small peptides into mammalian cells has been achieved using azobenzene-modified polymers (AMPs) as permeabilizing agents. Irradiation with UV and visible light triggers polarity switches upon cis-trans isomerization of the azobenzene moieties. Photoresponsive permeab...

It is common knowledge that aggregation of proteins may occur in aqueous solutions under mechanical stress (shaking or high shear), even in solutions that are stable at rest. Addition of surfactants is a practical generic means to prevent this stress-induced aggregation (e.g. in formulations of therapeutic proteins), which suggests that interfaces...

DOI: 10.1021/la204200z ; http://pubs.acs.org/articlesonrequest/AOR-qI5d5vScSeKWx5WMgb2P We report evidence for photocontrolled stability and breakage of aqueous foams made from solutions of a cationic azobenzene-containing surfactant over a wide range of concentrations. Exposure to UV or visible lights results in shape and polarity switches in the...

We study the interfacial behavior of photosurfactants containing an azobenzene moiety in the apolar tail --which switch from cis to trans conformation depending on the wavelength of light. We present here results on the effet of stimulation on the interfacial dynamics of such photosurfactants upon illumination. First, without light stimulus, the tr...

Cited By (since 1996):1, Export Date: 23 March 2014, Source: Scopus

We study the adsorption dynamics of an azobenzene-based photo-responsive charged surfactant to investigate how photo-stimulation impacts the dynamics at an air–water interface. The hydrophobic tail of this photo-responsive surfactant photo-converts reversibly from a cis to a trans conformation when the wavelength switches from UV to blue. This chan...

Amphipols (APols) are short amphipathic polymers that can substitute for detergents to keep integral membrane proteins (MPs) water soluble. In this review, we discuss their structure and solution behavior; the way they associate with MPs; and the structure, dynamics, and solution properties of the resulting complexes. All MPs tested to date form wa...

Seed lipid bodies constitute natural emulsions stabilized by specialized integral membrane proteins, among which the most abundant are oleosins, followed by the calcium binding caleosin. These proteins exhibit a triblock structure, with a highly hydrophobic central region comprising up to 71 residues. Little is known on their three-dimensional stru...

A 2-hydroxyazobenzene platform has been evaluated to photorelease protons in aqueous solutions. Three different systems relying on molecular, supramolecular and polymeric strategies have been investigated in order to tune the water solubility and the thermodynamic and kinetic properties. This paper first reports on the syntheses and the physico che...

Poly(ethylene oxide)-covered polystyrene nanoparticles were prepared by free radical miniemulsion polymerization after using an original low energy emulsification procedure called Near-PIT method. This procedure consisted in heating the initial monomer emulsion up to a temperature close to the phase inversion temperature (PIT) but lower. The surfac...

The design of photoresponsive macromolecules has opened the route to many applications, in particular to trigger macroscopic responses induced by light irradiation in complex fluids and polymer−surfactant formulations. In this report, we studied the association of three sets of azobenzene modified polymer (AMPs) derived from poly(acrylic)acid with...

Membrane permeabilization is achieved via numerous techniques involving the use of molecular agents such as peptides used in antimicrobial therapy. Although high efficiency is reached, the permeabilization mechanism remains global with a noticeable lack of control. To achieve localized control and more gradual increase in membrane perturbation, we...

The association behavior of light-responsive azobenzene modified poly(sodium acrylate)s (AMPs) with C(12)E(6) (hexa-oxyethyleneglycol n-dodecyl ether) surfactant micelles swollen with dodecane was investigated using dynamic light scattering, UV spectrophotometry, and capillary electrophoresis techniques. AMPs complexes with oligoethyleneglycol n-al...

We studied by light scattering and small angle x-rays scattering (SAXS) conformations and solvation of plant tannins (oligomers and polymers) in mixed water-ethanol solutions. Their structures are not simple linear chains but contain about 6% of branching. Ab initio reconstruction reveals that monomers within a branch are closely bound pairwise. Th...

The aggregation of integral membrane proteins (IMPs) in aqueous media is a significant concern for mechanistic investigations and pharmaceutical applications of this important class of proteins. Complexation of IMPs with amphiphiles, either detergents or short amphiphilic polymers known as amphipols (APols), renders IMPs water-soluble. It is common...

We examined by fluorescence microscopy the permeabilization of giant vesicles by hydrophobically modified polyacrylates (called amphipols). Amphipols trigger permeabilization to FITC-dextran of egg-PC/DPPA vesicles with no breakage of the lipid bilayers. The polyanionic amphipols were passing through bilayers as shown by permeabilization of multila...

Tannin-tannin and tannin-protein interactions in water-ethanol solvent mixtures are studied in the context of red wine tasting. While tannin self-aggregation is relevant for visual aspect of wine tasting (limpidity and related colloidal phenomena), tannin affinities for salivary proline-rich proteins is fundamental for a wide spectrum of organolept...

We examined light-triggered formation/dissociation of complexes between azobenzene-modified polymers (AMPs) and surfactants, and we found that the origin of their response to light clearly differs from that of self-assembling of micelles of photosurfactants. We studied a set of AMPs derived from polyacrylic acids with varying integration levels of...

Light Responsiveness of Solution Properties: A Question of Amplification From Cloud Point to Associative Phase Separation of Photopolymers Intrachain Association with Colloid Particles: Photorecognition Complexes on Disperse Interfaces: Photoreversible Emulsions Conclusion Acknowledgments References

The membrane protein bacteriorhodopsin (BR) can be kept soluble in its native state for months in the absence of detergent by amphipol (APol) A8-35, an amphiphilic polymer. After an actinic flash, A8-35-complexed BR undergoes a complete photocycle, with kinetics intermediate between that in detergent solution and that in its native membrane. BR/APo...

This review summarizes recent investigations on the association of macromolecules on lipid bilayers. Hydrophilic and flexible polymers can form soft coronae tenuously adsorbed or anchored on the lipidmembrane. Other synthetic macromolecules are embedded in the apolar region of the membrane. Recent experimental and theoretical works focus on the per...

Electrostatic interactions between synthetic polyelectrolytes and proteins can lead to the formation of dense, macroion-rich liquid phases, with equilibrium microheterogeneities on length scales up to hundreds of nanometers. The effects of pH and ionic strength on the rheological and optical properties of these coacervates indicate microstructures...

Amphiphilic macromolecules, known as amphipols, have emerged as promising candidates to replace conventional detergents for handling integral membrane proteins in water due to the enhanced stability of protein/amphipol complexes as compared to protein/detergent complexes. The limited portfolio of amphipols currently available prompted us to develop...

In the three-dimensional (3D) structure determination of macromolecules, cryo electron microscopy (cryo-EM) is an important method for obtaining micrographs of unstained specimens for the single-particle reconstruction approach. For cryo-EM, proteins are fixed in a frozen hydrated state by quick-freezing in a thin water layer on a holey carbon film...

The molecular interactions of grape-seed tannins dissolved in water-ethanol solutions have been studied through small angle neutron scattering, light scattering, and physical separation techniques. Through selective precipitation in different solvent mixtures, three populations of tannin macromolecules have been identified: T1 (2% of the total tann...