Ref HAL: hal-03328307_v1
PMID 34454365
DOI: 10.1016/j.colsurfb.2021.112054
WoS: 000702833400006
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14 Citations
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Isoniazid (INH) is one of the primary drugs used in tuberculosis treatment and its encapsulation in liposomal vesicles can both improve its therapeutic index and minimize toxicity. Here we consider mixtures of hydrogenated soy phosphatidylcholine-phosphatidylglycerol (HSPC-DPPG) to get novel biocompatible liposomes for INH delivery. We determined INH encapsulation efficiency by coupling for the first time UV and Laser Transmission Spectroscopy and we showed that HSPC-DPPG liposomes can load more INH than expected from simple geometrical arguments, thus suggesting the presence of drug-lipid association. To focus on this aspect, which has never been explored in liposomal formulations, we employed several complementary techniques, such as dynamic and static light scattering, calorimetry and surface pressure measurements on lipid monolayers. We find that INH-lipid interaction increases the entrapment capability of liposomes due to INH adsorption. Moreover, the preferential INH-HSPC dipole-dipole interaction promotes the modification of lipid ordering, favoring the formation of HSPC-richer domains in excess of DPPG. Our findings highlight how investigating the fundamental aspects of drug-lipid interactions is of paramount importance for the optimal design of liposomal nanocarriers.

Ref HAL: hal-03324137_v1
Ref Arxiv: 2107.13348
DOI: 10.1063/5.0057316
WoS: 000691864900008
Ref. & Cit.: NASA ADS
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2 Citations
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When a drop of fluid hits a small solid target of comparable size, it expands radially until reaching a maximum diameter and subsequently recedes. In this work, we show that the expansion process of liquid sheets is controlled by a combination of shear (on the target) and biaxial extensional (in the air) deformations. We propose an approach toward a rational description of the phenomenon for Newtonian and viscoelastic fluids by evaluating the viscous dissipation due to shear and extensional deformations, yielding a prediction of the maximum expansion factor of the sheet as a function of the relevant viscosity. For Newtonian systems, biaxial extensional and shear viscous dissipation are of the same order of magnitude. On the contrary, for thinning solutions of supramolecular polymers, shear dissipation is negligible compared to biaxial extensional dissipation and the biaxial thinning extensional viscosity is the appropriate quantity to describe the maximum expansion of the sheets. Moreover, we show that the rate-dependent biaxial extensional viscosities deduced from drop impact experiments are in good quantitative agreement with previous experimental data and theoretical predictions for various viscoelastic liquids.

Ref HAL: hal-03322429_v1
DOI: 10.1021/acsanm.1c00803
WoS: WOS:000668366800031
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Herein, we demonstrate that tuning of structural parameters and material chemistry enables control of the permeability and selectivity of gases (CO2, He, and CH4) in membranes based on poly(butyl methacrylate)-grafted nanoparticles (PGNs). Our data show that the presence of nanoparticles and the overall dense packing of grafted chains noticeable in PGNs with low grafting density have an adverse effect on the diffusivity of gases. This effect is compensated by an improvement in the solubility of CO2 gas promoted by the silica nanoparticle surface, yielding a substantial improvement in the permeability of CO2 versus CH4. In membranes with high grafting density, changes in the structural arrangements and alterations in the membrane porosity, evident from small-angle X-ray scattering and positron annihilation lifetime spectroscopy, positively influence the permeability of He and CO2 gases. In contrast, CH4 permeability in the same membranes is significantly suppressed, suggesting the formation of a unique, highly selective environment for gas separation. As a result, an improvement of up to 50% in selectivity for gas pairs containing large CH4 molecules is observed. Our studies provide fundamental insights into the role that structural parameters play in gas transport through polymer membranes, laying a foundation for the rational design of membranes with improved permeability and selectivity.

Ref HAL: hal-03384154_v1
DOI: 10.1021/acsanm.1c00725
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The liquid mixing process is an advantageous production method which has recently gained industrial interest for elaborating composites based on natural rubber (NR) and filler nanoparticles (NPs). Understanding how the relevant components such as polymer, fillers, as well as proteins and lipids coming from NR organize along the fabrication process is of importance for modulating material properties. Here, we successfully employed a combination of nano-imaging techniques to unravel the structure and evolution of hetero-aggregates formed by colloidal destabilization of a model NR latex - silica NPs liquid mixing process. First, field emission scanning electron microscopy (FESEM) was used to investigate the structures, from the early stage of contact between the particles until the formation of a composite. Results highlight an interaction in the liquid state between NR globules contained within the latex and silica NPs, hindering coalescence among globules. The latter can be achieved by applying shear in suspension or by solvent evaporation obtaining a dried composite. Atomic force microscopy coupled to infrared spectroscopy (AFM-IR) was employed to probe the in-depth nanoscopic distribution of silica NPs revealing a restricted mobility of the NPs during evaporation. Ultimately, the spatial distribution of proteins and lipids of NR, with respect to silica NPs, was investigated using dual color fluorescence images acquired with direct stochastic optical reconstruction microscopy (d-STORM) in a correlative light electron microscopy (CLEM) approach. The presence of silica NPs is found to influence the distribution of proteins and lipids in the composite; biomolecules form clusters of ~200 nm, which are partially colocalized with silica, highlighting an interaction between them. Our work provides comprehensive structural understanding of a model system undergoing liquid mixing, unlocking the potential of combining high-resolution imaging techniques to elucidate the structure of materials for tire applications.

Ref HAL: hal-03283831_v1
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Rubber-based nanocomposites prepared by solid-phase mixing with precipitated silica nanoparticlesare typically strongly aggregated systems with different levels of spatial organization. The strategy thatwe developed several years ago to investigate such systems is based on the study of simplifiedindustrial samples with ingredients limited to a strict minimum. On the scale of a micrometricsimulation box, tens of thousands of nanoparticles are embedded in the matrix, and their dispersionstrongly affects the mechanical properties of the material – and which is reflected in the scatteredintensity. A statistical method based on a reverse Monte Carlo solution of this many-parameterproblem will be presented, showing that some key features like percolation can be described. [1]Another key feature of rubber nanocomposites refers to the influence of the filler surfaces on thepolymer dynamics, and some recent progress – including incoherent neutron spin-echo measurements– will be discussed. [2] Such results may be confronted to dielectric spectroscopy measurements whichin some cases are not conclusive due the impossibility to correctly resolve the α-relaxation in presenceof strong interfacial polarization processes. An original application of dielectric spectroscopy with asurprising measurement of the adsorption isotherm of coating agents onto silica buried in the polymermatrix will also be discussed. [3][1] Musino D, Genix A-C, Chauveau E, Bizien T, Oberdisse J, Nanoscale 2020, 12:3907.[2] Musino D, Oberdisse J, Farago B, Alegria A, Genix A-C, ACS Macro Letters 2020, 9:910.[3] Musino D, Oberdisse J, Sztucki M, Alegria A, Genix A-C, Macromolecules 2020, 53:8083.

Ref HAL: hal-03283802_v1
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Polymerized ionic liquids (PolyILs) are an emerging class of polymer electrolytes which offer solutions to many problems in current battery technology. They combine the attractive features of ionic liquids with the mechanical strength of polymeric materials. However, a major obstacle in use of dry PolyILs is their low ionic conductivity at ambient temperature, which remains below the level required for many applications (ca. 10-3 S/cm). In this context, it has been shown that a significant enhancement of the ionic conductivity can be obtained by decoupling the ion motion from the segmental dynamics in polymers. We will review recent results obtained in this field using broadband dielectric spectroscopy, and discuss the microscopic parameters controlling ionic conductivity in PolyILs below Tg [1]. In particular, our detailed study of imidazolium-based PolyILs helped to unravel the interplay between nanostructure and ion conduction mechanism [2]. We also report first quasi-elastic neutron scattering experiments in these polymers suggesting the role of fast dynamics in assisting ion transport in the glassy state [3].[1] V. Bocharova and A.P. Sokolov, Macromolecules 2020, 53, 4141.[2] B. Doughty, A.C. Genix, I. Popov, B. Li, S. Zhao, T. Saito, D. Lutterman, R. Sacci, B.G. Sumpter, Z. Wojnarowska, V. Bocharova, Phys. Chem. Chem. Phys. 2019, 21, 14775.[3] V. Bocharova, A.C. Genix, A. Kisliuk, G. Sala, N.C. Osti, E. Mamontov, A. P. Sokolov, J. Phys. Chem. B 2020, 124, 10539.

Ref HAL: hal-03270654_v1
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The development of smart nanomaterials has attracted great attention in several fields like nanoscience, materials science,engineering and nanotechnology due to their unique response to external stimuli. Many of them are based on polymers thatcan exhibit great shape-changes when submitted to environmental modifications. Poly(N-isopropylacrylamide), PNIPAM, is sucha thermo-responsive polymer. It is water soluble at room temperature, forming gels by cross-linking but undergoes a reversiblecoil-to-globule volume phase transition (VPT) at a lower critical solution temperature (LCST) close to 32 °C due to thedehydration and subsequent collapse of its chains into compact globules.
Hybrid nanocomposite microgels associating PNIPAM and gold nanoparticles (GNP) have been designed in order to takeadvantage of the outstanding plasmonic and photo-thermal properties of GNP to promote the volume phase transition of themicrogels through an efficient photo-thermal conversion. With their strong diameter-dependent optical absorption in the nearinfrared (NIR) and their large surface area favoring photo-thermal transfer, semiconducting SWNT (s-SWNT) are goodcandidates for photo-thermal conversion in the NIR and may therefore be used to prepare multi-responsive hybrid microgels(Figure 1). However, to the best of our knowledge, no thorough studies of such nanomaterials have been reported so far.
Here we report the preparation of smart SWNT/PNIPAM nanocomposites through non-covalent functionalization techniques.These SWNT/PNIPAM hybrid microgels are stable in water and show a VPT, which can be promoted either by direct heating orby excitation of the resonant absorption of s-SWNT in the near infrared. Furthermore, the photoluminescence (PL) signal of s-SWNT is modulated at the phase transition and therefore, the PL signal can be used to monitor the VPT. This is illustrated inFigure 2, showing coupled Raman/PL measurements below and above the LCST, where a redshift of the PL bands is observedwhen crossing the LCST while the Raman signatures remain essentially the same.