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This work describes how nanostructured thin films obtained from the self-assembly of block copolymers (BCPs) systems can be used as a nanoelectrode array (NEA) that can be programmed to specifically detect targeted molecules. Namely, poly(styrene-b-methacrylate) (PS-b-PMMA) thin films, after removal of PMMA phase, produced regular spaced 560 pores μm-2 with 16 nm of diameter. The nanopores were then chemically modified by the introduction of β-cyclodextrin (β-CD) molecules. By using the supramolecular interaction of β-CD and ferrocene (Fc), the pores could be programed by the introduction of molecules linked to Fc able to interact with target species. In the model system shown here, the linker had a biotin unit, aiming the detection of streptavidin. By changing the linker, other molecules can also be detected. This concept opens a window to many possibilities, including the development of devices for fast and versatile molecule detection.

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International audience; Amphiphilic polymers are synthesized from various biobased compounds involving telomerization of glycerin-derived acrylate monomers with mercaptan-modified fatty acids. The effects of the chemical structure of the saturated or unsaturated hydrophobic block are investigated. Dynamic and static light scattering measurements, transmission electronic microscopy, and atomic force microscopy observations show that these copolymers are capable of self-assembling into nanosized spherical particles in aqueous solution, made from compound micelles. The critical micellar concentration of these polymers is in the range of 10-60 mg L−1 determined by fluorescence. These biobased polymers could have applications in various industrial fields, such as cosmetics and agrochemicals.

Polycaprolactone (PCL) nanoparticles decorated with a mucoadhesive polysaccharide chitosan (CS) containing curcumin were developed aiming the buccal delivery of this drug. These nanoparticles were prepared by the nanoprecipitation method using different molar masses and concentrations of chitosan and concentrations of triblock surfactant poloxamer (PEO-PPO-PEO), in order to optimize the preparation conditions. Chitosan-coated nanoparticles showed positive surface charge and a mean particle radius ranging between 114 and 125 nm, confirming the decoration of the nanoparticles with the mucoadhesive polymer, through hydrogen bonds between ether and amino groups from PEO and CS, respectively. Dynamic Light Scattering (DLS) studies at different scattering angles and concentrations have shown that the nanoparticles are monodisperse (polydispersity indices were lower than 0.3). The nanoparticle systems were also examined with Nanoparticle Tracking Analysis (NTA), and the results were in good agreement with those obtained by DLS. Colloidal systems showed mean drug content about 460 μg/mL and encapsulation efficiency higher than 99%. Finally, when coated with chitosan, these nanoparticles show a great ability to interact with mucin indicating also their suitability for mucoadhesive applications.

The preparation of biocompatible nanocarriers that have potential applications in the cosmetic and health industries is highly desired. The self-assembly of amphiphilic block copolymers displaying biosourced polysaccharides at the surface is one of the most promising approaches. In the continuity of our works related to the preparation of "hybrid" amphiphilic oligosaccharide-based block copolymers, we present here the design of a new generation of self-assembled nanoparticles composed entirely of oligosaccharide-based amphiphilic block co-oligomers (BCO). These systems are defined by a covalent linkage of the two saccharidic blocks through their reducing end units, resulting in a sweet "head-to-head" connection. As an example, we have prepared and studied a BCO in which the hydrophilic part is composed of a free maltoheptaosyl derivative clicked to a hydrophobic part composed of a peracetylated maltoheptaosyl derivative. This amphiphilic BCO self-assembles to form spherical micelles in water with an average diameter of 30 nm. The efficient enzymatic hydrolysis of the maltoheptaose that constitutes the shell of the micelles was followed by light scattering and colorimetric methods.

International audience; The influence of surfactant type and concentration on particle size, formulation yield and stability of the polyurethane (PUR) nanoparticles synthesized by miniemulsion polymerization was investigated. SDS, Tween 80 and Pluronic F68 were employed as surfactants in concentration ranging from 5 to 20% (vs monomer concentration). The surfactant SDS was found not efficient in our system, resulting in a low formulation yield (about 53%), two particle size distributions and zeta potential equal to - 52.3mV. On the other hand, the nonionic surfactants gave monomodal particle size distribution, good yields (> 85%) and zeta potential around to- 24mV. The particles synthesized with Tween 80 or Pluronic F68 were very similar to each other in terms of efficiency, particle size distribution and zeta potential. For instance, the particle diameter slightly decreases from 292nm to 261nm as the amount of Tween 80 surfactant increases from 5 to 20wt.% vs monomer. Moreover, we have observed that a concentration of at least 5wt. % of Tween 80 was necessary to favor particle stability and therefore to avoid aggregation.

International audience; We have studied the effect of polystyrene (PS) homopolymer addition on the morphology of self-assembled block copolymer micelles made from linear or cyclic poly(styrene-b-isoprene), PS-b-PI, in a selective solvent for the PI block (heptane). Both copolymers have the same composition: the degree of polymerization is 290 for the PS block, and 110 for the PI block, and we focused on the influence of the addition of small amounts of PS homopolymer on the micellar morphology. For the copolymer concentrations considered, the linear copolymer self-organizes into spherical micelles while the cyclic copolymer forms cylindrical micelles. PS and PI chains constitute the core and the corona of these micelles, respectively, due to the different affinity of the blocks for heptane. Consequently, the PS homopolymer added is "solubilized" into the micellar core. Dynamic light scattering (DLS) data combined with atomic force microscopy (AFM) results show that the addition of PS homopolymer induces a drastic change in the micellar organization. Indeed, a morphological transition, from spheres to cylinders for the linear copolymer, and from cylinders to vesicles for the cyclic copolymer, is observed. These results highlight the fact that a small incorporation of PS homopolymer is clearly sufficient to modify the morphology (size and shape) of the micelles. This approach could be a key parameter for the design/control of micelles for specific applications in nanotechnology.

International audience; Polyurethane nano- and microparticles were synthesized by suspension-polyaddition technique, using aqueous polymerization medium. Castor oil, a vegetable triglyceride possessing hydroxyl groups was used as natural polyol and methylene cliphenyl diisocyanate (MDI) as isocyanate. The levofloxacin, an antibacterial drug was used as model drug to measure the particles encapsulation efficiency. The effect of the addition of a second polyol, the poly(ethylene glycol) (PEG), and the stirring rate on the mean diameter and morphology of particles was also investigated. The poly(ethylene glycol) has an important effect in the reduction of particles size and their porosity. On the other hand, the poly(ethylene glycol) reduced the yield of encapsulation from 70% for the formulation without PEG to 20% for formulations with PEG. FTIR analysis confirmed the polyurethane formation. Dynamic light scattering study, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used to determine the nanoparticles size and shape. Spectrofluorimetric analysis was used to detect the levofloxacin.

International audience; A polycrystalline sample of Nd2Fe14B was prepared by induction melting and solidification in an intense applied magnetic field, to study the alignment due to residual magnetocrystalline anisotropy of this compound near the melting point. A well-defined direction of the thermal gradient perpendicular to the magnetic field was achieved by means of an appropriate experimental set-up. The results of measurements indicate that the sample is substantially textured, but not in parallel to the elaboration field. A numerical method is utilized for the determination of anisotropy parameters in Nd2Fe14B compound, involving the analysis of measured magnetization curves. The minimization of the free-energy density, expanded in terms of these constants, is performed to determine the sub-lattice terms which are necessary to calculate the polarization curves. A fitting of the measured magnetization curves obtained at room temperature is realized to obtain the anisotropy constants, texture parameters and saturation magnetization.

Made available in DSpace on 2021-06-25T11:48:19Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-09 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Background: Bioelectrical impedance vector analysis (BIVA) is able to identify differences in hydration status and body composition components, such as body cell mass (BCM) by means of plotting individuals in ellipses, when comparing groups with different characteristics. Objective: Compare the confidence and tolerance ellipses of BIVA in individual and team sports athletes with a non-athlete reference population. Design and participants: One hundred sixty-seven college athletes (team sports: 117 athletes, individual sports: 50 athletes) aged between 18 and 35 years. Bioelectrical impedance was used to measure resistance (R) and reactance (Xc) values that were used in the BIVA analysis to identify hydration status and BCM, respectively. Hotelling's t-test was used to identify differences between groups in the confidence ellipses and the comparison was made with a non-athlete Italian reference population. Results: There were no differences between male team sports and individual athletes (p = 0.151) and for female athletes (p = 0.624). Most athletes were located in the 50% tolerance ellipses, indicating adequate hydration. Compared to the Italian a non-athlete population, athletes of both sexes presented left impedance vector deviation in the minor axis (Xc) of the tolerance ellipses, indicating higher BCM. Conclusion: There were no differences in BIVA between team and individual sports athletes, but most athletes presented an adequate hydration state and, compared to a non-athlete population, the athletes of the present study presented higher BCM. Univ Fed Santa Catarina, Dept Educ Fis, Ctr Desportos, Campus Univ Trindade Caixa Postal 476, BR-88040900 Florianopolis, SC, Brazil Univ Estadual Paulista, Sao Paulo, Brazil Univ Estadual Paulista, Sao Paulo, Brazil

Nanoparticles based on block copolymers of oligosaccharides [β-cyclodextrin (βCyD) and maltoheptaose (Mal7)] and poly(e-caprolactone) (PCL) were prepared by microphase inversion method. Zeta-potential, particle size measurements and morphological analysis of drug-free and drug-loaded nanoparticles were performed by using, respectively, laser-doppler anemometry, dynamic and static light scattering and transmission electron microscopy. ρ-Ratio values were correlated with transmission electron microscopy observations. Both types of amphiphilic block copolymers, βCyD-b-PCL5k and Mal7-b-PCL5k, self-assembled in water to form spherical vesicles, presented a hydrodynamic diameter of 72 and 34 nm, respectively. The incorporation of drugs into nanoparticles did not affect significantly the particle size for βCyD-b-PCL5k-based nanoparticles with progesterone, unlike the other tested systems. On the other hand, all nanoparticles (with and without drug) were negatively charged. Both nanoparticulate systems showed high drug loading efficiency (higher than 95%), confirming their suitability as delivery system for lipophilic drugs.

International audience; The in vitro cytotoxicity and DNA damage evaluation of biodegradable polyurethane-based micro- and nanoparticles were carried out on animal fibroblasts. For cytotoxicity measurement and primary DNA damage evaluation, MTT and Comet assays were used, respectively. Different formulations were tested to evaluate the influence of chemical composition and physicochemical characteristics of particles on cell toxicity. No inhibition of cells growth surrounding the polyurethane particles was observed. On the other hand, a decrease of cell viability was verified when the anionic surfactant sodium dodecyl sulfate (SDS) was used as droplets stabilizer of monomeric phase. Polyurethane nanoparticles stabilized with Tween 80 and Pluronic F68 caused minor cytotoxic effects. These results indicated that the surface charge plays an important role on cytotoxicity. Particles synthesized from MDI displayed a higher cytotoxicity than those synthesized from IPDI. Size and physicochemical properties of the particles may explain the higher degree of DNA damage produced by two tested formulations. In this way, a rational choice of particles' constituents based on their cytotoxicity and genotoxicity could be very useful for conceiving biomaterials to be used as drug delivering systems.