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Prostate cancer (PCa) is a slow-growing neoplasm that has, when diagnosed in its early stages, great chances of cure. During initial tumor development, current diagnostic methods fail to have the desired accuracy, thus, it is necessary to develop or improve current detection methods and prognostic markers for PCa. In this scenario, films composed of hyaluronic acid (HA) and chitosan (CHI) have demonstrated significant capture potential of prostate tumor cells (PC3 line), exploring HA as a CD44 receptor ligand and direct mediator in cell-film adhesion. Here, we present a strategy to control structural and cell adhesion properties of HA/CHI films based on film assembly conditions. Films were built via Layer-by-layer (LbL) deposition, where the pH conditions (3.0 and 5.0) and number of bilayers (3.5, 10.5, and 20.5) were controlled. The characterization of these films was carried out using profilometry, ultraviolet-visible (UV-VIS), atomic force microscopy (AFM) and contact angle measurements. Multilayer HA/CHI films produced at pH 3.0 gave optimum surface wettability and availability of free carboxyl groups. In turn, at pH 5.0, the coverings were thinner and presented a smoother surface. Films prepared with 3.5 bilayers showed greater tumor cell capture regardless of the pH condition, while films containing 10.5 and 20.5 bilayers presented a significant swelling process, which compromised their cell adhesion potential. This study shows that surface chemistry and morphology are critical factors for the development of biomaterials designed for several cell adhesion applications, such as rapid diagnostic, cell signaling, and biosensing mechanisms.

The spontaneously self-organizing multilayered graphite-like carbon (denoted as GLC) /TiC films with various bilayer periods in the range of 13.3–17.5 nm were deposited on silicon and 1Cr18Mn8Ni5N stainless steel substrates using closed field magnetron sputtering deposition facility. The microstructures and chemical compositions of the prepared multilayered films were characterized by scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy respectively. The self-organizing multilayered structures in all of the films consisted of titanium carbide layers and sp2-rich carbon layers periodically alternate arrangement. The TiC contents and bilayer periods of the multilayered films can be controlled by means of adjusting of sputtering current of graphite target. Furthermore, the mechanical and tribological performances of the prepared films were appraised by nano-indentor, scratch measures, and ball-on-plate tribometer respectively. The results indicated that multilayer structure endowed the as-deposited TiC/GLC films outstanding mechanical and tribological properties, especially the multilayer film with 15.9 nm bilayer period deposited at 10 A sputtering current showed the excellent adhesion strength and hardness, Simultaneously it also exhibited the lowest average friction coefficient in the humid environment owing to its high content of sp2 hybrid carbon.

Introduction. An incomplete list of graphene properties includes high electric conductivity, thermal conductivity, strength, large surface area, high light transmittance. Graphene is a very promising material from the point of view of its application in micro- and nanoelectronics. In addition, graphene advantage is a possibility of its obtaining by various ways. It allows creating materials with desired physicochemical properties by using appropriate technological methods. Objective. The investigation of a thermal reduction temperature influence on physicochemical properties of graphene oxide (GO) films. Materials and methods. In the present work, GO films are obtained on a slide surface by its immersing and removing from a graphene oxide water dispersion (dip coating). Obtained samples are studied by methods of scanning electron microscopy, Raman spectroscopy, and elemental CHN analysis. A sheet resistance is measured by a four-point probes method. Results. A content difference of elements (C, H, N) in studied samples, and both graphene structure defectiveness and sheet resistance decrease, are found to be proportional to a reduction temperature increase. A GO films thickness decrease during a heat treatment is also observed, which is presumably associated with a functional GO groups loss while thermal reduction. Conclusion. Research results demonstrate a possibility of a carbon films with desired physicochemical properties obtaining from a reduced graphene oxide (RGO), which can be used in thin-film technologies. Presented materials can also be useful in issues related to GO and RGO obtaining and applying.

In this study, we report the isolation of cellulose nanocrystals (CNCs) from Isora plant fibers by sulfuric acid hydrolysis and their assembly on hydrophilic cellulose and silicon-di-oxide (SiO2) surfaces via a layer-by-layer (LBL) deposition method. The isolated CNCs were monodis-persed and exhibited a length of 200-300 nm and a diameter of 10-20 nm, a negative zetapotential (34-39 mV) over a wide pH range, and high stability in water at various concentrations. The multi-layered structure, adsorbed mass, conformational changes, and anticoagulant activity of sequen-tially deposited anionic (sulfated) CNCs and cationic polyethyleneimine (PEI) on the surfaces of cellulose and SiO2 by LBL deposition were investigated using a quartz crystal microbalance tech-nique. The organization and surface features (i.e., morphology, thickness, wettability) of CNCs ad-sorbed on the surfaces of PEI deposited at different ionic strengths (50-300 mM) of sodium chloride were analysed in detail by profilometry layer-thickness, atomic force microscopy and contact angle measurements. Compared to cellulose (control sample), the total coagulation time and plasma deposition were increased and decreased, respectively, for multilayers of PEI/CNCs. This study should provide new possibilities to fabricate and tailor the physicochemical properties of multilayer films from polysaccharide-based nanocrystals for various biomedical applications. Acknowledgments: The authors acknowledge Volker Ribitsch (retired) from the University of Graz/Austria for his support and valuable discussion for this manuscript. The authors also acknowledge the financial support from the Slovenian National Research Agency ARRS (Grant No. J4-1764). Scopus

Xingfang Yu,1,* Xin Liao,2,* Hongwei Chen1 1Department of Orthopedics, The Affiliated Yiwu Hospital of Wenzhou Medical University, Yiwu, Zhejiang, 322000, People’s Republic of China; 2Department of Orthopedics, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, Zhejiang, 325000, People’s Republic of China*These authors contributed equally to this workCorrespondence: Hongwei ChenDepartment of Orthopedics, The Affiliated Yiwu Hospital of Wenzhou Medical University, Yiwu, Zhejiang, 322000, People’s Republic of ChinaTel +86-13506896988Email sssaaa18@163.comBackground: Bone infections remain one of the most common and serious complications of orthopedic surgery, posing a tremendous economic burden to society and patients. This is because bacteria colonize and multiply on the surface of the implant. The (MMT/PLL)8 multilayer films have been shown to effectively release antibiotics depending on the changes in the microenvironment. Here, vancomycin was loaded into the (MMT/PLL)8 multilayer films, which were prepared to be used as a local delivery system for the treatment of bone infections.Methods: We used the layer-by-layer self-assembly method to prepare VA-loaded coatings (MMT/PLL-VA)8 consisting of montmorillonite (MMT), poly-L-lysine (PLL), and VA. The thickness and surface morphology of coatings were characterized using spectroscopic ellipsometry and scanning electron microscopy (SEM). In order to evaluate the drug release behavior from coatings in different media, we measured the size of the zone of inhibition. Additionally, in vitro antibacterial activity was assessed using the shake-flask culture method and SEM images, while that of in vivo was evaluated by establishing an animal model of bone infection.Results: Our findings revealed that small-molecule antibiotics were successfully loaded into the (MMT/PLL-VA)8 multilayer film structure during the hierarchical self-assembly process and subsequently the multilayer film structure depicted linear growth behavior. The PLL in the multilayer films was progressively degraded which triggered the VA release when contacted with CMS or bacterial infections. The release of VA from multilayer film structure depends on the concentration changes of CMS. Notably, the multilayer films presented great in vitro cell compatibility. Moreover, the prepared antibacterial multilayer films showed excellent antibacterial property by killing more than 99.99% of S. aureus in 24 h. More importantly, we found that multilayer film exhibits good sterilization effect and biocompatibility under the stimulation of bacterial liquid both in vitro and in vivo antibacterial ability tests.Conclusion: Altogether, this study shows that (MMT/PLL-VA)8 multilayer films containing CMS and bacteria-responsive drug release properties posess high bactericidal activity and good biocompatibility. This finding provides a novel strategy for the treatment of bone infections.Keywords: bone infections, multilayer films, microenvironment, layer-by-layer, antibacterial

Adjusting the inter-particle distances in ordered nanoparticle arrays can create new nano-devices and is of increasing importance to a number of applications such as nanoelectronics and optical devices. The assembly of negatively charged polystyrene (PS) nanoparticles (NPs) on Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes, quaternized PDMAEMA brushes and Si/PEI/(PSS/PAH)2, was studied using dip- and spin-coating techniques. By dip-coating, two dimensional (2-D), randomly distributed non-close packed particle arrays were assembled on Si/PEI/(PSS/PAH)2 and PDMAEMA brushes. The inter-particle repulsion leads to lateral mobility of the particles on these surfaces. The 200 nm diameter PS NPs tended to an inter-particle distance of 350 to 400 nm (center to center). On quaternized PDMAEMA brushes, the strong attractive interaction between the NPs and the brush dominated, leading to clustering of the particles on the brush surface. Particle deposition using spin-coating at low spin rates resulted in hexagonal close-packed multilayer structures on Si/PEI/(PSS/PAH)2. Close-packed assemblies with more pronounced defects are also observed on PDMAEMA brushes and QPDMAEMA brushes. In contrast, randomly distributed monolayer NP arrays were achieved at higher spin rates on all polyelectrolyte architectures. The area fraction of the particles decreased with increasing spin rate.

In this work, we prepared TiO2 and Co multilayer thin films via DC magnetron sputtering method on (100) GaAs and (100) Si substrates. The power for each target (TiO2 and Co), deposition time of the layers, and pressure during deposition were kept constant. From XRD, Raman, and IR measurements, the formation of the rutile and triclinic Co phases were identified in the multilayer thin films. An annealing process was carried in situ on all samples and subsequent to the deposition stage during 2 h. The substrate used was GaAs and Si wafer, favoring the formation and growth of the found phases. The diffusion and interdiffusion of the layers in the thin films were determined from Rutherford Backscattering Spectroscopy (RBS). In particular, Co and Ga were observed to associate after the annealing process according to the depth profiles. Due to the interdiffusion layers, the parallel magnetic contribution is not significant in the bilayer. Curves I-V of the Co/TiO2 bilayer showed the presence of resistive switching, according to the bipolar resistive. A correlation between synthesis parameters and the physical properties of the multilayers is presented, The Universidad Nacional de Colombia, COLCIENCIAS Conv. 727- 2015 and Universidad del Rosario supported this work. Heiddy Paola Quiroz is scholarship PhD of Doctorados COLCIENCIAS. Acknowledgments to the Universidad del Rosario for the EDI 2017 scholarship to professor Fredy Mesa

Transport, mechanical and global migration data concern multilayer food packaging films with different layouts, all incorporating a layered silicate/polyamide nanocomposite as oxygen barrier layer, and a low-density polyethylene (LDPE) as moisture resistant layer in direct contact with food. The data are related to “Tuning of co-extrusion processing conditions and film layout to optimize the performances of PA/PE multilayer nanocomposite films for food packaging” by Garofalo et al. (2017) [1] . Nanocomposite multilayer films, with different relative layer thicknesses and clay types, were produced using a laboratory scale co-extrusion blown-film equipment and were analyzed in terms of transport to oxygen and water vapor, mechanical properties and overall migration. The results have shown that all the multilayer hybrid films, based on the copolyamide layer filled with Cloisite 30B, displayed the most significant oxygen barrier improvements and the best mechanical properties compared to the unfilled films. No significant alteration of the overall migration values was observed, as expectable [2] , [3] , [4] . The performance improvement was more relevant in the case of the film with the thinner nanocomposite layer.

We demonstrate a method for the formation of multilayers composed of reduced graphene oxide (rGO), which can be used for transparent, conducting thin films. Using the layer-by-layer (LbL) assembly of positively and negatively charged GO sheets, we could obtain thin films with highly controllable sheet resistance. The natural negative charge of graphene oxide was turned to positive by the amidation reaction. After forming the multilayer films, the graphene oxide underwent thermal reduction at temperatures above 150 °C. The (rGO+/rGO−) films were characterized by UV-Vis and scanning electron microscopy (SEM), and their conductivity was measured by the four-point method. We found that after deposition of five (rGO+/rGO−), the coating structure reached the percolation limit, and the film resistance decreased more gradually to around 20 kΩ/sq for the films obtained by eleven deposition cycles with graphene oxide reduced at 250 °C. The formation of thin films on polyimide allows the forming of new flexible conductive materials, which can find applications, e.g., in biomedicine as new electroactive, low-cost, disposable sensors.

International audience; We have here developed a straightforward one-step route to surface modified polystyrene (PS) based microfibers for protein/enzyme immobilization. Our approach consists of wet electrospinning of a poly(styrene-alt-maleic anhydride) (PSMA) polymer in an aqueous solution collector which contains the (macro) molecules to be coupled, here PEG diamine (PEGDA) or hexamethylene diamine (hexDA). The amino groups on the fiber surface were then exploited for immobilization of the horseradish peroxidase (HRP) enzyme. The immobilized HRP amounts were higher on the PEG-and hexyl-modified fibers than on the non-modified PSMA ones. The HRP catalytic activity was evaluated with 2,2'-azino-bis(3-ethyl-benzothiazoline- 6-sulfonic acid) (ABTS) as a substrate. While the retained activity of the enzyme immobilized on unmodified PSMA microfibers was only 2.4% of free enzyme, that of the enzyme immobilized on the PEGylated fibers increased to 34%. As a comparison, HRP fixed on hexyl-functionalized fibers exhibited a retention activity of 19.7%, showing the impact of a PEG spacer on HRP activity. HRP immobilization on PEG and hexyl-coated fibers had also a beneficial impact on enzyme storage stability. This study highlights the impact of surface properties on the activity of the immobilized enzyme and provides a convenient route to simultaneous elaboration/modification of fibers, for suitable protein fixation.

In our work we focused on the electroactive and electrocatalytic properties of multilayer films formed from polyelectrolytes (PE) and Prussian blue nanoparticles (PBn), enhanced by addition of reduced graphene oxide (rGO). Films containing poly(allylamine hydrochloride) (PAH) and PBn were constructed using the layer-by-layer adsorption method. Graphene oxide (GO) was deposited from its aqueous suspension forming additional layers of the film. Then they were exposed to the elevated temperature, 180 °C to turn graphene oxide into its reduced form. We demonstrated, by cyclic voltamperometry, that the presence of conductive rGO greatly enhanced the electroactive properties of the PE/PB multilayer films. Simultaneously, they were also up to 40 times more effective for the electrocatalytic redox processes of hydrogen peroxide.

International audience; We describe a very simple and efficient route to functionalize boron-doped-diamond (BDD) electrodes with a chelating nitrilotriacetic acid (NTA) ligand. The BDD electrode surface was first functionalized with a carboxylic acid group via electrochemical grafting of 4-aminophenylcarboxylic acid in aqueous solution and subsequently linked to NTA ligand via a coupling reaction with amine terminated NTA ligand in PBS solution (pH 7.5). Modified BBD surfaces were characterized using X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The present study has demonstrated that NTA functionalized BDD surfaces can successfully be used for reversible Am-241 sequestration in aqueous solution

The present research reports on the development of bi- and multilayer polylactide (PLA) films by the incorporation of electrospun nanostructured PLA coatings and interlayers containing the antioxidant gallic acid (GA) at 40 wt% onto cast-extruded PLA films. To achieve the bilayer structures, submicron GA-loaded PLA fibers were applied on 200-&micro, m cast PLA films in the form of coatings by electrospinning for 1, 2, and 3 h. For the multilayers, the cast PLA films were first coated on one side by electrospinning, then sandwiched with 10-&micro, m PLA film on the other side, and the resultant whole structure was finally thermally post-treated at 150 &deg, C without pressure. Whereas the bilayer PLA films easily delaminated and lacked transparency, the multilayers showed sufficient adhesion between layers and high transparency for deposition times during electrospinning of up to 2 h. The incorporation of GA positively contributed to delaying the thermal degradation of PLA for approximately 10 &deg, C, as all films were thermally stable up to 345 &deg, C. The in vitro release studies performed in saline medium indicated that the GA released from the bilayer PLA films rapidly increased during the first 5 h of immersion while it stabilized after 45&ndash, 250 h. Interestingly, the PLA multilayers offered a high sustained release of GA, having the capacity to deliver the bioactive for over 1000 h. In addition, in the whole tested period, the GA released from the PLA films retained most of its antioxidant functionality. Thus, during the first days, the bilayer PLA films can perform as potent vehicles to deliver GA while the multilayer PLA films are able to show a sustained release of the natural antioxidant for extended periods.

The preparation of urea (bonded) cross-linked multilayer thin films by sequential deposition of bifunctional and tetrafunctional molecular building blocks is demonstrated. Multilayer growth as a function of deposition cycles was inspected using UV-vis absorption spectroscopy. From infrared results, three characteristic infrared bands of amide I, amide II, and asymmetric νa(N-C-N) stretching confirmed the formation of polyurea networks by alternate dipping into solutions of amine and isocyanate functionality monomers. The deconvoluted component of the C 1s and N 1s spectra obtained by X-ray photoelectron spectroscopy shows clear evidence of stable polyurea networks. The enhancement of structural periodicity with film growth was demonstrated by grazing-incidence small-angle X-ray scattering measurements. The thin film near the substrate surface seems to have an amorphous structure. However, molecular ordering improves in the surface normal direction of the substrate with a certain number of deposited layers. Constant mass density was not observed with deposition cycles. The mass density increased up to 16% within deposited layers from proximate layers to those extending away from the substrate surface. This difference in the packing density might derive from the different degrees of cross-linking among layers proximate to the substrate surface and extending away from the substrate surface.

Biomedical implant failure arises mainly from the degradation caused by tribological processes occurring in the corrosive environment the human body represents, known as tribocorrosion. The material loss and metal ion release resulting from tribocorrosion processes compromise the biocompatibility of metallic implants. The deposition of protective coatings on metallic substrates is a promising solution to overcome this problem. Pure titanium (Ti-cp) is widely used as an implant material due to its excellent corrosion resistance and high biocompatibility. However, its mechanical properties must be improved in order to ensure a longer durability. For this purpose, TaN monolayer and multilayer coatings were deposited on medical grade Ti-cp to enhance its tribocorrosion performance in simulated body fluids. TaN coatings were deposited by recently developed High Power Pulsed Magnetron Sputtering (HPPMS) technique. HPPMS enables the deposition of extremely dense coatings with superior properties compared to the ones grown by conventional sputtering. Columnar-free TaN monolayer and multilayer films were developed exhibiting corrosion resistances in the MΩ range, one order of magnitude higher than for Ti-cp. Friction coefficient of Ti-cp was reduced from 0.58 to 0.25 while wear rate was considerably decreased. The determined material loss after tribocorrosion tests for Ti-cp was 0.4 mm. It was reduced up to 1.55 × 10 mm by the application of best-performing TaN multilayer film., Financial support of this research program from the Basque Government (EMAITEK program) and Spanish National Department of the Education and Science in the projects: CSD2008-00323 FUNCOAT and MAT2014-57547-R is gratefully acknowledged.

A key challenge in the preparation of nanoplatelet-filled polymer composites is the ability to realize the nanometer-level dispersion and the planar orientation of nanosheets in polymer matrices. In this report, multilayer films were successfully fabricated by layer-by-layer assembly of regenerated cellulose and graphene oxide, in which graphene oxide nanosheets were used as the building blocks. The thickness of 50 layer film is about 20 μm and it exhibits a high degree of smoothness. This may be attributed to the well-defined layered structure with high degree of planar orientation and nanolevel assemblies of graphene oxide nanosheets in the polymer matrices. Typical field emission scanning electron microscope images demonstrate an ordered arrangement of layers. The electrical conductivity of the multilayer films shows a remarkable increase with increasing layer of the films. A significant enhancement of mechanical properties has been achieved, that is, a 110.8% improvement of elastic modulus and a 262.5% increase of hardness respectively.

This article is part of the Supramolecular Chemistry at Interfaces special issue. The layer-by-layer (LbL) assembly of salt-containing nonstoichiometric polyelectrolyte complexes (PECs) with oppositely charged uncomplexed polyelectrolyte for the fabrication of dewetting-induced porous polymeric films has been systematically investigated. Salt-containing poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) complexes (noted as PAH-PAA) with a molar excess of PAH were LbL assembled with polyanion poly(sodium 4-styrenesulfonate) (PSS) to produce PSS/PAH-PAA films. The structure of the PAH-PAA complexes is dependent on the concentration of NaCl added to their aqueous dispersions, which can be used to tailor the structure of the LbLassembled PSS/PAH-PAA films. Porous PSS/PAH-PAA films are fabricated when salt-containing PAH-PAA complexes with a large amount of added NaCl are used for LbL assembly with PSS. In-situ and ex-situ atomic force microscopy measurements disclose that the dewetting process composed of pore nucleation and pore growth steps leads to the formation of pores in the LbL-assembled PSS/PAH-PAA films. The present study provides a facile way to fabricate porous polymeric films by dewetting LbL-assembled polymeric films comprising salt-containing PECs. Refereed/Peer-reviewed

The layer-by-layer (LbL) adsorption technique allows construction of polyelectrolyte (PE) multilayer films with precisely defined properties and that opens a wide range of applications, where such materials can be used. One of the most important factors governing structure and interfacial properties of polyelectrolyte films is electrolyte concentration and pH of the PE solutions. In the present work we have focused our attention on multilayer films formed using combination of weak polyelectrolytes, PAH/PAA, whose charge can be tuned during the film preparation by pH of their solutions. PE films were formed by LbL technique on silicon wafers, Si/SiO 2 , and were characterized by ellipsometry, neutron reflectometry and AFM. Additionally quartz crystal microbalance (QCM) was used to determine mass of the films formed on the gold covered QCM crystals. We have found that the thickest films were formed when both polyelectrolytes were weakly charged, while the thinnest films were obtained for fully charged PAH and PAA. However, for the combination of weakly and strongly charged polyelectrolyte the non-monotonic increase of film thickness with a number of deposited PE layers was observed. We hypothesize, that it results from PE reorganization and formation of surface complexes during adsorption of polyelectrolyte layers.

Noncharged pyrene molecules were incorporated into multilayer films by first loading pyrene into poly(acrylic acid) (PAA)-stabilized cetyltrimethylammonium bromide (CTAB) micelles (noted as PAA&(Py@CTAB)) and then layer-by-layer (LbL) assembled with poly(diallyldimethylammonium chloride) (PDDA). The stable incorporation of pyrene into multilayer films was confirmed by quartz crystal microbalance (QCM) measurements and UV−vis absorption spectroscopy. The resultant PAA&(Py@CTAB)/PDDA multilayer films show an exponential growth behavior because of the increased surface roughness with increasing number of film deposition cycles. The present study will open a general and cost-effective avenue for the incorporation of noncharged species, such as organic molecules, nanoparticles, and so forth, into LbL-assembled multilayer films by using polyelectrolyte-stabilized surfactant micelles as carriers.

Interactions of native DNA with octadecylamine (ODA) and hexadecymdimethylammonium bromide (HTAB) monolayers at the air/water interface were studied by pi-A isotherms, ellipsometry, and X-ray reflectivity. We show that the microscopic structure of ODA-DNA complexes is definitely consistent with a single-stranded form for DNA. On the contrary, with HTAB, DNA complexes in its native form. The crucial difference in the behavior of these two fairly similar lipids is due to the presence of the amine group in ODA. These results should be relevant to applications such as DNA chips and sensors.

TSeveral polymers can be combined in one multilayer structure by reactive coextrusion. Tie-layers are often used to compatibilize adjacent layers and may reduce or suppress interfacial instabilities and defects in multilayer coextrusion flow. However, a new additional defect defined as “grainy” defect can be observed. In our best of knowledge, no study in literature has been dedicated to understand its origin. The phenomena are quite complex due to the coupling of the effects of flow and the physico-chemical mechanisms at the interface. The aim of this work is to understand the relationship between the instabilities and defects encountered in multilayer coextruded films and the role of the copolymer formed in-situ between tie and barrier layers. Polyamide 6 (PA6) and ethylene-vinyl alcohol copolymer (EVOH) were used as barrier layers sandwiched in polypropylene (PP) with or without tie-layer based on polypropylene grafted maleic anhydride (PP-g-MA). Influence of process parameters and nature of the polymer pair on the generation of “grainy” defect has been assessed and related to the rheological and the physico-chemical properties of layers. These experiments showed that this defect appeared mainly in the compatibilized EVOH system and could be distinguished from the usual coextrusion instabilities. Interfacial properties between tie and barrier layers have been investigated. Shear stress relaxation experiments have been carried out on reactive tie/barrier bilayers. Due to the interphase generated in-situ, the relaxation behavior was altered by extending the relaxation time. Investigation of interfacial morphology highlighted that the copolymer architecture significantly affected the interface/interphase development and interface roughness. Hence, relationships between relaxation process, interfacial morphology and copolymer structure were correlated with the generation of grainy defects in coextrusion.

International audience; Layer by Layer (LbL) thin films stemming from the formation of stereocomplex between oligolactate of opposite chirality (OLLA and ODLA) covalently anchored onto poly(vinyl alcohol) (PVA) chains is described herein for the first time. The feasibility to construct films by sequential adsorption of PVA-g-ODLA and PVA-g-OLLA graft copolymers is undertaken through the exploitation of two different film deposition techniques, namely dip-and spin-assisted processes. For both deposition methods, infrared spectroscopy in ATR mode reveals a progressive accumulation of matter on the flat substrate during the successive cycle depositions and proves that co-crystallisation involving the two homochiral copolymers is the main driving force for the step by step film build up. Also, the effect of the deposition technique is assessed on the film features in terms of (i) growth mechanism, (ii) internal organization and (iii) surface topology. The strong centrifugal forces associated with fast solvent elimination acting during spinning lead to thinner film with more uniform and homogeneous surface morphology in a much shorter time, than the ones resulting from the dip-assisted process. Such LbL nanometric films, induced by OLLA/ODLA interfacial stereocomplexation, open promising perspectives in the field of biodegradable self-assembled films.

Herein, hydroxypropyl-beta-cyclodextrin (HP beta CD) inclusion complex (IC) of a hydrophobic drug, sulfisoxazole (SFS) was incorporated in hydroxypropyl cellulose (HPC) nanofibers (HPC/SFS/HP beta CD-IC-NF) via electrospinning. SFS/HP beta CD-IC was characterized by DSC to investigate the formation of inclusion complex and the stoichiometry of the complex was determined by Job's plot. Modeling studies were also performed on SFS/HP beta CD-IC using ab initio technique. SEM images depicted the defect free uniform fibers and confirmed the incorporation of SFS/HP beta CD-IC in nanofibers did not alter the fiber morphology. XRD analyses showed amorphous distribution of SFS/HP beta CD-IC in the fiber mat. Release studies were performed in phosphate buffered saline (PBS). The results suggest higher amount of SFS released from HPC/SFS/HP beta CD-IC-NF when compared to free SFS containing HPC nanofibers (HPC/SFS-NF). This was attributed to the increased solubility of SFS by inclusion complexation. Sandwich configurations were prepared by placing HPC/SFS/HP beta CD-IC-NF between electrospun PCL nanofibrous mat (PCL-HPC/SFS/HP beta CD-IC-NF). Consequently, PCL-HPC/SFS/HP beta CD-IC-NF exhibited slower release of SFS as compared with HPC/SFS/HP beta CD-IC-NF. This study may provide more efficient future strategies for developing delivery systems of hydrophobic drugs. (C) 2015 Elsevier B.V. All rights reserved.

A mathematical model that predicts the water-permeability coefficient of multilayer films intended for food-packaging applications is presented. A 6-layer film composed of 5 polyolefinic layers and a layer made of a copolymer of ethylene and vinylalcohol (EVOH) was used to validate the proposed model. Water-permeability tests were run at 25°C both on each single layer and on the multilayer film; whereas the water-sorption isotherm and the water-sorption kinetics were determined only for the EVOH layer. Results suggest that the water-permeability coefficient of multilayer films can be predicted from the knowledge of the water-transport properties of each constituent layer.

Adsorption characteristics of a random copolymer of poly(ethylene oxide) monomethyl ether methacrylate and methacryloxyethyl trimethylammonium chloride (PEOMENIA:METAC) on silica were studied using stagnation point adsorption reflectometry (SPAR), quartz crystal microbalance with dissipation (QCM-D), and contact angle techniques. The PEOMEMA:METAC copolymer used in this study is a low charge density polyelectrolyte, with 2% of the monomer units carrying permanent positive charges and 98% containing poly(ethylene oxide) side chains that are approximately 45 repeating units long. The surface excess was determined as a function of pH and concentration of indifferent electrolyte. It was found that the presence of a small amount of 1: 1 electrolyte decreases the adsorbed amount significantly. Further, increasing the pH at a constant ionic strength, 10 mM, results in decreasing surface excess. It is suggested that the adsorption is realized via a combination of non-Coulomb interactions between the poly(ethylene oxide), PEO, grafts and protonated silanol groups at the silica-solution interface and an electrostatic interaction between the charged segments and the oppositely charged surface. Increasing pH and/or salt concentration results in progressive charging of the silica surface with the consequent decrease in affinity between silica and PEO, explaining the decrease in the adsorbed amount of the polymer.

In a marine environment, specific proteins are secreted by mussels and used as a bioglue to stick to a surface. These mussel proteins present an unusual amino acid 3,4-dihydroxyphenylalanine (known as DOPA). The outstanding adhesive properties of these materials in the sea harsh conditions have been attributed to the presence of the catechol groups present in DOPA. Inspired by the structure and composition of these adhesive proteins, we used dopamine-modified hyaluronic acid (HA-DN) prepared by carbodiimide chemistry to form thin and surface-adherent dopamine films. This conjugate was characterized by distinct techniques, such as nuclear magnetic resonance and ultraviolet spectrophotometry. Multilayer films were developed based on chitosan and HA-DN to form polymeric coatings using the layer-by-layer methodology. The nanostructured films formation was monitored by quartz crystal microbalance. The film surface was characterized by atomic force microscopy and scanning electron microscopy. Water contact angle measurements were also conducted. The adhesion properties were analyzed showing that the nanostructured films with dopamine promote an improved adhesion. In vitro tests showed an enhanced cell adhesion, proliferation and viability for the biomimetic films with catechol groups, demonstrating their potential to be used in distinct biomedical applications., The authors want to acknowledge the COST Action TD0906 - Biological adhesives: from biology to biomimetics. The authors also acknowledge the financial support from the Fundacao para a Ciencia e para a Tecnologia through the Ph.D. grants with the references SFRH/BD/73119/2010 and SFRH/BD/69529/2010. G. G. Ferrer acknowledges the support of the Spanish Ministry of Science and Innovation for the mobility grant JC2008-00135. G. Botelho acknowledges the NMR portuguese network (PTNMR, Bruker Avance III 400-Univ. Minho).

Complex formation between 4-(10,12-pentacosadiynamidomethyl)pyridine and metal ions in the subphase results in stable Langmuir monolayers up to surface pressures of 35 mN m(-1). Electron microscopy pictures show a flat monomer monolayer before polymerization and a polymer monolayer exhibiting a more striated structure after polymerization. Multilayers of the amphiphile can only be built up after complexation with metal ions. X-ray photoelectron spectroscopy (XPS) measurements definitely confirm the presence of metal ions in the multilayers, and the molar ratio between metal and amphiphile is derived from the spectra. These multilayers are further characterized by means of small-angle X-ray reflection measurements and Fourier transform infrared (FT-IR) spectroscopy, which show that the amphiphile has a large tilt angle (a) with respect to the surface normal. The multilayers are polymerized by means of UV irradiation, and UV-vis spectroscopy is used to study the polymerization process. The structural changes during polymerization are deduced from small-angle X-ray reflection measurements and FT-IR spectroscopy. In all cases, the bilayer spacing decreases during the polymerization process, whereas in some cases the regular plane of the all-trans conformation of the alkyl chains is converted to an irregular one containing gauche conformations. For multilayers built up from a CuCl2-containing subphase, the whole distinct layer structure is destroyed during the polymerization process.

The lanthanide-containing Keggin-type polyoxometalates (LnPOMs), [Ln(PINi O-39)(2)](11)-(Ln=Eu3+ and Sm3+), were incorporated for the first ime into porous chromium terephthalate MIL-101(Cr) via an impregnation method, originating two unprecedented composite materials, Eu(PIN11)(2)@MIL and Sm(PW11)(2)@MIL, to be used as heterogeneous catalysts. The characterization of these new composites was performed by vibrational spectroscopy (FT-IR and FT-Raman), powder X-ray diffraction (XRD), elemental analysis, UV-vis spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and textural analysis. Ln(PW11)(2)@MIL materials were tested as heterogeneous catalysts in the oxidation of styrene using hydrogen peroxide as the oxidant and acetonitrile as the solvent. Their catalytic activity was also compared with the homogeneous LnPOM(5) catalysts in order to evaluate the effect of their incorporation on the catalytic activity. The composite materials exhibit higher catalytic activities toward the oxidation of styrene than the corresponding isolated LnPOM(5) with complete conversion of the substrate after 4 h and 5 h for the samarium and europium composites, respectively. Furthermore, microwave-assisted oxidative reactions were also performed showing an increase in the selectivity values while maintaining similar conversion values, especially in the heterogeneous reactions. (C) 2013 Elsevier B.V. All rights reserved.

We report an experimental study on the growth and adsorption kinetics of polyelectrolyte multilayers (PEMs). PEMs composed of poly(diallyldimethyl ammonium chloride) (PDADMAC) and poly(sodium 4-styrenesulfonate) (PSS), and of poly(allylamine hydrochloride) (PAH) and PSS polyelectrolyte pairs were built and studied via dissipative quartz crystal microbalance (D-QCM) and ellipsometry. The results have pointed out that the growth trend of PEMs may be controlled by the assembly conditions that modify the layer structure and subsequently the film features. The study of adsorption kinetics of the layers suggests that, even though interdiffusion may take place during the growth of PEMs, it does not determine the growth mechanism. Analysis of the mechanical properties allows confirmation of the scenario proposed for the explanation of the PEMs growth. Independent of growth type, the adsorption kinetics of the layers is a bimodal process. The results here presented allow us to rule out any correlation between growth mechanism and adsorption dynamics. Fil: Guzmán, Eduardo. Universidad Complutense de Madrid; España Fil: Ritacco, Hernán Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Física del Sur. Universidad Nacional del Sur. Departamento de Física. Instituto de Física del Sur; Argentina Fil: Ortega, Francisco. Universidad Complutense de Madrid; España Fil: Rubio, Ramón G.. Universidad Complutense de Madrid; España

Take a metal powder and add aqueous hydrogen peroxide and a small amount of acetic acid (10:1 ratio) under ambient conditions and, in one simple step, colloidally stable dispersions of nanoparticle (NP) metal oxides of the respective metals form with diameters in the range approx. 3–8 nm. No complex work-up or time-consuming purification is required, just simple filtration and spin-coating to make a nanopar ticle metal oxide thin film. Furthermore, this straightforward approach avoids expensive organic surfactants, capping ligands and solvents, metal salts, coordination compounds, and sol–gel precursors commonly used in prior reported syntheses of metal oxide nanoparticles that often contaminate and therefore complicate their subsequent utilization. [1,2] This facile synthetic strategy provides a universal, clean, green, and simple approach to metal oxide nanoparticles, as well as single and multilayer metal oxide nanoparticle porous films perceived to provide diverse applications such as lithium batteries, solar and photoelectrochemical cells, electrochromics and sensors, photocatalysts, and photonic crystals. [3−7] Metal oxide nanoparticles and thin films thereof offer distinctive and desirable properties that make them attractive candidates for materials science and biomedical applications. [8] The synthesis begins with micrometer-scale metal powders exemplified by W, Mo, Ni, Co, Fe, Zn, and Mg (purity 99.5 to 99.95%) which dissolve in aqueous/H 2 O 2 (30 wt%) and acetic acid, AcH. (DANGER: Very exothermic reaction, instant ice-bath cooling is necessary in a well ventilated fumehood. Protective glasses, gloves, and a lab coat must be worn all the time during this synthetic procedure.) Contingent upon the choice of metal(s), this results in highly stable, single (M 1 O x ), binary Spinel (M 1 M 2 O 4 ) and ternary multi-metallic (M1M2M3Oz) aqueous dispersions of colloidally stable metal

Controllable fabrication of spontaneously ordered and varied geometry fullerene C 60 based molecular architecture was achieved upon hierarchical self-assembly of the fullerene-N,N-dimethylaminoazobenzene acceptor-donor hybrid (DPNME). Simple preparation techniques, such as Langmuir-Blodgett (LB), solution-cast, and immersion at the liquid-air and solid-air interfaces, were used without templates as a function of DPNME concentration, media pH, time, and supporting substrate characteristics. The resulting structures depending upon the preparation methods were investigated with field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), and molecular modeling, which revealed a delicate role of intermolecular donor-acceptor, ?-?, and van der Waals interactions between the electron deficient fullerene core and the N,N-dimethylaminoazobenzene electron donor under neutral conditions. Upon protonation, the electrostatics associated with the charged DPNME moiety and the dominant intermolecular fullerene-fullerene interactions guided the self-assembly process. Increased time scales led the molecular subunits to grow by maximizing the most favored orientations and yielded one-dimensional (1D) and two-dimensional (2D) structures in neutral and acidic conditions, respectively, which upon solvent evaporation formed the final multipods or stacked squares upon oriented attachment. For the protonated DPNME, 2D lamellar sheets formed from the bilayers gained cohesive energy, forming ultimately rectangular sheets. Interestingly, the Si(100) supported multilayer DPNME Langmuir films as a function of surface pressure and pH yielded a uniform and directional structure pattern in comparison with the geometry obtained from drop casting methods. This controllable structure architecture of the fullerene-azobenzene hybrid opens up a new alley in fullerene C 60 based self-assembly. � 2011 American Chemical Society.

dation. Here, we study the effect of the oxidation level on nonlinear optical properties of GO. We demonstrate that both electrochemically induced reversible reduction and optically induced photoreduction in GO result in changes in the nonlinear optical properties of GO thin films. We present the carrier dynamics and nonlinear optical properties of such films, studied by ultrafast wavelength-dependent pumpprobe spectroscopy. We show that ultrafast response of GO can be tuned by both reduction procedure. The preparation, characterization, linear optical, and electrochromism properties of GO were very recently reported. 10 We study the electrical reduction in GO in air, using multilayer GO thin films deposited on metalized glass substrates. The two terminal devices consist of thin 10‐50 nm Pd/Au planar contacts, separated by 0.3‐0.6 mm, with a thin multilayer GO film covering both contacts and in between Fig. 1a. The degree of chemical reduction and linear absorption spectrum can be tuned by applying a

International audience; Rapid differentiation of endothelial progenitor cells (EPCs) into confluent mature endothelial cells is important in tissue engineering for the design of autologous, nonthrombotic, vascular grafts. A new method based on EPC culture on poly(sodium-4- styrene-sulfonate)/poly(allylamine hydrochloride), that is, polyelectrolyte-multilayer-coated substrates, reduces the time from two months to two weeks.

The azobenzene-containing polyanion PAC-azoBNS was alternately assembled with the polycation diazoresin (DAR) to construct photo-cross-linkable multilayer films of PAC-azoBNS/DAR that contain photolabile groups of azobenzene. Upon mild UV irradiation, the interaction between PAC-azoBNS/DAR multilayers was converted from electrostatic interaction to covalent bonds. Because of the free carboxylic acid groups presented in the film, the photo-cross-linked multilayer film favors the selective permeation of positively charged species. After photolysis of the photo-cross-linked PAC-azoBNS/DAR films with intense UV irradiation, azobenzene groups decompose to produce imine groups, and a photo-cross-linked robust film containing free carboxylic acid and imine groups was fabricated. The resultant film allows the permeation of negatively charged species and meanwhile shows a pH-switchable permselectivity for positively charged species. Because of the covalently cross-linking structure, the photolyzed cross-linked PAC-azoBNS/DAR film shows high reversible switching behavior and has high stability in solution with high ionic strength.

WOS: 000231225900001, Three-layer films were prepared with polyethylene (PE) and poly(ethylene terephthalate) (PET) films as the outer layers and a film of high-density polyethylene (HDPE)/ethylene-methyl acrylate-glycidyl methacrylate (E-MA-GMA) terpolymer blend as the inner layer using compression molding. E-MA-GMA, an elastomer containing an epoxy functional group, was used as the adhesion promoting agent in the multilayer films. The effects of processing temperature, pressure application time and elastomer concentration on adhesion were investigated. The adhesion strength between PE and PET films increased with increasing bonding temperature, bonding time and elastomer concentration. From contact angle measurements, it was observed that the work of adhesion between the polymers increased with increasing amount of elastomer. Improved adhesion between PET and HDPE with 30% clastomer films was confirmed by SEM analyses of the film layers. Using FT-IR analysis of PE/HDPE-30% elastomer/PET delaminated film, the decrease in peak intensity of the epoxy groups tends to indicate reaction of epoxy functionality with functional groups in PET.

The express-method of diagnostics and selection of polymeric petroleum products is substantiated. Such products are processed by hot melt extrusion into films with technical purposes and then used in packaging. Bright visual effects in layers of polyolefin film materials are used in packaging of consumer goods; they can be seen in polarized light and depend on chemical and phase composition of films. For films application in smart packaging, for example, frozen food products, input control and diagnostics is required not only of mechanical and optical properties, but also of sensitivity of their optical properties to heat treatment. The two-stage method is suggested for checking the suitability of polyolefin films for the latent marking in polarized light for their usage in the production of intelligent packaging for frozen foods or other products with a strictly regulated mode of storage.

Color bright visual effects in polyolefin layered film materials for the production of consumer goods packaging are described. A multi-color light reflection by a package of films varies in case of a light angle change, depends on a thickness and number of layers. The relation between anisotropy, crystallinity and nanostructure of polyethylene and polypropylene films and their color in polarized light is identified. The fact of recrystallization of a part of fibrils in heat treatment in the course of films duplicating which reduces the effect of pleochroism is established by differential scanning calorimetry and electron microscopy techniques. The films duplicating processes with a simultaneous marking protecting the packed production against counterfeit are suggested.