Search

In this study, two packaging materials, modified polypropylene (MPP) and polyethylene terephthalate/aluminum/ low-density polyethylene (PETFA-Al-LDPE) were studied under various atmospheric conditions: 100% CO2, 70% N2 - 30% CO2, 80% N2 - 20% CO2 for packing probiotic ultrafiltered (UF) white brined cheese. pH, titratable acidity, moisture content, Lacticaseibacillus paracasei viability and overall acceptability were monitored within a 12-week period. The control samples were packaged in atmospheric air. Results revealed that samples packaged in PETFA-Al-LDPE with the combination of 70% N2 - 30% CO2 had the lowest pH, highest acidity and moisture content. The viability of Lacticaseibacillus paracasei was reported to be 4*106 CFU/g within 12 weeks. The highest and lowest overall acceptability was for the cheese packaged in 70% N2 - 30% CO2 and the control sample, respectively., U ovom istraživanju je ispitivana mogućnost primjene dvaju ambalažnih materijala - modificiranog polipropilena (MPP) i polietilen tereftalata/aluminij/polietilen niske gustoće (PETFA-Al-LDPE) u različitim uvjetima modificirane atmosfere (100 % CO2, 70 % N2 – 30 % CO2, 80 % N2 - 20 % CO2) za pakiranje probiotičkog sira iz salamure proizvedenog iz ultrafiltriranog (UF) mlijeka. Tijekom 12 tjedana čuvanja uzorcima sira su određivani pH, titracijska kiselost, sadržaj vlage, preživljavanje soja Lacticaseibacillus paracasei i prihvatljivost. Kontrolni uzorci su pakirani u normalnoj atmosferi (zrak). Dobiveni rezutati ukazuju kako uzorci pakirani u PETFA-Al-LDPE i modificiranoj atmosferi 70 % N2 - 30 % CO2 imaju najniži pH, te najveću kiselost i sadržaj vlage. Preživljavanje soja Lacticaseibacillus paracasei je bilo oko 4x106 CFU/g tijekom 12 tjedana. Najnižu i najvišu prihvatljivost su imali uzorak pakiran u atmosferi 70% N2 - 30 % CO2 te kontrolni uzorak.

Non-viral vectors represent versatile and immunologically safer alternatives for nucleic acid delivery. Nanoneedles and high-aspect ratio nanostructures are unconventional but interesting delivery systems, in which delivery is mediated by surface interactions. Herein, nanoneedles are synergistically combined with polysaccharide-polyplex nanofilms and enhanced transfection efficiency is observed, compared to polyplexes in suspension. Different polyplex-polyelectrolyte nanofilm combinations are assessed and it is found that transfection efficiency is enhanced when using polysaccharide-based polyanions, rather than being only specific for hyaluronic acid, as suggested in earlier studies. Moreover, results show that enhanced transfection is not mediated by interactions with the CD44 receptor, previously hypothesized as a major mechanism mediating enhancement via hyaluronate. In cardiac tissue, nanoneedles are shown to increase the transfection efficiency of nanofilms compared to flat substrates; while in vitro, high transfection efficiencies are observed in nanostructures where cells present large interfacing areas with the substrate. The results of this study demonstrate that surface-mediated transfection using this system is efficient and safe, requiring amounts of nucleic acid with an order of magnitude lower than standard culture transfection. These findings expand the spectrum of possible polyelectrolyte combinations that can be used for the development of suitable non-viral vectors for exploration in further clinical trials.

A pioneering study at WPI-MANA has resulted in the first direct exfoliation of zeolites into a liquid suspension of monolayers. This breakthrough provides proof of the presence of monolayers, and could lead to their use in the creation of catalysts, nanodevices, drug delivery systems and other products with tailored properties., MANA E-BULLETIN. 75 (2022)

Ferroelectric multilayer films attract great attention for a wide variation of applications. The synergistic effect by combining different functional layers induces distinctive electrical properties. In this study, ferroelectric BaZr0.2Ti0.8O3/PbZr0.52Ti0.48O3/BaZr0.2Ti0.8O3 (BZT/PZT/BZT) multilayer thin films are designed and fabricated by using the magnetron sputtering method, and a LaNiO3 (LNO) seed layer is introduced. The microstructures and electrical properties of the BZT/PZT/BZT films with and without the LNO seed layer are systematically studied. The results show that the BZT/PZT/BZT/LNO thin film exhibits much lower surface roughness and a preferred (100)-orientation growth, with the growth template and tensile stress provided by the LNO layer. Moreover, an enhanced dielectric constant, decreased dielectric loss, and improved ferroelectric properties are achieved in BZT/PZT/BZT/LNO thin films. This work reveals that the seed layer can play an important role in improving the microstructure and properties of ferroelectric multilayer films.

Orientador: Marisa Masumi Beppu Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química Resumo: A busca por materiais que possam constituir superfícies antimicrobianas é relevante uma vez que o contato com micro-organismos patogênicos representa um sério risco à saúde. Além das propriedades naturais biocidas de alguns materiais, a adição de compostos que também atuam como agentes antibióticos como íons metálicos ou peptídeos, podem potencializar essa funcionalidade. Existe também a alternativa de criar-se uma superfície antimicrobiana através da modificação da densidade e da mobilidade de cargas catiônicas dos materiais utilizados, assim como propriedades estruturais dos revestimentos visando dificultar a adesão ou crescimento de micro-organismos. Neste trabalho, os filmes foram construídos pela técnica layer-by-layer, na qual é feita a imersão de um substrato (lâmina de vidro) alternadamente em soluções que contêm cargas positivas ou negativas e, no intervalo entre cada submersão, o filme em formação passa por um processo de lavagem em água deionizada para a retirada do excesso de polieletrólitos. Especificamente, foram utilizados o biopolímero catiônico quitosana (CHI) e os polieletrólitos negativos alginato de sódio (ALG) e ácido hialurônico (HA). Os filmes constituídos de ALG/CHI e HA/CHI foram construídos em diferentes pH e força iônica das soluções polieletrolíticas. Por análises de perfilometria e microscopia de força atômica (AFM) foi possível monitorar mudanças de espessura e rugosidade dos recobrimentos e foi verificado que a presença de sal no meio de deposição faz com que os polímeros apresentem conformações com mais loops e tails e esse arranjo das cadeias em solução é transmitido para os filmes, que se tornam mais rugosos. Além disso, a espessura dos filmes pode ser controlada por meio do ajuste do pH do meio de deposição. A incorporação dos corantes rosa de bengala e azul de alciano, em conjunto com análises de FTIR possibilitou identificar os grupos funcionais responsáveis pela funcionalidade dos recobrimentos formados. Por fim, foram feitos testes dos recobrimentos, com e sem acetato de prata, frente à cepa Candida albicans e foi verificado que filmes contendo Ag+ foram capazes de inibir o crescimento do fungo. O uso sinérgico de polímeros naturais e da técnica LbL viabilizou, de uma maneira simples e versátil, a construção de filmes nanoestruturados com potencial para aplicações antimicóticas Abstract: The search for materials that can constitute antimicrobial surfaces is relevant since the contact with pathogenic microorganisms is a serious health risk. Besides the natural biocidal properties of some materials, the addition of compounds that also act as antimicrobial agents, such as metal ions or peptides, may enhance this capability. There is also the alternative to create an antimicrobial surface by modifying the density and mobility of cationic charges of the materials used, as well as structural properties of the coatings in order to hinder the adhesion or proliferation of microorganisms. In this work, the nanostructured films were built by the layer-by-layer (LbL) technique, whose interaction among species with opposite electrostatic charges is, in most cases, the primary phenomenon responsible for the formation of multilayers. Specifically, we chose the cationic biopolymer chitosan (CHI) and the negative polyelectrolytes sodium alginate (ALG) and hyaluronic acid (HA). The aim of this study was to evaluate the effect of ionic strength (0 versus 200 mM) and pH (3 versus 5) on ALG/CHI and HA/CHI nanostructured multilayered thin films properties. From profilometry and atomic force microscopy (AFM) analysis, it was possible to monitor changes in thickness and roughness of the coatings and it was found that the presence of salt in polyelectrolyte solutions promoted polymer chains conformations with more loops and tails and this arrangement in solution is transmitted to films, resulting in rougher coatings. Furthermore, the film thickness can be precisely controlled by adjusting the pH of the polyelectrolyte solution. The incorporation of rose bengal and alcian blue dyes in conjunction with FTIR analysis allowed identifying the functional groups responsible for the functionality of the coatings formed. Finally, we evaluated the antifungal activity of the LbL coatings (with and without silver ions) against Candida albicans strain and we observed that films containing Ag+ were able to inhibit the growth of the fungus. The synergistic use of natural polymers and LbL technique made possible, in a simple and versatile way, the construction of nanostructured films with great potential for antifungal surfaces Mestrado Engenharia de Processos Mestre em Engenharia Química

BackgroundBacterial proliferation on the endosseous implants surface presents a new threat to the using of the bone implants. Unfortunately, there is no effective constructed antibacterial coating which is bacterial anti-adhesion substrate-independent or have long-term biofilm inhibition functions.MethodsDrug release effect was tested in Chymotrypsin (CMS) solution andS. aureus. We used bacterial inhibition rate assays and protein leakage experiment to analyze the in vitro antibacterial effect of (Montmorillonite/Poly-l-lysine-Chlorhexidine)10[(MMT/PLL-CHX)10] multilayer film. We used the CCK-8 assay to analyze the effect of (MMT/PLL-CHX)10multilayer films on the growth and proliferation of rat osteoblasts. Rat orthopaedic implant-related infections model was constructed to test the antimicrobial activity effect of (MMT/PLL-CHX)10multilayer films in vivo.ResultsIn this study, the (MMT/PLL-CHX)10multilayer films structure were progressively degraded and showed well concentration-dependent degradation characteristics following incubation withStaphylococcus aureusand CMS solution. Bacterial inhibition rate assays and protein leakage experiment showed high levels of bactericidal activity. While the CCK-8 analysis proved that the (MMT/PLL-CHX)10multilayer films possess perfect biocompatibility. It is somewhat encouraging that in the in vivo antibacterial tests, the K-wires coated with (MMT/PLL-CHX)10multilayer films showed lower infections incidence and inflammation than the unmodified group, and all parameters are close to SHAM group.Conclusion(MMT/PLL-CHX)10multilayer films provides a potential therapeutic method for orthopaedic implant-related infections.

Small plastic packaging films make up a quarter of all packaging waste generated annually in Austria. As many plastic packaging films are multilayered to give barrier properties and strength, this fraction is considered hardly recyclable and recovered thermally. Besides, they can not be separated from recyclable monolayer films using near-infrared spectroscopy in material recovery facilities. In this paper, an experimental sensor-based sorting setup is used to demonstrate the effect of adapting a near-infrared sorting rig to enable measurement in transflection. This adaptation effectively circumvents problems caused by low material thickness and improves the sorting success when separating monolayer and multilayer film materials. Additionally, machine learning approaches are discussed to separate monolayer and multilayer materials without requiring the near-infrared sorter to explicitly learn the material fingerprint of each possible combination of layered materials. Last, a fast Fourier transform is shown to reduce destructive interference overlaying the spectral information. Through this, it is possible to automatically find the Fourier component at which to place the filter to regain the most spectral information possible.

High dielectric constant ceramics fillers are widely used as fillers in polymer matrix to prepare high performance dielectric composites. Homogeneous filler distribution in these composites films is found to be quite difficult to achieve balance between high dielectric constant and high breakdown strength. Herein, multilayer structured composites films containing nickelous hydroxide (Ni(OH)2) as fillers, with different multilayered structures were designed and prepared, including 2–5 layers structure with various filler distribution. The effects of multilayer structure on the dielectric performance are explored by keeping the overall filler content constant. Combined with computer simulation, it is suggested that the variation in filler distribution in these films can effectively redistribute electric field intensity. Meanwhile, the dielectric constant and breakdown strength of the overall composites can be adjusted by changing the volume ratio between high filler content layer and low filler content layer. It is noted that at least 1/3 of the overall film volume should be occupied by a high breakdown strength layer to keep rather high overall breakdown strength. Moreover, high dielectric constant layer should be the outer layers to achieve overall high dielectric constant. Among all the layered structures investigated, the maximum energy density of 6.03 J/cm3 is obtained for film with a 3-layer nonsequential arrangement structure, which is 68% higher than single layer film with identical composition. This study provides some reference value for the preparation of multilayered dielectric polymer composites films for energy storage applications.

Multilayer thin films polymer have been commonly used in a wide range of electronics applications, such as solar cells, photoconductors, semiconductors, and light-emitting diodes, in which failure due to delamination can occur. For evaluating and improving the quality of a multilayer thin-film product, the interfacial strength between its layers must be measured correctly and accurately. In this work, the interfacial strength of a multilayer thin-film polymer was quantified by measuring the interfacial energy release rate (interfacial fracture toughness), Gi , using the nanoindentation test technique. Three specimens of four-layer thin films were fabricated on a glass substrate. The top layer of each specimen was prepared with different thicknesses. The unloading curve technique introduced by Kozuki and Kishimoto (2010) was implemented to quantify the Gi of each specimen. Then, cross-sectional observation of the specimens was performed to confirm the layer thicknesses and to identify the delamination condition after the test. The measured Gi tended to increase as the range between the two unloading curves used to calculate the delamination energy widened. This phenomenon is believed to be caused by the plastic energy of the deformed films during the indentation process. Finally, an empirical method for eliminating the effect of the plastic energy on the measured Gi was proposed. Using this method, a pure Gi value can be effectively extracted; thus, the interfacial strength of multilayer thin-film polymers can be measured correctly and accurately.

In the increasingly pressing context of improving recycling, optical technologies present a broad potential to support the adequate sorting of plastics. Nevertheless, the commercially available solutions (for example, employing near-infrared spectroscopy) generally focus on identifying mono-materials of a few selected types which currently have a market-interest as secondary materials. Current progress in photonic sciences together with advanced data analysis, such as artificial intelligence, enable bridging practical challenges previously not feasible, for example in terms of classifying more complex materials. In the present paper, the different techniques are initially reviewed based on their main characteristics. Then, based on academic literature, their suitability for monitoring the composition of multi-materials, such as different types of multi-layered packaging and fibre-reinforced polymer composites as well as black plastics used in the motor vehicle industry, is discussed. Finally, some commercial systems with applications in those sectors are also presented. This review mainly focuses on the materials identification step (taking place after waste collection and before sorting and reprocessing) but in outlook, further insights on sorting are given as well as future prospects which can contribute to increasing the circularity of the plastic composites’ value chains.

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

Orientadores: Marisa Masumi Beppu, Bradley David Olsen Tese (doutorado)- Universidade Estadual de Campinas, Faculdade de Engenharia Química Resumo: A funcionalização de superfícies com recobrimentos nanoestruturados tem sido explorada para superar desafios biotecnológicos, da entrega direcionada de fármacos à captura seletiva de analitos para diagnóstico. Proteínas recombinantes tem um papel de destaque no desenvolvimento de superfícies bioativas, permitindo o desenvolvimento de macromoléculas com as funcionalidades desejadas. A técnica layer-by-layer (LbL) tem se popularizado como uma estratégia simples e versátil para a funcionalização de superfícies com mínimas restrições quanto à superfície e aos materiais depositados. Ambas as estratégias, no entanto, requerem esforços significativos para determinar as condições adequadas produzir novos materiais. Esta tese teve como objetivo facilitar a produção de materiais à base de biopolímeros e proteínas recombinantes, a partir de métodos automatizados de alta produtividade (high-throughput). Inicialmente, a técnica LbL foi adaptada para a deposição de filmes multicamadas em placas de 96 de poços, permitindo a investigação de diferentes condições de deposição dos recobrimentos na mesma batelada. Este método mostrou-se efetivo para a produção de recobrimentos de polissacarídeos, indicando que a quantidade de grupos amino e carboxílicos livres dos recobrimentos varia de acordo com o pH de deposição. Filmes híbridos à base de polipeptídios do tipo elastina (ELPs) e polissacarídeos, formados a partir de interações eletrostáticas, demostraram que condições de pH que promoveram baixos graus de ionização dos polieletrólitos e a presença de aminoácidos com resíduos hidrofóbicos nas ELPs favoreceram o crescimento dos recobrimentos. Esta tese também explorou a versatilidade no design de ELPs para investigar uma biblioteca de interações complementares para a formação de recobrimentos multicamadas. Interações do tipo Spy-Tag/Spy-Catcher e ZE/ZR (ou zíperes de leucina), dentre outras, mostraram-se capazes de direcionar a deposição auto-organizada dos recobrimentos. Recobrimentos formados por interações Spy-Tag/Spy-Catcher também apresentaram significativa estabilidade em diversas condições de pH (3.0 - 12.0) e força iônica (5.0 mol/L NaCl) que dissociaram filmes formados por interações eletrostáticas. O método high-throughput-LbL também foi usado para investigar o efeito das condições de deposição na incorporação e liberação de uma molécula modelo (calceína) em recobrimentos de poli(ácido acrílico)/poli(alilamina). Neste caso, maiores valores de pH (> 8.5) e a presença de sais como NaCl ou MgCl2 (ambos a 0.05 mol/L) nas soluções polieletrolíticas favoreceram a incorporação de calceína nos recobrimentos. O método de incorporação também alterou a morfologia dos recobrimentos e os mecanismos de liberação de calceína, resultando em taxas de liberação mais lentas para incorporação durante a deposição das multicamadas. Por fim, esta tese também explorou estratégias high-throughput para testar a síntese de proteínas recombinantes. Protocolos de biologia molecular, da transformação à biossíntese das proteínas, foram automatizados, permitindo testar dezenas de combinações de linhagem celular-vetor em cada experimento. Foram desenvolvidos ainda protocolos automatizados para a quantificação de proteína total (Bradford) e específica (6×His-tag immunoassay), auxiliando na triagem das condições adequadas para a biossíntese de mCherry (proteína modelo). De modo geral, esta tese destacou o uso de métodos high-throughput para facilitar o desenvolvimento de materiais à base de biopolímeros e proteínas que demandem inúmeras etapas de testagem e otimização, contribuindo para acelerar os ciclos de inovação na área de biotecnologia Abstract: Surface functionalization has been explored to overcome biotechnologically relevant challenges, from the targeted drug delivery to the selective capture of bioactive agents for diagnosis. Recombinant protein plays an important role in designing bioactive surfaces by designing macromolecules with the desired functionalities. The layer-by-layer (LbL) technique became a popular strategy for surface functionalization with minimal restrictions regarding the coated surface and the materials deposited. Nevertheless, both strategies demand substantial efforts to determine the appropriate conditions to prepare the newly designed materials. This thesis aimed to streamline the production of biopolymer- and recombinant protein-based materials through high-throughput methods. At first, the LbL method was adapted to deposit multilayer films on 96-well plates, enabling one to investigate different assembly conditions into the same batch. This method effectively produced polysaccharide-based films, indicating the dependence of free amino and carboxylate groups on multilayers to the assembly pH conditions. Hybrid polysaccharide/recombinant elastin-like polypeptides (ELPs) were also assembled based on electrostatic interactions. ELP variants containing a higher number of hydrophobic residues and assembly pH conditions that promoted lower ionization degrees of both polyelectrolytes led to higher film growth. This thesis also explored protein engineering's versatility for designing a library ELPs fused with complementary isopeptide binding domains for self-assembly LbL films. Spy-Tag/Spy-Catcher and leucine zipper ZE/ZR interactions, among others, were effective to drive the self-assembly deposition of multilayer films. Spy-Tag/Spy-Catcher also led to resistant multilayers over a wide range of pH (3.0 – 12.0) and ionic strength (5.0 mol/L NaCl), which may disassemble traditional polyelectrolyte-based multilayers. The high-throughput-LbL method was also used to investigate the role of film assembly conditions on the loading and release of a model drug molecule (calcein) on poly(acrylic acid)/poly(allylamine hydrochloride) multilayer films. Higher values of pH (> 8.5) and the presence of NaCl or MgCl2 salts (both at 0.05 mol/L) in the polyelectrolyte solutions favored the model drug loading in multilayer films. The drug loading method also affected the film morphology and drug transport mechanisms, leading to slower drug release rates for films loaded during polyelectrolyte multilayer deposition. Finally, this thesis explored the use of the high-throughput approach for recombinant protein test expression. Molecular biology protocols, from cell transformation to protein biosynthesis, were automated to screen tens of different cell strain-vector combinations per batch. The study also focused on automating analytical total (Bradford) and histidine-tagged (immunoassay) protein quantification to determine the most favorable condition for mCherry biosynthesis (model protein). Overall, this thesis sheds light on using high-throughput methods to facilitate the development of biopolymer- or protein-based materials that demand intense testing and optimization, contributing to accelerating the innovation cycles in the biotechnology arena Doutorado Engenharia Química Doutor em Engenharia Química FAPESP 2016/10193-9 CAPES 33003017034P8

A research team at MANA has developed a surprisingly simple method for fabricating highly organized mono- and multilayers of 2D nanosheets. All you need is a pipette and a hotplate., MANA E-BULLETIN. 67 (2021)

The goal of this research was to study the potential of polyelectrolyte multilayers as buccal dosage forms for drug delivery and to investigate how the properties of the drugs impact the overall performance of the delivery system. Multilayer films based on the polyelectrolyte interaction between casein and chitosan were developed using benzydamine, tolfenamic acid and betahistine as model drugs. The samples were characterized for surface pH, moisture content and moisture absorption, swelling behavior and mucoadhesion. Additionally, surface morphology was investigated, as well as the drugs’ physical state after incorporation in the multilayer films. The samples proved to be non-irritant (pH was within the physiological range), physically stable (moisture content and moisture absorption below 5%) and mucoadhesive, adsorbing from 60 to 70% mucin. The release behavior corelated to the swelling index profiles of the samples and was strongly dependent on the drug solubility. The developed multilayer films appeared to be an optimum delivery system for sparingly soluble drugs due to the high drug loading achieved.

Electromagnetic interference (EMI), an unwanted phenomenon, often affects the reliability of precise electronic circuitry. To prevent this, an effective shielding is prerequisite to protect the electronic devices. In this study, an attempt was made to understand how processing of polymeric blend nanocomposites involving multiwalled carbon nanotubes (MWCNTs) affects the evolving interconnected network structure of MWCNTs and eventually their EMI shielding properties. Thereby, the overall blend morphology and especially the connectivity of the polycarbonate (PC) component, in which the MWCNTs tend to migrate, as well as the perfectness of their migration, and the state of nanotube dispersion are considered. For this purpose, blends of varying composition of PC and poly(methyl methacrylate) were chosen as a model system as they show a phase diagram with lower critical solution temperature type of characteristic. Such blends were processed in two different ways: solution mixing (from the homogeneous state) and melt mixing (in the biphasic state). In both the processes, MWCNTs (3 wt %) were mixed into the blends, and the evolved structures (after phase separation induced by annealing in solution-mixed blends) and the quenched structures (as the blends exit the extruder) were systematically studied using transmission electron microscopy (TEM). Both the set of blends were subjected to the same thermal history, however, under different conditions such as under quiescent conditions (in the case of solution mixing) and under shear (in the case of melt mixing). The electrical volume conductivity and the evolved morphologies of these blend nanocomposites were evaluated and correlated with the measured EMI shielding behavior. The results indicated that irrespective of the type of processing, the MWCNTs localized in the PC component; driven by thermodynamic factors and depending on the blend composition, sea-island, cocontinuous, and phase-inverted structures evolved. Interestingly, the better interconnected network structures of MWCNTs observed using TEM in the solution-mixed samples together with larger nanotube lengths resulted in higher EMI shielding properties (-27 dB at 18 GHz) even if slightly higher electrical volume conductivities were observed in melt-mixed samples. Moreover, the shielding was absorption-driven, facilitated by the dense network of MWCNTs in the PC component of the blends, at any given concentration of nanotubes. Taken together, this study highlights the effects of different blend nanocomposite preparation methods (solution and melt) and the developed morphology and nanotube network structure in MWCNT filled blend nanocomposites on the EMI shielding behavior.

Encapsulation of cells has been an active area of research. Among various methods for encapsulation, Layer-by-Layer (LbL) offers extensive flexibility in the design of surfaces and their interfacial nanoarchitectonics. A diverse range of functionalities have been recently demonstrated for cell encapsulation including protection and improved circulation. Here, we present a new strategy of cell encapsulation in a hybrid coating containing LbL assembly functionalized with gold nanoparticle aggregates. The effect of this hybrid coating on cell viability was assessed. Subsequently, upon laser illumination the encapsulated cells undergo immediate necrosis caused by the localized heat generated by the laser beam on gold nanoparticle aggregates. Similarly to affecting polyelectrolyte multilayer capsules, one envisions controlling surface properties of cells remotely by a laser beam. Further applications of the proposed approach are expected to be in biomedicine.

Self-defensive antibiotic-loaded coatings have shown promise in inhibiting growth of pathogenic bacteria adhering to biomaterial implants and devices, but direct proof that their antibacterial release is triggered by bacterially-induced acidification of the immediate environment under buffered conditions remained elusive. Here, we demonstrate that Staphylococcus aureus and Escherichia coli adhering to such coatings generate highly localized acidification, even in buffered conditions, to activate pH-triggered, self-defensive antibiotic release. To this end, we utilized chemically crosslinked layer-by-layer hydrogel coatings of poly(methacrylic acid) with a covalently attached pH-sensitive SNARF-1 fluorescent label for imaging, and unlabeled-antibiotic (gentamicin or polymyxin B) loaded coatings for antibacterial studies. Local acidification of the coatings induced by S. aureus and E. coli adhering to the coatings was demonstrated by confocal-laser-scanning-microscopy via wavelength-resolved imaging. pH-triggered antibiotic release under static, small volume conditions yielded high bacterial killing efficiencies for S. aureus and E. coli . Gentamicin-loaded films retained their antibacterial activity against S. aureus under fluid flow in buffered conditions. Antibacterial activity increased with the number of polymer layers in the films. Altogether, pH-triggered, self-defensive antibiotic-loaded coatings become activated by highly localized acidification in the immediate environment of an adhering bacterium, offering potential for clinical application with minimized side-effects. Statement of significance Polymeric coatings were created that are able to uptake and selectively release antibiotics upon stimulus by adhering bacteria in order to understand the fundamental mechanisms behind pH-triggered antibiotic release as a potential way to prevent biomaterial-associated infections. Through fluorescent imaging studies, this work importantly shows that adhering bacteria produce highly localized pH changes even in buffer. Accordingly such coatings only demonstrate antibacterial activity by antibiotic release in the presence of adhering bacteria. This is clinically important, because ad libitum releasing antibiotic coatings usually show a burst release and have often lost their antibiotic content when bacteria adhere.

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.

The direct local delivery of short interfering RNA (siRNA) to tissues may present solutions to several complex medical conditions. In particular, chronic wound healing is a serious and painful complication of diabetes mellitus (DM) affecting as many as one in four patients with a three year recurrence rate of more than 50% and leaving over 70,000 patients in the United States alone facing amputation. Here we describe the use of siRNA delivered locally into the diabetic ulcer directly and in a sustained fashion to knockdown a chronically upregulated extracellular matrix protease, matrix metalloproteinase-9 (MMP-9), to improve wound healing. A self-assembled polymer thin film coating, when applied conformally to commercially available nylon bandages, sustains the delivery of small interfering RNA (siRNA) into the wound bed while maintaining activity and facilitating transfection. This approach reduces protein expression and enzyme activity within the wound for over two weeks, leading to a significant improvement in chronic wound healing.

Single-layer metal oxide nanosheets sandwiched between graphene layers exhibit record energy storage figures of merit., MANA E-BULLETIN. 37 (2018)

A high-resolution hard x-ray microscope is described. This system is capable of detecting line features as small as 0.6 micrometer in width, and resolving line pairs 1.2 micrometers wide and 1.2 micrometers apart. Three types of two-dimensional image detectors are discussed and compared for use with hard x rays in high resolution. Principles of x-ray image magnification are discussed, based on x-ray optics and diffraction physics. Examples of applications are shown in microradiography with fiber reinforced composite materials (SiC in Ti3Al Nb) and in diffraction imaging (topography) with device patterns on a silicon single crystal. High-resolution tomography has now become a reality.

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

Indium-tin-oxide (ITO) thin films were prepared by reactive magnetron sputtering; their optical constants and thickness were determined by spectral reflectometry (SR) in the wavelength range from 400 nm to 800 nm and spectroscopic ellipsometry (SE) in the wavelength range from 191 nm to 1690 nm. A comparative evaluation of the measured data from SR and SE has been made using the same single layer optical model based on the Cauchy dispersion relation. The introduction of a surface roughness layer into the optical model considerably improved the fit quality during evaluation of SE data. Vertical inhomogeneity of the ITO thin films was assessed using a multilayer optical model describing porosity gradient and the three-layer optical model suggested by Jung [Y.S. Jung, Thin Solid Films 467, 36 (2004)] from the SE data. Copyright � 2014 Materials Research Society.

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.

Short (5 min) post-deposition thermal treatments under magnetic field at low temperature (up to 200 °C) performed in exchange-coupled FeNi(40 nm)/FeMn(20 nm) bilayer thin films prepared by magnetron sputtering are shown to be effective to significantly modify their exchange field (from around 40 Oe down to 27 Oe) between FeNi and FeMn layers. A similar exchange field decrease was observed for the first deposited FeNi layer of the FeNi(40 nm)/FeMn(20 nm)/FeNi(40 nm) trilayer films after the same thermal treatments. The exchange field value for the second FeNi layer was not substantially changed. The X-ray diffraction patterns indicates that such a heat treatment has no effect on the grain size and crystalline texture of the films, while atomic force microscope studies reveal an increase of the surface roughness after the treatment which is more noticeable in the case of the trilayer film. Analysis of the experimental results leads us to conclude that the variations of the exchange field after heat treatment are likely caused by a modification of interfacial roughness and/or interfacial magnetic structure, but unlikely by the changes in the microstructure and/or changes of composition of the antiferromagnetic FeMn layer., This work was supported by the Ministry of Education and Science of the Russian Federation (Project No. 1362), and ACTIMAT project of Etortek program of the Basque Government and UPV-EHU. Support from Spanish MINECO under project MAT2013-48059-C2-1-R is also 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.

International audience; A tunable strategy, based on the combination of Surface-Initiated Atom Transfer Radical Polymerization (SI-ATRP) and the Layer by Layer (LbL) deposition of polyelectrolytes, was exploited to design tailor-made polyelectrolyte multilayers (PEM) with unusual nanometric features. The cornerstone of the approach is to use polyelectrolytes grafted onto a planar inorganic substrate with different chain conformations as a template for depositing PEM. More particularly, tethered poly(trimethylammonium ethyl methacrylate iodide) (PTMAEMAI) grafts provide various 3D distributions of charge due to a conformation transition of the precursor quaternizable poly(N, N-dimethylamino)ethyl methacrylate (PDMAEMA) chains from 'pancake' to brush-like regime. The change of regime was ensured through the controlled variation of the graft molecular weight using SI-ATRP. The regions made of attached-polycations may serve as preferential positively charged anchoring sites and act as structure-directing agents for the subsequent LbL self-assembly of poly(sodium 4-styrenesulfonate) (PSS)/poly(diallyldimethylammonium chloride) (PDADMAC) multilayers. We have revealed the possibility to fine manipulate (i) the interaction abilities and (ii) the topology of (PSS/PDADMAC) films through the spatial organization exhibited by the PTMAEMAI grafts. This appears as a well-suited and straightforward tool to create an adjustable nanoscale patterning of the resulting multilayers.

When aqueous solutions of polycations and polyanions are mixed, polyelectrolyte complexes form. These are usually insoluble in water, so that they separate out as a new concentrated polymer phase, called a complex coacervate. The behavior of these complexes is reviewed, with emphasis on new measurements that shed light on their structural and mechanical properties, such as cohesive energy, interfacial tension, and viscoelasticity. It turns out that stoichiometric complexes can be considered in many respects as pseudo-neutral, weakly hydrophobic polymers, which are insoluble in water, but become progressively more soluble as salt is added. In fact, the solubility-enhancing effect of salt is quite analogous to that of temperature for polymers in apolar solvents. Since two-phase systems can be prepared in colloidal form, we also discuss several kinds of colloids or 'microphases' that can arise due to polyelectrolyte complexation, such as thin films, 'zipper' brushes, micelles, and micellar networks. A characteristic feature of these charge-driven two-phase systems is that two polymeric ingredients are needed, but that some deviation from strict stoichiometry is tolerated. This turns out to nicely explain how and when the layer-by-layer method works, how a 'leverage rule' applies to the density of the 'zipper brush', and why soluble complexes or micelles appear in a certain window of composition. As variations on the theme, we discuss micelles with metal ions in the core, due to incorporation of supramolecular coordination polyelectrolytes, and micellar networks, which form a new kind of physical gels with unusual properties.

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

In this paper, we numerically demonstrate mid-IR nearly perfect resonant absorption and coherent thermal emission for both polarizations and wide angular region using multilayer designs of unpatterned films of hexagonal boron nitride (hBN). In these optimized structures, the films of hBN are transferred onto a Ge spacer layer on top of a one-dimensional photonic crystal (1D PC) composed of alternating layers of KBr and Ge. According to the perfect agreements between our analytical and numerical results, we discover that the mentioned optical characteristic of the hBN-based 1D PCs is due to a strong coupling between localized photonic modes supported by the PC and the phononic modes of hBN films. These coupled modes are referred as Tamm phonons. Moreover, our findings prove that the resonant absorptions can be red-or blue-shifted by changing the thickness of hBN and the spacer layer. The obtained results in this paper are beneficial for designing coherent thermal sources, light absorbers, and sensors operating within 6.2 mu m to 7.3 mu m in a wide angular range and both polarizations. The planar and lithography free nature of this multilayer design is a prominent factor that makes it a large scale compatible design. (C) 2017 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

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.

The irreversibility temperatures were measured for a-axis oriented and c-axis in-plane aligned Y123/Pr123 multilayer films in various magnetic fields. Pr123 layers act as two-dimensional (planer) c-axis correlated artificial pinning centers (APCs) in the multilayer films. In the irreversibility field-temperature (B irr - T) curves, the crossover was observed near matching field B phi for the multilayer films, when the magnetic fields were applied parallel to the c -axis of the film (B//c). It is suggested the vortex state in Y123 films with two-dimensional APCs is Bose glass below the crossover field. The B irr - T curves under B // a shifted toward lower temperature and magnetic field regions.

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.

The adsorption of quaternized poly(vinylpyridine) (QPVP) on controlled pore glass (CPG) size, over the ionic strength range 0.001-0.5 M was found to display nonmonotonic behavior as a function of pore size. Both adsorption kinetics and ionic strength effects deviated dramatically from behavior typical of adsorption on flat surfaces when the ratio of the pore radius Rp to the polymer hydrodynamic radius Rh became smaller than ca. 2. Ionic strength enhancement of adsorption for small pore sizes was observed at much higher salt concentrations than is typical for polycation adsorption on flat surfaces. The amount of polymer adsorbed per unit surface area of glass GammaA, in 0.5 M NaCl, exhibited a shallow maximum at Rp/Rh approximately 5. Since the value of GammaA for small pore size CPG is strongly depressed by the large surface area, an alternative and more interesting observation is that the amount of polymer adsorbed per gram of CPG, Gammaw, displays a strong maximum when Rp is equal to or slightly smaller than Rh. The efficiency with which QPVP binds anionic micelles to (negatively charged) CPG (grams of surfactant/grams of QPVP) increases strongly with diminishing pore size, indicating that the configuration of polycation bound to small pores favors micelle binding. Since the micelles are larger than small pores, the results indicate that when RpRh, adsorbed polycation molecules reside only partially within the pore. The results of this study are supported by simulations of polyelectrolytes within cylindrical cavities.

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.

Researchers developed ultrathin high-performance capacitors using LEGO-like game of oxide nanosheets., MANA E-BULLETIN. 13 (2014)

Molecularly thin two-dimensional crystals can alleviate the lattice matching restrictions of epitaxial crystalline thin film growth, as reported by researchers in Japan., MANA E-BULLETIN. 8 (2013)

The first observation of massive swelling and shrinkage of inorganic layered materials like a biological cell provides insights into the production of two-dimensional nanocrystals., MANA E-BULLETIN. 6 (2013)

MANA researchers have developed the world's highest performance thin-film capacitors using a new high-permittivity (high-κ) dielectric sheet with molecular-level thickness (~1 nm). This technology may revolutionize the next-generation electronics., MANA E-BULLETIN. 2 (2012)

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

Copper thin films have been deposited on Si substrates by molecular beam epitaxy (MBE) at different deposition rates varying from I up to 22 angstrom/s. X-ray reflectivity and theta-2 theta measurements have shown that the surface roughness correlation length, the structural disorder and the grain dimensions are strongly affected by the deposition rate. Comparing these results with those obtained for sputtered deposited thin films with a low deposition rate (2.5 angstrom/s), a clear similarity between the MBE samples deposited with the highest deposition rate and the sputtering Cu films is observed. This result has been interpreted considering the different energies of the particles that approach the substrate in the two deposition techniques. (c) 2007 Elsevier Ltd. All rights reserved.

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.

Antimicrobial materials with immobilized/entrapped silver nanoparticles (AgNPs) are of considerable interest. There is significant debate on the mode of bactericidal action of AgNPs, and both contact killing and/or ion mediated killing have been proposed. In this study, AgNPs were immobilized on an amine-functionalized silica surface and their bactericidal activity was studied concurrently with the silver release profile over time. This was compared with similar studies performed using colloidal AgNPs and AgCl surfaces that released Ag ions. We conclude that contact killing is the predominant bactericidal mechanism and surface immobilized nanoparticles show greater efficacy than colloidal AgNPs, as well as a higher concentration of silver ions in solution. In addition, the AgNP immobilized substrate was used multiple times with good efficacy, indicating this immobilization protocol is effective for retaining AgNPs while maintaining their disinfection potential. The antibacterial surface was found to be extremely stable in aqueous medium and no significant leaching (similar to 1.15% of total silver deposited) of the AgNPs was observed. Thus, immobilization of AgNPs on a surface may promote reuse, reduce environmental risks associated with leaching of AgNPs and enhance cost effectiveness.

La synthèse de film mince d'AISb est réalisée à partir de films sandwiches Al/Sb soumis soit à un rayonnement laser, soit à une décharge capacitive. La comparaison entre ces deux techniques permet une meilleure compréhension de la nature de la transformation. L'énergie de seuil nécessaire pour que la transformation soit complète (dans le cas de films multicouches dont l'épaisseur totale est de l'ordre de 1 000 Å) est mesurée en fonction de la durée de la pulsation, sur une gamme s'étendant de 10-7 à 10-1 s. La température induite par ces pulsations d'énergie est ensuite calculée être d'au moins 900 K, soit approximativement les points de fusion des composants.