Search results for "Layer-by-layer"
showing 10 items of 10 documents
CHARACTERIZATION AND DEVELOPMENT OF DIFFERENT METHODS TO EXTEND THE SHELF LIFE OF FRESH-CUT FRUIT
2017
La frutta di IV gamma è un prodotto altamente deperibile, con una shelf-life molto corta (5-7 giorni) influenzata dalle numerose variabili che entrano in gioco accelerando la senescenza del prodotto. Il suo alto valore aggiunto può giustificare l’utilizzo di soluzioni di conservazione più o meno costose. I metodi attualmente esistenti sono numerosi, spaziano dal dipping in sostanze naturali o sintetiche, all’utilizzo di packaging attivi, all’impiego di atmosfere modificate, ecc. Queste metodiche di conservazione incidono in maniera diversa sui costi finali del prodotto ma soprattutto sulla conservazione dello stesso e sul mantenimento della sua qualità lungo tutto il periodo di shelf-life. …
Self-assembled PAA-based nanoparticles as potential gene and protein delivery systems
2012
A series of nanoparticles is prepared via layer-by-layer assembly of oppositely charged, synthetic biocompatible polyamidoamine polymers as potential carriers. Particle size, surface charge and internal chain mobility are quantified as a function of the polymer type and number of layers. The effect of addition of surfactant is examined to simulate the effects of nanoparticle dissolution. The cyctotoxicity of these particles (in epithelia and murine cell lines) are orders of magnitude lower than polyethyleneimine controls. Stable nanoparticles may be prepared from mixtures of strongly, oppositely charged polymers, but less successfully from weakly charged polymers, and, given their acceptabl…
LbL multilayer capsules: recent progress and future outlook for their use in life sciences.
2010
In this review we provide an overview of the recent progress in designing composite polymer capsules based on the Layer-by-Layer (LbL) technology demonstrated so far in material science, focusing on their potential applications in medicine, drug delivery and catalysis. The benefits and limits of current systems are discussed and the perspectives on emerging strategies for designing novel classes of therapeutic vehicles are highlighted. © 2010 The Royal Society of Chemistry.
From the solution processing of hydrophilic molecules to polymer-phthalocyanine hybrid materials for ammonia sensing in high humidity atmospheres.
2014
We have prepared different hybrid polymer-phthalocyanine materials by solution processing, starting from two sulfonated phthalocyanines, s-CoPc and CuTsPc, and polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), poly(acrylic acid-co-acrylamide) (PAA-AM), poly(diallyldimethylammonium chloride) (PDDA) and polyaniline (PANI) as polymers. We also studied the response to ammonia (NH3) of resistors prepared from these sensing materials. The solvent casted films, prepared from s-CoPc and PVP, PEG and PAA-AM, were highly insulating and very sensitive to the relative humidity (RH) variation. The incorporation of s-CoPc in PDDA by means of layer-by-layer (LBL) technique allowed to stabilize the fi…
Poly(3,4-Ethylenedioxythiophene) nanoparticles as building blocks for hybrid thermoelectric flexible films
2019
Hybrid thermoelectric flexible films based on poly(3,4-ethylenedioxythiophene) (PEDOT) nanoparticles and carbon nanotubes were prepared by using layer-by-layer (LbL) assembly. The employed PEDOT nanoparticles were synthesized by oxidative miniemulsion polymerization by using iron(III) p-toluenesulfonate hexahydrate (FeTos) as an oxidant and poly(diallyldimethylammonium chloride) (PDADMAC) as stabilizer. Sodium deoxycholate (DOC) was used as a stabilizer to prepare the aqueous dispersions of the carbon nanotubes. Hybrid thermoelectric films were finally prepared with different monomer/oxidant molar ratios and different types of carbon nanotubes, aiming to maximize the power factor (PF). The …
Stable n-type thermoelectric multilayer thin films with high power factor from carbonaceous nanofillers
2016
Abstract High power factor n-type organic thermoelectric nanocomposites are assembled by alternately depositing double walled-nanotubes (DWNT), stabilized by polyethyleneimine (PEI), and graphene stabilized by polyvinylpyrrolidone (PVP), from water using the layer-by-layer (LbL) assembly technique. This unique combination of carbon nanomaterials exhibits an electrical conductivity of 300 S cm−1 and a relatively stable power factor of 190 μW m−1 K−2 at room temperature.
Characterization and development of different methods to extend shelf life of fresh cut fruit. Case study: novel controlled release system by layer-b…
2016
The research project aimed at the investigation of different methods for the storage of fresh-cut fruit. This case study relates to the proposal of an innovative controlled release system to improve the shelf life of ready-to-eat fruit. The methods applied during three research years included the application of active molecules from natural substances, some widely used in commerce and other tested for the first time; first analyzed in vitro and then applied in vivo. The under consideration methods concerned dipping, coating and the layer-by-layer assembly. The analysis carried out on the fruit have monitored pomological traits performances (soluble solids content, titratable acidity, pH, co…
Protection of yeast cells in micro-organized shells of natural polyelectrolytes during drying process
2016
The encapsulation techniques are applied in various fields and for various applications. The layer-by-layer self-assembly (LbL), one of the encapsulation techniques, is built by the electrostatic attraction between oppositely charged polyelectrolytes, and the topmost layer determines essentially the sur-face properties of the edifice. This technique offers several advantages (low cost, simplicity of process and equipment, biocompatibility and biodegra-dation, etc.). In this present paper, results of the protection of Saccharomyces cerevisiae yeast cells in microorganized shell of natural polyelectrolytes during dehydration process are reported. To apply the LbL method to individually encaps…
Protection of living yeast cells by micro-organized shells of natural polyelectrolytes
2015
International audience; Saccharomyces cerevisiae, a eukaryotic model organism, plays a key role in the oxidative stability of fermented products. In order to protect cells against environmental stresses, we report a method of modifying the cell surface architecture while maintaining the internal working properties of the system. The objective was to encapsulate living yeast cells in micro-organized polyelectrolyte shells using layer-by-layer (LbL) assembly. For the first time, the natural polyelectrolytes, β-lactoglobulin and sodium alginate, were alternately deposited on the surface of S. cerevisiae. Transmission electron microscopy coupled with immune-cytochemistry and scanning electron m…
Electrochemical Synthesis of an Organic Thermoelectric Power Generator.
2020
[EN] Energy harvesting through residual heat is considered one of the most promising ways to power wearable devices. In this work, thermoelectric textiles were prepared by coating the fabrics, first with multiple-wall carbon nanotubes (MWCNTs) by using the layer-by-layer technique and second with poly(3,4-ethylenedioxythiophene) (PEDOT) deposited by electrochemical polymerization. Sodium deoxycholate and poly(diallyldimethylammonium chloride) were used as stabilizers to prepare the aqueous dispersions of MWCNTs. The electrochemical deposition of PEDOT on the MWCNT-coated fabric was carried out in a three-electrode electrochemical cell. The polymerization of PEDOT on the fabric increased the…