1,721,131 research outputs found
Tuning the properties of hybrid SiO2/ poly(glycerol monomethacrylate) nanoparticles for enzyme nanoencapsulation
No full textWe explored a versatile enzyme nanoencapsulation process based on the synthesis of silica gel nanoparticles, decorated with a dense hydrophilic poly(glycerol monomethacrylate) (PGMMA) shell for biological and therapeutic applications. These hybrid enzyme-SiO2-polymer nanoparticles were obtained through an aqueous solgel process, followed by the adsorption of cationic macroinitiators by electrostatic complexation. Surface-initiated Atom Transfer Radical Polymerisation (ATRP) was applied to obtain a dense hydrophilic (protein repellent) PGMMA layer of tunable size, under conditions which are compatible with the nanoencapsulation of horseradish peroxidase. The sol-gel synthetic procedure, the composition and molecular weight of the macroinitiators, the polymer adsorption and purification methods, and the final ATRP conditions, were optimised to control the properties of these nanoparticles, in terms of particle size, Z-potential, PGMMA decoration, while preserving enzymatic activity
Yeast Cells in Microencapsulation. General Features and Controlling Factors of the Encapsulation Process
No full textBesides their best-known uses in the food and fermentation industry, yeasts have also found application as microcapsules. In the encapsulation process, exogenous and most typically hydrophobic compounds diffuse and end up being passively entrapped in the cell body, and can be released upon application of appropriate stimuli. Yeast cells can be employed either living or dead, intact, permeabilized, or even emptied of all their original cytoplasmic contents. The main selling points of this set of encapsulation technologies, which to date has predominantly targeted food and—to a lesser extent—pharmaceutical applications, are the low cost, biodegradability and biocompatibility of the capsules, coupled to their sustainable origin (e.g., spent yeast from brewing). This review aims to provide a broad overview of the different kinds of yeast-based microcapsules and of the main physico-chemical characteristics that control the encapsulation process and its efficiency
"Linear Polarizers Based on Polyethylene-Compatible Multifunctional Terthiophene Chromophores".
No full textNonlinear optical properties of some side chain copolymers based on benzoxazole containing chromophores
No full textPhotomodulation of the hydrophilic properties of acrylic polymers containing side-chain azobenzene chromophores
No full textPartially hydrophilic polymers have been prepared by free-radical copolymerization of trans-4-acryloyloxyazobenzene with N-tert-butylacrylamide and N-isopropylacrylamide. A turbidimetric method has been adapted to investigate the dependence of the polymer hydrophilic-hydrophobic balance on chemical composition and extent of photoisomerization of side-chain azobenzene chromophores. Irradiation at 366 nm of polymer suspension in THF-water induces the isomerization of azobenzene groups from the planar apolar trans form to the nonplanar polar cis form. Correspondingly, the solution turbidity is appreciably modified. Experimental results are discussed in terms of polymer structural parameters. Suspension stability and the possibility of carrying out photochemical cycles have been also investigated
Mesoscale modelling of near-contact interactions for complex flowing interfaces
No full textWe present a mesoscale kinetic model for multicomponent flows, augmented with a short range forcing term, aimed at describing the combined effect of surface tension and near-contact interactions operating at the fluid interface level. Such a mesoscale approach is shown to (i) accurately capture the complex dynamics of bouncing colliding droplets for different values of the main governing parameters, (ii) predict quantitatively the effective viscosity of dense emulsions in micro-channels and (iii) simulate the formation of the so-called soft flowing crystals in microfluidic focusers
Host-guest absorption polarizers based on polyethylene and new terthiophene compatible chromophores
No full textSynthesis and photobehaviour of hydrophilic acrylic polymers containing azobenzene groups
No full textNew hydrophilic photochromic polymeric systems containing side-chain azobenzene groups were synthesized by radical copolymerization of 4-acryloyloxyazobenzene with hydrophilic acrylic comonomers containing in the side chain either amide or quaternary onium groups. In all cases copolymerization products characterized by an almost random distribution of monomeric units were obtained. On irradiation at 366 nm, azobenzene-containing copolymers underwent trans-to-cis photoisomerization of the side-chain azo groups and in all cases monoexponential decay of the 320 nm absorbance was observed. Copolymer properties were investigated by DSC analysis, solubility measurements, UV spectroscopy and photoisomerization kinetics. The results obtained are discussed in terms of nature and content of hydrophilic comonomer and water content of the solvent used. The possibility of photomodulating copolymer solubility is also suggested
Design of the molecular structure of the dye to optimized dispersion in polyethylene films for optical application
No full textNonlinear optical properties of some side chain copolymers based on benzoxazole containing chromophores
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