Search results for "polymers"
showing 10 items of 3567 documents
The application of the supported liquid membrane and molecularly imprinted polymers as solid acceptor phase for selective extraction of biochanin A f…
2018
An efficient sample clean-up and preconcentration procedure for phytoestrogens analysis in urine has been developed. It was based on a combination of solid phase extraction with hollow-fiber supported liquid membrane and molecularly imprinted beads (MIPs-HF-SLM-SPE). The molecularly imprinted polymers (MIPs) were synthesized by precipitation polymerization technique with biochanin A (BCA) as a template, giving narrowly dispersed microspheres with a regular shape. As the functional monomer, (dimethylamino)ethyl methacrylate (-DEM) turned out to be better than methacrylic acid (MAA) to get the best-imprinted effects. The MIPs used as sorbents in the MIPs-HF-SLM-SPE extraction process exhibite…
"Writing biochips": high-resolution droplet-to-droplet manufacturing of analytical platforms.
2022
The development of high-resolution molecular printing allows the engineering of analytical platforms enabling applications at the interface between chemistry and biology, i.e. in biosensing, electronics, single-cell biology, and point-of-care diagnostics. Their successful implementation stems from the combination of large area printing at resolutions from sub-100 nm up to macroscale, whilst controlling the composition and the volume of the ink, and reconfiguring the deposition features in due course. Similarly to handwriting pens, the engineering of continuous writing systems tackles the issue of the tedious ink replenishment between different printing steps. To this aim, this review articl…
Squaric Ester-Based, pH-Degradable Nanogels: Modular Nanocarriers for Safe, Systemic Administration of Toll-like Receptor 7/8 Agonistic Immune Modula…
2021
Small-molecular Toll-like receptor 7/8 (TLR7/8) agonists hold promise as immune modulators for a variety of immune therapeutic purposes including cancer therapy or vaccination. However, due to their rapid systemic distribution causing difficult-to-control inflammatory off-target effects, their application is still problematic, in particular systemically. To address this problem, we designed and robustly fabricated pH-responsive nanogels serving as versatile immunodrug nanocarriers for safe delivery of TLR7/8-stimulating imidazoquinolines after intravenous administration. To this aim, a primary amine-reactive methacrylamide monomer bearing a pendant squaric ester amide is introduced, which i…
Straightforward Approach for Preparing Durable Antibacterial ZnO Nanoparticle Coatings on Flexible Substrates
2022
Flexible antibacterial materials have gained utmost importance in protection from the distribution of bacteria and viruses due to the exceptional variety of applications. Herein, we demonstrate a readily scalable and rapid single-step approach for producing durable ZnO nanoparticle antibacterial coating on flexible polymer substrates at room temperature. Substrates used are polystyrene, poly(ethylene-co-vinyl acetate) copolymer, poly(methyl methacrylate), polypropylene, high density polyethylene and a commercial acrylate type adhesive tape. The deposition was achieved by a spin-coating process using a slurry of ZnO nanoparticles in toluene. A stable modification layer was obtained when tolu…
Thermodynamics of Surfactant, Block Copolymer and Their Mixtures in Water: The Role of the Isothermal Calorimetry
2009
The thermodynamics of conventional surfactants, block copolymers and their mixtures in water was described to the light of the enthalpy function. The two methodologies, i.e. the van't Hoff approach and the isothermal calorimetry, used to determine the enthalpy of micellization of pure surfactants and block copolymers were described. The van't Hoff method was critically discussed. The aqueous copolymer+surfactant mixtures were analyzed by means of the isothermal titration calorimetry and the enthalpy of transfer of the copolymer from the water to the aqueous surfactant solutions. Thermodynamic models were presented to show the procedure to extract straightforward molecular insights from the …
Pentafluorophenyl Ester-based Polymersomes as Nanosized Drug-Delivery Vehicles
2015
In this work, activated ester chemistry is employed to synthesize biocompatible and readily functionalizable polymersomes. Via aminolysis of pentafluorophenyl methacrylate-based precursor polymers, an N-(2-hydroxypropyl) methacrylamide (HPMA)-analog hydrophilic block is obtained. The precursor polymers can be versatile functionalized by simple addition of suitable primary amines during aminolysis as demonstrated using a fluorescent dye. Vesicle formation is proven by cryoTEM and light scattering. High encapsulation efficiencies for hydrophilic cargo like siRNA are achieved using dual centrifugation and safe encapsulation is demonstrated by gel electrophoresis. In vitro studies reveal low cy…
Galactosylated polyaspartamide copolymers for siRNA targeted delivery to hepatocellular carcinoma cells
2017
The limited efficacy of available treatments for hepatocellular carcinoma (HCC) requires the development of novel therapeutic approaches. We synthesized a novel cationic polymer based on α,β-poly-(N-2-hydroxyethyl)-D,L-aspartamide (PHEA) for drug delivery to HCC cells. The copolymer was synthesized by subsequent derivatization of PHEA with diethylene triamine (DETA) and with a polyethylene glycol (PEG) derivative bearing galactose (GAL) molecules, obtaining the cationic derivative PHEA-DETA-PEG-GAL. PHEA-DETA-PEG-GAL has suitable chemical-physical characteristics for a potential systemic use and can effectively deliver a siRNA (siE2F1) targeted against the transcription factor E2F1, a gen…
In-line monitoring of the photooxidation behaviour of a PP/clay nanocomposite through creep measurements
2016
Abstract The photooxidation behaviour of a polypropylene/organomodified clay nanocomposite sample has been monitored by means of a new apparatus through the record of the creep curves measured while the sample is subjected to the contemporary action of temperature, tensile strength and UV radiation. The creep curves of the irradiated samples are higher than those of the non-irradiated samples and the curves diverge when the molecular weight begins to decrease because of the degradation. At the same the formation of carbonyl groups is observed. The creep curves of the non-irradiated and irradiated samples give, then, an immediate evaluation of the begin and of the development of the photooxi…
Hygrothermal effect on moisture kinetics and mechanical properties of hemp/polypropylene composite: Experimental and numerical studies
2015
The exposition of thermoplastic composites reinforced with natural fibers to moisture and heat is likely to lower their mechanical properties and restrain their use in the design of parts. The present work is focussed on investigating the effects of hygrothermal aging on the mechanical behaviour of injected polypropylene reinforced with short hemp fibers. Moreover, the kinetic of isothermal moisture absorption has been studied for four immersion temperatures. The experimental results show that the time taken to reach saturation decreases significantly with increase in immersion temperature. These tests also reveal that moisture absorption in this type of materials does not follow Fick's law…
Recycling of compatibilized and uncompatibilized nylon/polypropylene blends
2001
The recycling of compatibilized and uncompatibilized nylon6/polypropylene blends has been carried out by repetitive extrusions. The change of the properties of the blends is a function not only of the number of reprocessing steps but also of the type of compatibilizer. The worsening of the mechanical properties is small and, indeed, some improvement can be observed after one or two extrusion steps for some blends. It is hypothesised that the decrease of the molecular weight, the typical effect occurring during this thermomechanical treatment, is counterbalanced and overcome by the possible formation of new copolymers that act as bridges between the two phases. This behaviour is displayed by…