Search results for "Janus"
showing 10 items of 139 documents
Enzyme pretreatment and negative pressure cavitation extraction of genistein and apigenin from the roots of pigeon pea [Cajanus cajan (L.) Millsp.] a…
2012
Abstract An enzyme pretreatment and negative-pressure cavitation extraction (E-NPCE) method was investigated for extraction genistein and apigenin from pigeon pea roots. The important parameters involved in E-NPCE process were optimized by single-factor experiments and then critical parameters were investigated by a 2 3 full factorial central composite design (CCD) to optimize extract conditions. Under optimal conditions, the yields of genistein and apigenin were 0.628 mg/g and 0.359 mg/g, which represented an increase of 44.70% and 53.05%, respectively, compared to standard NPCE. Furthermore, from DPPH scavenging activity test the extract of E-NPCE showed better antioxidant activity than t…
Antioxidant properties, superoxide dismutase and glutathione reductase activities in HepG2 cells with a fungal endophyte producing apigenin from pige…
2012
Abstract A fungal endophyte MD89 with obvious antioxidant activities was isolated from pigeon pea and identified as Chaetomium globosum by ITS sequence. Different fractions from MD89 culture were compared and evaluated by total phenol (TP) content, total flavonoid (TFL) content, DPPH radical scavenging, reducing power and lipid peroxidation assays, respectively. Results showed that EtOAc extracts had high content of TP and TFL, and strong antioxidant activities (IC 50 value was 6.87, 15.19, 16.78 μg/mL, respectively). Furthermore, the EtOAc extracts were analyzed by LC–MS/MS and a good antioxidant compound, apigenin, was found. The activities of superoxide dismutase (SOD) and glutathione re…
Polymeric janus particles.
2009
Since de Gennes' Nobel lecture in 1991, in which he coined the term "Janus grains", research into asymmetric particles has boomed. Macroscopic, microscopic and nanoscopic particles have been prepared in which certain parts of their surface differ in chemical composition, polarity, color, or any other property. Spherical, cylindrical, disc-like, snowman-, hamburger-, and raspberry-like structures have been synthesized from organic or inorganic materials or even as hybrids of both. Synthetic strategies towards such particles vary greatly from simple polymer mixtures to the bulk self-assembly of sophisticated terpolymers to immobilization methods of symmetric particles. Polymeric Janus particl…
Silica-coated Au@ZnO Janus particles and their stability in epithelial cells
2020
Multicomponent particles have emerged in recent years as new compartmentalized colloids with two sides of different chemistry or polarity that have opened up a wide field of unique applications in medicine, biochemistry, optics, physics and chemistry. A drawback of particles containing a ZnO hemisphere is their low stability in biological environment due to the amphoteric properties of Zn2+. Therefore we have synthesized monodisperse Au@ZnO Janus particles by seed-mediated nucleation and growth whose ZnO domain was coated selectively with a thin SiO2 layer as a protection from the surrounding environment that imparts stability in aqueous media while the Au domain remained untouched. The thi…
Interfacial Assembly and Jamming Behavior of Polymeric Janus Particles at Liquid Interfaces
2017
The self-assembly and interfacial jamming of spherical Janus nanoparticles (JNPs) at the water/oil interface were investigated. Polymeric JNPs, made by cross-linking polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (PS-PB-PMMA), with a high interfacial activity assemble at the water/oil interface. During the self-assembly at the interface, the interfacial energy was reduced and a dynamic interlayer was observed that is responsive to the pH of the aqueous phase. Unlike hard particles, the JNPs are composed of polymer chains that can spread at the liquid-liquid interface to maximize coverage at relatively low areal densities. In a pendant drop geometry, the interfacial area of …
Structured Nanoparticles from the Self-Assembly of Polymer Blends through Rapid Solvent Exchange
2017
Molecular dynamics simulations were performed to study systematically the rapid mixing of a polymer blend in solution with a miscible nonsolvent. In agreement with experiments, we observe that polymers self-assemble into complex nanoparticles, such as Janus and core-shell particles, when the good solvent is displaced by the poor solvent. The emerging structures can be predicted on the basis of the surface tensions between the polymers as well as between the polymers and the surrounding liquid. Furthermore, the size of the nanoparticles can be independently tuned through the mixing rate and the polymer concentration in the feed stream; meanwhile, the composition of the nanoparticles can be c…
Nanoscale hybrid silica/polymer Janus particles with a double-responsive hemicorona
2015
Abstract We report a versatile large-scale synthesis strategy for hybrid Janus nanoparticles with a silica core and a unilaterally attached polymer corona in a size range below 100 nm. The stimuli-responsive behavior of these nanoparticles with a poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) hemicorona is investigated. The synthesis is based on a modified version of the Pickering emulsion polymerization technique in combination with surface-initiated atom transfer radical polymerization (ATRP) in a “grafting from” approach. In a first step, poly(vinyl acetate) (PVAc) latex particles are prepared via Pickering emulsion polymerization. Colloidal stability is provided by 30 nm silica nan…
Colloidal stability and self-assembling behavior of nanoclays
2020
Abstract Currently, nanoclays are attracting the attention of a wide part of the scientific community, due to some of their most peculiar features that make them good candidates for applications in different fields. In light of this, some strategies can be pursued in order to obtain stable colloidal dispersions of nanoclays with the aim to improve their features and to expand their use. Hence, this chapter presents an overview on the structural and morphological characteristics, the physico-chemical properties and the main approaches that are taken into account for the preparation of homogeneous suspensions of Halloysite, Imogolite and Laponite in both aqueous and apolar solvent media. In p…
ChemInform Abstract: Polymeric Janus Particles
2010
Since de Gennes' Nobel lecture in 1991, in which he coined the term "Janus grains", research into asymmetric particles has boomed. Macroscopic, microscopic and nanoscopic particles have been prepared in which certain parts of their surface differ in chemical composition, polarity, color, or any other property. Spherical, cylindrical, disc-like, snowman-, hamburger-, and raspberry-like structures have been synthesized from organic or inorganic materials or even as hybrids of both. Synthetic strategies towards such particles vary greatly from simple polymer mixtures to the bulk self-assembly of sophisticated terpolymers to immobilization methods of symmetric particles. Polymeric Janus particl…
Bisfunctionalized Janus Molecules
2004
[reaction: see text] Bisfunctionalized dendritic multiester molecules were synthesized by combined protection-deprotection and divergent-convergent-divergent sequences in high yields leading to dendritic molecules that combine two functionally different surfaces, polar aliphatic arborol and nonpolar gallate ether moieties, resulting in a two-faced Janus molecule.