Search results for "dextrin"

Photocleavable microcapsules built from photoreactive nanospheres.

2005

We show how photo-cross-linking of nanoparticles within the micrometer-sized thin oil shell of water-oil-water emulsion droplets leads to a new species of optically addressable microcontainers. The inner water droplet of these emulsions may contain drugs, dyes, or other water-soluble components, leading to filled containers. The thickness, mechanical stability, and light resistance of the container walls can be controlled in a simple way by the amount and adjustable photoreactivity of the nanoparticles. Importantly, the chemical bonds between the nanoparticles constituting the microcapsule shell can be cleaved photochemically by irradiation with UV light. This optically controlled destructi…

Aggregation in aqueous media of tri-block copolymers tuned by the molecular selectivity of cyclodextrins

2009

The water + cyclodextrin + poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) mixtures have been investigated to explore the temperature effect on the aggregation of the copolymer in the presence of cyclodextrins (CDs). The CDs with different cavity sizes were chosen because they may include either the hydrophilic poly(ethylene oxides) block or both kinds of blocks. The differential scanning calorimetry and viscosity experiments straightforwardly evidenced that the critical micellar temperature is shifted to larger values by adding a CD which is able to include the middle poly(propylene oxide) block while it is not influenced by the presence of CD which is selective to the poly…

Cellulose-click-ferrocenes as docking spots for cyclodextrin

2012

A novel synthesis of ferrocene-modified cellulose, prepared from 6-azido-6-deoxy-cellulose and ethynylferrocene, is presented. The two components were coupled via copper-catalyzed click-type cycloaddition under microwave-assisted conditions. The surface structure of the cellulose derivative was investigated in comparison with that of pure, microcrystalline cellulose using electron microscopy (scanning, transmission and scanning transmission), showing iron atoms of ferrocene as homogeneously distributed particles. They are detectable as clear signals in the energy-dispersive X-ray profile. In addition, Rame-β-cyclodextrin was supramolecularly attached to cellulose and the complex formed was …

Cyclodextrins in polymer synthesis: free radical polymerization of cyclodextrin complexes with oxazoline-functionalized vinyl monomers as guest molec…

2000

The synthesis of five new oxazoline functionalized vinyl monomers N-[4-(4′,5′-dihydrooxazol-2-yl)phenyl]acrylamide (3 a), N-[4-(4′,5′-dihydrooxazol-2-yl)phenyl]-2-methylacrylamide (3 b), N-{10-[4-(4′,5′-dihydrooxazol-2-yl)phenylcarbamoyl]decyl}-2-acrylamide (5 a), N-{10-[4-(4′,5′-dihydrooxazol-2-yl)phenylcarbamoyl]decyl}-2-methylacrylamide (5 b) and N-[4-(4′,5′-dihydrooxazol-2-yl)-phenyl]-4-vinylbenzamide (7) is described. With an equimolar amount of 2,6-dimethyl-β-cyclodextrin (DMCD) these monomers formed hydrophilic inclusion complexes 3 a,b-DMCD, 5 a,b-DMCD and 7-DMCD. These complexes were polymerized radically in an aqueous medium. Resulting polymers P-(3 a, b), P-(5 a, b) and P-(7) pre…

(Co-)solvent selection for single-wall carbon nanotubes: best solvents, acids, superacids and guest-host inclusion complexes.

2011

Analysis of 1-octanol-water, cyclohexane-water and chloroform (CHCl(3))-water partition coefficients P(o-ch-cf) allows calculation of molecular lipophilicity patterns, which show that for a given atom log P(o-ch-cf) is sensitive to the presence of functional groups. Program CDHI does not properly differentiate between non-equivalent atoms. The most abundant single-wall carbon nanotube (SWNT), (10,10), presents a relatively small aqueous solubility and large elementary polarizability, P(o-ch-cf) and kinetic stability. The SWNT solubility is studied in various solvents, finding a class of non-hydrogen-bonding Lewis bases with good solubility. Solvents group into three classes. The SWNTs in so…

Volumes and heat capacities of the aqueous sodium dodecanoate/sodium perfluorooctanoate mixtures in the presence of β-cyclodextrin

2003

Apparent molar volumes (VΦ) and heat capacities (CΦ) of the sodium dodecanoate (NaL)/sodium perfluorooctanoate (NaPFO) mixtures in the water/β-cyclodextrin (β-CD) solvent as functions of the surfactant total molality (mt) were determined at 25°C. For a given surfactant mixture, VΦ decreases with mt to ca. 0.05 mol kg−1 thereafter it increases tending to a constant value. CΦ displays a behaviour opposite to VΦ. The mt values where the apparent molar properties exhibit extrema are nearly coincident with the critical micellar concentrations determined by conductivity. An equation correlating VΦ to mt was derived by assuming that the equilibria for the 1∶1 surfactant/cyclodextrin complex format…

Spectrophotometric determinations of binding constants between cyclodextrins and aromatic nitrogen substrates at various pH values

2001

The inclusion capacity of native β-cyclodextrin (1) and mono-(6-amino-6-deoxy)-β-cyclodextrin (2) versus aromatic compounds having a nitro or an amino group or both has been investigated at three different pH values. Molecular interactions in inclusion complexes have also been investigated by means of molecular mechanics (MM2/QD) models. Electrostatic and van der Waals interactions and the formation of a hydrogen bond between the donor amino group and the oxygen atom of the secondary hydroxyl group seem to be the more important contributions in determining complex stability. The inclusion capacity of two different cyclodextrins versus aromatic compounds has been investigated at three differ…

2017

Abstract In this study, an adsorption-oriented process for the removal of fungicides from polycontaminated aqueous solutions was applied. To remove triazole fungicides from aqueous mixtures of propiconazole (PROPI), tebuconazole (TEBU), epoxiconazole (EPOXI), bromuconazole (BROMU) and difenoconazole (DIFENO), several materials used as adsorbents were compared using batch experiments, namely two conventional activated carbons (ACs) and five nonconventional cross-linked cyclodextrin (CD)-based materials (α-CDP, β-CDP, γ-CDP, αβγ-CDP mixture, and hydroxypropyl-β-CDP). This article presents the abatements obtained. As expected, ACs exhibited the highest levels of triazole fungicide removal: the…

Cyclodextrin‐Calixarene Nanosponges as Potential Platforms for pH‐Dependent Delivery of Tetracycline

2019

Four mixed cyclodextrin-calixarene nanosponges were tested as possible Drug Delivery Systems, using Tetracycline antibiotic as a suitable model drug. The selected nanosponges featured a different composition ratio between the two host co-monomer components, and the possible presence of ionisable amine or carboxyl groups deriving from chemical post-modification. The pH-dependent absorption and release abilities of the materials were verified; in particular release kinetics showed the occurrence of a simple first-order profile. The antibacterial activity of nanosponge-tetracycline composites suitably prepared under sterile conditions was assayed towards both Gram-positive and Gram-negative ty…

Functionalized halloysite multivalent glycocluster as a new drug delivery system.

2020

A new design for halloysite nanotube materials was obtained by grafting chemically modified cyclodextrin units onto the nanotube surface. In particular, grafted cyclodextrins were decorated with thiosaccharide pendants, in order to mimic the well-known binding of sugars to proteins and the glyco-cluster effect occurring during cellular recognition events. The obtained materials were characterized by using a combination of varied techniques (FT-IR spectroscopy, thermogravimetric analysis, scanning electron microscopy, dynamic light scattering, turbidimetry), and their potential drug-delivery abilities were tested by studying their interactions with the common naturally occurring anticancer a…