Preparation of β-cyclodextrin/polysaccharide foams using saponin.

Cyclodextrins, cyclic oligosaccharides with a hydrophobic cavity that form inclusion complexes with nonpolar molecules, can be used to functionalize other polysaccharides. Xanthan gum, locust bean gum or chitosan can be crosslinked using citric acid in the presence of β-cyclodextrin to produce insoluble matrices. In this work, polymeric foams based on those polysaccharides and saponin have been prepared using a green synthesis method to increase the porosity of the matrices.

Locust Bean Gum, a Vegetable Hydrocolloid with Industrial and Biopharmaceutical Applications.

Locust bean gum (LBG), a vegetable galactomannan extracted from carob tree seeds, is extensively used in the food industry as a thickening agent (E410). Its molecular conformation in aqueous solutions determines its solubility and rheological performance. LBG is an interesting polysaccharide also because of its synergistic behavior with other biopolymers (xanthan gum, carrageenan, etc.

Green synthesis and chemometric characterization of hydrophobic xanthan matrices: Interactions with phenolic compounds.

Polysaccharides such as xanthan, locust bean gum or chitosan are easily crosslinked and purified using citric acid in an ecofriendly process. In order to achieve an improved sorption capability towards hydrophobic solutes, β-cyclodextrin, a cyclic oligosaccharide, and lignin, a natural aromatic polymer, are incorporated in the same process. Once crosslinked, the influence of these on the sorption capacities towards model solutes has been assessed by comparing the sorption isotherms of matrices with or without the hydrophobic modifications.

History of cyclodextrin-based polymers in food and pharmacy: a review.

Cyclodextrins are glucose macrocycles whose inclusional capabilities towards non-polar solutes can be modulated with the help of other macrostructures. The incorporation of cyclodextrin moieties into larger structures produces five types of new materials: crosslinked networks, functionalized chains, amphiphilic cyclodextrins, polyrotaxanes and nanocomposites. This review presents crosslinking and grafting to prepare covalently-attached cyclodextrins, and applications in the food and pharmaceutical sectors, from an historical point of view.

Chitosan, xanthan and locust bean gum matrices crosslinked with β-cyclodextrin as green sorbents of aromatic compounds.

Three different polysaccharides, xanthan gum, chitosan and locust bean gum, were crosslinked with or without β-cyclodextrin, using citric acid in different ratios, to create 'green' hydrogel matrices. The crosslinking of these polysaccharides was produced through an inexpensive and innocuous solvent-free synthesis process. A favorable swelling behavior of the hydrophilic matrices facilitates the sorption of the solutes tested.

Solventless Crosslinking of Chitosan, Xanthan, and Locust Bean Gum Networks Functionalized with β-Cyclodextrin.

The incorporation of cyclodextrins into polymeric crosslinked gels of hydrophilic nature can be useful for promoting the sorption of hydrophobic molecules and/or modulating the release of active principles. The covalent addition of these excipients to the matrix integrates their solubilizing effect that can contribute to increase the capacity of retention of hydrophobic substances. In this study, three diverse polysaccharides, chitosan, xanthan gum, and locust bean gum, were crosslinked with or without β-cyclodextrin, using citric acid in different ratios, to create hydrogel matrices.

Interpenetrated polymer networks of poly(β-cyclodextrin) and polyvinylpyrrolidone with synergistic and selective sorption capacities.

Interpenetrating polymer network (IPN) hydrogels were synthesised using β-cyclodextrin (β-CD) and N-vynil-2-pyrrolidone (NVP) crosslinked with epichlorohydrin and divinylbenzene, respectively, and prepared by four different procedures: simultaneous, sequential, hybrid and a novel one named hybrid-sequential. The IPNs prepared have been characterised by infrared spectroscopy and thermal analysis. The equilibrium swelling in water and the sorption of model substances into the IPNs have also been studied.

Cyclodextrin-Grafted TiO₂ Nanoparticles: Synthesis, Complexation Capacity, and Dispersion in Polymeric Matrices.

The modification of the surface of titanium dioxide nanoparticles (TiO₂ NPs) by the incorporation of cyclodextrins (CDs), cyclic oligosaccharides with a hydrophobic cavity, can largely improve the functionality of TiO₂ by lodging molecules of interest in the CD to act directly on the surface of the nanoparticles or for further release. With this aim, we have synthesized βCD-modified nanoparticles (βCDTiO₂ NPs) by a two-step reaction that involves the incorporation of a spacer and then the linking of the macrocycle, and characterized them by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The capacity of the functionalized structures to trap model compounds (Rhodamine and 1-naphthol) has been compared to that of bare TiO₂ NPs by fluorescence and Ultraviolet-visible (UV-visible) spectroscopy.

Supramolecular Hybrid Structures and Gels from Host-Guest Interactions between α-Cyclodextrin and PEGylated Organosilica Nanoparticles.

Polypseudorotaxanes are polymer chains threaded by molecular rings that are free to unthread; these "pearl-necklace" can self-assemble further, leading to higher-order supramolecular structures with interesting functionalities. In this work, the complexation between α-cyclodextrin (α-CD), a cyclic oligosaccharide of glucopyranose units, and poly(ethylene glycol) (PEG) grafted to silica nanoparticles was studied. The threading of α-CD onto the polymeric chains leads to their aggregation into bundles, followed by either the precipitation of the inclusion complex or the formation of a gel phase, in which silica nanoparticles are incorporated.

Drug Carrier Systems Based on Cyclodextrin Supramolecular Assemblies and Polymers: Present and Perspectives.

The pharmaceutical applications of cyclodextrins (CDs), cyclic oligosaccharides capable of including hydrophobic molecules inside their cavities, have been known for decades. Besides the solubilising and encapsulating abilities of natural and modified CDs due to the formation of inclusion complexes, there is an increasing interest in organized macrostructures based on CDs as potential drug delivery devices and gene carrier systems. The present review discusses first the case of drug carriers based on monomeric modified CDs (amphiphilic and CD core-star polymers), in which self-assembly plays a major role.

Release of β-galactosidase from poloxamine/α-cyclodextrin hydrogels.

All mammals lose their ability to produce lactase (β-galactosidase), the enzyme that cleaves lactose into galactose and glucose, after weaning. The prevalence of lactase deficiency (LD) spans from 2 to 15% among northern Europeans, to nearly 100% among Asians. Following lactose consumption, people with LD often experience gastrointestinal symptoms such as abdominal pain, bowel distension, cramps and flatulence, or even systemic problems such as headache, loss of concentration and muscle pain.

Non-covalent hydrogels of cyclodextrins and poloxamines for the controlled release of proteins.

Different types of gels were prepared by combining poloxamines (Tetronic), i.e. poly(ethylene oxide)/poly(propylene oxide) (PEO/PPO) octablock star copolymers, and cyclodextrins (CD).

In Vitro release from reverse poloxamine/α-cyclodextrin matrices: modelling and comparison of dissolution profiles.

Gels obtained by complexation of octablock star polyethylene oxide/polypropylene oxide copolymers (Tetronic 90R4) with α-cyclodextrin (α-CD) were evaluated as matrices for drug release. Both molecules are biocompatible so they can be potentially applied to drug delivery systems. Two different types of matrices of Tetronic 90R4 and α-CD were evaluated: gels and tablets.

Phase behavior of reverse poloxamers and poloxamines in water.

The phase behavior of two types of poly(ethylene oxide)/poly(propylene oxide) (PEO/PPO) copolymers in aqueous solutions was studied by light scattering, viscometry, and infrared spectroscopy. Both the reverse poloxamer (Pluronic 10R5) and the star type poloxamine (Tetronic 90R4) have practically the same PEO/PPO ratio with their hydrophobic blocks (PPO) located in the outer part. The temperature-composition phase diagrams show that both 10R5 and 90R4 tend to form aggregates in water.

Self-assembled supramolecular gels of reverse poloxamers and cyclodextrins.

A series of supramolecular aggregates were prepared using a poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) (PPO-PEO-PPO) block copolymer and β- or α-cyclodextrins (CD). The combination of β-CD and the copolymer yields inclusion complexes (IC) with polypseudorotaxane structures. These are formed by complexation of the PPO blocks with β-CD molecules producing a powder precipitate with a certain crystallinity degree that can be evaluated by X-ray diffraction (XRD).

Influence of the chitosan nature on the transfection efficacy of DNA-loaded nanoparticles after hydrodynamic administration in mice.

A commercially available chitosan with a degree of deacetylation (DD) of 85% and a molecular weight (Mw) of 400 kDa was modified by acetylation with acetic anhydride to obtain a chitosan with a DD of 75%. Both polysaccharides were used to prepare DNA-chitosan nanoparticles by charge interactions with pDNA (coacervation process). Both resulting nanoparticles showed an almost total DNA loading efficiency (96%) and displayed similar physico-chemical properties with a size of approximately 200 nm and a zeta potential close to +20 mV.

Influence of soluble and insoluble cyclodextrin polymers on drug release from hydroxypropyl methylcellulose tablets.

Background: The influence of beta-cyclodextrin (beta-CD) polymers on drug release from hydroxypropyl methylcellulose (HPMC) matrices has not been reported in the literature.

Aim: The influence of monomeric beta-CD and both soluble and insoluble beta-CD polymers on drug release from tablets containing either 30% or 50% hydroxypropyl methylcellulose has been studied using diflunisal (DF) as model drug.

Method: The DF-beta-CD inclusion complex (1:1 M) was prepared by coevaporation and characterised using X-ray diffraction, differential thermal analysis, and IR spectroscopy.

Sorption models in cyclodextrin polymers: Langmuir, Freundlich, and a dual-mode approach.

The classic Langmuir and Freundlich sorption models and a dual-mode approach have been tested to study the sorption of aromatic molecules onto beta-cyclodextrin polymers as well as onto analogous sucrose polymers, obtained using the same crosslinking agents (epichlorohydrin, succinyl chloride, toluene diisocyanate, and hexamethylene diisocyanate). The host-guest interaction of the sorbate within the cyclodextrin cavities corresponds to the hole-filling mechanism considered in the dual-mode approach, while the polymer crosslinking networks are capable of entrapping more sorbate molecules via partition. In some cases, when the sorption is governed by the inclusion within the cyclodextrin moieties, a simple Langmuir isotherm fits the data properly.

Feasibility study of degradation of phenol in a fluidized bed bioreactor with a cyclodextrin polymer as biofilm carrier.

This work is focused on the evaluation of a beta-cyclodextrin polymer as a carrier medium in a fluidized bed bioreactor treating aqueous phenol as a model pollutant. The insoluble polymer support was obtained in the shape of spherical beads by crosslinking beta-cyclodextrin with epichlorohydrin. A batch of swollen polymer particles was loaded into the reactor and inoculated with a mixed bacterial culture.

Isosteric heats of sorption of 1-naphthol and phenol from aqueous solutions by beta-cyclodextrin polymers.

The sorption of phenol and 1-naphthol from aqueous solutions by beta-cyclodextrin polymers has been analyzed using the isosteric heat approach. This has proven to be a useful tool for comparing the interactions between the sorbents and the sorbates. With the purpose of ascertaining the role of the cyclodextrin cavities and the crosslinking network in the sorption process, analogous sucrose polymers have been prepared using the same crosslinking reagents (epichlorohydrin, succinyl chloride, 1,6-hexamethylene diisocyanate, and toluene-2,4-diisocyanate).

Sorption of dibenzofuran derivatives from aqueous solutions by beta-cyclodextrin polymers: an isosteric heat approach.

Crosslinked polymers containing beta-cyclodextrin units have been used to remove dibenzofuran and three of its derivatives from aqueous solutions close to their saturation concentrations. The temperature dependence behavior for the compounds analyzed shows significant differences, attributable both to the influence of the polarity of their substituents and to the heterogeneity of the sorbent, since the cyclodextrin cavity sites are more favorable for interaction with the sorbate molecules than the crosslinking network.