betadex and benzophenone

Novel βCD-based hydrogels have been synthesized using sodium trimetaphosphate (STMP) as non-toxic reagent. Straightforward mixing of βCD with dextran and STMP in basic aqueous media led to hydrogels incorporating dextran chains, phosphate groups and βCD units. The hydrogels have been characterized by swelling measurements, XPS and (31)P NMR. The swelling ratio was correlated to the content in phosphated groups, which give a polyelectrolyte character to these hydrogels. The significant rise of the swelling ratio with the βCD content increase has been attributed to a decrease of the number of phosphate-based crosslinks, the βCD units playing the role of dangling ends in the tridimensional network. Their loading capacity and their release properties have been investigated for methylene blue and benzophenone in order to demonstrate their potentiality for drug delivery. Through different interaction mechanisms, electrostatic and inclusion complex interactions, these compounds are loaded with different efficiencies. The release involves deswelling, diffusion mechanisms and partition equilibrium.

Topics: Benzophenones; beta-Cyclodextrins; Cross-Linking Reagents; Dextrans; Drug Carriers; Enzyme Inhibitors; Hydrogels; Methylene Blue; Photosensitizing Agents; Polyphosphates

The aim of this work was to incorporate a hydrophobic compound benzophenone (BP) into core-shell nanoparticles (NPs) and to study its release. The core of these NPs is based on polylactic acid (PLA) and serves as a nanocontainer to accommodate BP. The shell is constituted of a β-cyclodextrin polymer (Poly-β-CD) which ensures the control of BP release through non-covalent host-guest interactions. Studies were focused on the preparation, physico-chemical analysis of the BP-loaded NPs and on the elucidation of the release mechanisms. The main features which are the slow kinetics, the dilution-induced release and the total release of encapsulated BP are in good agreement with a mechanism mainly controlled by diffusion of BP and by its binding with the β-CDs cavities present at the surface of NPs.

Topics: Benzophenones; beta-Cyclodextrins; Calorimetry, Differential Scanning; Hydrophobic and Hydrophilic Interactions; Kinetics; Lactic Acid; Microscopy, Electron, Scanning; Nanoparticles; Polyesters; Polymers

The entrapment of two hydrophobic molecules, benzophenone and tamoxifen, into self-assembling cyclodextrin (CD)-based nanogels has been studied. These nanogels formed spontaneously upon the association of a hydrophobically modified dextran (MD) and a cyclodextrin polymer (pbetaCD). The interactions of benzophenone and tamoxifen with MD and pbetaCD were investigated using phase solubility studies, circular dichroism, and isothermal titration calorimetry. Both hydrophobic molecules were included into the CD cavities of the pbetaCD and were also solubilized by MD into its hydrophobic microdomains. We took advantage of these interactions to form benzophenone- and tamoxifen-loaded nanogels. The highest benzophenone loadings were obtained by solubilizing it in both pbetaCD and MD solutions before mixing them to form nanogels. These studies open new possibilities of applications of the nanogels, mainly in the cosmetic field, as sun screen carriers prepared by a simple "green" technology.

Topics: Benzophenones; beta-Cyclodextrins; Dextrans; Hydrophobic and Hydrophilic Interactions; Nanogels; Polyethylene Glycols; Polyethyleneimine; Solubility; Tamoxifen

Associative networks have been elaborated by mixing in aqueous media a cyclodextrin polymer to a dextran bearing adamantyl groups. The two polymers interact mainly via inclusion complexes between adamantyl groups and cyclodextrin cavities, as evidenced by the high complexation constants determined by isothermal titration microcalorimetry (approximately 10(4) L mol(-1)). Additional interaction mechanisms participating in the strength of the network, mainly hydrogen bonding and electrostatic interactions, are sensitive to the pH and ionic strength of the medium, as shown by pH-dependent rheological properties. The loading and release of an apolar model drug, benzophenone, has been studied at two pH values and different cyclodextrin polymer content. Slow releases have been obtained (10-12 days) with slower kinetics at pH 2 than at pH 7. Analysis of the experiments at pH 7 shows that drug release is controlled both by diffusion in the network and by inclusion complex interactions with cyclodextrin cavities.

Topics: Benzophenones; beta-Cyclodextrins; Dextrans; Drug Delivery Systems; Models, Chemical; Photosensitizing Agents; Rheology

This study aims to investigate the rheological properties of self-assembling gels containing cyclodextrins with potential application as injectable matrix for the sustained delivery of poorly soluble drugs. The ability of these gels to entrap two hydrophobic molecules, benzophenone (BZ) and tamoxifen (TM), and to allow their in vitro sustained release was evaluated. In view of their future pharmaceutical use, gels were sterilized by high hydrostatic pressures (HHP) and tested for their biocompatibility. The gels formed instantaneously at room temperature, by mixing the aqueous solutions of two polymers: a beta-cyclodextrin polymer (pbetaCD) and a hydrophobically modified dextran by grafting alkyl side chains (MD). MD-pbetaCD gels presented a viscoelastic behavior under low shear, characterized by constant values of the loss modulus G'' and the storage modulus G'. The most stable gels were obtained for a total polymer concentration C(p) of 6.6% and 7.5% (w/w), and a polymer ratio MD/pbetaCD of 50/50 and 33/67 (w/w). BZ and TM were successfully incorporated into MD-pbetaCD gels with loading efficiencies as high as 90%. In vitro, TM and BZ were released gradually from the gel matrix with less than 25% and 75% release, respectively, after 6 days incubation. HHP treatment did not modify the rheological characteristics of MD-pbetaCD gels. Moreover, the low toxicity of these gels after intramuscular administration in rabbits makes them promising injectable devices for local delivery of drugs.

Topics: Animals; Benzophenones; beta-Cyclodextrins; Biocompatible Materials; Biomechanical Phenomena; Dextrans; Drug Delivery Systems; Hydrogels; Hydrophobic and Hydrophilic Interactions; Hydrostatic Pressure; Materials Testing; Microscopy, Electron, Transmission; Proteins; Rabbits; Rheology; Salts; Skin; Tamoxifen

New nanoassemblies were instantaneously prepared by mixing two aqueous solutions, one containing a beta-cyclodextrin polymer (pbetaCD), and the other a hydrophobically modified by alkyl chains dextran (MD). The formation mechanism and the inner structure of these nanoassemblies were analysed using surface tension measurements and (1)H NMR spectroscopy. The effect of a hydrophobic guest molecule, such as benzophenone (BZ), on the formation and stability of the nanoassemblies was also evaluated. MD exhibited the typical behaviour of a soluble amphiphilic molecule and adsorbed at the air/water interface. Whereas the injection of native beta-CDs in the solution beneath the adsorbed MD monolayer did not produce any change in the surface tension, that of the pbetaCD resulted in an increase in the surface tension, indicating the desorption of the polymer from the interface. This result accounts for a cooperative effect of beta-CDs linked together in the pbetaCD polymer on dextran desorption. The presence of benzophenone in the system hindered the sequestration of dextran alkyl moieties by beta-CD in the polymer without impeding the formation of associative nanoassemblies of 100-200 nm. (1)H NMR investigations demonstrated that, in the BZ-loaded nanoassemblies, the hydrophobic molecule was mainly located into the cyclodextrin cavities.

Topics: Benzophenones; beta-Cyclodextrins; Dextrans; Hydrophobic and Hydrophilic Interactions; Magnetic Resonance Spectroscopy; Nanoparticles; Propylene Glycols

We show here, for the first time, that two neutral polymers may completely associate together in water to spontaneously form supramolecular nanoassemblies (nanogels) of spherical shape. The cohesion of these stable structures of about 200 nm is based upon a "lock and key" mechanism: inclusion complexes are formed between the hydrophobic alkyl chains grafted on a polysaccharide (dextran) and the molecular cavities contained in a poly-cyclodextrin polymer. Production yields reached 95%. It was established that all the alkyl chains were included within the cyclodextrins' cavities in these nanoassemblies. The multivalent character of the interactions between the two polymers ensures the stability of the nanoassemblies. Moreover, empty cyclodextrin units remained accessible for the inclusion of compounds of interest such as benzophenon or tamoxifen.

Topics: Antineoplastic Agents, Hormonal; Benzophenones; beta-Cyclodextrins; Dextrans; Drug Carriers; Gels; Magnetic Resonance Spectroscopy; Models, Molecular; Nanostructures; Polymers; Surface Tension; Tamoxifen; Water