ß-Cyclodextrin functionalized agarose-based hydrogels for multiple controlled drug delivery of ibuprofen.

Agarose hydrogels are three-dimensional hydrophilic polymeric frameworks characterised by high water content, viscoelastic properties, and excellent ability as cell and drug delivery systems. However, their hydrophilicity as gel systems makes loading of hydrophobic drugs difficult and often ineffective. The incorporation of amphiphilic molecules (e.g. cyclodextrins) into hydrogels as hosts able to form inclusion complexes with hydrophobic drugs could be a possible solution. However, if not properly confined, the host compounds can get out of the network resulting in uncontrolled release. Therefore, in this work, ß-cyclodextrins-based host-guest supramolecular hydrogel systems were synthesised, with ß-cyclodextrins (ß-CD) covalently bound to the polymeric network, preventing leakage of the host molecules. Hydrogels were prepared at two different ß-CD-functionalized polyvinyl alcohol (PVA)/agarose ratios, and characterised chemically and physically. Then ibuprofen, a drug often used as a gold standard in studies involving ß-CD both in its hydrophilic and hydrophobic forms, was selected to investigate the release behavior of the synthesised hydrogels and the influence of ß-CD on the release. The presence of ß-CD linked to the polymeric 3D network ensured a higher and prolonged release profile for the hydrophobic drug and also seemed to have some influence on the hydrophilic one.

Hyaluronic acid-based hydrogels: Drug diffusion investigated by HR-MAS NMR and release kinetics.

Hydrogels based on hyaluronic acid (HA) and agarose-carbomer (AC) raised an increasing interest as drug delivery systems. The complex architecture of the polymer network, such as mesh size, HA molecular weight and drug-polymer non covalent interactions across the 3D polymer matrix strongly influence the release capability/profile of these materials. In this study, AC-HA hydrogels with different mesh sizes have been prepared and characterised. High Resolution Magic Angle Spinning (HR-MAS) NMR spectroscopy has been used to investigate the motion of two drugs, such as ethosuximide (neutral molecule) and sodium salicylate (net negative charge) within the AC and AC-HA hydrogel networks. Analysis of the experimental data provides evidence of superdiffusive motion for all formulations containing sodium salicylate, while ethosuximide molecules undergo unrestricted diffusion within the gel matrix. We further speculate that the superdiffusive motion, observed at the nanoscale, can be responsible for the faster release of sodium salicylate from all hydrogel formulations.

Bijels as a Fluid Labyrinth for Drugs: The Effect of Nanoparticles on the Release Kinetics of Ethosuximide and Dimethyl Fumarate.

Bijels (bicontinuous interfacially jammed emulsion gels) raised an increasing interest as biomaterials for controlled drug delivery due to their biphasic nature organized in mesoscopic tortuous domains. Two bijel formulations were prepared and explored as delivery systems for both hydrophilic and lipophilic drugs, ethosuximide and dimethyl fumarate. The two bijel-like structures, based on polymerized ε-caprolactone/water, differ in the stabilizing nanoparticle hydroxyapatite (inorganic) and nanogel-based nanoparticles (organic). Diffusion nuclear magnetic resonance spectroscopy has been used to characterize the bijel structure and the transport behavior of the drug molecules confined within the water/organic interconnected domains. A reduced diffusion coefficient is observed for several concentrations of the drugs and both bijel formulations. Moreover, in vitro release profiles also reveal the effect of the microstructure and drug-nanoparticle interactions.

Insights into the Effect of Lithium Doping on the Deep Eutectic Solvent Choline Chloride:Urea.

Choline-based deep eutectic solvents (DESs) are potential candidates to replace flammable organic solvent electrolytes in lithium-ion batteries (LIBs). The effect of the addition of a lithium salt on the structure and dynamics of the material needs to be clarified before it enters the battery. Here, the archetypical DES choline chloride:urea at 1:2 mole fraction has been added with lithium chloride at two different concentrations and the effect of the additional cation has been evaluated with respect to the non-doped system via multinuclear NMR techniques. 1H and 7Li spin-lattice relaxation times and diffusion coefficients have been measured between 298 K and 373 K and revealed a decrease in both rotational and translational mobility of the species after LiCl doping at a given temperature. Temperature dependent 35Cl linewidths reflect the viscosity increase upon LiCl addition, yet keep track of the lithium complexation. Quantitative indicators such as correlation times and activation energies give indirect insights into the intermolecular interactions of the mixtures, while lithium single-jump distance and transference number shed light into the lithium transport, being then of help in the design of future DES electrolytes.