We prepared a buoyancy matched binary mixture of polydisperse polystyrene microgel spheres of size ratio Γ = 0.785 at a volume fraction of Φ = 0.567 just below the kinetic glass transition. In line with theoretical expectations, a eutectic phase behaviour was observed, but only a minor fraction of the samples crystallized at all. By adding a short non-adsorbing polymer we enforce interspecies fractionation into coexisting pure component crystals, which in turn also shows signs of intra-species fractionation. We show that in formerly inaccessible regions of the phase diagram binary hard sphere physics are made observable using attractive hard spheres.Binary colloidal mixtures are valuable model systems for fundamental studies of crystallization [1][2][3] . Detailed predictions of their phase behaviour exist for hard sphere (HS) systems of different size ratio Γ = R S /R L (where R i are the radii of small (S) and large (L) spheres, respectively). These show a sequence of spindle to azeotropic to eutectic phase diagram types with decreasing Γ, vanishing miscibility in the crystal phase for Γ < 0.85 and a huge variety of crystal structures for compounds [4][5][6][7][8][9] . For zero miscibility eutectics the inter-species fractionation is expected to cause a pronounced slowing of nucleation 8 . Polydispersities above 6% destabilize the crystal phases 11,12 (10% in 2D 10 ), hence additional intraspecies fractionation is expected for strongly polydisperse systems 13,14 1,2,7,18,19 and also the general sequence of phase diagram types was confirmed 20 , most parts of the phase diagram escape from a detailed experimental investigation; e.g., the exact locations of phase boundaries in compound forming systems have not yet been determined. Moreover, crystallization kinetics have not been obtained and, except for a recent 2D-study 21 , fractionation into coexisting Land S-crystals has not yet been observed. One main reason for this is the interference of crystallization with the glass transition (GT) at large volume fractions 22 . Furthermore, gravity seemingly enhances the trend to dynamically arrest the systems 23 . In addition, it may lead to differential sedimentation and inhomogeneities in composition 24,25 .In the present paper we avoid sedimentation using a binary mixture of buoyancy matched microgel particles. We further exploit earlier observations on a variety of systems, in which both vitrification can be suppressed [26][27][28] and crystallization be accelerated 29 by adding a short chained, non adsorbing polymer. Doing so, one moves from HS to attractive HS (AHS), which in principle may significantly alter both phase behaviour and crystallization kinetics [30][31][32][33][34][35][36][37] . However, using a binary AHS mixture at a size ratio of Γ = 0.785 we here give the first demonstration of the simultaneous precipitation of S-and L-crystals over the full range of compositions. Thus, we recover the zero miscibility eutectic solidification process expected for pure HS. Moreover, we provide experimental support...

In this work the crystallization kinetics of colloidal binary mixtures with attractive interaction potential (Asakura-Oosawa) has been addressed. Parameters such as fraction of crystals, linear crystal dimension and crystal packing have been quantified in order to understand how the crystal formation is driven in terms of the depth of the attractive potential and the composition of the binary mixture (described by the number ratio). It was found that inside the eutectic triangle, crystallization is mainly governed by nucleation and the crystal packing is close to the close-packing of hard spheres. Moving out from the eutectic triangle towards small component results in the crystallization of small spheres. Enrichment of the eutectic mixture with large component results in the crystallization of both large and small spheres, however, the kinetics are completely different from those of the eutectic composition. Crosslinked polystyrene microgels with nearly hard sphere interactions were used as model systems. Attraction was introduced by addition of linear polystyrene. The time evolution of crystallization has been followed by static light scattering.

Nanostructured titania reservoirs were synthesized by the sol-gel method. An antiepileptic drug phenytoin was encapsulated for the targeted drug delivery. NMR studies confirmed that the drug does not undergo substantial modifications during the sol-gel process. The water/alkoxide ratio r w was varied from 2 to 24 to evaluate the role of hydrolysis degree on the drug-matrix interactions. The interactions were found to be of hydrogen-type between amine and carbonyl groups of phenytoin and hydroxyl groups of titania. Tridental complex was found to be the most favorable out of three complexes proposed. To form this complex for each phenytoin molecule, two hydroxyl groups of titania are needed. It was found that when the water/alkoxide ratio r w ) 16 the hydroxylation degree is the highest, which allows us to bind the largest amount of the drug.

Chromophores susceptible to light-induced trans–cis isomerization embedded in cylindrical micelles can modify micelles and their light-responsive performance. A small chromophore (4-(phenylazo)­benzoate ion) is embedded in cylindrical micelles made of cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal) in water. The microstructure is examined by scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR). Rheological behavior and the length scales of the micellar network are determined by rheology and microrheology. The chromophore substantially modifies the micelles even without UV irradiation. The larger is the chromophore concentration, the smaller is the micellar length. Additional length scales of the micellar network do not substantially vary even when NaCl is added. Chromophore incorporation also modifies the rheology of the micellar solution, although gradient shear banding is preserved. Viscosity decreases as the chromophore concentration increases, and viscoelastic spectra are modified, but when they are correctly rescaled, they can be superimposed. The addition of the chromophore makes the fluids more Maxwellian, particularly when NaCl is also added. When the chromophore is incorporated into the micelles, there is a response after UV irradiation, although it does not produce a significant rheological change.

The sol-gel method was used to synthesize inorganic reservoirs with encapsulated antiepileptic drug phenytoin. The drug release profile was shown to depend on the morphology and surface properties of the matrix. A parameter of the synthesis such as water/alkoxide ratio r(w) was varied in order to investigate its influence on the matrix properties and as a result on the drug release profile. It was found that the specific surface area and crystallization degree decrease with an increase of r(w), whereas the hydroxyl group coverage increases with an increase of r(w). Drug release kinetics studies revealed that the initial release rate increases with an increase of water content in the reaction, whereas the long time release rate first slightly increases with an increase of water content from 4 to 8 and then decreases for r(w) = 16. The interplay of different parameters of the matrix is shown to be responsible for such a dependence and is discussed in the Article.

Metabolic syndrome (MS) results from excessive consumption of high-calorie foods and sedentary lifestyles. Clinically, insulin resistance, abdominal obesity, hyperglycemia, dyslipidemia, and hypertension are observed. MS has been considered a risk factor in the development of dementia. In the brain, a metabolically impaired environment generates oxidative stress and excessive production of pro-inflammatory cytokines that deteriorate the morphology and neuronal function in the hippocampus, leading to cognitive impairment. Therapeutic alternatives suggest that phenolic compounds can be part of the treatment for neuropathies and metabolic diseases. In recent years, the use of Gallic Acid (GA) has demonstrated antioxidant and antiinflammatory effects that contribute to neuroprotection and memory improvement in animal models. However, the effect of GA on hippocampal neurodegeneration and memory impairment under MS conditions is still unclear. In this work, we administered GA (20 mg/kg) for 60 days to rats with MS. The results show that GA treatment improved zoometric and biochemical parameters, as well as the recognition memory, in animals with MS. Additionally, GA administration increased hippocampal dendritic spines and decreased oxidative stress and inflammation. Our results show that GA treatment improves metabolism: reducing the oxidative and inflammatory environment that facilitates the recovery of the neuronal morphology in the hippocampus of rats with MS. Consequently, the recognition of objects by these animals, suggesting that GA could be used therapeutically in metabolic disorders that cause dementia.

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