Controlling the release of the drugs Propranolol and Persantin from sol-gel materials by molecular interactions and particle engineering

Two drug molecules, Propranolol and Persantin, have been encapsulated by a sol gel process in an organic-inorganic hybrid matrix by in-situ self-assembly. The synthesis parameter, compositions and pH values in the sol-gel synthesis controls the dissolution of the drugs, and pore size and distribution of the gels. The main difference between an ordinary physical encapsulation and a structure directing role of the guest molecule on the matrix genesis critically depends on the strengths, selectivities and cooperativities of non-covalent host-guest interactions. The local molecular interaction between the drug and the host matrix has been investigated by employing two-dimensional heteronuclear correlation NMR spectroscopy. The results from the NMR studies provide deeper insights into the molecular level interactions between the host and the guest which will help us to design better materials for controlled drug release

Embedding monomers and dimers of sulfonamide antibiotics into high silica zeolite Y: an experimental and computational study of the tautomeric forms involved

This work is a second step towards the systematic study of the embedding of sulfonamide antibiotics into a synthetic high silica zeolite Y (HSZ-Y) with hydrophobic properties. In the previous paper [Braschi et al., Langmuir 2010, 31, 9524], the irreversible adsorption from water into HSZ-Y of three sulfonamides was studied by enlightening the host-guest interactions and, in the case of the smallest sized sulfadiazine, the guest-guest interactions of dimeric species inside the zeolite cage. Here the HSZ-Y was loaded with six sulfonamides, namely: sulfanilamide, sulfapyridine, sulfathiazole, sulfadimethoxine, sulfadoxine and sulfamerazine. With the exception of sulfanilamide, which showed scarce affinity for HSZ-Y (maximum loading 3% zeolite dry weight), the other sulfa drugs adsorbed at ca. 28% zeolite dry weight on average, and this is relevant for both water depollution and drug delivery issues. The low affinity of sulfanilamide for HSZ-Y was ascribed to its high hydrophilicity (water solubility 15-40 times higher than other drugs). The most stable tautomeric (amide or imide) form of each antibiotic adsorbed in zeolite Y was proposed by means of IR and solid state NMR spectroscopy augmented by computational modelling. The small dimensions and favourable stabilization energy allow the embedding of imidic and amidic dimers of sulfathiazole and sulfapyridine, respectively, inside the zeolite cage whereas the remaining sulfa drugs adsorbed in monomeric amidic form

The Loveland and Peorian Loesses of Iowa

Two Pleistocene eolian deposits, the Loveland loess and the Peorian loess, have wide distribution in Iowa. The Loveland loess, the older, was deposited, wholly or in large part, in an interglacial age - in late Sangamon time; the Peorian loess, the younger, was deposited in a glacial age - in the Iowan phase of the Wisconsin Age

Fingerprinting the Hydration Products of Hydraulic Binders Using Snapshots from Time-Resolved In Situ Multinuclear MAS NMR Spectroscopy

The very early hydration behavior of a hydraulic binder phase, ye'elimite, Ca4Al6O12SO4, in the absence and in the presence of calcium sulfate, has been investigated. A time-resolved in situ multin..

Hyper Cross-Linked Polymers as Additives for Preventing Aging of PIM-1 Membranes

Mixed-matrix membranes (MMMs) are membranes that are composed of polymers embedded with inorganic particles. By combining the polymers with the inorganic fillers, improvements can be made to the permeability compared to the pure polymer membranes due to new pathways for gas transport. However, the fillers, such as hyper cross-linked polymers (HCP), can also help to reduce the physical aging of the MMMs composed of a glassy polymer matrix. Here we report the synthesis of two novel HCP fillers, based on the Friedel\u2013Crafts reaction between a tetraphenyl methane monomer and a bromomethyl benzene monomer. According to the temperature and the solvent used during the reaction (dichloromethane (DCM) or dichloroethane (DCE)), two different particle sizes have been obtained, 498 nm with DCM and 120 nm with DCE. The change in the reaction process also induces a change in the surface area and pore volumes. Several MMMs have been developed with PIM-1 as matrix and HCPs as fillers at 3% and 10wt % loading. Their permeation performances have been studied over the course of two years in order to explore physical aging effects over time. Without filler, PIM-1 exhibits the classical aging behavior of polymers of intrinsic microporosity, namely, a progressive decline in gas permeation, up to 90% for CO2 permeability. On the contrary, with HCPs, the physical aging at longer terms in PIM-1 is moderated with a decrease of 60% for CO2 permeability.13C spin-lattice relaxation times (T1) indicates that this slowdown is related to the interactions between HCPs and PIM-1

Synthetic Saponite Clays as Additives for Reducing Aging Effects in PIM1 Membranes

Polymers of intrinsic microporosity represent one of the most promising polymeric materials for gas separation applications. Their very rigid and contorted backbone induces unusually high free volumes and high internal surface area, with high gas permeabilities and moderate ideal selectivity, especially for O2/ N2 and CO2/N2 pairs with values lying above Robeson's upper bound. However, the high FFV of PIM1 tends to be short-lived, soon collapsing to leave fewer transport pathways and reduce gas permeability. One way to tackle this problem is the addition of fillers within the polymeric matrix. Here we report the use of synthetic clays named saponites as fillers to slow down the physical aging of PIM1 membranes. Mixed matrix membranes (MMMs) based on two different saponite samples (one completely inorganic and one functionalized with a surfactant) have been obtained, and their permeation performances have been studied in the course of one year to explore physical aging effects over time. Without filler, PIM1 exhibits the classical aging behavior of polymers of intrinsic microporosity, namely, a progressive decline in gas permeation. On the contrary, with saponites, MMMs present a plateau after 1 week within the aging showing that the fillers slow down the aging of PIM1 membranes in the long term. After one year of aging, the total reduction for CO2 permeability for native PIM1 was 80%, whereas for the MMMs it was 53% and 59% for the inorganic and the functionalized saponite, respectively. Interactions between the fillers and the polymeric matrix in addition to aging effects have been also monitored through SS-NMR spectroscopy. The 13C spin 12lattice relaxation time (T1) measurements reveal that PIM1 chains intercalation between T 12O 12T lamellar sheets could be one of the mechanisms responsible for PIM1 slowing down aging. Chains confinement between lamellar sheets could play a significant role in reducing the densification of chains, while maintaining small free volumes

Influence of silicodactyly in the preparation of hybrid materials

The organic⁻inorganic hybrid materials have attracted great attention due to their improved or unusual properties that open promising applications in different areas such as optics, electronics, energy, environment, biology, medicine and heterogeneous catalysis. Different types of silicodactyl platforms grafted on silica inorganic supports can be used to synthesize hybrid materials. A careful evaluation of the dactyly of the organic precursors, normally alkoxysilanes, and of the type of interaction with the inorganic supports is presented. In fact, depending on the hydrophilicity of the silica surface (e.g., number and density of surface silanols) as well as on the grafting conditions, the hydrolysis and condensation reaction of the silylated moieties can involve only one or two out of three alkoxysilane groups. The influence of silicodactyly in the preparation of organic-inorganic silica-based hybrids is studied by TGA, 29Si, 1H and 13C solid-state NMR and FTIR spectroscopies, with the support of Molecular Dynamics calculations. Computational studies are used to forecast the influence of the different grafting configurations on the tendency of the silane to stick on the inorganic surface

Properties of a mixed-valent iron compound with the kagomélattice

An organically templated iron sulfate of the formula [HN(CH2)6NH][FeIIIFe2IIF6(SO4)2]·[H3O] possessing the kagomé lattice has been prepared and characterized by single-crystal crystallography and other techniques. This mixed-valent iron compound shows complex magnetic properties including spin-glass behavior and magnetic hysteresis. The low-temperature specific heat data show deviation from the T2 behavior found in two-dimensional frustrated systems. Simple calculations have been carried out to understand the properties of this kagomé compound