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A mesoporous silica nanoparticle-based intracellular cysteine delivery system that could be induced and regulated by cell-produced natural antioxidants was synthesized.

Microcalorimetry and vibrational spectroscopy have jointly been used to study the interaction at room temperature between CO2 and Na-ZSM-5. This interaction consists of a reversible, two-step adsorption on sites approximately all equal and noninteracting, which constitute an ideal ensemble in the thermodynamic sense. From the volumetric and calorimetric adsorption isotherms, standard changes in enthalpy and Gibbs free energy due to adsorption were calculated for both the 1:1 and 2:1 adducts formed by CO2 and Na + ions, and from these data, the standard changes in entropy were determined. All vibrational modes of adsorbed CO2 have been measured, including the usually elusive intermolecular ones, thus allowing the entropy of the adsorbed phase to be calculated by means of statistical mechanics. The vibrational modes of the carbon dioxide molecule are only slightly perturbed from the corresponding values for the gas phase. The most prominent ν3 mode is at 2356 cm -1 in the 1:1 adduct and at 2352 cm -1 in the 2:1 adduct, as compared to 2349 cm -1 in the gas phase. The ν1 and ν2 modes are at 1382 and 656 cm -1 for both adducts (1388 and 667 cm -1 , respectively, in the gas phase). Comparison between volumetric and optical adsorption isotherms has allowed the estimate of the related molar adsorption coefficients for all vibrational modes of the two adducts, with the exception of the corresponding value for the ν3 mode in the 2:1 adduct, because the related band is exceedingly intense.

The effects of Stöber silica nanoparticles on neuronal survival, proliferation, and on the underlying perturbations in calcium homeostasis are investigated on the well-differentiated neuronal cell line GT1-7. The responses to nanoparticles 50 and 200 nm in diameter are compared. The 50-nm silica affects neuronal survival/proliferation in a dose-dependent way, by stimulating apoptotic processes. In contrast, the 200-nm silica does not show any toxic effect even at relatively high concentrations (292 μg mL−1). To identify the mechanisms underlying these effects, the changes in intracellular calcium concentration elicited by acute and chronic administration of the two silica nanoparticles are analyzed. The 50-nm silica at toxic concentrations generates huge and long-lasting increases in intracellular calcium, whereas the 200-nm silica only induces transient signals of much lower amplitude. These findings provide the first evidence that silica nanoparticles can induce toxic effects on neuronal cells in a size-dependent way, and that these effects are related to the degree of perturbation of calcium homeostasis.

Purpose:To evaluate the ability of heparin coating to inhibit Double J stent encrustation and compare it with the classic polyurethane Double J stent.Patients and Methods: The study involved five patients with bilateral obstructions, who required bilateral ureteral Double J stent placement. Every patient received a heparin-coated Double J stent and a traditional polyurethane Double J stent for 1 month. After removal, the stents were analyzed using field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS). and micro-infrared spectrophotometry (Micro-IR). These same techniques were used to analyze the heparin-coated and uncoated stents before insertion. The thickness, extension, and composition of encrustation of the coated and uncoated stents were compared. Moreover, two heparin-coated stents were analyzed with the same techniques after they had been in place for 10 and 12 months.Results: FESEM analysis showed that the difference in encrustation thickness and extension between the two groups was significant. EDS and Micro-IR confirmed that in the heparinized stents the encrustations were not as uniform and compact as those in the uncoated stents. The stents that were left in place long-term were free of encrustations and had no changes in the heparin layer.Conclusions: Heparin coating reduces stent encrustation. Moreover, as no changes were seen in the heparin layer, we concluded that covalent heparin bonding enhances its adhesion to the polyurethane surface and ensures its stability for long periods. The heparin-coated stent appears to be a useful tool for long-term urinary drainage.

When a molecule, engaged in H-bonding with an acidic proton in zeolites, is large enough to interact with the surrounding walls, the IR spectroscopic measure of the acidity is affected, but information may be gained on the geometry of the site. Examples concerning MCM-22, ZSM-5, SAPO-40, and Theta-1 are discussed.

Two samples of SBA-15 mesoporous silica with a different content of carboxylic groups (-COOH) were prepared by a co-condensation route, using 4-(triethoxysilil)butyronitrile as the organosilane agent, then treating the samples with sulfuric acid, which removes the template and simultaneously hydrolyses the -CN to -COOH groups, as shown by IR spectroscopy. Both incorporation of organosilane agents and subsequent acid treatment do not affect the ordered SBA-15 structure. The proton-donor ability of carboxylic groups, as well their accessibility to reactants, has been studied in the IR by dosing ammonia, which forms reversibly COO- groups and NH4+ ions. The related equilibrium constants have been determined by elaboration of IR data. Outgassing the samples at progressively increasing temperatures destabilizes to an increasing extent the ammonium/carboxylate ion pair, because of the decrease in surface polarity brought about by dehydration: this decreases the related equilibrium constants. The amount of carboxylic groups undergoing reaction appears instead to be constant with dehydration, and to coincide with the whole population of COOH groups. Titration with alkali solutions yielded surface concentrations for the two samples of ca. 1.0 and 0.45 COOH/nm2. Proportionality between the surface concentrations and the intensities of the C=O IR band is observed: this suggests that COOH groups are noninteracting with each other and allows the computation of the related extinction molar coefficient.