Biofunctionalization of Porous Ti Substrates Coated with Ag Nanoparticles for Potential Antibacterial Behavior

Ti prosthesis have shown better biological compatibility, mechanical performance, and resistance to corrosion in cases of bone replacements. Nevertheless, fully dense Ti in connection with bone-host tissues show stress-shielding phenomenon that, together with the development of frequent undesirable microbial infections, may lead to implant failures. To overcome these issues, the present study aimed at the development of a novel combination of a chemically functionalized porous Ti substrate with a potentially therapeutic AgNPs coating. Fully dense and porous Ti substrates (30 and 60 vol.%, 100–200 and 355–500 μm, as spacer particles) were studied. Ti surface was treated with acid or basic medium followed by silanization and deposition of AgNPs by “submerged” and “in situ” methods. In general, for similar porosity, mechanical resistance decreased as pore size increased. Acidic reagent and submerged methodology were the best combination for fully dense Ti substrates. Hence, they were also employed for porous Ti substrates. Depending on the porosity of the substrates, variations can be observed both in the size and degree of agglomeration of the deposited AgNPs, entailing differences in the antibacterial behavior of the samples.

NaBH4/NaHSO4·H2O a Heterogeneous Acidic System for a Mild and Convenient Reduction of Carbonyl Compounds under Protic Condition

NaBH4 in the presence of sodium bisulfate (NaHSO4·H2O), a weakly acidic reagent, efficiently reduces a variety of carbonyl compounds such as aldehydes, ketones, α,β -unsaturated aldehydes and ketones, α-diketones and acyloins to their corresponding alcohols in acetonitrile under heterogeneous condition. Reduction reactions were accomplished at room temperature or under reflux condition

Solid-Phase Traceless Synthesis of Selected Nitrogen-Containing Heterocyclic Compounds. The Encore Technique for Directed Sorting of Modular Solid Support

The acid lability of electron-rich N-benzylanilines has been exploited in a linker for the traceless solid-phase synthesis of benzimidazoles, 2-aminobenzimidazoles, quinoxalinones and tetrahydroquinoxalines. The target compound precursors were assembled on a solid-phase support derivatized with either a benzylamine or a benzhydrylamine linker. Exposure to an acidic reagent caused cleavage of the C(benzyl)-N(aniline) bond, releasing the product with only a hydrogen atom on the descending nitrogen. The Encore technique for directed sorting on SynPhase Lanterns has been developed and applied to combinatorial synthesis of generic drug discovery libraries.

Studies with 2-Arylhydrazono-3-oxopropanaIs: A Novel Route to 4-Aroyl-2-aryl-1,2,3-triazoIes, 3-Substituted 4-Arylazopyrazoles, 2-Substituted Glyoxalonitrile and 3-Oxoalkanonitriles

2-Arylhydrazono-3-oxopropanals 1 react with hydroxylamine hydrochloride to yield the corresponding oximes 3 that are cyclized into isoxazoles 9 on reflux in acetic anhydride and are converted into 2-arylhydrazono-3-oxonitriles (4) on treatment with pyridine. The reaction of 1 with hydrazines afforded dihydrazones 10 which were converted to arylazopyrazoles 11 when treated with pyridine, whereas treatment with an acidic reagent resulted in the formation of 3-aroyl-2-phenyl-l,2,3-triazoles 12.