Monitoring of oil-based polyurethane synthesis by FTIR-ATR

Oil-based polyurethanes were synthesized from triglyceride oil-based hydroxyl containing material and toluene diisocyanate or hexamethylene diisocyanate for wound dressing applications. The reactions were carried out with or without catalyst at 90 °C. The amount of free isocyanate during the reaction was determined by a FTIR-ATR method, and the results were compared with those from a back-titration method. The data obtained were used for determination of kinetic parameters.     

Fused heterocycles: synthesis of some new imidazo[1,2-a]- pyridine derivatives

Some new thiazolidines and spirothiazolidines derived from hydrazones of 2-methylimidazo[1,2-a]pyridine-3-carboxylic acid hydrazide, a bioisosteric derivative of isoniazid, were synthesized and characterized by analytical, IR, (1)H- and (13)C-NMR and mass spectral data. Some of the newly synthesized compounds were screened for their antimycobacterial activities. None of the tested compounds showed significant in vitro antituberculous activity at 6.25 mirog/mL (MIC rifampin 0.031 microg/mL).     

Production of Magnetic Nano‐bioconjugates via Ball Milling of Commercial Boron Powder with Biomolecules

Mechanochemical preparation and characterization of surface‐functionalized magnetic boron nanoparticles for biomedical applications are presented. Alloying with the stainless steel ball milling material during mechanochemical activation proved to be an alternative route to introduce magnetic properties to the nanomaterials, while functionalization with biomolecules provided biocompatible surfaces for bioconjugation.     

Calcification resistance of polyisobutylene and polyisobutylene‐based materials

Calcification of implanted biomaterials is highly undesirable and limits clinical applicability. Experiments were carried out to assess the calcification resistance of polyisobutylene (PIB), PIB‐based polyurethane (PIB‐PU), PIB‐PU reinforced with (CH₃)₃N⁺CH₂CH₂CH₂NH₂ I^?‐modified montmorillonite (PIB‐PU/nc), PIB‐based polyurethane urea (PIB‐PUU), PIB‐PU containing S atoms (PIB_S‐PU), PIB_S‐PU reinforced with (CH₃)₃N⁺CH₂CH₂CH₂NH₂ I^?‐modified montmorillonite (PIB_S‐PU/nc), and poly(isobutylene‐b‐styrene‐b‐isobutylene) (SIBS), relative to that of a clinically widely implanted polydimethylsiloxane (PDMS)–based PU, Elast‐Eon (the “control”). Samples were incubated in simulated body fluid for 28 days at 37°C, and the extent of surface calcification was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy‐dispersive X‐ray spectroscopy (EDX), X‐ray photoelectron spectroscopy (XPS), and Fourier‐transform‐infrared (FT‐IR) spectroscopy. Whereas the PDMS‐based PU showed extensive calcification, PIB and PIB‐PU containing 72.5% PIB, ie, a polyurethane whose surface is covered with PIB, were free of calcification. PIB_S‐PU and PIB‐PUU, ie, polyurethanes that contain S or urea groups, respectively, were slightly calcified. The amine‐modified montmorillonite‐reinforcing agent reduced the extent of calcification. SIBS was found slightly calcified. Evidently, PIB and materials fully coated with PIB are calcification resistant.     

Studies on the interaction of iron(III) with tetraaza macrocycles

Tetraaza macrocycles and their Fe³⁺ complexes have been prepared and characterized by elemental analysis, i.r., n.m.r., and e.s.–m.s. spectroscopic techniques. The solution behaviour of the macrocycles and their complexes was studied by potentiometric titrations.