Synthesis, X-ray crystallography and antimicrobial activity of 2-cyanoguanidinophenytoin.

The optimized synthesis of [5-oxo-4,4-diphenylimidazolidin-2-ylidene]cyanamide, which is known as 2-cyanoguanidinophenytoin (CNG-DPH) (3), and (imidazo[4,5-d]imidazole-2,5-diylidine)dicyanamide (4) has been reported in the present work. Furthermore, new Mannich bases derived from CNG-DPH were synthesized via its reaction with formaldehyde and using the corresponding amines, piperidine (base 5), and morpholine (base 6). Also, the antimicrobial activity and X-ray crystal structures for CNG-DPH and their Mannich bases were studied. The bases 3 and 6 crystallized in a monoclinic system; the crystal structure of 3 containing four molecules in the unit cell with a P21/c space group. The unit cell of 6 has eight molecules with a C2/c space group. The inter and intra hydrogen bond contacts packed and stabilized both of the structures. The morpholine ring of base 6 demonstrated a distinctive chair configuration. Mannich bases 5 and 6 showed promising antimicrobial effects. base 4 has a greater percentage for in vitro cytotoxicity (IC50) against normal cells, whereas 3 has the lowest ratio.

Molecular and biological activities of metal oxide-modified bioactive glass.

Bioactive glass (BG) was prepared by sol-gel method following the composition 60-([Formula: see text]) SiO2.34CaO.6P2O5, where x = 10 (FeO, CuO, ZnO or GeO). Samples were then studied with FTIR. Biological activities of the studied samples were processed with antibacterial test. Model molecules for different glass compositions were built and calculated with density functional theory at B3LYP/6-31 g(d) level. Some important parameters such as total dipole moment (TDM), HOMO/LUMO band gap energy (ΔE), and molecular electrostatic potential beside infrared spectra were calculated. Modeling data indicated that P4O10 vibrational characteristics are enhanced by the addition of SiO2.CaO due to electron rush resonating along whole crystal. FTIR results confirmed that the addition of ZnO to P4O10.SiO2.CaO significantly impacted the vibrational characteristics, unlike the other alternatives CuO, FeO and GeO that caused a smaller change in spectral indexing. The obtained values of TDM and ΔE indicated that P4O10.SiO2.CaO doped with ZnO is the most reactive composition. All the prepared BG composites showed antibacterial activity against three different pathogenic bacterial strains, with ZnO-doped BG demonstrating the highest antibacterial activity, confirming the molecular modeling calculations.

Effect of germanium oxide on the structural aspects and bioactivity of bioactive silicate glass.

Ternary silicate glass (69SiO2-27CaO-4P2O5) was synthesized with the sol-gel route, and different percentages of germanium oxide GeO2 (6.25, 12.5, and 25%) and polyacrylic acid (PAA) were added. DFT calculations were performed at the B3LYP/LanL2DZ level of theory for molecular modelling. X-ray powder diffraction (XRPD) was used to study the effect of GeO2/PAA on the structural properties. The samples were further characterized using DSC, ART-FTIR, and mechanical tests. Bioactivity and antibacterial tests were assessed to trace the influence of GeO2 on biocompatibility with biological systems. Modelling results demonstrate that molecular electrostatic potential (MESP) indicated an enhancement of the electronegativity of the studied models. While both the total dipole moment and HOMO/LUMO energy reflect the increased reactivity of the P4O10 molecule. XRPD results confirmed the samples formation and revealed the correlation between the crystallinity and the properties, showing that crystalline hydroxyapatite (HA) is clearly formed in the highest percentages of GeO2, proposing 25% as a strong candidate for medical applications, consistent with the results of mechanical properties and the rest of the characterization results. Simulated body fluid (SBF) in vitro experiments showed promising biocompatibility. The samples showed remarkable antimicrobial and bioactivity, with the strongest effect at 25%. The experimental findings of this study revealed that the incorporation of GeO2 into the glass in terms of structural characteristics, bioactivity, antimicrobial properties, and mechanical properties is advantageous for biomedical fields and especially for dental applications.

New and efficient NiO/chitosan/polyvinyl alcohol nanocomposites as antibacterial and dye adsorptive films.

The development of composite films with enhanced antibacterial and dye decolorization properties for water treatment has attracted a great attention. In this study, nickel oxide/chitosan/polyvinyl alcohol nanocomposite films containing different weight percentage of NiO nanoparticles with a dual functionality, removal of toxic dye and antibacterial properties, were prepared. Methyl orange (MO) was selected as a target pollutant. Additionally, the antimicrobial activity of the films against two Gram positive bacteria (Staphylococcus aureus and Bacillus cereus) and two Gram negative bacteria (Escherichia coli and Salmonella Typhimurium) was studied. The prepared samples were characterized by XRD, HRTEM, FESEM, ATR-FTIR, UV-Vis spectroscopy, and dielectric measurements. The morphological examination proved that the nanocomposite film has more porous structure compared to the unmodified chitosan/PVA. The antimicrobial tests indicated that the modified chitosan/PVA films have higher activity than pure chitosan/PVA toward all the tested pathogenic bacteria. The impact of the NiO amount (0.5, 1.5, 3, and 5 wt%), contact time (0-150 min), and adsorbent dose (40, 80, and 100 mg) on the removal of MO was studied. Dye adsorption results proved that the incorporation of 5 wt% NiO led to more than 2 fold increase in the dye removal percentage in comparison with the unmodified PVA/chitosan film.