Inhibition of biofilm, quorum-sensing, and swarming motility in pathogenic bacteria by magnetite, manganese ferrite, and nickel ferrite nanoparticles.

Resistance to antibiotics by pathogenic bacteria constitutes a health burden and nanoparticles (NPs) are being developed as alternative and multipurpose antimicrobial substances. Magnetite (Fe3O4 np), manganese ferrite (MnFe2O4 np) and nickel ferrite (NiFe3O4 np) NPs were synthesized and characterized using thermogravimetric analysis, transmission electron microscopy, Fourier transformed infra-red, and X-ray diffraction. The minimal inhibitory concentrations (MIC) ranged from 0.625 to 10 mg/mL against gram-positive (Staphylococcus aureus ATCC 25923 and Enterococcus faecalis ATCC 29212), gram-negative (Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853) and candida (Candida albicans ATCC 10239 and Candida tropicalis ATCC 13803) species. The NPs exhibited violacein inhibition against Chromobacterium violaceum CV12472 of 100% at MIC and reduced to 27.2% ± 0.8% for magnetite NPs, 12.7% ± 0.3% for manganese ferrite NPs and 43.1% ± 0.2% for nickel ferrite NPs at MIC/4. Quorum-sensing (QS) inhibition zones against C. violaceum CV026 were 12.5 ±0.6 mm for Fe3O4 np, 09.1 ± 0.5 mm for MnFe3O4 NP and 17.0 ± 1.2 mm for NiFe3O4 np. The NPs inhibited swarming motility against P. aeruginosa PA01 and biofilm against six pathogens and the gram-positive biofilms were more susceptible than the gram-negative ones. The NiFe2O4 np had highest antibiofilm activity against gram-positive and gram-negative bacteria as well as highest QS inhibition while Fe3O4 NP had highest biofilm inhibition against candida species. The synthesized magnetic NPs can be used in developing anti-virulence drugs which reduce pathogenicity of bacteria as well as resistance.

Developing of N-(4-methylpyrimidine-2-yl)methacrylamide Langmuir-Blodgett thin film chemical sensor via quartz crystal microbalance technique.

In the present work, the characterization and gas sensing properties of newly synthesized N-(4-methylpyrimidine-2-yl)methacrylamide (N-MPMA) monomer Langmuir-Blodgett (LB) thin films were investigated. The UV-visible spectroscopy, quartz crystal microbalance (QCM), and atomic force microscopy were utilized to characterize N-MPMA LB thin films. The surface behavior of N-MPMA monolayer was stable and allowed an effective transfer at a surface pressure of 14 mN/m. The mass change/unit area value of the N-MPMA LB thin film deposited quartz crystal surfaces was investigated. The amount of N-MPMA LB thin film deposited on the substrate for bilayer was calculated as 228.72 ng (86.31 ng/mm2 ) and 12.5 Hz frequency shift was observed for each layer of the N-MPMA film. The kinetic responses of N-MPMA LB film against chloroform, dichloromethane, benzene, and toluene were measured via QCM system at room temperature. N-MPMA QCM sensor results displayed that chloroform has the largest frequency shifts compared with the other vapors used in the present work and these results can be illuminating in terms of physical properties of organic vapors.

Recent applications of chiral calixarenes in asymmetric catalysis.

The use of calixarenes in asymmetric catalysis is receiving increasing attention due to their tunable three-dimensional molecular platforms along with their easy syntheses and versatile modification at the upper and lower rims. This review summarizes the recent progress of synthesis and use of chiral calixarenes in asymmetric syntheses which emerged later than 2010.

Enantioselective recognition of carboxylic acids by novel fluorescent triazine-based thiazoles.

Hydrogen bonding and π-π interactions take special part in the enantioselectivity task. In this regard, because of having both hydrogen acceptor and hydrogen donor groups, melamine derivatives become more of an issue for enantioselectivity. In the light of such information, triazine-based chiral, fluorescence active novel thiazole derivatives L1 and L2 were designed and synthesized from (S)-(-)-2-amino-1-butanol and (1S,2R)-(+)-2-amino-1,2-diphenylethanol. The structural establishment of these compounds was made by spectroscopic methods such as FTIR, 1 H, and 13 C NMR. While the solution of these compounds in DMSO did not show any fluorescence emission, it was observed that the emission increased 44-fold for L1 and 55-fold for L2 in 95% water, similar to the aggregation-induced emission (AIE) characterized compounds. In this regard, enantioselective capabilities of these compounds against carboxylic acids were tested, and in experiments carried out at a ratio of 40/60 DMSO/H2 O, it was determined that R-2ClMA increased the fluorescence emission of L1 chiral receptor by 2.59 times compared to S-isomer.

Chiral calix[4]arenes bearing amino alcohol functionality as membrane carriers for transport of chiral amino acid methylesters and mandelic acid.

Novel chiral calix[4]arene derivatives bearing amino alcohol moieties at the lower rim have been synthesized from the reaction of p-tert-butylcalix[4]arene diester with various amino alcohols. The transport of amino acid esters (phenylglycine, phenylalanine, and tryptophan methyl esters hydrochloride) and mandelic acid were studied through chloroform bulk liquid membrane system using chiral calix[4]arenes 15-20. All these receptors have been found to act as carriers for transport of aromatic amino acid methylesters and mandelic acid from the aqueous source phase to the aqueous receiving phase. The influence of calixarene and guest structures upon transport through liquid membrane is discussed.

Application of L-proline derivatives as chiral shift reagents for enantiomeric recognition of carboxylic acids.

Four proline-derived chiral receptors 5-8 were readily synthesized starting from L-proline. The enantiomeric recognition ability of chiral receptors was examined with a series of carboxylic acids by (1) H NMR spectroscopy. The molar ratio and the association constants of the chiral compounds with each of the enantiomers of guest molecules were determined by using Job plots and a nonlinear least-squares fitting method, respectively. The Job plots indicate that the hosts form 1:1 instantaneous complexes with all guests. The receptors exhibited different chiral recognition abilities toward the enantiomers of racemic guests. Among the chiral receptors used in this study, prolinamide 6 was found to be the best chiral shift reagent and is effective for the determination of the enantiomeric excess of chiral carboxylic acids.

Synthesis and dichromate anion sorption of silica gel-immobilized calix[4]arenes.

Three new silica gel-immobilized calix[4]arene polymers 9-11 have been prepared via modification of calix[4]arene mono amido derivatives 3-5 with 3-aminopropyl triethoxysilane (APTES) and activated silica gel, respectively. The polymers were characterized by Fourier transform infrared spectroscopy, elemental analysis and thermal gravimetric analysis. The solid-liquid extraction properties of ligands 3-5 along with their immobilized derivatives 9-11 towards dichromate (HCr(2)O(7)(-)/Cr(2)O(7)(2-)) anions were reported. It was found that these calix[4]arene-based polymers have high extraction abilities towards dichromate anions as compared to their monomeric precursors.