Synergy Effects in Heavy Metal Ion Chelation with Aryl- and Aroyl-Substituted Thiourea Derivatives.

Detection and removal of metal ion contaminants have attracted great interest due to the health risks that they represent for humans and wildlife. Among the proposed compounds developed for these purposes, thiourea derivatives have been shown as quite efficient chelating agents of metal cations and have been proposed for heavy metal ion removal and for components of high-selectivity sensors. Understanding the nature of metal-ionophore activity for these compounds is thus of high relevance. We present a theoretical study on the interaction between substituted thioureas and metal cations, namely, Cd2+, Hg2+, and Pb2+. Two substituent groups have been chosen: 2-furoyl and m-trifluoromethylphenyl. Combining density functional theory simulations with wave function analysis techniques, we study the nature of the metal-thiourea interaction and characterize the bonding properties. Here, it is shown how the N,N'-disubstituted derivative has a strong affinity for Hg2+, through cation-hydrogen interactions, due to its greater oxidizing capacity.

One-minute and green synthesis of magnetic iron oxide nanoparticles assisted by design of experiments and high energy ultrasound: Application to biosensing and immunoprecipitation.

The present study is focused on the ultrafast and green synthesis, via the co-precipitation method, of magnetic nanoparticles (MNPs) based on iron oxides using design of experiments (DOE) and high energy sonochemical approach, considering two main factors: amplitude (energy) of the ultrasound probe and sonication time. The combination of these techniques allowed the development of a novel one-minute green synthesis, which drastically reduced the amount of consumed energy, solvents, reagents, time and produced residues. This green sonochemical synthesis permitted to obtain mean particle sizes of 11 ± 2 nm under the optimized conditions of amplitude = 40% (2826 J) and time = 1 min. Their composition, structure, size, morphology and magnetic properties were assessed through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning and transmission electron microscopy (SEM & TEM), and vibrating sample magnetometry (VSM). The characterization results indicate the proper formation of MNPs, and the correct functionalization of MNPs with different coating agents. The functionalized MNPs were used as: i) biosensor, which could detect mercury in water in the range of 0.030-0.060 ppm, and ii) support onto which polyclonal antibodies were anchored and successfully bound to an osteosarcoma cell line expressing the target protein (TRIB2-GFP), as part of an immunoprecipitation assay.

The intrinsic antimicrobial activity of citric acid-coated manganese ferrite nanoparticles is enhanced after conjugation with the antifungal peptide Cm-p5.

Diseases caused by bacterial and fungal pathogens are among the major health problems in the world. Newer antimicrobial therapies based on novel molecules urgently need to be developed, and this includes the antimicrobial peptides. In spite of the potential of antimicrobial peptides, very few of them were able to be successfully developed into therapeutics. The major problems they present are molecule stability, toxicity in host cells, and production costs. A novel strategy to overcome these obstacles is conjugation to nanomaterial preparations. The antimicrobial activity of different types of nanoparticles has been previously demonstrated. Specifically, magnetic nanoparticles have been widely studied in biomedicine due to their physicochemical properties. The citric acid-modified manganese ferrite nanoparticles used in this study were characterized by high-resolution transmission electron microscopy, which confirmed the formation of nanocrystals of approximately 5 nm diameter. These nanoparticles were able to inhibit Candida albicans growth in vitro. The minimal inhibitory concentration was 250 µg/mL. However, the nanoparticles were not capable of inhibiting Gram-negative bacteria (Escherichia coli) or Gram-positive bacteria (Staphylococcus aureus). Finally, an antifungal peptide (Cm-p5) from the sea animal Cenchritis muricatus (Gastropoda: Littorinidae) was conjugated to the modified manganese ferrite nanoparticles. The antifungal activity of the conjugated nanoparticles was higher than their bulk counterparts, showing a minimal inhibitory concentration of 100 µg/mL. This conjugate proved to be nontoxic to a macrophage cell line at concentrations that showed antimicrobial activity.

1-Furoylthiourea-Sonogel-Carbon electrodes: structural and electrochemical characterization.

A new type of sensor based on Sonogel-Carbon materials modified with 1-(2-furoyl)-3-(1-naphthyl)thiourea is presented to be used as an amperometric sensor for metals. Different percentages of modifier were tested in order to optimise the structural and mechanical properties, as well as the electrochemical behaviour. Scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), Fourier transform-infrared spectroscopy (FTIR), single crystal X-ray diffraction (XRD) and powder XRD were used for the structural characterization of these electrodes. The 1-(2-furoyl)-3-(1-naphthyl)thiourea did not modify significantly the structural and mechanical properties of the Sonogel-Carbon electrodes, being similar to other modifications carried out previously in these materials. For the study of the electrochemical response, anodic stripping differential pulse voltammetry (ASDPV) was employed, optimising other parameters of measurement such as pH of the buffer, potential and accumulation time and pulse amplitude. The electrochemical response of the modified electrodes improved significantly with respect to the non-modified electrode, giving good signals and acceptable detection limit.

1-Furoyl-3-methyl-3-phenyl-thio-urea.

The title compound, C(13)H(12)N(2)O(2)S, crystallizes with two independent mol-ecules in the asymmetric unit. The two mol-ecules differ in the conformation of the thio-carbonyl and carbonyl groups, and show the typical geometric parameters of substituted thio-urea derivatives. The crystal structure is mainly stabilized by inter-molecular N-H⋯O hydrogen bonding.

1-(o-Tol-yl)thio-urea.

In the title compound, C(8)H(10)N(2)S, the o-tolyl group and the thio-urea core are planar. The mean planes of the two groups are almost perpendicular [82.19 (8)°]. The thio-urea group is in the thio-amide form, in which resonance is present. In the crystal structure, mol-ecules are linked by inter-molecular N-H⋯S hydrogen bonds, forming two infinite chains parallel to the (110) and (10) planes.

1-Benzyl-3-(2-furo-yl)thio-urea.

In the title compound, C(13)H(12)N(2)O(2)S, the dihedral angle between the two aromatic ring planes is 87.52 (12)°. The mol-ecule shows an intra-molecular N-H⋯O hydrogen bond. The crystal structure is stabilized by inter-molecular N-H⋯S and C-H⋯O hydrogen bonding.

1-(2-Furo-yl)-3-(1-naphth-yl)thio-urea.

In the title compound, C(16)H(12)N(2)O(2)S, the carbonyl-thio-urea group forms dihedral angles of 75.4 (1) and 13.1 (2)°, respectively, with the naphthalene ring system and furan ring. The mol-ecule adopts a trans-cis configuration with respect to the positions of the furoyl and naphthyl groups relative to the S atom across the thio-urea C-N bonds. This geometry is stabilized by an N-H⋯·O intra-molecular hydrogen bond. In the crystal structure, mol-ecules are linked by N-H⋯S hydrogen bonds, forming centrosymmetric dimers which are inter-linked through C-H⋯π inter-actions.

1-(3-Cyano-phen-yl)-3-(2-furo-yl)thio-urea.

The title compound, C(13)H(9)N(3)O(2)S, was synthesized from furoyl isothio-cyanate and 3-amino-benzonitrile in dry acetone. The thio-urea group is in the thio-amide form. The thio-urea fragment makes dihedral angles of 3.91 (16) and 37.83 (12)° with the ketofuran group and the benzene ring, respectively. The mol-ecular geometry is stabilized by N-H⋯O hydrogen bonds. In the crystal structure, centrosymmetrically related mol-ecules are linked by two inter-molecular N-H⋯S hydrogen bonds to form dimers.