Water-soluble peptide-coated nanoparticles: control of the helix structure and enhanced differential binding to immune cells

The stabilizing action of C(α)-tetrasubstituted α-amino acids inserted into a sequence of short peptides allowed for the first time the preparation of water-soluble nanoparticles of different materials coated with a helix-structured undecapeptide. This peptide coating strongly favors nanoparticle uptake by human immune system cells.     

Biological Pretreatment of Chicken Feather and Biogas Production from Total Broth

Chicken feathers are available in large quantities around the world causing environmental challenges. The feathers are composed of keratin that is a recalcitrant protein and is hard to degrade. In this work, chicken feathers were aerobically pretreated for 2–8 days at total solid concentrations of 5, 10, and 20 % by Bacillus sp. C₄, a bacterium that produces both α- and β-keratinases. Then, the liquid fraction (feather hydrolysate) as well as the total broth (liquid and solid fraction of pretreated feathers) was used as substrates for biogas production using anaerobic sludge or bacteria granules as inoculum. The biological pretreatment of feather waste was productive; about 75 % of feather was converted to soluble crude protein after 8 days of degradation at initial feather concentration of 5 %. Bacteria granules performed better during anaerobic digestion of untreated feathers, resulting in approximately two times more methane yield (i.e., 199 mlCH₄/gVS compared to 105 mlCH₄/gVS when sludge was used). Pretreatment improved methane yield by 292 and 105 % when sludge and granules were used on the hydrolysate. Bacteria granules worked effectively on the total broth, yielded 445 mlCH₄/gVS methane, which is 124 % more than that obtained with the same type of inoculum from untreated feather.     

Molybdenum triamidoamine complexes that contain hexa-tert-butylterphenyl, hexamethylterphenyl, or p-bromohexaisopropylterphenyl substituents. An examination of some catalyst variations for the catalytic reduction of dinitrogen

Three new tetramines, (ArNHCH(2)CH(2))(3)N, have been synthesized in which Ar = 3,5-(2,4,6-t-Bu(3)C(6)H(2))(2)C(6)H(3) (H(3)[HTBTN(3)N]), 3,5-(2,4,6-Me(3)C(6)H(2))(2)C(6)H(3) (H(3)[HMTN(3)N]), or 4-Br-3,5-(2,4,6-i-Pr(3)C(6)H(2))(2)C(6)H(2) (H(3)[pBrHIPTN(3)N]). The diarylated tetramine, [3,5-(2,4,6-t-Bu(3)C(6)H(2))(2)C(6)H(3)NHCH(2)CH(2)](2)NCH(2)CH(2)NH(2), has also been isolated, and the "hybrid" tetramine [3,5-(2,4,6-t-Bu(3)C(6)H(2))(2)C(6)H(3)NHCH(2)CH(2)](2)NCH(2)CH(2)NH(4-t-BuC(6)H(4)) has been prepared from it. Monochloride complexes, [(TerNCH(2)CH(2))(3)N]MoCl, have been prepared, as well as a selection of intermediates that would be expected in a catalytic dinitrogen reduction such as [(TerNCH(2)CH(2))(3)N]Mo[triple bond]N and [[(TerNCH(2)CH(2))(3)N]Mo(NH(3))][BAr'(4)] (Ter = HTBT, HMT, or pBrHIPT and Ar' = 3,5-(CF(3))(2)C(6)H(3))). Intermediates that contain the new terphenyl-substituted ligands are then evaluated for their efficiency for the catalytic reduction of dinitrogen under conditions where analogous [HIPTN(3)N]Mo species give four turnovers to ammonia under "standard" conditions with an efficiency of approximately 65%. Only [pBrHIPTN(3)N]Mo compounds are efficient catalysts for dinitrogen reduction. The reasons are explored and discussed.     

l- and d-Proline Thiosemicarbazone Conjugates: Coordination Behavior in Solution and the Effect of Copper(II) Coordination on Their Antiproliferative Activity

Two enantiomerically pure thiosemicarbazone-proline conjugates with enhanced aqueous solubility, namely, 2-hydroxy-3-methyl-(S)-pyrrolidine-2-carboxylate-5-methylbenzaldehyde thiosemicarbazone [l-Pro-STSC or (S)-H(2)L] and 2-hydroxy-3-methyl-(R)-pyrrolidine-2-carboxylate-5-methylbenzaldehyde thiosemicarbazone [d-Pro-STSC or (R)-H(2)L] have been synthesized and characterized by elemental analysis, spectroscopic methods (UV-vis and (1)H and (13)C NMR), and electrospray ionization mass spectrometry. The metal complexation behavior of l-Pro-STSC, stoichiometry, and thermodynamic stability of iron(II), iron(III), copper(II), and zinc(II) complexes in 30% (w/w) dimethyl sulfoxide/H(2)O solvent mixture have been studied by pH-potentiometric, UV-vis-spectrophotometric, circular dichroism, electron paramagnetic resonance, (1)H NMR spectroscopic, and spectrofluorimetric measurements. By the reaction of CuCl(2)·2H(2)O with (S)-H(2)L and (R)-H(2)L, respectively, the complexes [Cu[(S)-H(2)L]Cl]Cl and [Cu[(R)-H(2)L]Cl]Cl have been prepared and comprehensively characterized. An X-ray diffraction study of [Cu[(R)-H(2)L]Cl]Cl showed the formation of a square-planar copper(II) complex, which builds up stacks with interplanar separation of 3.3 ?. The antiproliferative activity of two chiral ligands and their corresponding copper(II) complexes has been tested in two human cancer cell lines, namely, SW480 (colon carcinoma) and CH1 (ovarian carcinoma). The thiosemicarbazone-proline conjugates l- and d-Pro-STSC show only moderate cytotoxic potency with IC(50) values of 62 and 75 μM, respectively, in CH1 cells and >100 μM in SW480 cells. However, the corresponding copper(II) complexes are 13 and 5 times more potent in CH1 cells, based on a comparison of IC(50) values, and in SW480 cells the increase in the antiproliferative activity is even higher. In both tested cell lines, l-Pro-STSC as well as its copper(II) complex show slightly stronger antiproliferative activity than the compounds with a d-Pro moiety, yielding IC(50) values of 4.6 and 5.5 μM for [Cu(l-Pro-STSC)Cl]Cl in CH1 and SW480 cells, respectively.     

Novel Dithiolene Complexes and Tetrathiafulvalenes

Abstract

Novel dithiolene metal complexes, some of which absorb in the near infrared, and tetrathiafulvalenes, in particular tetraiodotetrathia- fulvalene, have been prepared, and their magnetic properties studied.