Impact of biological factors on binding media identification in art objects: identification of animal glue in the presence of Aspergillus niger

The materials and especially organic materials used for creation of art objects can be utilized by various microorganisms for their growth and facilitate the microbial colonization of the object. An understanding of the chemical alterations in artefacts caused by the presence of microorganisms can be crucial for correct identification of the materials initially used for the artefact creation--nowadays an important step in restoration and/or art-historical investigation of the art object. The present article describes a model experiment in which we investigated the possible chemical alterations in animal glue films used as substrate for growth of the fungus Aspergillus niger. The sterilized animal glue solution was poured into Petri dishes, inoculated with Aspergillus niger, and subsequently incubated at 15 degrees C for 0, 7, 9, 14, and 28 days. After interruption of incubation, the content of the Petri dish was analyzed for amino acid composition by the GC-MS based method. It was found that the growth of Aspergillus niger on animal glue films did not cause significant changes in the amino acid composition of the film and had no impact on animal glue identification.     

Employing (half-)titanocene complexes as initiators for the synthesis of end-functionalized polylactides by coordination polymerization

Seven (half-)titanocene alkoxide complexes, [Cp₂TiCl(OEt)], [Cp₂TiCl(O-2-Bu)], [Cp₂TiCl(OCH₂CF₂CF₂H)], [CpTiCl₂(OEt)], [CpTiCl₂(O-(S)-2-Bu)], [CpTiCl₂(OCH₂CF₃)], and [Cp₂TiCl(OCH₂CF₃)], were synthesized and employed in lactide coordination polymerization. These organotitanium (IV) compounds proved to be very efficient initiators for the ring-opening polymerization of enantiomeric l -lactide and racemic mixture of rac-lactide, leading to end-functionalized polymers. Kinetic studies illustrated that these compounds produce well-defined polymers in a controlled manner. This was further demonstrated by synthesizing poly(l -lactide-b-hexyl isocyanate) diblock copolymer. The effect of the alkoxy end groups on the thermal behavior of the polymers was also studied by thermogravimetric analysis and differential scanning calorimetry. The polymers were characterized using size exclusion chromatography and proton nuclear magnetic resonance spectroscopy. The optical properties of the diblock copolymer were also investigated. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2192–2202     

Poly{dl-lactide-b-[oligo(ethylene glycol) methyl ether (meth)acrylate)]} block copolymers. Synthesis,characterization, micellization behavior in aqueous solutions and encapsulation of model hydrophobic compounds

A series of well-defined poly{dl -lactide-b-[oligo(ethylene glycol) methyl ether (meth)acrylate)]} (PDLLA-b-POEG[M]A) functional amphiphilic diblock copolymers was synthesized by employing a multistep procedure involving: (a) ring-opening polymerization of dl -lactide using n-decanol and stannous octoate as the initiating system, (b) esterification reaction of the PDLLA hydroxyl end groups with 2-bromoisobutyryl bromide, (c) atom transfer radical polymerization of OEG(M)A with the newly created bromoisobutyryl initiating site, and (d) incorporation of biotin or folic acid at the POEGA chain ends using click chemistry. The products were characterized by NMR spectroscopy and SEC analysis. The aggregation behavior of the synthesized block copolymers was investigated by dynamic light scattering at 25°C in aqueous solutions. The hydrophobic model compounds Nile red and pyrene were efficiently incorporated into the copolymer aggregates in aqueous solutions. High partition coefficient values were determined by fluorescence spectroscopy.     

Low‐Fouling Electrosprayed Hemoglobin Nanoparticles with Antioxidant Protection as Promising Oxygen Carriers

Despite all the attempts to create advanced hemoglobin (Hb)‐based oxygen carriers (HBOCs) employing an encapsulation platform, major challenges including attaining a high Hb loading and long circulation times still need to be overcome. Herein, the fabrication, for the first time, of nanoparticles fully made of Hb (Hb‐NPs) employing the electrospray technique is reported. The Hb‐NPs are then coated by antioxidant and self‐polymerized poly(dopamine) (PDA) to minimize the conversion of Hb into nonfunctional methemoglobin (metHb). The PDA shell is further functionalized with poly(ethylene glycol) (PEG) to achieve stealth properties. The results demonstrate that the as‐prepared Hb‐NPs are hemo‐ and biocompatible while offering antioxidant protection and decreasing the formation of metHb. Additionally, decoration with PEG results in decreased protein adsorption onto the Hb‐NPs surface, suggesting a prolonged retention time within the body. Finally, the Hb‐NPs also preserve the reversible oxygen‐binding and releasing properties of Hb. All in all, within this study, a novel HBOCs with high Hb content is fabricated and its potential as an artificial blood substitute is evaluated.     

Polybrominated diphenyl ethers (PBDEs) in marine sediment of Thermaikos Gulf,Greece

Polybrominated diphenyl ether (PBDE) concentrations were determined in marine sediment samples collected from 7 different locations around Thermaikos Gulf in north Greece. PBDEs were detected in all sampling sites and their average total concentration (ΣPBDEs) ranged from 0.26 to 4.92?ng?g^?1?d.w. Concentrations were an order of magnitude higher in locations outlining the inner part of the Gulf, which were also closer to industrial areas, sewage treatment plant discharges, the city's harbour and landfill area. These findings suggest pollution in the aquatic ecosystem from industrial and urban activities in the area. Congener profiles exhibit predominance of BDE-209, while concentrations of other PBDE congeners were usually lower, when compared to similar studies from other countries globally, indicating that Thermaikos Gulf is among the low-polluted areas. Statistical analysis showed significant differences among the higher polluted sampling stations. Statistically significant differences also existed between sampling stations with high and low PBDE concentrations. Correlations between congeners suggested local contamination sources; however, specific point sources of pollution were not established.     

Hypercoordination in Organotin Chemistry – A Novel O,C,O-Coordinating Ligand

Recent results are reported on the application of the novel O,C,O-coordinating pincer ligand {2,6-[P(O)(OEt)₂]₂-4-tert-Bu-C₆H₂} (A) for the synthesis of hypercoordinate organotin(IV) compounds ASnR₃ (R = Ph, Cl), heteroleptic stannylenes ASnR (R = Cl, CH₂SiMe3) and intramolecularly coordinated 1,2,5-oxaphosphastannolanes.