TY - JOUR A1 - Meißner, T. A1 - Bergmann, R. A1 - Oswald, J. A1 - Rode, K. A1 - Stephan, H. A1 - Richter, W. A1 - Zänker, H. A1 - Kraus, Werner A1 - Emmerling, Franziska A1 - Reck, Günter T1 - Chitosan-encapsulated Keggin anion [Ti2W10PO40]7-.Synthesis, characterization and cellular uptake studies JF - Transition metal chemistry N2 - The Keggin type polyoxotungstate [Ti2W10PO40]7- forms stable associates with the biopolymer chitosan in the nanometer size range. The cluster compound crystallizes from aqueous solution as K4H3[Ti2W10PO40] · 15H2O having a tetragonal structure. Both, the cluster compound and the chitosan/[Ti2W10PO40] associates show a high hydrolytic stability at pH 7.4. The associates formed between the cluster anion [Ti2W10PO40]7- with the polyaminosaccharide chitosan have been characterized by photon correlation spectroscopy, scanning electron microscopy, filtration, centrifugation and zeta potential measurements. The size of the associates formed is in the range of ca. 5×101 to 5×102 nm. These particles have a defined stoichiometry with 5–6 cluster anions bound per molecule chitosan. The isoelectric point determined by zeta potential measurements was found for a cluster anion to chitosan molar ratio of 5.5, indicating the charge neutralization between protonated chitosan and [Ti2W10PO40]7- anions. Cellular uptake studies with [Ti2W10PO40]7- using tumor cell lines FaDu (human squamous carcinoma) and HT-29 (human adenocarcinoma) showed that the tungsten amount inside the cells is remarkably enhanced in the presence of chitosan. KW - Cluster compound KW - Keggin structure KW - Bipolymer KW - Chitosan PY - 2006 DO - https://doi.org/10.1007/s11243-006-0035-z SN - 0340-4285 SN - 1572-901X VL - 31 IS - 5 SP - 603 EP - 610 PB - Springer CY - Dordrecht AN - OPUS4-12568 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Krüger, Oliver A1 - Kalbe, Ute A1 - Meißner, K. A1 - Sobottka, S. T1 - Sorption effects interfering with the analysis of polycyclic aromatic hydrocarbons (PAH) in aqueous samples JF - Talanta N2 - Polycyclic aromatic hydrocarbons (PAH) are severe environmental pollutants that are analyzed frequently. The risk assessment of PAH impact to groundwater can be performed using leaching tests. Therby a liquid–solid separation step including centrifugation may be required, which in turn might lead to loss of analytes due to sorption on the equipment. Thus we determined the PAH recoveries from various container materials (polyethylene (PE), polypropylene (PP), polytetraflourethylene (PTFE), stainless steel (ES), and perflouroalkoxy (PFA)) and compared them to selected PAH properties. We found the best recoveries for PFA (68%) and PTFE (65%) containers. We found good negative correlations (-0.93 and better) between PAH recovery and log partition coefficient organic carbon–water (log KOC) for PFA, PTFE, and ES containers. KW - PAH recoveries KW - Sorption KW - Plastic surfaces KW - Centrifuge containers PY - 2014 DO - https://doi.org/10.1016/j.talanta.2014.01.038 SN - 0039-9140 VL - 122 SP - 151 EP - 156 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-31383 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -