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An improved carboxylation method of (OC‐6‐33)‐dichloro(ethane‐1,2‐diamine)dihydroxyplatinum(IV) based on succinic anhydride is reported. Reaction of the uncoordinated carboxylic acid with simple amines and alcohols leads to the corresponding amides and esters in the presence of 1,1′‐carbonyldiimidazole. The resulting new complexes are characterized by IR, 1H, 13C, 15N, and 195Pt NMR spectroscopy, mass spectrometry, and elemental analysis. This reaction provides an entry to a new class of kinetically inert platinum(IV) complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

We have developed a silver-releasing biomaterial with promising potential for wound healing applications. The material is made of ultrashort peptides which can self-assemble in water to form hydrogels. Silver nanoparticles (Ag NPs) were synthesized in situ within the biomaterial, using only UV irradiation and no additional chemical reducing agents. The synthetic strategy allows precise control of the nanoparticle size, with the network of peptide fibers preventing aggregation of Ag NPs. The biomaterial shows increased mechanical strength compared to the hydrogel control. We observed a sustained release of Ag NPs over a period of 14 days. This is a crucial prerequisite for effective anti-bacterial therapy. The ability to inhibit bacterial growth was tested using different bacterial strains, namely gram-negative Escherichia coli and Pseudomonas aeruginosa and gram-positive Staphylococcus aureus. Inhibition of bacterial growth was observed for all strains. The best results were obtained for Pseudomonas aeruginosa which is known for exhibiting multidrug resistance. Biocompatibility studies on HDFa cells, using Ag NP-containing hydrogels, did not show any significant influence on cell viability. We propose this silver-releasing hydrogel as an excellent biomaterial with great potential for applications in wound healing due to its low silver content, sustained silver nanoparticle release and biocompatibility.

Octahedrally configured diaminedichloro- and diamineoxalatoplatinum(IV) complexes with axial hydroxo ligands were carboxylated with succinic or glutaric anhydride. The free, uncoordinated carboxylic acid groups were further derivatized with amines and alcohols to the respective amides and esters and characterized in detail by elemental analysis, mass spectrometry, and multinuclear (1H, 13C, 15N, and 195Pt) NMR spectroscopy. Cytotoxicity of the complexes was studied in four human cancer cell lines derived from ovarian carcinoma (CH1, SK-OV-3), cervical carcinoma (HeLa), and colon carcinoma (SW480) by means of the MTT assay. Structure-activity relationships revealed a low activity for platinum complexes with underivatized carboxylic acid moieties and amide derivatives displaying the hydroxyethylamino residue. Within the series of amides, cyclopentylamino analogues were equipped with the highest cytotoxic potential. However, ester derivatives yielded IC50 values mostly in the low micromolar range and comparable to those of cisplatin. DNA platination studies of selected complexes revealed a high DNA platination capacity in parallel to a high cytotoxic potential and vice versa.

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We describe Janus metal organic framework crystals that are propelled by bubble ejection. The Janus crystals are prepared by selective epitaxial growth of ZIF-67 on ZIF-8. The Janus crystals catalyse the decomposition of H2O2 into H2O and O2 on the ZIF-67 surface but not on the zinc containing ZIF-8 surface, resulting in propulsion of the Janus crystals.

A series of ruthenium(II) arene complexes with 3-(1H-benzimidazol-2-yl)-1H-quinoxalin-2-one, bearing pharmacophoric groups of known protein kinase inhibitors, and related benzoxazole and benzothiazole derivatives have been synthesized. In addition, the corresponding osmium complexes of the unsubstituted ligands have also been prepared. The compounds have been characterized by NMR, UV-vis, and IR spectroscopy, ESI mass spectrometry, elemental analysis, and by X-ray crystallography. Antiproliferative activity in three human cancer cell lines (A549, CH1, SW480) was determined by MTT assays, yielding IC(50) values of 6-60 μM for three unsubstituted metal-free ligands, whereas values for the metal complexes vary in a broad range from 0.3 to 140 μM. Complexation with osmium of quinoxalinone derivatives with benzimidazole or benzothiazole results in a more consistent increase in cytotoxicity than complexation with ruthenium. For selected compounds, the capacity to induce apoptosis was confirmed by fluorescence microscopy and flow-cytometric analysis, whereas cell cycle effects are only moderate.

Stimuli-responsive liquid marbles for controlled release typically rely on organic moieties that require lengthy syntheses. We report herein a facile, one-step synthesis of hydrophobic and oleophobic TiO2 nanoparticles that display photoresponsive wettability. Water liquid marbles stabilized by these photoresponsive TiO2 particles were found to be stable when shielded from ultraviolet (UV) radiation; however, they quickly collapsed after being irradiated with 302 nm UV light. Oil- and organic-solvent-based liquid marbles could also be fabricated using oleophobic TiO2 nanoparticles and show similar UV-induced collapse. Finally, we demonstrated the formation of the micronized form of water liquid marbles, also known as dry water, by homogenization of the TiO2 nanoparticles with water. The TiO2 dry water displayed a similar photoresponse, whereby the micronized liquid marbles collapsed after irradiation and the dry water turned from a free-flowing powder to a paste. Hence, by exploiting the photoresponsive wettability of TiO2, we fabricated liquid marbles and dry water that display photoresponse and studied the conditions required for their collapse.