Copper bis(1‐methyl‐5‐nitriminotetrazolate) (1) was synthesized and investigated as a new primary explosive. Compound 1 was obtained by dehydration of diaquabis(1‐methylnitriminotetrazolato)copper(II) dihydrate (2) or diaquabis(1‐methylnitriminotetrazolato)copper(II) (3) at 120 °C. Complexes 2 and 3 are easily formed by the reaction of 1‐methyl‐5‐nitrimino‐1,2,3,4‐tetrazole (4) with copper(II) nitrate in aqueous solution in high yields. Single crystals of 1 were obtained by recrystallization from dry methanol, whereas wet methanol favors the yield of diaquabis(1‐methyl‐nitriminotetrazolato)copper(II) dimethanolate (5). Compound 1 was characterized by using single‐crystal X‐ray diffraction, IR spectroscopy, elemental analysis, and differential scanning calorimetry (DSC). The sensitivities were investigated by using the BAM drophammer and friction tests, and the heat of formation was calculated on the basis of electronic energies at the B3LYP/SDD level of theory. Compound 1 shows an impact sensitivity that is five times higher and a friction sensitivity that is ten times lower than that of lead azide, which is appropriate. In addition, the long‐term stability of 1 at higher temperatures was tested by using isothermal safety calorimetry (TSC). Compounds 2 and 3 were characterized by single‐crystal X‐ray diffraction, IR spectroscopy, elemental analysis, DSC, bomb calorimetry, and BAM sensitivity tests. In addition, compound 5 was characterized by single‐crystal X‐ray diffraction and elemental analysis. The dehydration of 2 was determined by using thermal gravimetry (TG) to occur by the loss of crystal water in one discrete step. (© WILEY‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

The aim of this study was to elucidate photodynamic therapy (PDT) effects mediated by hypericin and a liposomal meso-tetrahydroxyphenyl chlorin (mTHPC) derivative, with focus on their 1:1 mixture, on head and neck squamous cell carcinoma cell lines. Absorption, excitation and photobleaching were monitored using fluorescence spectrometry, showing the same spectral patterns for the mixture as measured for single photosensitizers. In the mixture mTHPC showed a prolonged photo-stability. Singlet oxygen yield for light-activated mTHPC was Φ(Δ) = 0.66, for hypericin Φ(Δ) = 0.25 and for the mixture Φ(Δ) = ~0.4. A linear increase of singlet oxygen yield for mTHPC and the mixture was found, whereas hypericin achieved saturation after 35 min. Reactive oxygen species fluorescence was only visible after hypericin and mixture-induced PDT. Cell viability was also more affected with these two treatment options under the selected conditions. Examination of death pathways showed that hypericin-mediated cell death was apoptotic, with mTHPC necrotic and the 1:1 mixture showed features of both. Changes in gene expression after PDT indicated strong up-regulation of selected heat-shock proteins. The application of photosensitizer mixtures with the features of reduced dark toxicity and combined apoptotic and necrotic cell death may be beneficial in clinical PDT. This will be the focus of our future investigations.

Polyoxometalate/carboxymethyl chitosan nanocomposites with an average diameter of 130 nm are synthesized and labeled with fluorescein isothiocyanate (FITC) for a combined drug-carrier and cellular-monitoring approach. [Eu(β(2) -SiW(11) O(39) )(2) ](13-) /CMC nanospheres as a representative example do not display cytotoxicity for POM concentrations up to 2 mg mL(-1) . Cellular uptake of fluoresecently labelled {EuSiW(11) O(39) }/FITC-CMC nanoparticles is monitored with confocal laser scanning microscopy. Nanoparticle uptake occurs after incubation times of around 1 h and no cyctotoxic effects are observed upon prolonged treatment. The preferential location of the POM/CMC nanocomposites in the perinuclear region is furthermore verified with transmission electron microscopy investigations on unlabeled nanoparticles. Therefore, this approach is a promising dual strategy for the safe cellular transfer and monitoring of bioactive POMs.

As functionalized chitosans hold great potential for the development of effective and broad-spectrum antibiotics, representative chitosan derivatives were tested for antimicrobial activity in neutral media: trimethyl chitosan (TMC), carboxy-methyl chitosan (CMC), and chitosan-thioglycolic acid (TGA; medium molecular weight: MMW-TGA; low molecular weight: LMW-TGA). Colony forming assays indicated that LMW-TGA displayed superior antimicrobial activity over the other derivatives tested: a 30 min incubation killed 100% Streptococcus sobrinus (Gram-positive bacteria) and reduced colony counts by 99.99% in Neisseria subflava (Gram-negative bacteria) and 99.97% in Candida albicans (fungi). To elucidate LMW-TGA effects at the cellular level, microscopic studies were performed. Use of fluorescein isothiocyanate (FITC)-labeled chitosan derivates in confocal microscopy showed that LMW-TGA attaches to microbial cell walls, while transmission electron microscopy indicated that this derivative severely affects cell wall integrity and intracellular ultrastructure in all species tested. We therefore propose LMW-TGA as a promising and effective broad-band antimicrobial compound.

Chitosan and its derivates continue to attract considerable research interest as effective drug carriers with good biocompatibility and high cellular uptake rates. We used these versatile features to tap the considerable biomedical potential of polyoxometalates (POMs) through their encapsulation into a carboxymethyl chitosan (CMC) matrix. The nanocapsules were prepared by ionic gelification with Ca(2+); their size distribution ranges from 60 to 150 nm. Because [Co(4)(H(2)O)(2)(PW(9)O(34))(2)](10-) is well known for its manifold properties, such as antiviral activity, it was selected as a model POM. The resulting composites were characterised with a wide range of analytical methods, which pointed to quantitative encapsulation of intact POMs within the CMC matrix. We studied the biocompatibility of the POM/CMC nanocomposites on HeLa cells through MTT and proliferation assays. Even after prolonged incubation times at high concentrations, the composites did not display cytotoxicity, thereby drastically reducing the side effects of the pristine POMs. This opens up new avenues for designing novel inorganic drug prototypes from bioactive POMs.