Metallosupramolecular cages and capsules have gained increasing popularity as both molecular containers and anticancer agents. For successful combination of these properties a thorough analysis of the effect of guest encapsulation on the host's cytotoxic properties is highly required. Here we report on the cytotoxicity modulation of Pt(ii) and Pd(ii)-linked M2L4 coordination capsules upon encapsulation of guest molecules such as pyrene and caffeine. The anticancer activity of the capsules against various human cancer cells (HT-29, T-24, HL-60 and its resistant counterparts HL-60/Dox and HL-60/CDDP) significantly altered upon the guest encapsulation. The encapsulation of pyrene molecules causes a decrease in the cytotoxicity of the Pt(ii) capsule, which is stronger than that of the Pd(ii) capsule. The cytotoxicities of the caffeine containing capsules are lower than that of the empty capsules (except for HL-60), but still superior to cisplatin under the same conditions. The observed trends in the anticancer activity of the capsules and their host-guest complexes correlate with their different stabilities toward glutathione, estimated by NMR-based kinetic experiments. Mechanistic insights into the observed cytotoxicities are obtained by fluorescence microscopy imaging of tumor cells treated with the capsules and their pyrene complexes. The data suggest the glutathione-triggered disassembly of the capsular structures as a potential activation pathway for their cytotoxicities.
The structural complexity of the 3-D surface of poly(methylmethacrylate) films with immobilized europium b-diketonates was studied by atomic force microscopy and fractal analysis. Fractal analysis of surface roughness revealed that the 3-D surface has fractal geometry at the nanometer scale. Poly(methylmethacrylate) (PMMA) as immobilization matrix is dense and uniform, and a tendency for formation of chain structures was observed. Fractal analysis can quantify key elements of 3-D surface roughness such as the fractal dimensions D f determined by the morphological envelopes method of the Eu(DBM) 3 and Eu(DBM) 3 Á dpp nanostructures, which are not taken into account by traditional surface statistical parameters.
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