Effect of polydiacetylene-based nanosomes on cell viability and endocytosis.

Polydiacetylene-based nanoparticles have been developed as nanocarriers for various bio-applications. However, how nanocarriers enter the cell environment and affect cell viability has not yet been considerably explored. In this study, polydiacetylene-based nanoliposomes (nanosomes) were electrostatically complexed with rhodamine fluorophores. Based on real-time cell imaging and cell viability assessment, the most highly polymerized nanosomes were found to be less toxic to cells. Moreover, it was revealed that the rhodamine/polydiacetylene nanosome complex dissociates at cell environment, the polydiacetylene nanosome penetrates into cells, as suggested by the fluorescence observed in confocal microscopy images.

Metal Ion-Mediated Interliposomal Aggregation of Polydiacetylene Liposomes Incorporating a Phenolic Lipid.

Intercolloidal behaviors mediated by metal-ligand coordination have rarely been studied. In this work, such intercolloidal behaviors were demonstrated visibly using blue-colored polydiacetylene liposomes containing a phenolic lipid that acts as a binding ligand toward metal ions. The optimized liposomes were 150-200 nm in diameter and stable in aqueous solution. In incubation tests with various neocortical metal ions, iron(III) ions produced the most obvious colloidal aggregation of the liposomes. As the pH of the incubation medium was increased from acid to basic, stronger aggregation and increased precipitation behavior were observed. The phenolic lipid is believed to contribute to the interliposomal bridging interaction, and the pH dependence of the complexation between iron(III) and the phenolic lipid inserted in the liposomes were verified.

Carrier transport mechanisms of the writing and the erasing processes for Al/ZnO nanoparticles embedded in a polymethyl methacrylate layer/C60/p-Si diodes.

Transmission electron microscopy images showed that ZnO nanoparticles were randomly distributed inside the polymethyl methacrylate (PMMA) layer. Capacitance-voltage (C-V) measurements on the Al/ZnO nanoparticles embedded in a PMMA layer/C60/p-Si diode at 300 K showed a clockwise hysteresis with a flatband voltage shift due to existence of the ZnO nanoparticles and a C60 buffer layer. The insertion of the C60 layer enlarged the memory window of the device containing the ZnO nanoparticle, as estimated by the flatband voltage shift in the C-V hysteresis. Capacitance-time measurements showed that the devices exhibited excellent memory retention ability at ambient conditions. Operating mechanisms of the charge injection, capture, and emission in the active layer and the charging and the discharging processes in the devices are described on the basis of the C-V results.

Operating mechanisms of organic bistable devices containing ZnO nanoparticles embedded in a poly-4-vinyl-phenol layer.

Scanning electron microscopy images showed that self-assembled ZnO nanoparticles were created inside a poly-4-vinyl-phenol (PVP) layer. Current-voltage (I-V) measurements on the Al/ZnO nanoparticles embedded in a PVP layer/indium tin oxide (ITO)/glass device fabricated by using a simple spin coating method at 300 K showed an electrical hysteresis behavior, indicative of an essential feature for a bistable device. The data fitting results of the I-V curves showed that the carrier transport mechanisms at low and high voltages were attributed to the space charge limited current and the Fowler-Nordheim tunneling processes, respectively. Possible operating mechanisms for the memory effects in the Al/ZnO nanoparticles embedded in a PVP layer/ITO devices are described on the basis of the I-V results.

Advances in medical adhesives inspired by aquatic organisms' adhesion.

In biomedicine, adhesives for hard and soft tissues are crucial for various clinical purposes. However, compared with that under dry conditions, adhesion performance in the presence of water or moisture is dramatically reduced. In this review, representative types of medical adhesives and the challenging aspects of wet adhesion are introduced. The adhesion mechanisms of marine mussels, sandcastle worms, and endoparasitic worms are described, and stemming from the insights gained, designs based on the chemistry of molecules like catechol and on coacervation and mechanical interlocking platforms are introduced in the viewpoint of translating these natural adhesion mechanisms into synthetic approaches.