Photoinduced Fusion of Lipid Bilayer Membranes

We have developed a novel system for photocontrol of the fusion of lipid vesicles through the use of a photosensitive surfactant containing an azobenzene moiety (AzoTAB). Real-time microscopic observations clarified a change in both the surface area and internal volume of vesicles during fusion. We also determined the optimal cholesterol concentrations and temperature for inducing fusion. The mechanism of fusion can be attributed to a change in membrane tension, which is caused by the solubilization of lipids through the isomerization of AzoTAB. We used a micropipet technique to estimate membrane tension and discuss the mechanism of fusion in terms of membrane elastic energy. The obtained results regarding this novel photoinduced fusion could lead to a better understanding of the mechanism of membrane fusion in living cells and may also see wider applications, such as in drug delivery and biomimetic material design

Entrapment and Removal of Carbon Nanotubes and Fullerenes by Coprecipitation with Calcium Carbonate Beads

Production, growth, and obvious health and environmental concerns about engineered nanomaterials (ENM) require development of methods for their entrapping/removal. Here, we propose a facile method for removal of carbon nanomaterials from water solutions based on coprecipitation with vaterite (CaCO₃) beads. CaCO₃ beads are formed by an aggregation of initially formed amorphous CaCO₃ nanoparticles that efficiently incorporate nanomaterials in solution into the growing beads so that can be finally removed by settling. We show that by using this approach, a high percentage of fullerenes and carbon nanotubes (typically over 95%) can be removed in a broad range of ENM concentrations. We also discuss potential applications of the method for treatment of contaminated water

DNA Hydrogel as a Template for Synthesis of Ultrasmall Gold Nanoparticles for Catalytic Applications

DNA cross-linked hydrogel was used as a matrix for synthesis of gold nanoparticles. DNA possesses a strong affinity to transition metals such as gold, which allows for the concentration of Au precursor inside a hydrogel. Further reduction of HAuCl₄ inside DNA hydrogel yields well dispersed, non-aggregated spherical Au nanoparticles of 2–3 nm size. The average size of these Au nanoparticles synthesized in DNA hydrogel is the smallest reported so far for in-gel metal nanoparticles synthesis. DNA hybrid hydrogel containing gold nanoparticles showed high catalytic activity in the hydrogenation reaction of nitrophenol to aminophenol. The proposed soft hybrid material is promising as environmentally friendly and sustainable material for catalytic applications