Gold nanoparticles produced in a microalga

An efficient biological route to production of gold nanoparticles which allows the nanoparticles to be easily recovered remains elusive. Live cells of the green microalga Chlorella vulgaris were incubated with a solution of gold chloride and harvested by centrifugation. Nanoparticles inside intact cells were identified by transmission electron microscopy and confirmed to be metallic gold by synchrotron based X-ray powder diffraction and X-ray absorption spectroscopy. These intracellular gold nanoparticles were 40–60 nm in diameter. At a concentration of 1.4% Au in the alga, a better than 97% recovery of the gold from solution was achieved. A maximum of 4.2% Au in the alga was obtained. Exposure of C. vulgaris to solutions containing dissolved salts of palladium, ruthenium, and rhodium also resulted in the production of the corresponding nanoparticles within the cells. These were surmised to be also metallic, but were produced at a much lower intracellular concentration than achieved with gold. Iridium was apparently toxic to the alga. No nanoparticles were observed using platinum solutions. C. vulgaris provides a possible route to large scale production of gold nanoparticles.     

Synthesis of Spirocyclic Indolenines

This Review provides an in‐depth account of the synthesis of spirocyclic indolenines. Over the last 77 years, a wide array of diverse synthetic methods has been developed in order to generate these synthetically useful and biologically important spirocyclic scaffolds. The main synthetic strategies discussed are grouped into three main categories, namely interrupted Fischer indolisations, dearomatisation reactions of indoles and condensation reactions. The historical background, common synthetic challenges, current state‐of‐the‐art and future perspectives of this field are examined.     

Self-assembled alkanethiol structures on gold: A further insight into the origins of structural rearrangement phenomena

Self-assembled structures of alkanethiols that have been deposited on gold from ethanolic solutions are susceptible to both chemical and physical changes: ethanol provides a medium for the formation of S-alkyl hydrogen thiocarbonates and related compounds via reaction with dissolved, atmospheric, CO₂. Deposition from ethanolic solutions results in multilayered structures incorporating these compounds, which at room temperature are susceptible to time-dependent structural rearrangement and molecular migration.