Truly-Biocompatible Gold Catalysis Enables Vivo-Orthogonal Intra-CNS Release of Anxiolytics

Being recognized as the best-tolerated of all metals, the catalytic potential of gold (Au) has thus far been hindered by the ubiquitous presence of thiols in organisms. Herein we report the development of a truly-catalytic Au-polymer composite by assembling ultrasmall Au-nanoparticles at the protein-repelling outer layer of a co-polymer scaffold via electrostatic loading. Illustrating the in vivo-compatibility of the novel catalysts, we show their capacity to uncage the anxiolytic agent fluoxetine at the central nervous system (CNS) of developing zebrafish, influencing their swim pattern. This bioorthogonal strategy has enabled -for the first time- modification of cognitive activity by releasing a neuroactive agent directly in the brain of an animal.     

Synthesis by extrusion: continuous,large-scale preparation of MOFs using little or no solvent

Grinding solid reagents under solvent-free or low-solvent conditions (mechanochemistry) is emerging as a general synthetic technique which is an alternative to conventional solvent-intensive methods. However, it is essential to find ways to scale-up this type of synthesis if its promise of cleaner manufacturing is to be realised. Here, we demonstrate the use of twin screw and single screw extruders for the continuous synthesis of various metal complexes, including Ni(salen), Ni(NCS)₂(PPh₃)₂ as well as the commercially important metal organic frameworks (MOFs) Cu₃(BTC)₂ (HKUST-1), Zn(2-methylimidazolate)₂ (ZIF-8, MAF-4) and Al(fumarate)(OH). Notably, Al(fumarate)(OH) has not previously been synthesised mechanochemically. Quantitative conversions occur to give products at kg h^–1 rates which, after activation, exhibit surface areas and pore volumes equivalent to those of materials produced by conventional solvent-based methods. Some reactions can be performed either under completely solvent-free conditions whereas others require the addition of small amounts of solvent (typically 3–4 mol equivalents). Continuous neat melt phase synthesis is also successfully demonstrated by both twin screw and single screw extrusion for ZIF-8. The latter technique provided ZIF-8 at 4 kg h^–1. The space time yields (STYs) for these methods of up to 144 × 10³ kg per m³ per day are orders of magnitude greater than STYs for other methods of making MOFs. Extrusion methods clearly enable scaling of mechanochemical and melt phase synthesis under solvent-free or low-solvent conditions, and may also be applied in synthesis more generally.     

Plant protein-based feeds and commercial feed enable isotopic tracking of aquaculture emissions into marine macrozoobenthic bioindicator species

Brittle stars (Ophiura spp.) and other benthic macrofauna were collected in a prospective mariculture area in the North Sea to determine if these taxa could be used as indicator species to track nutrients released from future offshore aquaculture sites. We analysed natural carbon and nitrogen stable isotopic signatures in tissues from macrofauna and compared these to six feed ingredients and four experimental diets made thereof, as well as to a commercial feed with and without lipid and carbonate removal. Our data suggest practicability of using isotopic signatures of Ophiura spp. to track aquaculture-derived organic material if plant-based fish diet ingredients and commercial feed were used for fish farming in the German Exclusive Economic Zone. Diets with high fish meal content would not be detected in Ophiura spp. using isotopic measures due to the similarity with the marine background. Our data provide valuable baseline information for studies on the impact of offshore aquaculture on the marine environment.