3D printing of microbial communities: A new platform for understanding and engineering microbiomes.

3D printing has emerged as a powerful way to produce complex materials on-demand. These printing technologies are now being applied in microbiology, with many recent examples where microbes and matrices are co-printed to create bespoke living materials. Here, we propose a new paradigm for microbial printing.

Droplet printing reveals the importance of micron-scale structure for bacterial ecology.

Bacteria often live in diverse communities where the spatial arrangement of strains and species is considered critical for their ecology. However, a test of this hypothesis requires manipulation at the fine scales at which spatial structure naturally occurs. Here we develop a droplet-based printing method to arrange bacterial genotypes across a sub-millimetre array.

Controlled packing and single-droplet resolution of 3D-printed functional synthetic tissues.

3D-printing networks of droplets connected by interface bilayers are a powerful platform to build synthetic tissues in which functionality relies on precisely ordered structures. However, the structural precision and consistency in assembling these structures is currently limited, which restricts intricate designs and the complexity of functions performed by synthetic tissues. Here, we report that the equilibrium contact angle (θ) between a pair of droplets is a key parameter that dictates the tessellation and precise positioning of hundreds of picolitre-sized droplets within 3D-printed, multi-layer networks.

Fabrication of Micropatterned Dipeptide Hydrogels by Acoustic Trapping of Stimulus-Responsive Coacervate Droplets.

Acoustic standing waves offer an excellent opportunity to trap and spatially manipulate colloidal objects. This noncontact technique is used for the in situ formation and patterning in aqueous solution of 1D or 2D arrays of pH-responsive coacervate microdroplets comprising poly(diallyldimethylammonium) chloride and the dipeptide N-fluorenyl-9-methoxy-carbonyl-D-alanine-D-alanine. Decreasing the pH of the preformed droplet arrays results in dipeptide nanofilament self-assembly and subsequent formation of a micropatterned supramolecular hydrogel that can be removed as a self-supporting monolith.

Cerium oxide nanoparticle-mediated self-assembly of hybrid supramolecular hydrogels.

Hybrid supramolecular hydrogels are prepared by non-enzymatic dephosphorylation of N-fluorenylmethyloxycarbonyl tyrosine-(O)-phosphate (FMOC-Tyr-P) using catalytic cerium oxide nanoparticles. The organic-inorganic hydrogels exhibit enhanced viscoelastic properties compared with analogous materials prepared using alkaline phosphatase.

A new route to high yield sugars from biomass: phosphoric-sulfuric acid.

We have developed a simple and effective route for the high yield extraction of sugars from cellulosic based biomass. This process uses a combination of a cellulose decrystallization step with a mixture of phosphoric and sulfuric acid, followed by a hydrolysis step producing sugars (xylose and glucose) with yields of approximately 90%.