Bottom-up synthetic biology aims to reproduce the structures and behaviours of cellular organisms by combining molecules that mimic the structural, functional and information containing roles present in biology. These structures are known as synthetic cells, and they can act as a framework to study biological processes (such as movement or replication), as well as act as miniature test-tubes, within which chemical and biochemical reactions can be carried out. Taking further inspiration from biology, the assembly of individual synthetic cells leads to the creation of synthetic tissues, where different compartment types can be integrated within a larger structure to act as optimised microscale reaction vessels, which can be activated through the exchange of molecular reactants between compartments. As synthetic cells and tissues are constructed from molecular parts, there is huge flexibility in the design of these systems, and this has been exploited to form compartments from lipids, polymers and protein-based membranes. One area that is significantly less explored is the encapsulation of novel biocatalysts structures within synthetic cells and tissues. One such catalyst are polyhedrin protein crystals, which can be used to embed co-produced enzyme catalysts via expression of crystals in cells. This exploits the high stability of polyhedrin crystals (used to protect viral capsids in the external environment in nature) to create long-lasting catalysts. Here, we propose to use microfluidic approaches to assembling synthetic tissues that i) encapsulate enzyme-embedded polyhedrin crystals within different compartments of the tissue and ii) possess a hydrogel shell to increase the durability of the tissue material. We will assemble water in oil emulsion droplets on-chip, encapsulating the crystals within the aqueous compartments of these droplets, before gelating the hydrogel around the emulsion to produce milliscale devices that can be handled in liquid and air. We will then test the catalytic activity of these tissues, with the aim of producing robust soft materials with long catalytic lifetime that can be used simply via incubation in reactant-containing solution. After reactant takeup and conversion within the synthetic tissue, we will aim to release product through washing cycles, setting up the next tissue-based catalysis cycle. This proof-of-concept work will demonstrate the potential for hybrid tissue mimics in catalysis, and this framework could be extended to design new, combined bio- and chemo-catalytic routes currently impossible in one-pot systems due to catalyst poisoning. In order to achieve this we are bringing together world leading research expertise in the UK and Japan with a view to bringing together expertise not available in concert elsewhere in the word: namely Ces (synthetic cells and microfluidics), Ueno (multiscale catalytic biomaterials) and Abe (catalytic protein crystal biomaterials).

Cells are the building blocks of life. They have been sculpted over billions of years of evolution to perform some of the most complex tasks known to humankind. However, at their core, they can be thought of as a web of interacting molecules, albeit a very complex one. We can ask ourselves: what if we could create entirely artificial cells from scratch? Can we make life from inanimate matter? Achieving this ambitious objective will underpin disruptive applications and address some of the grand societal challenges of our time. Building a new biology will also transform our understanding of living systems. The ultimate aim of artificial cell research is to manufacture synthetic microrobots that possess the hallmark behaviours of cellular life, including the ability to move, harvest and covert energy, communicate with each other and with biological cells, adapt to the environment, replicate, make 'decisions', repair themselves, grow, divide, and even evolve. One of the key aims of the field is to engineer synthetic cells that are capable of making their own machinery from a genetic programme, which will allow them to be autonomous. This is critical if synthetic cells are to have applications beyond academic environments as therapeutic agents, tools in drug discovery, bioremediation, sensing and chemical manufacture. Proteins are the molecular machines that give cells their functions. The scientific community are now broadly able to engineer synthetic cells that can produce soluble proteins, such as the enzymes that catalyse chemical reactions. There is a whole other class of proteins that due to technological limitations, are out of reach when it comes to autonomous synthetic cell design: membrane proteins. This is a damaging bottleneck, as these proteins are responsible for diverse cellular behaviours, ranging from motility, communication and signalling through to energy generation, replication and cell-cell adhesion. In this project, by bringing together world-leading researchers in the UK and Japan, and combining our expertise in membrane biophysics, molecular biology, DNA nanotechnology and microfluidics, we will remedy this oversight. We will conduct the feasibility studies that enable the design and construction of synthetic cells that can generate their own membrane-based machinery. We will also organise activities to bring together vibrant communities in Japan and the UK in this space. This level of international cooperation and engagement is required if the scientific community is to achieve the grand challenge of engineering synthetic life.