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 (θDIB) 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. When θDIB approximates the geometrically-derived critical angle (θc) of 35.3°, the resulting networks of droplets arrange in regular hexagonal close-packed (hcp) lattices with the least fraction of defects. With this improved control over droplet packing, we can 3D-print functional synthetic tissues with single-droplet-wide conductive pathways. Our new insights into 3D droplet packing permit the fabrication of complex synthetic tissues, where precisely positioned compartments perform coordinated tasks

Learning transmission dynamics modelling of COVID-19 using comomodels

This is the author accepted manuscript. The final version is available on open access from Elsevier via the DOI in this recordThe COVID-19 epidemic continues to rage in many parts of the world. In the UK alone, an array of mathematical models have played a prominent role in guiding policymaking. Whilst considerable pedagogical material exists for understanding the basics of transmission dynamics modelling, there is a substantial gap between the relatively simple models used for exposition of the theory and those used in practice to model the transmission dynamics of COVID-19. Understanding these models requires considerable prerequisite knowledge and presents challenges to those new to the field of epidemiological modelling. In this paper, we introduce an open-source R package, comomodels, which can be used to understand the complexities of modelling the transmission dynamics of COVID-19 through a series of differential equation models. Alongside the base package, we describe a host of learning resources, including detailed tutorials and an interactive web-based interface allowing dynamic investigation of the model properties. We then use comomodels to illustrate three key lessons in the transmission of COVID-19 within R Markdown vignette

A lipid-based parallel processor for chemical signals

A key goal of drug delivery and bottom-up synthetic biology is to construct structures that interact with their environment. Biological cells and tissues can process several external chemical signals, often in parallel, without cross-talk. However, so far, cell- and tissue-like structures with only one signalling pathway have been generated. Here, using lipid-bounded aqueous compartments, we build a three-compartment processor with an architecture analogous to that of dual-core central processing units. Each compartment is optimised for a distinct task such as signal transmission, sensing, and enzymatic processing. Recombinantly generated pore-forming membrane protein alpha-hemolysin in the signal transmission compartment enables fast exchange of chemicals between the processing compartments and the external environment. The processor can receive two chemical signals from the environment, process them orthogonally, and produce an output for each signal. The output can be fluorescence or the production and release of a molecule into the external environment. We build the processor from the bottom up, in a modular fashion. In two compartment processors containing a signal transmission compartment and another compartment of varying contents, we demonstrate signal release, signal intake, enzymatic DNA cleavage and enzymatic hydrolysis. We then combine various compartments to build three-compartment processors able to process chemical signals in parallel

Synthetic tissues

While significant advances have been achieved with non-living synthetic cells built from the bottom-up, less progress has been made with the fabrication of synthetic tissues built from such cells. Synthetic tissues comprise patterned three-dimensional (3D) collections of communicating compartments. They can include both biological and synthetic parts and may incorporate features that do more than merely mimic nature. 3D-printed materials based on droplet-interface bilayers are the basis of the most advanced synthetic tissues and are being developed for several applications, including the controlled release of therapeutic agents and the repair of damaged organs. Current goals include the ability to manipulate synthetic tissues by remote signaling and the formation of hybrid structures with fabricated or natural living tissues

Controlled deprotection and release of a small molecule from a compartmented synthetic tissue module

Synthetic tissues built from communicating aqueous droplets offer potential applications in biotechnology, however, controlled release of their contents has not been achieved. Here we construct two-droplet synthetic tissue modules that function in an aqueous environment. One droplet contains a cell-free protein synthesis system and a prodrug-activating enzyme and the other a small-molecule prodrug analog. When a Zn2+-sensitive protein pore is made in the first droplet, it allows the prodrug to migrate from the second droplet and become activated by the enzyme. With Zn2+ in the external medium, the activated molecule is retained in the module until it is released on-demand by a divalent cation chelator. The module is constructed in such a manner that one or more, potentially with different properties, might be incorporated into extended synthetic tissues, including patterned materials generated by 3D-printing. Such modules will thereby increase the sophistication of synthetic tissues for applications including controlled multidrug delivery

Synthetic tissues

While significant advances have been achieved with non-living synthetic cells built from the bottom-up, less progress has been made with the fabrication of synthetic tissues built from such cells. Synthetic tissues comprise patterned three-dimensional (3D) collections of communicating compartments. They can include both biological and synthetic parts and may incorporate features that do more than merely mimic nature. 3D-printed materials based on droplet-interface bilayers are the basis of the most advanced synthetic tissues and are being developed for several applications, including the controlled release of therapeutic agents and the repair of damaged organs. Current goals include the ability to manipulate synthetic tissues by remote signaling and the formation of hybrid structures with fabricated or natural living tissues

Controlled deprotection and release of a small molecule from a compartmented synthetic tissue module

Synthetic tissues built from communicating aqueous droplets offer potential applications in biotechnology, however, controlled release of their contents has not been achieved. Here we construct two-droplet synthetic tissue modules that function in an aqueous environment. One droplet contains a cell-free protein synthesis system and a prodrug-activating enzyme and the other a small-molecule prodrug analog. When a Zn2+-sensitive protein pore is made in the first droplet, it allows the prodrug to migrate from the second droplet and become activated by the enzyme. With Zn2+&nbsp;in the external medium, the activated molecule is retained in the module until it is released on-demand by a divalent cation chelator. The module is constructed in such a manner that one or more, potentially with different properties, might be incorporated into extended synthetic tissues, including patterned materials generated by 3D-printing. Such modules will thereby increase the sophistication of synthetic tissues for applications including controlled multidrug delivery.</p

Developing a graduate training program in Synthetic Biology: SynBioCDT

This article presents the experience of a team of students and academics in developing a post-graduate training program in the new field of Synthetic Biology. Our Centre for Doctoral Training in Synthetic Biology (SynBioCDT) is an initiative funded by the United Kingdom's Research Councils of Engineering and Physical Sciences (EPSRC), and Biotechnology and Biological Sciences (BBSRC). SynBioCDT is a collaboration between the Universities of Oxford, Bristol and Warwick, and has been successfully running since 2014, training 78 students in this field. In this work, we discuss the organization of the taught, research and career development training. We also address the challenges faced when offering an interdisciplinary program. The article concludes with future directions to continue the development of the SynBioCDT

Developing a graduate training program in Synthetic Biology: SynBioCDT

This article presents the experience of a team of students and academics in developing a post-graduate training program in the new field of Synthetic Biology. Our Centre for Doctoral Training in Synthetic Biology (SynBioCDT) is an initiative funded by the United Kingdom's Research Councils of Engineering and Physical Sciences (EPSRC), and Biotechnology and Biological Sciences (BBSRC). SynBioCDT is a collaboration between the Universities of Oxford, Bristol and Warwick, and has been successfully running since 2014, training 78 students in this field. In this work, we discuss the organization of the taught, research and career development training. We also address the challenges faced when offering an interdisciplinary program. The article concludes with future directions to continue the development of the SynBioCDT