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Precise discrimination between similar cellular states is essential for autonomous decision‐making scenarios, such as in vivo targeting of diseased cells. Discrimination could be achieved by delivering an effector gene expressed under a highly active context‐specific promoter. Yet, a single‐promoter approach has linear response and offers limited control of specificity and efficacy. Here, we constructed a dual‐promoter integrator, which expresses an effector gene only when the combined activity of two internal input promoters is high. A tunable response provides flexibility in choosing promoter inputs and effector gene output. Experiments using one premalignant and four cancer cell lines, over a wide range of promoter activities, revealed a digital‐like response of input amplification following a sharp activation threshold. The response function is cell dependent with its overall magnitude increasing with degree of malignancy. The tunable digital‐like response provides robustness, acts to remove input noise minimizing false‐positive identification of cell states, and improves targeting precision and efficacy.

The assembly of artificial cells capable of executing synthetic DNA programs has been an important goal for basic research and biotechnology. We assembled two-dimensional DNA compartments fabricated in silicon as artificial cells capable of metabolism, programmable protein synthesis, and communication. Metabolism is maintained by continuous diffusion of nutrients and products through a thin capillary, connecting protein synthesis in the DNA compartment with the environment. We programmed protein expression cycles, autoregulated protein levels, and a signaling expression gradient, equivalent to a morphogen, in an array of interconnected compartments at the scale of an embryo. Gene expression in the DNA compartment reveals a rich, dynamic system that is controlled by geometry, offering a means for studying biological networks outside a living cell.

Understanding how biochemical networks lead to large-scale nonequilibrium self-organization and pattern formation in life is a major challenge, with important implications for the design of programmable synthetic systems. Here, we assembled cell-free genetic oscillators in a spatially distributed system of on-chip DNA compartments as artificial cells, and measured reaction–diffusion dynamics at the single-cell level up to the multicell scale. Using a cell-free gene network we programmed molecular interactions that control the frequency of oscillations, population variability, and dynamical stability. We observed frequency entrainment, synchronized oscillatory reactions and pattern formation in space, as manifestation of collective behavior. The transition to synchrony occurs as the local coupling between compartments strengthens. Spatiotemporal oscillations are induced either by a concentration gradient of a diffusible signal, or by spontaneous symmetry breaking close to a transition from oscillatory to nonoscillatory dynamics. This work offers design principles for programmable biochemical reactions with potential applications to autonomous sensing, distributed computing, and biomedical diagnostics.

When multicellular systems need to communicate over long distances, and signalling molecules are too slow to diffuse, travelling fronts of these molecules emerge—a phenomenon now reconstituted in a coupled array of artificial cells. Living systems employ front propagation and spatiotemporal patterns encoded in biochemical reactions for communication, self-organization and computation 1 , 2 , 3 , 4 . Emulating such dynamics in minimal systems is important for understanding physical principles in living cells 5 , 6 , 7 , 8 and in vitro 9 , 10 , 11 , 12 , 13 , 14 . Here, we report a one-dimensional array of DNA compartments in a silicon chip as a coupled system of artificial cells, offering the means to implement reaction–diffusion dynamics by integrated genetic circuits and chip geometry. Using a bistable circuit we programmed a front of protein synthesis propagating in the array as a cascade of signal amplification and short-range diffusion. The front velocity is maximal at a saddle-node bifurcation from a bistable regime with travelling fronts to a monostable regime that is spatially homogeneous. Near the bifurcation the system exhibits large variability between compartments, providing a possible mechanism for population diversity. This demonstrates that on-chip integrated gene circuits are dynamical systems driving spatiotemporal patterns, cellular variability and symmetry breaking.

The cell-free biogenesis of the protein translation machinery is essential for the creation of a self-regenerating synthetic cell. Here, we demonstrate the autonomous and simultaneous biogenesis of all thirty proteins of the translation machinery of E. coli in a reconstituted transcription-translation system. We first establish self-regeneration of every translation protein by determining the threshold concentration required for its own synthesis from a synthetic gene coding for the protein, thereby demonstrating the functionality of all nascent proteins, separately. Simultaneous biogenesis of multiple translation proteins at their threshold results in delayed synthesis below detection levels. To achieve self-regeneration of multiple translation proteins, we induce boundary-free compartmentalization of the reaction by immobilizing the genes on a surface at high density. The co-localization of genes, molecular machinery, messenger RNA and nascent proteins at the surface create sufficient conditions to catalyze the simultaneous self-regeneration of sub-groups up to all thirty translation proteins, as measured by total internal reflection fluorescence on the surface. Our approach provides mechanistic insight and presents a general methodology for the biogenesis of cellular machines toward autonomous synthetic systems. The cell-free biogenesis of the protein translation machinery is essential for the creation of a self-regenerating synthetic cell. Here the authors synthesise all 30 E. coli translation proteins in a cell-free system and demonstrate functionality.

The assembly of protein machines in cells is precise, rapid, and coupled to protein synthesis with regulation in space and time. The assembly of natural and synthetic nanomachines could be similarly controlled by genetic programming outside the cell. Here, we present quasi-two-dimensional (2D) silicon compartments that enable programming of protein assembly lines by local synthesis from surface-immobilized DNA brushes. Using this platform, we studied the autonomous synthesis and assembly of a structural complex from a bacteriophage and a bacterial RNA-synthesizing machine. Local synthesis and surface capture of complexes provided high assembly yield and sensitive detection of spatially resolved assembly intermediates, with the 3D geometry of the compartment and the 2D pattern of brushes dictating the yield and mode of assembly steps. Localized synthesis of proteins in a single gene brush enhances their interactions, and displacement of their genes in separated brushes leads to step-by-step surface assembly. This methodology enables spatial regulation of protein synthesis, and deciphering, reconstruction and design of biological machine assembly lines.Gene brushes patterned as synthetic operons on two-dimensional silicon compartments with defined geometry allow the investigation and regulation of nanoscale multi-protein assemblies.

Protein complex assembly facilitates the combination of individual protein subunits into functional entities, and thus plays a crucial role in biology and biotechnology. Recently, we developed quasi-twodimensional, silicon-based compartmental biochips that are designed to study and administer the synthesis and assembly of protein complexes. At these biochips, individual protein subunits are synthesized from locally confined high-density DNA brushes and are captured on the chip surface by molecular traps. Here, we investigate single-gene versions of our quasi-twodimensional synthesis systems and introduce the trap-binding efficiency to characterize their performance. We show by mathematical and computational modeling how a finite trap density determines the dynamics of protein-trap binding and identify three distinct regimes of the trap-binding efficiency. We systematically study how protein-trap binding is governed by the system’s three key parameters, which are the synthesis rate, the diffusion constant and the trap-binding affinity of the expressed protein. In addition, we describe how spatially differential patterns of traps modulate the protein-trap binding dynamics. In this way, we extend the theoretical knowledge base for synthesis, diffusion, and binding in compartmental systems, which helps to achieve better control of directed molecular self-assembly required for the fabrication of nanomachines for synthetic biology applications or nanotechnological purposes.

Cell-free gene expression in localized DNA brushes on a biochip has been shown to depend on gene density and orientation, suggesting that brushes form compartments with partitioned conditions. At high density, the interplay of DNA entropic elasticity, electrostatics, and excluded volume interactions leads to collective conformations that affect the function of DNA-associated proteins. Hence, measuring the collective interactions in dense DNA, free of proteins, is essential for understanding crowded cellular environments and for the design of cell-free synthetic biochips. Here, we assembled dense DNA polymer brushes on a biochip along a density gradient and directly measured the collective extension of DNA using evanescent fluorescence. DNA of 1 kbp in a brush undergoes major conformational changes, from a relaxed random coil to a stretched configuration, following a universal function of density to ionic strength ratio with scaling exponent of 1/3. DNA extends because of the swelling force induced by the osmotic pressure of ions, which are trapped in the brush to maintain local charge neutrality, in competition with the restoring force of DNA entropic elasticity. The measurements reveal in DNA crossover between regimes of osmotic, salted, mushroom, and quasineutral brush. It is surprising to note that, at physiological ionic strength, DNA density does not induce collective stretch despite significant chain overlap, which implies that excluded volume interactions in DNA are weak.

The coalescence of basic biochemical reactions into compartments is a major hallmark of a living cell. Using surface-bound DNA and a transcription reaction, we investigate the conditions for boundary-free compartmentalization. The DNA self-organizes into a dense and ordered phase with coding sequences aligned at well-defined distances and orientation relative to the surface, imposing directionality on transcription. Unique to the surface in comparison to dilute homogeneous DNA solution, the reaction slows down early, is inhibited with increased DNA density, is favorable for surface-oriented promoters, and is robust against DNA condensation. We interpret these results to suggest that macromolecules (RNA polymerase and RNA), but not solutes (ions and nucleotides), are partitioned between immobilized DNA and the reservoir. Without any physical barrier, a nonequilibrium directional DNA transaction forms macromolecular gradients that define a compartment, thus offering a boundary-free approach to the assembly of a synthetic cell.

Ensembles of micrometre-sized water droplets in a laminar oil flow are ideal systems for studying non-equilibrium dynamics. In the case of two-dimensional confinement, the interactions between the droplets’ flow-induced dipole moments lead to long-range velocity correlations and four-fold angular symmetry—behaviour that can be understood from first-principle hydrodynamics calculations. Dynamic restructuring and ordering are prevalent in driven many-body systems with long-range interactions, such as sedimenting particles 1 , 2 , 3 , dusty plasmas 4 , flocking animals 5 , 6 , 7 and microfluidic droplets 8 . Yet, understanding such collective dynamics from basic principles is challenging because these systems are not governed by global minimization principles, and because every constituent interacts with many others. Here, we report long-range orientational order of droplet velocities in disordered two-dimensional microfluidic droplet ensembles. Droplet velocities exhibit strong long-range correlation as 1/ r 2 , with a four-fold angular symmetry. The two-droplet correlation can be explained by representing the entire ensemble as a third droplet. The correlation amplitude is non-monotonous with density owing to excluded-volume effects. Our study puts forth a many-body problem with long-range interactions that is solvable from first principles owing to the reduced dimensionality, and introduces new experimental tools to address open problems in many-body non-equilibrium systems 9 , 10 .