Engineering motile artificial cells capable of swimming up concentration gradients

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Billions of years of evolution shaped cells into highly sophisticated micromachines, whose intricate network of molecular interactions are difficult to unravel. Bottom-up synthetic biology aims at constructing artificial cells by combining a small number of molecular agents into compartmentalised microenvironments. This reductionist approach enables the study of biological processes in a simplified setting. More importantly however, it offers the opportunity of producing smart cell-like agents to tackle pressing needs in diagnostics, therapeutics, biosynthesis, and bioremediation. Most attempts at engineering life-like 'behaviours' into artificial cells have focused on metabolism, energy generation, computation, and communication. One behaviour which has been neglected so far is motility: directed motion towards a target site. Motility (e.g. swimming and crawling) is a characteristic that is found across all life classes: from unicellular photosynthetic organisms that perform vertical migrations to optimise light exposure, swimming sperm cells, and macrophages that chase down pathogens. In most instances, cells are able to direct their motion following environmental cues, typically gradients in light intensity (phototaxis), temperature (thermotaxis), or the concentration of chemicals (chemotaxis). Despite the unquestionable benefits that controllable taxis would bring for most foreseen applications of artificial cells, viable technologies for engineering motion in synthetic cells have not been developed. This is because the protein assemblies needed to drive motility (e.g. flagella) are the most complex macromolecular structures in existence, and reconstituting them into synthetic systems is simply not possible using current state of the art. In this project we will develop a cellular bionics solution to this challenge: instead of using native cellular machineries, we will develop novel nanotechnologies based on DNA biophysics to propel a synthetic cell forwards, up a concentration gradient, with cell engineered to elicit a response (protein synthesis) when reaching its target site.