Engineering Native Cells by TiO₂ Nanoparticles and Polypyrrole for Light-Responsive Manipulation of Collective Behaviors of Unicellular Organisms

Cell surface engineering is an effective strategy to improve the tolerance of living cells against harsh environments as well as endow cells with various properties and functionalities, which they do not possess inherently. However, the research emphasis on single-cell surface engineering with the emergence of collective functionality is still rare. In this study, we encapsulate a single living cell with TiO 2 nanoparticles (Degussa P25, composed of anatase and rutile crystallites) and conductive polymer polypyrrole (PPy). The driving force generated from the nanoparticles TiO 2 and PPy could be utilized to manipulate cells that are more than a hundred times their own body size. Different collective behaviors of unicellular organisms can be achieved under various conditions. Especially, the engineered cells could be endowed with a swarming negative phototaxis migration under UV light in the presence of ferrocene methanol (MFc). Given that the collective behaviors of organismic swarms can greatly improve the adaptability and survivability compared to individual ones, we thus anticipate that such a studied technique could open up opportunities for the manipulation of the collective behaviors of unicellular organisms and have great potential in cell therapy as well as biosensors.