Reconfigurable Phototactic Micromotors from Fractal Self‐Assembly of Dark Carbon Nanodot Sols: A Perfect Mimic of Colonial Green Algae

Abstract Bottom‐up synthesized carbon nanodots (CNDs) are surface‐active, biocompatible nanomaterials well‐known for their bright photoluminescence properties. This paper introduces the potential of dark (non‐emissive) CNDs in crafting phototactic micro‐motors. Hydrogen bond mediated fractal self‐assembly of dark CNDs manifests colloidal superstructures with hierarchical dimensions in alcohol media resembling properties of natural green algae in terms of appearance, phototactic movement, and colony dynamics. Akin to the natural counterpart, the characteristic helical microswimming, and bi‐directional phototaxis following the gradient of light and shade by a school of swimmers are observed, establishing the unprecedented intelligence of any artificial constructs to date. The artificial algae produce a photocurrent upon light exposure, which drives the phototactic motility. Laser beam‐directed anti‐gravity propulsion implies the potentiality of these biocompatible micro‐motors for cargo‐delivery and microsurgery applications. In the condensed phase, alco‐algae reversibly transform to green‐transmitting leafy architectures that turn golden‐brown upon aging, resembling natural photosynthetic organisms. In one direction, this study establishes an inexpensive and powerful approach for crafting intelligent artificial living systems from bio‐available precursors. Furthermore, it pushes the boundaries of applications that can be achieved by CNDs.