Microalga-Powered Microswimmers toward Active Cargo Delivery.

Nature presents intriguing biological swimmers with innate energy harvesting abilities from their local environments. Use of natural swimmers as cargo delivery agents presents an alternative strategy to transport therapeutics inside the body to locations otherwise difficult to access by traditional delivery strategies. Herein, a biocompatible biohybrid microswimmer powered by a unicellular freshwater green microalga, Chlamydomonas reinhardtii, is reported. Polyelectrolyte-functionalized magnetic spherical cargoes (1 µm in diameter) are attached to surface of the microalgae via noncovalent interactions without the requirement for any chemical reaction. The 3D swimming motility of the constructed biohybrid algal microswimmers is characterized in the presence and absence of a uniform magnetic fields. In addition, motility of both microalgae and biohybrid algal microswimmers is investigated in various physiologically relevant conditions, including cell culture medium, human tubal fluid, plasma, and blood. Furthermore, it is demonstrated that the algal microswimmers are cytocompatible when co-cultured with healthy and cancerous cells. Finally, fluorescent isothiocyanate-dextran (a water-soluble polysaccharide) molecules are effectively delivered to mammalian cells using the biohybrid algal microswimmers as a proof-of-concept active cargo delivery demonstration. The microswimmer design described here presents a new class of biohybrid microswimmers with greater biocompatibility and motility for targeted delivery applications in medicine.