Synthetic microrobots are typically made of rigid metallic or polymeric structures that are difficult to manufacture. They’re unable to access certain organs and tissues, and they can be toxic to humans.

Microalgae overcome these concerns. For one, microalgae can move autonomously by using a hair-like appendage called flagella to propel themselves through organs such as the lungs. They are less toxic compared with other microorganisms. They are also cheaper and easier to produce.

Our biohybrid microrobot – called algae-NP(DOX)-robot– combines microscopic, live green microalgae commonly used in pharmaceuticals, Chlamydomonas reinhardtii, with nanoparticles coated with red blood cell membranes. The cell membranes act as a natural “camouflage” to enhance the microrobot’s biocompatibility and prevent it from being attacked by the patient’s immune system. Within the nanoparticles is a common type of chemotherapy drug called doxorubicin.