For many years now, medical researchers have been trying to develop targeted therapies to treat diseases like cancer. The advantage of targeted therapy, in which a drug is sent to a specific site in the body to heal or destroy damage cells or disease-causing agents, is that they do not affect health cells in the body and so produce fewer unwanted side effects. The latest development in this field is the use of the algae Spirulina as a microrobot that can be controlled remotely to deliver drugs to a site of disease of infection.

A team of researchers at the Chinese University of Hong Kong in Shatin turned tiny coiled strands of Spirulina into magnetic microrobots by coating them with iron oxide. The algae’s natural helical structure turns out to be ideal to propel it through tissues in the body. It can move forward by twirling around its central axis. The scientists were able to control the movement of the Spirulina strands within bodies of rat test subjects by using applying a magnetic field from the outside. Moreover, they were able to track the tiny biohybrids due to the algae’s natural flouroscence.

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The researchers point to another advantage of using algae as a medical microrobot. The natural biological agent degrades within the body in just a few hours or days without damaging most cells.

They did, however, note one exception to Spirulina’s action on tissue. The algae seemed to be able to destroy certain types of cancer cells. The algae destroyed about 90% of tumour cells growing in a lab dish in 48 hours. They conducted further tests that indicated Spirulina produces a compound that is toxic to cancer cells.

The team notes that more rigorous tests need to be performed to check how the algae can be used to carry drugs into the body and deliver them efficiently where they are needed. Here is a video by Science explaining the study that was published earlier this month in the journal Science Robotics.