1. . How Do They Work? By Sara Pike and Ali Balubaid What are Magnetic Microbots?Magnetic Microbots and the Tumor Environment Sustainability Application to Cancer Therapy Magnetic microbots are particles on the scale of 10 -6 capable of being controlled by a magnetic field. Scientists can attach drugs encased in lysosomes to the surface of these microbots via antibodies, place a swarm of these bacterial microbots in a bubble-like vesicle, and then use the gradient coils of an MRI machine to steer the bacteria through the body to the target site, such as the location of a tumor. If the target site is within smaller bodily pathways that the encasing vesicle is too big to traverse, then the vesicle can burst and release the individual microbots. From there, a set of more finely tuned magnetic coils can be used to finish guiding the microbots to their destination where they can then deliver their drug treatment. This current model of magnetic microbots utilizes the MC-1 bacterium as the microcarrier. The MC-1 bacterium as it is found in nature contains magnetosomes, magnetic nanocrystals, that allow it to be controlled by a magnetic field. In addition to being extremely efficient, the design of magnetic microbots is also highly sustainable. Due to the fact that current magnetic microbots utilize the MC-1 bacterium, this technology relies on largely renewable components that are found in nature. The MC-1 bacterium not only makes magnetic microbot technology highly sustainable because of its ability to reproduce in its natural environment, but also because of its ability to reproduce in axenic culture in labs after being harvested. the MC- 1 bacterium also causes minimal toxicity with its breakdown, making for a highly environmentally sustainable process. This allows for easy disposal after use with very little harm to either to human body or the environment. This bacterium also causes minimal toxicity with use, having less harmful side effects than comparable treatments like chemotherapy. There is also minimal damage to surrounding cells as collateral damage to the treatment, making magnetic microbot technology sustainable in the context of both human and environmental health. Magnetic microbots are currently a promising alternative to chemotherapy, radiotherapy, or hormone therapy in the application of cancer treatment. These other methods require systemic circulation throughout the vascular network to deliver therapeutics, causing more toxicity for the patient with distribution over healthy tissues and organs and lower concentrations of accumulation at the tumor site. Magnetic microbots, on the other hand, are able to deliver anti-tumor drugs locally, directly to the target site. These microbots are small enough to navigate the angiogenesis network of tumors with ease, something that is not a possibility for larger local drug delivery strategies. Additionally, even when the external magnetic field is not strong enough to produce a directional torque on the chain of magnetosomes, the MC-1 bacterium will naturally seek out ~0.5% oxygen level concentrations, which generally corresponds to the oxygen level expected at the hypoxic regions of solid tumors. Scientists are also looking for ways that magnetic microbots can treat brain tumors locally by temporarily opening up the blood-brain barrier, something that is out of reach of today’s medicine. These nanocrystals coupled with the bacterium’s flagella, a natural means of propulsion, allow the bacterium to maneuverer through the pathways of the human body. However, when flagella alone are not enough to provide sufficient propulsion, the catalytic decomposition of hydrogen peroxide carried out within the bacterium can be used to provide additional thrust. With this propulsion system, the microbots need only a slight magnetic tug from the MRI coils to point them in the proper direction, acting as a compass needle. Differential microwave imaging (DMI) is used to track the magnetic microbots’ progress through the body and thereby adjust the magnetic field accordingly.