MPI-IS
Researchers from the Max Planck Institute for Intelligent Systems in Stuttgart have developed a hybrid biological nanorobots from microalgae by coating them with a magnetic material.
The development is expected to be used for controlled delivery of drugs into the body. In the natural environment, single-celled microalgae measuring 10 microns move with the help of two flagella placed in front. The researchers were interested in how the movement of microorganisms would change after coating them with a thin layer of the natural polymer chitosan, which improves adhesion
The scientists decided to test how such biological nanorobots in narrow spaces or in a liquid with a density similar to mucus. It turned out that the microscopic swimmer robots they created based on green algae almost did not lose their mobility after receiving an additional load in the form of an artificial coating. The average speed of their movement was 115 micrometers per second.
Project leaders Birgül Akolpoglu and Saadet Fatma Baltaci have been researching biological nanorobots for several years on the basis of microbes. The movement of which can be controlled by a thin layer of magnetic coating. When immersed in living organisms and moving through the fluids present there, they can be used for targeted drug delivery.
The researchers turned their attention to microalgae. They tried to make them functional and controllable with a magnetic coating. The coating was applied in a matter of minutes. Nine out of ten algae were successfully coated with a layer of magnetic nanoparticles. The first tests of the hybrid biorobot were conducted in a liquid with a density close to water.
By using external magnetic fields, they were able to control the direction in which their microalgae moved. The researchers then had one of these nanorobots move along tiny 3D-printed cylinders, the largest of which was only three times the size of the of the microbe itself.
To test the effectiveness of the control, the researchers created two different systems: one with magnetic coils and the other — with permanent magnets around the microscope, creating a homogeneous magnetic field and constantly changing its direction.
«We found that the microalgae biohybrids move through the 3D-printed microchannels in three ways: by moving backwards, moving forwards, and moving under the influence of magnets. Without magnetic navigation, the algae would often get stuck and go back to the beginning. But with magnetic guidance, they moved more smoothly, avoiding boundaries. Magnetic guidance helped the biohybrids align themselves with the field direction, demonstrating a real potential for navigation in confined spaces — as if to give them a tiny GPS!», — Birgül Akolpoglu notes.
Next, the researchers used a higher viscosity fluid and forced the microscopic robots to move through narrow channels. According to Saadet Baltaci, the goal was to test how these nanorobots would move in a mucus-like liquid. He noted that viscosity affects the way the microalgae move forward.
«Higher viscosity slows them down and changes the way they swim forward. When we applied a magnetic field, the swimmers oscillated, moving forward in zigzags. This emphasizes how fine-tuning viscosity and magnetic alignment can optimize microrobot navigation in complex environments», — Saadet Baltaci added.
The article was published in the journal Matter
Source: ScitechDaily