Nano-robots in industrial cleaning and drug distribution applications

Due to their ability to be controlled remotely, fast nano-robots may show promising performance in major industrial applications, from cleaning the environment to transporting pharmaceutical agents to a desired location in the body.

Image Credit: Marko Aliaksandr / Shutterstock.com

Professor Daniel Schwartz and his team at the University of Colorado have discovered tiny self-propelling particles called “nanowaves” with a diameter of 250 nm that can escape labyrinths 20 times faster than passive debris; properties that are incredibly beneficial in various applications (Simpkins, 2021).

What are nanonaggers?

The tiny spherical particles are made of polymer or silica with two halves, each with distinctive properties. Their unusual characteristic has earned them their nickname “Janus Particle”, named after a two-faced god from Roman mythology. Although Janus particles were first introduced in 1989 (Casagrande, et al., 1989) while describing a glass particle with hydrophobic and hydrophilic faces, nanonaggers only gained attention about two decades ago, when the research community understood their potential applications.

At that time, a lack of equipment and an incompetent modeling setup limited any progress. Now, with enough research and study on the subject, researchers believe that these nanonaggers have a catalytic surface on one of the hemispheres that encourages chemical reactions. As a result, the entire particle draws energy from its surroundings and causes it to move independently, and this ability is known as self-propulsion (Bustos, 2021).

Nanonageurs as nano-robots

The most distinctive feature of these nanonaggers is their ability to self-propel, meaning they can transduce free energy from their surroundings and convert it into motion that helps them move in a particular direction. In 2017, scientists from the Max Planck Institute for Intelligent Systems presented the world’s smallest jet propulsion system, with a tube diameter of 220 nm (Max Plank Institute for Intelligent Systems, 2017). With him, the research group announced two new approaches to building propulsion systems for tiny floaters.

First, generated by bubbles, which oscillate ultrasonically, and second, due to an enzymatic reaction that causes a current (Max Planck Institute, 2017). Typically, passive particles, called Brownian particles, circulate randomly in Brownian motion.

Prof. Schwartz’s team converted these passive Brownian particles into self-propelled nanonaggers that can circulate in a porous labyrinth. Due to the self-propelling property, these nanonaggers engineered the extra force needed to bypass exit holes in the maze.

Initially, the team struggled to observe these tiny nanonaggers in complex, interconnected areas. To overcome this, Haichao Wu, a graduate student of Prof. Schwartz, created a platform using a refractive index liquid in the porous medium that affected the speed of light passing through a material. This made the labyrinth invisible, making it easier to track 3D particle trajectories and create visual representations, which greatly aided the observation of motion (Montalbano, 2021).

Competence of nanonaggers in cleaning and drug delivery applications

An ongoing Horizon2020 project, SONOBOTS, led by a team from ETH Zurich, has developed nano-robots showing promising development towards the treatment of cancer and blood clots. The team used ultrasound to guide the nanoscale robots to the disease site, allowing them to deliver drugs effectively and efficiently without impacting red blood cells.

The researchers also demonstrated the properties of nano-robots as nanonageurs. Here, they were visualized guiding air bubbles trapped in a polymer shell next to an imaging chemical (European Commission, 2019). Another interesting consideration is the self-healing property of these nanonaggers when they are taken out of the lab in harsh real-life environments and expected to take damage.

Recently, scientists at the University of California invented fish-shaped robots 2 cm long, which consist of a conductive bottom layer and a hydrophobic middle layer covered with powerful magnetic microparticles. The tail contained platinum which can bubble oxygen when reacting with hydrogen peroxide, dragging the robots into the fluids (Karshalev, et al., 2021).

The robots moved around the edge of the dish filled with hydrogen peroxide fuel, and no matter how many times and where it was cut, the robots could heal themselves through strong magnetic interaction. They can perform crucial operations with this ability, such as cleaning the environment and delivering drugs to targeted tissues.

The future of nano-robots

Nanonaggers have great potential to be the next generation nano-robots that can positively contribute to many industries. In the medical field, they can facilitate targeted drug delivery and aid in effective treatment while reducing the severity of damage from chronic disease.

When it comes to cleaning technology, researchers have already noticed the usefulness of the movement of nanonaggers as a positive side effect in cleaning the environment of unwanted contaminants as they move. Once it is clear how a larger population of nanonaggers behaves in defined areas, they could be an attractive option for escaping cavities inside labyrinthine environments to clean up the soil, improve the filtration of the soil. water or even provide drugs to cells and tissues.

The self-healing strategy of nanonageurs could help the sustainable development of the miniaturization of robots, which opens the door to many other applications.

References and further reading

Bustos brand (2021) The Janus Particle: How These Two-Sided ‘Nanonaggers’ Could Improve Drug Delivery and Waste Recovery [Online] The Time of Sciences. Available at: https://www.sciencetimes.com/articles/32010/20210630/janus-particle-two-faced-nanoswimmers-improve-drug-delivery-waste-recovery.htm (Accessed July 28, 2021).

Casagrande C. et al. (1989) “Janus Beads”: Realization and behavior at water / oil interfaces. EPL (Europhysics Letter). 10.1209 / 0295-5075 / 9/3/011.

European Commission (2019) Acousto-magnetic micro / nanorobots for biomedical applications [Online] European Commission – Cordis. Available at: https://cordis.europa.eu/project/id/853309 (Accessed July 28, 2021).

Karshalev Emil. et al. (2021) Swimmers heal on the move after catastrophic damage. Nano letters. 10.1021 / acs.nanolett.0c05061.

Max Planck Institute (2017) New engine for small vessels [Online] Max Planck Institute. Available at: https://www.mpg.de/11051373/microrobot-nanorobot-propulsion (Accessed July 28, 2021).

Max Plank Institute for Intelligent Systems (2017) The world’s smallest jet engine invented in Stuttgart [Online] Max Plank Institute for Intelligent Systems. Available at: https://www.is.mpg.de/news/world-s-smallest-jet-engine-invented-in-stuttgart (Accessed July 28, 2021).

Montalbano Elisabeth (2021) Want tiny particles that can travel in tight places? Meet the nanonageurs [Online] DesignNews. Available at: https://www.designnews.com/materials/want-tiny-particles-can-move-through-tight-spots-meet-nanoswimmers (Accessed July 28, 2021).

Simpkins Kelsey (2021) Fast nano-robots could one day clean soil and water, deliver drugs [Online] ScienceDaily. Available at: https://www.sciencedaily.com/releases/2021/06/210629144307.htm (Accessed July 28, 2021).

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Mavis R. Bernier