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How Ninja Particles Work


What It Takes to Be a Ninja Particle
Looks like a bacterial cell with nothing to fear, right? Go to the next page to see what it looks like after a ninja particle gets to it.
Looks like a bacterial cell with nothing to fear, right? Go to the next page to see what it looks like after a ninja particle gets to it.
Image courtesy IBM

When researcher Yi Yan Yang heard about the work chemist Jim Hedrick was doing at IBM on microelectronics, she immediately approached him about a collaboration, telling him his research advances could be put to better use in medicine. Since then, their partnership has resulted in the development of a very promising group of nanoparticles dubbed "ninja particles."

The human immune system inspired their creation. When a person gets sick, his or her body secretes antimicrobial peptides. These bacteria-fighting molecules seek out a microbe, latch onto it and kill it (that last part can happen in a few different ways). Hedrick and Yang set out to make a particle in the lab that would do the same thing.

The nanoparticle they created is made of a special type of polymer. Polymers are super long, chained molecules. Plastics, for example, are all polymers. The polymer nanoparticle that Hedrick and Yang developed has three parts that make it so adept at killing bacteria.

  1. The chains have a dopamine molecule hanging off it. Yup, we're talking about the same dopamine that helps to control the brain's reward and pleasure centers. Here, it's serving a purely functional purpose of helping to attach the polymer nanoparticle to its target.
  2. The long chains also contain a short chain of a different type of polymer, polyethylene glycol (or PEG). PEG has a lot of industrial and medicinal uses. In this case, it works to fight organism growth on surfaces, as a preventative measure to combat bacteria.
  3. Finally, the nanoparticles contain a positively charged portion that has antibacterial properties. This part helps to target the negatively charged bacteria in the body and kill them off once found.

With these three parts, ninja particles have been shown to be effective at killing methicillin-resistant Staphylococcus aureus (MRSA), E. coli and certain types of fungi [source: Yang]. In addition, the nanoparticles can be used to coat medical devices like catheters, which are notorious for growing bacteria-ridden biofilms. The coating prevents bacteria from forming on the surfaces, reducing the chance of infections in patients with these implanted devices.


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