: Scientists are using nanoparticles to develop ways to fight bacteria that are resistant to conventional antibiotics. These tiny drugs physically punch holes through bacteria instead of killing them chemically, which means that they could be especially effective on antibiotic-resistant bacteria strains like the dangerous methicillin-resistant Staphylococcus aureus (MRSA). “The applications are going to be very diverse, whether we’re talking about wound healing or dressing, skin infection, and quite possibly injections into the bloodstream,” James Hedrick, master inventor at IBM Almaden Research Center in San Jose, California, told Popular Science. How the Heck:
What's the News
Developed by IBM (yes, that IBM), but tested at the Singapore Institute of Bioengineering and Nanotechnology, the nanoparticles are made of bits of polycarbonate plastic that are amphilic: with one part that's attracted to water (hydrophilic), and another that's attracted to fats (hydrophobic). This means when you inject these particles into blood, for example, the hydrophilic parts of the polycarbonates hide within the hydrophobic parts, forming self-assembled clots about 200 nanometers wide.
These nanoparticles then glom onto certain kinds of bacteria, including drug-resistant staph, because of electrical attraction: The outer side of the particles is positively charged, whereas the microbes are negatively charged.
By attaching to the surface of the bacteria's cell wall, the nanoparticles disrupt the wall and burst it open.
Hedrick told Popular Science that scientists aren't sure why the particles are so good at killing bacteria. His experiments showed that the particles killed some bacteria and even fungi.
What's the Context:
There have been other potential membrane-bursting drugs in the past, but they were found to be impractical because they were toxic to animal cells. This present research is promising because of its positive results with live mice, which survived the treatment.
The idea of attaching a substance to the cell wall of an undesired microbe isn't new: Penicillin weakens the cell wall of E. coli in a similar way, eventually causing it to burst.
In other superbug-killing news, scientists recently discovered that copper surfaces effectively wipe out MRSA in minutes.
Not So Fast:
Will this technique be used for healing wounds and injecting into the bloodstream to fight bacteria? Hedrick says "this is way early in the discovery process to be going there."
The technique only killed some kinds of bacteria: the ones whose charges attracted the nanoparticles. This means that other kinds of harmful bacteria were unaffected. The researchers say that they can tweak the nanoparticles by changing their charge, shape, and solubility to target other kinds in the future.
Next Up: Now the scientists are marking larger batches of nanoparticles so that they'll have enough for tests in humans. In the years to come, IBM hopes to partner with healthcare companies to make the drug available for medical use. Reference: Nederberg, F. et al. "Biodegradable nanostructures with selective lysis of microbial membranes." Nature Chemistry. doi:10.1038/nchem.1012.
Image: The left-hand images show an intact Enterococcus faecalis
bacteria cell; the right-hand images shows the bacteria with its cell wall broken by nanoparticles. IBM.