Ever since the emergence of Methicillin-resistant Staphylococcus aureus
(MRSA), a bacterium that shows resistance to our strongest antibiotics,
the race has been on to outwit this deadly organism. Now, a team of
scientists think they might have found an ingenious solution: cunningly
disguised nanosponges.
The team have created a gel with bacteria-fighting nanosponges mixed
in that can be applied to infected wounds. They tested the effects of
the mixture on mice with skin lesions caused by MRSA.
"One way to treat these infections is to remove the toxins, which act
as a weapon and a defense shield for the bacteria that produce them," said Liangfang Zhang, a nanoengineering professor at the Jacobs School of Engineering.
"We hypothesize that without the toxins, the bacteria become
significantly weakened and exposed, allowing the body's immune system to
kill them more easily without the use of drugs."
The team made the nanosponges by taking absorbant nanoparticles and
combining them with dangerous toxins that are produced by MRSA, E. Coli
and other antibiotic-resistant nasties. Each little sponge is then
cloaked in a red blood cell membrane. Since the toxins produced by MRSA
target these cells, this coat lures them towards their deadly clutches,
allowing the heroic nanosponges to then safely eject the bacteria from
the bloodstream.
To be effective, the nanosponges need to hang around the bacteria in
large quantities. To make the nanoparticles a bit more clingy, the team
mixed the sponges into a hydrogel made of water and polymers. The
nanosponges need to be mixed into a hydrogel that gently adheres to the
infected site to keep the concentration of nanosponges near the bacteria
high.
"We combined the strengths of two different materials—nanosponges and
hydrogels—to create a powerful formulation to treat local bacterial
infections," said
Zhang. "Nanosponges alone are difficult to use on local tissues because
they diffuse away to other parts of the body very quickly. By
integrating the nanosponges into a hydrogel, we can retain them at the
site of infection."
"After injecting the nanosponge-hydrogel at the infected spot, we
observed that it absorbed the toxins secreted by the bacteria and
prevented further damage to the local blood, skin and muscle tissues," said Zhang. The mouse legions that were treated with the hydrogel compound were significantly smaller than the ones left untreated.
The team also noticed that the hydrogel held fast: Two days after the hydrogel was injected under the skin of the mouse, just under 80%
of the nanosponges were still located at the site of injection. Compare
this to when the nanosponges were injected without the hydrogel: Only 20%
of the nanosponges stuck around. The gel doesn't contain any
antibiotics, so the team is hopeful that bacteria will not
develop resistance.
This is a very interesting way to sidestep the use of
antibiotics, and is especially exciting for people who may have
allergies to certain antibiotics. But don't hold your breath, there's
still a long way to go.
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