The nanosponges are made of a biocompatible polymer core wrapped in a natural red blood cell membrane

'Nanosponges' remove whole toxin class from blood

Engineers have invented a "nanosponge" capable of removing dangerous toxins from the bloodstream including those of MRSA.

The ball-shaped nanosponge, which is 3,000 times smaller than a red blood cell, soaks up dangerous chemicals and transports them to the liver where they are broken down.

In tests on mice, US scientists successfully neutralised the alpha-haemolysin toxin produced by Methicillin Resistant Staphylococcus Aureus (MRSA) with pre-injection of the nanosponges allowing 89 per cent of mice to survive normally lethal infections and treatment after infection saving 44 per cent of the animals.

"This is a new way to remove toxins from the bloodstream,” said study leader and nanoengineering professor at the University of California San Diego Jacobs School of Engineering, Liangfang Zhang.

“Instead of creating specific treatments for individual toxins, we are developing a platform that can neutralise toxins caused by a wide range of pathogens, including MRSA and other antibiotic resistant bacteria."

The nanosponges can neutralize a broad class of "pore-forming toxins", which destroy cells by poking holes in their cell membranes, meaning they could also combat toxins from the food bug Escherichia coli (E.coli) and venom from poisonous snakes and insects.

Each nanosponge has a diameter of approximately 85 nanometers, about 3,000 times smaller than a red blood cell, and is made of a biocompatible polymer core wrapped in segments of red blood cells membranes.

To evade the immune system, the sponge balls are disguised as red blood cells by wrapping them in red blood cells membrane, with just one red blood cell membrane able to make thousands of nanosponges.

The cloaking allows the nanosponges to act as decoys, attracting toxins that would otherwise be drawn to red blood cells and inflict damage by punching holes through cell membranes.

When they encounter a nanosponge, they break through its outer surface and become trapped and in this way the harmful molecules are diverted away from vulnerable living cells.

Eventually the nanosponges, which had a half-life of 40 hours in the researchers' experiments in mice, reach the liver, where both they and their toxic cargo are metabolised and rendered harmless, with the liver incurring no discernible damage.

The scientists now aim to develop approved nanosponge therapies that can be used to treat human patients.

"One of the first applications we are aiming for would be an anti-virulence treatment for MRSA," said co-author Dr Che-Ming Hu. "That's why we studied one of the most virulent toxins from MRSA in our experiments."

An army of thousands of nanosponges can be administered with a single injection, but their capacity for absorbing dangerous substances depends on the type of toxin according to the research.

In mice, the nanosponges were able to neutralise MRSA toxin with no side effects when they outnumbered the toxic molecules by 70 to one.

The findings were reported in the journal Nature Nanotechnology.

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