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Tuesday, September 21, 2021

A sponge that cleans more than your kitchen

If you have ever taken leftover antibiotics for a common cold, you may have been contributing to a growing problem. Bacterial resistance to antibiotics seems to be a more frequent issue, and one that worries many professionals in the health field. Methicillin-resistant Staphylococcus aureus (MRSA) outbreaks are extremely difficult to combat when they occur, but in the near future, they may become easier to control.

Engineers at University of California, San Diego have created a nanosponge that can safely remove a wide variety of toxins and pathogens from the bloodstream. A study using a lethal dose of a toxin from MRSA was administered to two groups of mice. One group was given an inoculation with nanosponges two minutes prior to the toxin and 89 percent of the mice survived. The other group was given the nanosponge inoculation after the toxin, and only 44 percent survived.

In order for the nanosponge to work, researchers took a commonly used medical nanoparticle and coated it with natural red blood cell material. These new particles essentially act as decoys in the body, with the membrane camouflaging the particles. The artificial “sponges” outnumber natural blood cells by about 3,000 to one, and harmlessly absorb the toxins floating in the bloodstream.

“With so many nanosponges, the chances of toxins interacting with [them] are much higher than the chances of [the toxins] interacting with natural red blood cells,” said Brian T. Luk, a contributing author of the study. “Upon coming into contact with a toxin, the nanosponge will absorb the toxin, thus neutralizing [it] and diverting it away from healthy cells. Eventually, the liver safely metabolizes both the nanosponges and the sequestered toxins without any discernible damage to the liver itself.”

These nanosponges have been designed to absorb and neutralize a multitude of toxins and pathogens — not just those originating from MRSA.

“Current treatments for toxins are tailored specifically to act against the molecular structure of a given toxin, and are therefore quite narrow in their use given the wide-ranging molecular structures of toxins,” Luk said. “We wanted to develop a system that could be used to treat a whole class of toxins, called pore-forming toxins. What all the toxins in this class have in common is that they lock into cellular membranes and punch holes in the membranes, causing the cells to burst.”

Most anti-toxin platforms, or antidotes, must be custom synthesized to the individual toxin type. This is the reason different venomous animals have different anti-venoms. The nanosponges, on the other hand, can remove a broad list of toxins, including snake venom and E. coli, which could revolutionize treatment for a wide range of ailments.

“Instead of creating specific treatments for individual toxins, we are developing a platform that can neutralize toxins caused by a wide range of pathogens, including MRSA and other antibiotic resistant bacteria,” said Liangfang Zhang, a nanoengineering professor at the UCSD Jacobs School of Engineering and the senior author on the study, in the original press release.

There is some concern, as with any new medical technology, that the risks may outweigh the benefits, especially since it has not yet been tested in humans.

Yet the research team at UCSD is confident that when the nanosponges are introduced, they will be effective with no apparent risks at all. Other people in the medical field agree that the risk is minimal.

“If the technology works as described, the risks are pretty minimal from a rejection standpoint. They are constructed of polymer cores that are unlikely to induce a strong immune response and they are also covered in host red cell membranes. The body will probably tolerate these things for a while,” said Stephen McSorley, an associate professor in comparative anatomy, cell biology and physiology at UC Davis. “The other issue is that even if they were rejected, they are designed to do their work so quickly that they don’t need to be in the body for a long period. Anti-venoms work in a similar way, they consist of foreign antibodies (usually from horse or goat) that will eventually be rejected, but they act quickly enough that they neutralize the venom before that becomes an issue.”

These tiny particles are making big waves in the medical field. Should these nanosponges prove successful in human trials, we should expect to see them entering the consumer market in a big way.

NICOLE NOGA can be reached at science@theaggie.org.

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