MIT researchers develop nanoparticle that targets infection

Researchers at Massachusetts Institute of Technology (MIT) and Brigham and Women’s Hospital in the US have developed a nanoparticle that evades the immune system and homes in on infection sites, then unleashes a focused antibiotic attack.

Aleks Radovic-Moreno, an MIT graduate student and leading author of a paper describing the particles in the journal ACS Nano, says this approach would mitigate the side-effects of some antibiotics and protect the beneficial bacteria that normally live inside our bodies.

Professor Robert Langer of MIT and Omid Farokzhad, director of the Laboratory of Nanomedicine and Biomaterials at Brigham and Women’s Hospital, are senior authors of the paper. Timothy Lu, an assistant professor of electrical engineering and computer science, and MIT undergraduates Vlad Puscasu and Christopher Yoon also contributed to the research.

The team created the nanoparticle from a polymer capped with polyethylene glycol (PEG), which is commonly used for drug delivery because it is non-toxic and can help nanoparticles travel through the bloodstream by evading detection by the immune system. The next step was to induce the particles specifically to target bacteria.

Researchers have previously tried to target particles to bacteria by giving them a positive charge, which attracts them to bacteria’s negatively charged cell walls. However, the immune system tends to clear positively charged nanoparticles from the body before they can encounter bacteria. To overcome this, the researchers designed antibiotic-carrying nanoparticles that can switch their charge depending on their environment. While they circulate in the bloodstream, the particles have a slight negative charge. However, when they encounter an infection site, the particles gain a positive charge, allowing them to bind tightly to bacteria and release their drug payload.

In this study, the researchers designed the particles to deliver vancomycin, used to treat drug-resistant infections, but they say the particles could be modified to deliver other antibiotics or drug combinations.

Although further development is needed, the researchers hope the high doses delivered by their particles could eventually help overcome bacterial resistance.

There are also negatively charged tissue cells and proteins at infection sites that can compete with bacteria in binding to nanoparticles and potentially block them from binding to bacteria. The researchers are studying how much this might limit the effectiveness of their nanoparticle delivery.

They are also conducting studies in animals to determine whether the particles will remain pH-sensitive in the body and circulate for long enough to reach their targets.