A team of researchers from MIT and other institutions has achieved a long-sought goal of creating magnetic nanoparticles that emit a colorful fluorescent glow in a biological environment and could be precisely manipulated into position within living cells.

Such particles could be tracked with great accuracy as researchers position them within the body or inside a cell by applying a magnetic field. A bioreactive coating applied to the particles could seek out and bind with particular molecules, such as markers for tumor cells or other disease agents.

“We wanted to be able to manipulate these structures inside the cells with magnetic fields but also know exactly what it is we’re moving,” says chemistry professor Moungi Bawendi, leader of the team that developed the particles. The wavelength of the nanoparticles’ fluorescent emissions serves as a precise identifying mechanism.

The new method produces the combination of desired properties “in as small a package as possible,” Bawendi says. The techniques they used could also help pave the way for the development of particles with other useful properties, such as the ability to bind with a specific type of bioreceptor.

Initially, at least, the particles might be used to probe basic biological functions within cells, Bawendi says. As additional materials are added to the particles’ coating, they could interact in specific ways with molecules or structures within the cell, either for diagnosis or for treatment.