MIT researchers have created an inexpensive method to screen for millions of different biomolecules (DNA, proteins, etc.) in a single sample–a technology that could make possible the development of low-cost clinical bedside diagnostics.

The researchers’ particle fabrication method gives them exquisite control over the particles’ shape and chemical characteristics. As two streams of monomers (liquid precursors loaded with fluorescent dye or molecular probe) flow side by side through a microfluidic device, ultraviolet light repeatedly strikes the streams. A chemical reaction initiated by the light causes the liquid to solidify, forming a single particle with two distinct ends. Each particle takes on the shape of a “mask” (similar to a transparency film) through which the UV light is aimed.

One end of each particle is a fluorescent “dot-pattern” barcode that reveals what the target molecule of the particle is, and the other end is loaded with a probe and only turns fluorescent if the target molecule is present. The particles can also be designed to each test for multiple targets, by adding several unique regions.

For a paper published in the March 9 issue of Science, the researchers created particles with DNA probes attached at one end. They demonstrated that the particles could accurately and reproducibly detect the presence of multiple target DNA sequences, and they anticipate similar results with RNA, proteins and cytokines.

The researchers are focusing on bedside diagnostics and “theranostics”-the emerging concept of providing personalized diagnostic therapy. This method for tailoring therapies to each patient could be a breakthrough for treating diseases like cancer and cardiovascular disease. The particles could also be used to genetically profile individual patients and screen for bioterrorism or other hazardous environmental agents.