The researchers at Georgia Tech, Emory and Georgia State universities tagged the molecules with particles called nanoprobes that bind only to specific types of molecules, and which illuminate when they are found.

The researchers developed the imaging method by adapting techniques designed for stellar photometry -- a branch of astronomy focused on measuring the brightness of stars.

"As more powerful imaging technologies are developed, scientists face a real challenge to quantitatively analyze and interpret these new mountains of data," said Assistant Professor May Wang of Georgia Tech and Emory University.

Before development of the new technique, "we had no way of knowing for sure if we were looking at one molecule or two or three molecules very near one another," said Wang. She said the new system allows scientists to collect quantitative data and prove -- not hypothesize -- how genes are behaving.

The research, which is expected to lead to a better understanding of the structure of complex biological molecules, appears in the early online edition of the Proceedings of the National Academy of Sciences.