The test tubes are actually bubble-like nanocontainers that are porous to small molecules. Researchers can easily feed needed ions and other chemicals into the ultra-tiny reaction chambers.

Many scientists say that more can be learned about the dynamics of chemical reactions that power biological processes by studying the behavior of individual molecules rather than observing the collective behavior of many molecules, as scientists do now. But techniques for single-molecule studies are limited and often highly specialized. The new nanocontainers, however, will make single-molecule techniques both more accessible and more powerful
…
The researchers say their technique can be easily applied in other laboratories, to enable scientists to study individual molecular reactions free of the complications of analyzing reactions in bulk solution. The new approach also improves on other methods used for observing the behavior of single molecules. One of the most common methods required that single molecules be tethered to a surface. With nanocontainers, however, the vesicles themselves are attached to a surface, meaning the molecules inside do not have to be. This simplifies analysis, because the effects of the surface on the reaction do not have to be taken into account, the researchers said.