Nanofluidic single-molecule sorting of DNA: a new concept in separation and analysis ofbiomolecules towards ultimate level performance

Abstract

Separation and separation-based analysis of biomolecules are fundamentally importanttechniques in the field of biotechnology. These techniques, however, depend onstochastic processes that intrinsically involve uncertainty, and thus it is not possible toachieve 100% separation accuracy. Theoretically, the ultimate resolution andsensitivity should be realized in a single-molecule system because of the deterministicnature of single-molecule manipulation. Here, we have proposed and experimentallydemonstrated the concept of a ‘single-molecule sorter’ that detects and correctly identifiesindividual single molecules, realizing the ultimate level of resolution and sensitivity forany separation-based technology. The single-molecule sorter was created using ananofluidic network consisting of a single inlet channel that branches off intomultiple outlet channels. It includes two major functional elements, namely asingle-molecule detection and identification element and a flow path switching elementto accurately separate single molecules. With this system we have successfullydemonstrated the world’s first single-molecule sorting using DNA as a samplemolecule. In the future, we hope to expand the application of such devices tocomprehensive sorting of single-proteins from a single cell. We also believe thatin addition to the single-molecule sorting method reported here, other types ofsingle-molecule based processes will emerge and find use in a wide variety of applications.