The dynamics of single-molecule DNA in flow

Within the last decade, fluorescence microscopy of single molecules of DNA in a plethora of flow fields has allowed an unprecedented examination of the dynamics of polymers in flow. As a result, new principles (e.g. “molecular individualism”) have been developed regarding these dynamics and old debates (e.g. conformational hysteresis of polymers in extensional flow) have received a fresh airing. The coupling of the microscopy, employing a spectrum of possible DNA molecules, fragments, and concatemers with dynamic simulation (e.g. Brownian dynamics) has created a tremendous opportunity to both revisit unanswered questions in the field of polymer solution dynamics (particularly in the nonlinear flow regime), as well as to examine new areas surrounding the engineering of flow dynamics of complex fluids in microfluidic devices. The foundation for future studies has been laid by careful experimentation and computer simulation of DNA dynamics in bulk or locally linear flows of many types. Future studies involving collective effects, complex flows, flow-induced reaction, adsorption and so forth are just beginning and again the promise is to develop a new understanding of these polymer processes by examining DNA “one molecule at a time.”