Single molecule DNA intercalation in continuous homogenous elongational flow

Dynamic behavior of DNA molecules in microchannels: exploring deflective, elliptical, and spin motions induced by Saffman and Magnus forces

Precise manipulation of individual DNA molecules entering and leaving the channel ports, as well as their smooth passage across the channel, is essential for the detection and screening of DNA molecules using nano-/micro-fluidic technologies. In this paper, by combining single-molecule fluorescence imaging and numerical simulations, the motion states of DNA molecules translocating through a microfluidic channel under the action of the applied electric field are monitored and analyzed in detail. It is found that, under certain conditions of the applied electric field DNA molecules exhibit various motion states, including translation crossing, deflection outflow, reverse outflow, reciprocal movement, and elliptical movement. Simulations indicate that, under the action of Saffman force, DNA molecules can only undergo deflective motion when they experience a velocity gradient in the microchannel flow field; and they can only undergo elliptical motion when their deflective motion is accompanied by a spin motion. In this case, the Magnus force also plays an important role. The detailed study and elucidation of the movement states, dynamic characteristics and mechanisms of DNA molecules such as the deflective and elliptical motions under the actions of Saffman and Magnus forces have helpful implications for the development of related DNA/gene nano-/microfluidic chips, and for the separation, screening and detection of DNA molecules.

Analysis of single nucleic acid molecules in micro- and nano-fluidics

Nucleic acid analysis has enhanced our understanding of biological processes and disease progression, elucidated the association of genetic variants and disease, and led to the design and implementation of new treatment strategies. These diverse applications require analysis of a variety of characteristics of nucleic acid molecules: size or length, detection or quantification of specific sequences, mapping of the general sequence structure, full sequence identification, analysis of epigenetic modifications, and observation of interactions between nucleic acids and other biomolecules. Strategies that can detect rare or transient species, characterize population distributions, and analyze small sample volumes enable the collection of richer data from biosamples. Platforms that integrate micro- and nano-fluidic operations with high sensitivity single molecule detection facilitate manipulation and detection of individual nucleic acid molecules. In this review, we will highlight important milestones and recent advances in single molecule nucleic acid analysis in micro- and nano-fluidic platforms. We focus on assessment modalities for single nucleic acid molecules and highlight the role of micro- and nano-structures and fluidic manipulation. We will also briefly discuss future directions and the current limitations and obstacles impeding even faster progress toward these goals.