Issue 19, 2011

Extensional rheology of DNA suspensions in microfluidic devices

Abstract

Newtonian liquids that contain even small amounts (∼ppm) of flexible polymers can exhibit viscoelastic behavior in extensional flows. Here, the effects of the presence of DNA molecules in viscous fluids on the dynamics of filament thinning and drop breakup are investigated experimentally in a cross-slot microchannel. Both bulk flow and single molecule experiments are presented. Suspensions of DNA molecules of different molecular weights (MW) are used, namely λ-DNA (MW = 3 × 107) and T4 DNA (MW = 1 × 108). Results of both dilute (c/c* = 0.5) and semi-dilute (c/c* = 1) suspensions are compared to those of a viscous, Newtonian liquid. Results show that the dynamics of the high MW, semi-dilute suspension of T4 DNA are similar to viscoelastic fluids such as slow, exponential decay of the fluid thread and beads-on-a-string morphology. The exponential decay rate of the filament thickness is used to measure the steady extensional viscosity of all fluids. We find that the semi-dilute T4 DNA suspension exhibits extensional strain rate thinning extensional viscosity, while for all other fluids the extensional viscosity is independent of strain rate. Direct visualization of fluorescently labeled λ-DNA molecules using high-speed imaging shows that the strong flow in the thinning fluid threads provide sufficient forces to stretch the majority of DNA molecules away from their equilibrium coiled state. The distribution of molecular stretch lengths, however, is very heterogeneous due to molecular individualism and initial conditions.

Graphical abstract: Extensional rheology of DNA suspensions in microfluidic devices

Supplementary files

Article information

Article type
Paper
Submitted
25 Feb 2011
Accepted
27 Jul 2011
First published
25 Aug 2011

Soft Matter, 2011,7, 9444-9452

Extensional rheology of DNA suspensions in microfluidic devices

G. Juarez and P. E. Arratia, Soft Matter, 2011, 7, 9444 DOI: 10.1039/C1SM05347G

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements