Abstract

Fine Control of DNA Compaction using Microfluidics

Ciprian Iliescu, Senior Research Scientist, Institute of Bioengineering and Nanotechnology

The talk will be focused on using of microfluidic hydrodynamic flow focusing to enable an accurate control of self-assembling nanoparticles with a special focus on DNA compaction using microfluidics methods. Two approaches will be illustrated. First method is based on rapid change of solvent quality. Upon bulk mixing, DNA collapses in a non-controlled manner with local excess concentrations yielding large aggregates non suitable for efficient gene delivery applications. A mixture of surfactant and DNA dispersed in 35% ethanol is focused between two streams of pure water in a microfluidic channel. As a result, a rapid change of solvent quality takes place in the central stream, and the surfactant-bound DNA molecules undergo a fast coil-globule transition. By adjusting the concentrations of DNA and surfactant, fine-tuning of the nanoparticle size – down to a hydrodynamic diameter of 70 nm with a polydispersity index below 0.2 – can be achieved with a good reproducibility. The second method relied on the controlled diffusive mixing of surfactant and DNA solutions through a water stream of tunable width. Using this method the smallest nanoparticles achieved were about 30 nm in hydrodynamic diameter, meaning that most of them contained a single DNA molecule (<2 kbp). Due to the consistent 'batch-to-batch' results, the well-controlled nanoparticle size, current microfluidic methods can be successfully used for gene therapy applications as well as for the synthesis of tailored soft nanoparticles. Co-authors: G. Tresset (CNRS, France), M. Ni (IBN), C. Marculescu (IMT Romania)