The goal of this project is to develop techniques for the ordered deposition and elongation of single DNA strands on different types of substrates by means of capillary forces.
Combing DNA strands on microstructured PDMS
Draining of a droplet of DNA on a microstructured PDMS substrate allows the deposition and elongation of DNA molecules. The process involves the dewetting of the liquid over a set of micro wells that create a perturbation of the dewetting line. Singles DNA strands are then pinched and elongated when the the liquid breaks in the vicinity of microholes.
Schematic of the deposition process
SEM of microructures PDMS substrate and GFP fluorescence imaging of ordered Lambda phage DNA molecule on a PDMS substrate
B.Charlot, F.Bardin, N.Sanchez, P.Roux, S.Teixeira and E.Schwob, "Elongated unique DNA strand deposition on microstructured substrate by receding meniscus assembly and capillary force", Biomicrofluidics 8, 014103 (2014).
The previous combing techniques relies on a physical phenomenon that arise during dewetting of a DNA solution on a substrate with microholes. Another technique allows to comb DNA strands on a substrate by using a DNA terminaison / substrate intercation. A low pH, the endings of the molecules opens and let the base interact with a fonctionalised substrate allowing an effective anchoring of the molecule ending on the substrate. By adding a nano topography, i.e a set of parallel grooves, it is possible to deposit DNA strand with a perfectly linear configuration along the substrate. The figure below shows examples of such elongated DNA on nanorails.
GFP fluorescence imaging of Lambda phage DNA strands combed on a nanograting
SEM picture of the nanograting, 800nm pitch.
B.Charlot, R.Teissier, M.Drac, E.Schwob, "DNA on rails: Combing DNA fibers on nanogratings", Applied Physics Letters, 105, 243701 (2014).