Surface modification of poly(methyl methacrylate) microfluidic devices for high‐resolution separations of single‐stranded DNA

Abstract

While polymer-based microfluidic devices offer some unique opportunities in developing low-cost systems for a variety of application areas, the ability to sort electrophoretically with high efficiency a number of different targets has remained somewhat elusive with an example consisting of achieving single base resolution as required for DNA sequencing. While the reasons for this are many-fold, it is clear that some type of coating is required on the polymer substrate to suppress the EOF and/or minimize potential solute/wall interactions. To this end, we report on a simple grafting procedure to allow the formation of polymer coats, which in this example used linear polyarcylamides (LPAs), onto a poly(methyl methacrylate) (PMMA) microfluidic device. The procedure involved creating an amine-terminated PMMA surface by appropriately functionalizing the PMMA through either a chemical or photochemical process. The aminated surface could then be used to covalently anchor methacrylic acid, which was used as a scaffold to produce LPAs on the surface through radical polymerization of acrylamide. The resulting surfaces demonstrated EOFs that were nearly an order of magnitude smaller than native PMMA. In addition, these LPA-coated devices could produce highly reproducible migration times of over approximately 20 runs with plate numbers exceeding 10(5) m(-1). Using gel electrophoretic analysis of a single base track generated from an M13mp18 template using Sanger cycle sequencing and dye-primer chemistry, the resolution value obtained for bases 199 and 200 was 0.18 while for bases 208 and 209 it was 0.21. For the native PMMA, these bands were found to comigrate.

Thermoplastic microfluidic devices and their applications in protein and DNA analysis

“…For instance, Soper’s research group reported formation of a layer of linear polyacrylamide on the channel surfaces of a PMMA device via an amide bond and they achieved high-resolution electrophoretic separation of single-stranded DNA with a single base pair resolution. 64 Polyacrylamide can also be coated on the surfaces of PMMA, COC and polycarbonate via photografting. 32,65 Other materials such as poly(ethylene glycol) (PEG) have also been grafted onto the channel surfaces of a PMMA device for electrophoresis of proteins and peptides.…”

Fabrication, modification, and application of poly(methyl methacrylate) microfluidic chips

“…Soper and co-workers [53] have developed a simple grafting procedure to allow the formation of linear polyarcylamides onto a PMMA microfluidic device to suppress the EOF and minimize potential solute-wall interactions. The procedure involved creating an amine-terminated PMMA surface by appropriately functionalizing the PMMA through either a chemical or photochemical process.…”

Improving the separation efficiency of DNA biosamples in capillary electrophoresis microchips using high-voltage pulsed DC electric fields

“…DNA separation is an essential operation in many genetic engineering processes and is commonly performed when executing biochemical and biological analyses (Bown and Meinhart 2006;Das et al 2006;Gutsche et al 2006;Szantai and Guttman 2006;Wang et al 2006Liu et al 2007Llopis et al 2007;Ohashi et al 2007;Prakash and Kaler 2007;Sun et al 2007). However, the conventional slab-gel DNA separation method has a number of drawbacks, including a long separation time, an excessive sample consumption and a low separation efficiency.…”