Electrophoresis or electrochromatography carried out in nanometer columns (width and depth) offers some attractive benefits compared to microscale columns. These advantages include unique separation mechanisms that are scale dependent, fast separation times, and simpler workflow due to the lack of a need for column packing and/or wall coatings to create a stationary phase. We report the use of thermoplastics, in this case PMMA, as the substrate for separating single‐stranded DNAs (ssDNAs). Electrophoresis nanochannels were created in PMMA using nanoimprint lithography (NIL), which can produce devices at lower cost and in a higher production mode compared to the fabrication techniques required for glass devices. The nanochannel column in PMMA was successful in separating ssDNAs in free solution that was not possible using microchip electrophoresis in PMMA. The separation could be performed in <1 s with resolution >1.5 when carried out using at an electric field strength of 280 V/cm and an effective column length of 60 μm (100 nm × 100 nm, depth and width). The ssDNAs transport through the PMMA column was driven electrokinetically under the influence of an EOF. The results indicated that the separation was dominated by chromatographic effects using an open tubular nano‐electrochromatography (OT‐NEC) mode of separation. Interesting to these separations was that no column packing was required nor a wall coating to create the stationary phase; the separation was affected using the native polymer that was UV/O3activated and an aqueous buffer mobile phase.
Reversed phase and size‐exclusion chromatography methods are commonly used for protein separations, although they are based on distinctly different principles. Reversed phase methods yield hydrophobicity‐based (loosely‐termed) separation of proteins on porous supports, but tend to be limited to proteins with modest molecular weights based on mass transfer limitations. Alternatively, size‐exclusion provides complementary benefits in the separation of higher mass proteins based on entropic, not enthalpic, processes, but tend to yield limited peak capacities. In this study, microbore columns packed with a novel trilobal polypropylene capillary‐channeled polymer fiber were used in a reversed phase modality for the separation of polypeptides and proteins of molecular weights ranging from 1.4 to 660 kDa. Chromatographic parameters including gradient times, flow rates, and trifluoroacetic acid concentrations in the mobile phase were optimized to maximize resolution and throughput. Following optimization, the performance of the trilobal fiber column was compared to two commercial‐sourced columns, a superficially porous C4‐derivatized silica and size exclusion, both of which are sold specifically for protein separations and operated according to the manufacturer‐specified conditions. In comparison to the commercial columns, the fiber‐based column yielded better separation performance across the entirety of the suite, at much lower cost and shorter separation times.
more » « less- Award ID(s):
- 2107882
- PAR ID:
- 10446184
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Journal of Separation Science
- Volume:
- 45
- Issue:
- 9
- ISSN:
- 1615-9306
- Page Range / eLocation ID:
- p. 1502-1513
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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