Monolithic Superhydrophobic Polymer Layer with Photopatterned Virtual Channel for the Separation of Peptides Using Two-Dimensional Thin Layer Chromatography-Desorption Electrospray Ionization Mass Spectrometry

Abstract

Superhydrophobic monolithic porous polymer layers with a photopatterned hydrophilic channel have been prepared. These layers were used for two-dimensional thin layer chromatography of peptides. The 50 μm thin poly(butyl methacrylate-co-ethylene dimethacrylate) layers supported onto 4.0 × 3.3 cm glass plates were prepared using UV-initiated polymerization in a simple glass mold. Photografting of a mixture of 2-acrylamido-2-methyl-1-propanesulfonic acid and 2-hydroxyethyl methacrylate carried out through a mask afforded a 600 μm wide virtual channel along one side of the layer. This channel, which contains ionizable functionalities, enabled the first dimension separation in ion exchange mode. The aqueous mobile phase migrates only through the channel due to the large difference in surface tension at the interface of the hydrophilic channel and the superhydrophobic monolith. The unmodified part of the layer featuring hydrophobic chemistry was then used for the reversed phase separation in the orthogonal second dimension. Practical application of our technique was demonstrated with a rapid 2D separation of a mixture of model peptides differing in hydrophobicity and isoelectric point using a combination of ion-exchange and reversed phase modes. In the former mode, the peptides migrated 11 mm in less than 1 min. Detection of fluorescently labeled peptides was achieved through UV light visualization. Separation of the native peptides was monitored directly using a desorption electrospray ionization (DESI) source coupled to a mass spectrometer. Unidirectional surface scanning with the DESI source was found suitable to determine both the location of each separated peptide and its molecular mass.

Atomic layer deposition of aluminum-free silica onto patterned carbon nanotube forests in the preparation of microfabricated thin-layer chromatography plates

“…From Poole and Poole [38], the variance in the band, σ 2 chrom , was taken as: (6) where σ 2 obs is the variance of the separated (developed) analyte band, σ 2 SA is the variance of the band at its point of application, and σ 2 den is the variance of the densitometer used. Here, σ 2 den = 0 (no densitometer was used).…”

“…Of late, various research groups have shown interest in developing TLC plates with new materials and fabrication techniques. These include monolithic silica [1], glancing angle deposition (GLAD) [2][3][4], polymer monoliths [5][6][7][8], and electrospun polymers [9,10]. Our group has also been active in this area, reporting TLC plates with high efficiencies and short run times prepared from microfabricated, patterned, and infiltrated carbon nanotube (CNT) forests [11][12][13][14].…”

A Facile Approach to Superhydrophilic–Superhydrophobic Patterns in Porous Polymer Films

“…We recently have shown an application of such virtual microfl uidic channels for two-dimensional peptide separation. [ 16 ] Herein, we demonstrate the versatility of the approach by using two hydrophilic monomers to produce superhydrophilic patterns with positively or negatively charged surface functional groups, different pattern geometries, and with feature sizes down to several micrometers. STC microchannels have been prepared inside porous polymer fi lms with different thicknesses and with both microand nanoporous structures.…”

Retention and separation efficiency of some synthetic oligopeptides in reversed-phase thin-layer chromatography

“…Hovewer, TLC enables to evaporate the mobile phase components from the adsorbent layer before MS analysis. Separation of peptides in TLC system with mobile phase comprised of trifluoroacetic acid and combination of it with mass spectrometry were presented before [11,12]. No problems with interferention of trifluoroacetic acid in MS detection were reported.…”