Monolithic polymer layer with gradient of hydrophobicity for separation of peptides using two‐dimensional thin layer chromatography and MALDI‐TOF‐MS detection

Abstract

Superhydrophobic monolithic porous polymer layers supported onto glass plates with a gradient of hydrophobicity have been prepared and used for 2-D thin layer chromatography of peptides. The 50 μm-thin poly(glycidyl methacrylate-co-ethylene dimethacrylate) layers prepared using UV-initiated polymerization in a simple mold were first hydrolyzed using dilute sulfuric acid and then hydrophilized via two-step grafting of poly(ethylene glycol) methacrylate to obtain superhydrophilic plates. The hydrophobicity was then formed by photografting of lauryl methacrylate. The exposure to UV light that initiates photografting was spatially controlled using moving shutter that enabled forming of the diagonal gradient of hydrophobicity. This new concept enables the solutes to encounter the gradient for each of the two sequential developments. Practical application of our novel plates was demonstrated with a rapid 2-D separation of a mixture of model peptides gly-tyr, val-tyr-val, leucine enkephalin, and oxytocin in dual reversed-phase mode using different mobile phases in each direction. Detection of fluorescent-labeled peptides was achieved through UV light visualization while separation of native leucine enkephalin and oxytocin was monitored directly using MALDI mass spectrometry.

Microfabrication, separations, and detection by mass spectrometry on ultrathin-layer chromatography plates prepared via the low-pressure chemical vapor deposition of silicon nitride onto carbon nanotube templates

“…Recently, several unconventional methods and materials have been used for nanostructured or binder-free ultrathin-layer chromatography (UTLC) plate manufacture. These include glancing angle deposition (GLAD) [1][2][3], monoliths [4][5][6][7][8][9][10], and electrospun polymers [11][12][13][14]. To this end, patterned, infiltrated, microfabricated carbon nanotube (CNT)-templated UTLC plates based on a zigzag geometry have also been introduced [15][16][17][18][19].…”

“…Next, a fast (ca. 10 deposition of silicon dioxide was investigated [20]. Unfortunately, this silica did not adhere well to the rather inert CNTs so it was necessary to chemically modify them prior to this deposition.…”

Simple thin layer chromatography–ultraviolet spectrophotometric method for quality assessment of binary fixed‐dose‐combinations of lamivudine/tenofovir disoproxil fumarate and lamivudine/zidovudine in tablet formulations

“…TLC has been used for routine analysis in various fields of chemistry and applied chemistry for separation and determination of numerous classes of compounds [22]. The use of improved silica gel (without binders) and other polymeric monolithic thin‐layer sorbents (like acrylic and styrene ploymers) have led to achieving separation features such as short elution distances and time, high analysis throughput, high sensitivity, and low consumption of solvents and reagents [23,24]. The application of small silica gel thickness layer and the structural properties of these polymeric sorbents gave rise to the monolithic silica gel ultra‐thin layer chromatography (UTLC) plates and high‐performance TLC (HPTLC), with separation patterns that differ significantly from those of traditional TLC [22].…”

Controlling selectivity of polymer-based monolithic stationary phases

“…We have incorporated phosphorylcholine functionality monomer onto a sulfobetaine-based monolithic column. This process was achieved by a two-step photografting process [37] -initially introduced to the field of monolithic stationary phases by Svec [38][39][40][41][42][43][44] -to segmentally modify sulfobetaine zwitterionic stationary phases with phoshorylcholine functionality leading to a preparation of stationary phases possessing dual-functionality. Length of modified segment and mobile phase composition has been thoroughly optimized.…”