Gold Nanoparticle-Modified Etched Capillaries for Open-Tubular Capillary Electrochromatography

Abstract

The use of gold nanoparticles in conjunction with etched capillary-based open-tubular capillary electrochromatography (OTCEC) to improve the efficiency of separation and the selectivity between selected solutes is described. The fused-silica capillaries (50-microm i.d.) were etched with ammonium hydrogen difluoride, followed by prederivatization of the new surface with (3-mercaptopropyl)trimethoxysilane (MPTMS) for the immobilization of dodecanethiol gold nanoparticles, for OTCEC. The electrochromatography of a "reversed-phase" test mixture and of selected polycylic aromatic hydrocarbons was investigated, and efficient separations and high theoretical plate numbers per meter were obtained. The electroosmotic flow characteristics of the etched gold nanoparticle capillary, unetched gold nanoparticle capillary, bare capillary, and etched bare capillary were studied by varying the percentage of organic modifier in buffer, buffer pH, and separation voltage. Optical microscopy and scanning electron microscopy were used to examine the process of etching and modification and the surface features of the etched gold nanoparticle capillary. The results confirm that dodecanethiol gold nanoparticles bonded on the etched inner wall of the fused-silica capillary can provide sufficient solute-bonded phase interactions to obtain OTCEC separations with reproducible retention, as well as characteristic reversed-phase behavior, even with the inner diameter of the capillary of 50 microm.

Open‐tubular capillary electrochromatography using a capillary coated with octadecylamine‐capped gold nanoparticles

“…However, gold nanoparticles acting as coating materials have been employed in OTCEC to enhance the separation efficiency by only a few groups [13][14][15][16]. Glennon and co-workers [13] reported the immobilized dodecanethiol gold nanoparticles on prederivatized 3-aminopropyltrimethoxysilane (APT-MS) or 3-mercaptopropyltrimethoxysilane (MPTMS) fused-silica capillaries, which confirmed the use of gold nanoparticles as a novel stationary phase for OTCEC.…”

“…Open tubular capillaries have advantages over packed capillary columns in several aspects including ease of preparation, no bubble formation, and simple instrumental handling. The main methods used to prepare the stationary phase for the open tubular CEC (OTCEC) include chemical bonding [1][2][3][4], sol-gel derived phases [5,6], molecular imprinting [7], porous layers [8,9], physical coating [10][11][12], and nanoparticle phases [13][14][15][16][17][18]. Among these techniques, coating of capillaries with nanoparticles provided high separation efficiencies for various analytes [19].…”

Polyhedral oligomeric silsesquioxanes as functional monomer to prepare hybrid monolithic columns for capillary electrochromatography and capillary liquid chromatography

“…Taken advantage of their property of large surface area, to date, the nanostructured materials, such as carbon nanotubes, silica, magnetic and non-magnetic metal oxides, silver and gold nanoparticles, have been adopted in chromatographic and electrophoretic techniques, in which nanoparticles serve as additives, or permanent/dynamic capillary inner surface coatings in capillary electrophoresis (CE) [2][3][4][5], as stationary phases in capillary electrochromatography (CEC) [6][7][8][9][10][11][12] and gas chromatography (GC) [13,14], as well as liquid chromatography (LC) [15].…”

Electrophoretic Separation of Proteins in Capillaries Filled with Poly(ethylene oxide)-stabilized Silver Nanoparticles

“…Dodecanethiol-protected NPs has been demonstrated as efficient stationary phase for gas chromatography in separating organic compounds. 7,8 NPs were also used in electrophoresis techniques, either as modifiers to the wall of capillary or microchip, [9][10][11][12] or as pseudostationary phases (PSPs) in which they were added into the running buffers. [13][14][15] NPs used as PSPs can be replaced from run to run, and the stationary carry-over effects are thus avoided, favoring sample analysis in complex matrices.…”