Electrokinetic studies of inorganic coated capillaries

doi:10.1016/S0378-4347(94)80005-7

Journal of Chromatography B: Biomedical Sciences and Applications

Volume 657, Issue 2, 15 July 1994, Pages 285-290

https://doi.org/10.1016/S0378-4347(94)80005-7 Get rights and content

Abstract

The procedures for the preparation of silica capillaries coated with titanium oxide or aluminum oxide are developed. These inorganic coated capillaries are studied for their applicability in capillary electrophoresis. The points of zero charge are measured as pH 5 and pH 7 for titanium oxide- and aluminum oxide-coated capillaries, respectively. Both titanium oxide and aluminum oxide coatings give better protein separations in comparison to the use of fused-silica capillaries. Separation efficiency of lysozyme as model protein is measured in the range of 20 000 theoretical plates/m of inorganic coated capillaries. However, the hydrophobic interaction between proteins and modified capillary wall possibly contributes to the tailing of observed protein peaks.

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A novel core–shell composite (SiO₂–nLPD), consisting of micrometer-sized silica spheres as a core and nanometer titania particles as a surface coating, was prepared by liquid phase deposition (LPD). Here, we show the resulting core–shell composite to have better efficient and selective enrichment for mono- and multi-phosphopeptides than commercially available TiO₂ spheres without any enhancer. The material exhibited favorable characteristics for HPLC, which include narrow pore size distribution, high surface area and pore volume. We also show that the core–shell composite can efficiently separate adenosine phosphate compounds due to the Lewis acid–base interaction between titania and phosphate group when used as HPLC packings. After coating the silica sphere with titania by LPD, the silanol of silica spheres will be shielded and that the stationary phase, C₁₈ bonded SiO₂–3LPD, could be used under extreme pH condition.
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While most chronic diseases are on the decline, medical pulmonary disease is on the increase. The unrelenting nature of chronic lung disease has long energized the pulmonary community to seek technologies to replicate the capacity of the lungs to exchange oxygen for carbon dioxide. While most such artificial lung technologies work by delivering oxygen to the blood through a system of hollow fibers or tubes, our approach employs photolytic energy to generate oxygen from the water already present in blood, thus eliminating the need for gas delivery. To this end, progress in the development of a photolytic artificial lung (PAL) is reported. The device provides photolytically driven electrochemistry for blood oxygenation or for maintenance of breathing air in confined spaces. The device is based on the catalyzed photoactivity of a transition metal oxide such as titanium dioxide (TiO₂). Photoactive anatase TiO₂ films have been developed for use in a photolytic artificial lung. The PAL is capable of facilitating gas exchange in the blood, thereby bypassing alveolar–capillary interfaces. The device will eventually be used in ex-vitro and in-vitro devices. The direct photolytic process, using UV laser radiation, converts water to liquid phase oxygen (dissolved oxygen), with commensurate reduction of carbon dioxide. The test cell consisted of an indium tin oxide coating, an anatase TiO₂ coating (∼2 μm thick), and a MnO₂ overcoat deposited on fused silica by reactive magnetron sputtering. Blood flowed over the coated side and oxygen exchange occurred at the MnO₂ interface. Three hundred and fifty-four nanometers UV radiation was incident on the silica/indium tin oxide (ITO) side. Electron–hole pairs were generated in the TiO₂ layer by the laser radiation, which catalyzed a redox reaction with water in the blood. The MnO₂ was also used as a catalyst to dissolve oxygen in the blood. Oxyhemoglobin increased as much as 90% with this process. The maximum rate of oxygen generation was 1.08 ml O₂/(m² min), thus projecting an alveolar surface area of 75 m². We conclude that it is feasible to photolytically oxygenate the hemoglobin contained in whole blood with oxygen derived from the blood's own water content.
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Journal of Chromatography B: Biomedical Sciences and Applications

Electrokinetic studies of inorganic coated capillaries

Abstract

J. Colloid Interface Sci.

J. Chromatogr.

J. Chromatogr.

J. Chromatogr.

J. Colloid Interface Sci.

J. Chromatogr.

J. Colloid Interface Sci.

J. Colloid Interface Sci.

J. Colloid Interface Sci.

J. Chromatogr.

Clin. Chem.

Application of liquid phase deposited titania nanoparticles on silica spheres to phosphopeptide enrichment and high performance liquid chromatography packings

Preparation of a TiO<inf>2</inf> nanoparticle-deposited capillary column by liquid phase deposition and its application in phosphopeptide analysis

Recent advances in analytical chemistry - A material approach

Progress towards development of a photolytic artificial lung

High pH-resistant, surface-bonded sol-gel titania hybrid organic-inorganic coating for effective on-line hyphenation of capillary microextraction (in-tube solid-phase microextraction) with high-performance liquid chromatography

Nonaqueous capillary electrophoresis using a titania-coated capillary