Development of Macroporous Titania Monoliths Using a Biocompatible Method. Part 1:  Material Fabrication and Characterization

Abstract

Monolithic titania could offer significant potential as a support for bioaffinity chromatography because of its stability, unlike silica, to a wide range of pH conditions and its ability to selectively bind phosphorylated proteins and peptides. However, traditional routes to monolithic titania utilize harsh conditions incompatible with most biomolecules. To address this, titania monoliths were prepared in a biocompatible sol−gel process from Ti(OiPr)4 and glycerol. Varied porosities could be introduced by the additional use of high-molecular-weight poly(ethylene oxide) in the sol, which led to the formation of two phases prior to gelation. Morphologies, including bimodal meso- and macroporous structures, and the polymerization of either the dispersed or condensed phases could be controlled by the fraction and molecular weight of PEO in the sol. The roles of glycerol and PEO are to retard hydrolysis and condensation reactions so that phase separation of titanium-rich species precedes gelation processes. PEO also facilitates aggregation of growing TiO2 oligomers and particles.

Solvothermal Synthesis, Characterization, and Formation Mechanism of a Single‐Layer Anatase TiO2 Nanosheet with a Porous Structure

“…In this process, as a polyol, glycerol can participate in intramolecular reactions that reform alkoxytitanates and form nanosheet structures in the present system, leading to the complex carbon chemical environments. [33] Figure 6. Solid-state CP/MAS 13 C NMR spectrum of the precursor prepared from the 24 h solvothermal reaction (A) and solution spectrum of pure glycerol (B).…”

Nano-Doped Monolithic Materials for Molecular Separation

“…Despite these unique features, the challenge in incorporating titania into monoliths as a chromatographic adsorbent include their fast hydrolysis/condensation kinetics, denaturing of proteins from isopropyl alcohol byproducts, and mechanisms to control and engineer pore formation [142,143]. A technique to overcome these setbacks was attempted by Chen, Yi, Brennan, and Brook [142] through the introduction of glycerol and high molecular weight poly(ethylene oxide) to control the kinetic reactions, phase separations, and pore formation of titania monoliths.…”

“…Despite these unique features, the challenge in incorporating titania into monoliths as a chromatographic adsorbent include their fast hydrolysis/condensation kinetics, denaturing of proteins from isopropyl alcohol byproducts, and mechanisms to control and engineer pore formation [142,143]. A technique to overcome these setbacks was attempted by Chen, Yi, Brennan, and Brook [142] through the introduction of glycerol and high molecular weight poly(ethylene oxide) to control the kinetic reactions, phase separations, and pore formation of titania monoliths. Some of the other reported techniques utilised in the preparation of titanium monoliths include; (i) sol-gel [144]; phase separation induced [145]; template free sol-gel process with phase separation [146]; templated sol-gel process [147].Černigoj, Gašperšič, Fichtenbaum, Lendero Krajnc, Vidič, Mitulović, and Štrancar [140] recently created a methacrylate based monolith with immobilised TiO 2 nanoparticles for the enrichment of phosphorylated peptides under low salt concentrations and wide pH variation.…”

Preparing titania aerogel monolithic chromatography columns using supercritical carbon dioxide

“…The monolithic TiO 2 column was tested for its characteristic enrichment of phosphopeptides. A mixture containing a synthetic phosphopeptide (synthesized using the standard FMOC protocol [34]) (SHELEpSpSpSSEVN, [M12H] 21 5 772.73 m/z) at a concentration of 2 pmol/mL, and a non phosphorylated peptide, Glufib (EGVND-NEEGFFSAR, [M12H] 21 5 785.84 m/z, Sigma), at a concentration of 10 pmol/mL, were used for the separation tests. The enrichment experimental conditions were based on a previously reported method [13].…”

“…In addition, TiO 2 has a higher chemical stability than SiO 2 , particularly under alkaline conditions, which makes it attractive for chromatography stationary materials [19]. However, it is very challenging to prepare TiO 2 monolith because of its fragility [20]; thus very few reports on monolithic TiO 2 synthesized by sol-gel technique have been documented [21,22].…”