Inorganic Porous Bulk Discs as a Matrix for Thin-Layer Chromatography and Translucent Hard Composite Materials

Magnesium-stabilized amorphous calcium carbonate (Mg-ACC), amorphous magnesium calcium silicate hydrate (MCSH), and hydroxyapatite (HAp) are prepared by a precipitation method. By cold-pressing these particles, it is possible to produce porous bulk discs with a narrow pore size distribution. These porous inorganic discs (Mg-ACC, MCSH, and HAp) are investigated as stationary phases to study the chromatographic behavior and adsorption ability of rhodamine B, methylene blue, and ribonuclease. The adsorption affinities of different biomolecules can be easily observed and evaluated through this method. Furthermore, by infiltrating fabricated opaque porous discs with benzyl ether, which has a similar refractive index as the used inorganic particles (Mg-ACC, MCSH, and HAp), their optical properties significantly change and the discs become translucent. Moreover, by infiltrating the MCSH discs with a light-curing polymer, translucent composites with good surface hardness are fabricated. By doping particles with ions such as Ni²⁺, Co²⁺, Fe³⁺, and Eu³⁺, the color and UV-visible spectrum of the bulk discs can be adjusted. Typically, by using iron-doped MCSH particles as the inorganic matrix, nanocomposites, which show a steep UV-absorption edge at 400 nm, are fabricated. Our work provides a simple and economical method to evaluate the affinity of biomolecules to inorganic materials and a novel way to fabricate translucent hard composite materials. The fabricated nanocomposite discs show a great UV shielding effect and superior surface hardness compared to polymethyl methacrylate and commercial sunglasses, suggesting their potential as new sunglass materials.