Three-dimensional ultralarge-pore Ia3d mesoporous silica with various pore diameters and their application in biomolecule immobilization

Highly ordered mesoporous three-dimensional Ia3d silica (KIT-6) with different pore diameters has been synthesized by using pluronic P123 as surfactant template and n-butanol as cosolvent at different synthesis temperatures in a highly acidic medium. The materials were characterized by XRD and N₂ adsorption. The synthesis temperature plays a significant role in controlling the pore diameter, surface area, and pore volume of the materials. The material prepared at 150°C, KIT6-150, has a large pore diameter (11.3 nm) and a high specific pore volume (1.53 cm³ g ^-1). We alsodemonstrate immobilization of lysozyme, which is a stable and hard protein, on KIT-6 materials with different pore diameters. The amount of lysozyme adsorbed on large-pore KIT-6 is extremely large (57.2 μmolg ^-1) and is much higher than that observed for mesoporous silicas MCM-41, SBA-15, and KIT-5, mesoporous carbons, and carbon nanocages. The effect of various parameters such as bufferconcentration, adsorption temperature, concentration of the lysozyme, and the textural parameter of the adsorbent on the lysozyme adsorption capacity of KIT-6 was studied. The amount adsorbed mainly depends on solution pH, ionic strength, adsorption temperature, and pore volume and pore diameter of the adsorbent. The mechanism of adsorption on KIT-6 under different adsorption conditions is discussed. In addition, the structural stability of lysozyme molecules and the KIT-6 adsorbent before and after adsorption were investigated by XRD, nitrogen adsorption, and FTIR spectroscopy.