Hard-templating synthesis of mesoporous carbon spheres with controlled particle size and mesoporous structure for enzyme immobilization

Mesoporous carbon spheres (MCSs) with controlled particle size and pore structure were synthesized via a combined hard templating and sol–gel processing within water-in-oil emulsions, using resorcinol–formaldehyde polymer as carbon precursor and colloidal silica nanoparticles as hard templates. The addition of silica nanoparticles in polymer sol not only served as the pore structure reagents but also shortened the gelation time, making it easy to control the emulsion process. The sphere size of MCSs can be controlled in the range from 10 to 500 μm by changing the emulsification conditions. The pore structure of MCSs can be tuned by adjusting the mass ratio of resorcinol–formaldehyde polymer to silica nanoparticles and the diameter of silica nanoparticles. The as-prepared MCSs possessed large surface area (>600 m2 g−1), large pore volume (>1 cm3 g−1) and a narrow pore size distribution replicated from the silica nanoparticles used. These MCSs exhibited extraordinary high adsorption capacities (ca. 1100 mg g−1) for α-Chymotrypsin (Chy) in solution. Due to their well-developed pore structure and the controllable pore size, as well as the unique shape and good affinity to biomolecules, the as-prepared MCSs should have a good potential in enzyme immobilization.