Mesoporous protein particles through colloidal CaCO3 templates

Porous colloidal particles can be tailored using templating techniques to maximize their effectiveness for a wide range of applications, including separation, catalysis, and drug delivery. However, templating usually involves harsh and complex preparation conditions, thereby complicating the fabrication of sensitive bio-functionalized particles. Here a simple, yet versatile and mild approach us used to create porous protein particles using mesoporous CaCO3 colloids as sacrificial templates. The three-step preparation procedure involves infiltrating the colloidal templates with the protein by solvent evaporation, protein crosslinking, and removal of CaCO3. Using this method one can obtain porous particles consisting of virtually any protein. To explore the applicability of the particles for various scenarios particles composed of different proteins are fabricated focusing on hemoglobin and trypsin and particle morphology, porosity, mechanical properties, the protein redox state, and enzymatic activity are determined. The results show that the nanoporous template structure is replicated and that the proteins are fully functional. By varying preparation conditions such as crosslinker concentration and protein content the elastic modulus is adjusted in the range of red blood cells. This ensures high deformability upon flow in microchannels and makes the porous protein particles a versatile platform for biomedical applications.