Adsorption of globin proteins in mesoporous (designed) titania for biosensors development

Mesoporous materials are ideal substrates for the incorporation and immobilizations of proteins due to their high surface area, pore volume and the possibility to obtain a very homogeneous, controllable pore size. Mesoporous... [ view full abstract ]

Mesoporous materials are ideal substrates for the incorporation and immobilizations of proteins due to their high surface area, pore volume and the possibility to obtain a very homogeneous, controllable pore size. Mesoporous TiO2 could be very promising with respect to the possible joined effects of semiconductor properties and redox active proteins. However, the controlled synthesis of titanium dioxide is a challenging step often leading to disordered mesoporous structures and non-uniform pore networks.
We successfully synthesised highly ordered mesoporous titania with differnt pore diameters, homogeneous pore size, large surface area and pore volume.
The designed mesoporous titanium dioxide with different pore sizes has been used for the adsorption of horse hearth myoglobin (hhMb); a globular shape proteins with a mean diameter of 5 nm. The effect of different parameters (buffer type and concentration, solution pH) on the incorporation and the rate of the adsorption have been studied in depth. The encapsulation rate has been monitored by UV-vis spectroscopy and a kinetic model for the adsorption has been elaborated. TGA/DTG, FT IR, UV DR spectroscopy and electron paramagnetic resonance (EPR) have been used to detect changes in the secondary structure or in the heme center upon the adsorption. The stability of the encapsulated hhMb has been evaluated by its electrochemical activity (Cyclic Voltammetry) and peroxidase like activity in the presence of ABTS. The results clearly show the beneficial effect of the incorporation into the pores. The study of the adsorption of human neuroglobin on both unmodified and functionalized mesoporous titania will be the next step of this work.