Functionalization of nanostructured porous silicon microcavities for glucose oxidase detection

Stable porous silicon microcavities (PSiMcs) are designed in order to detect the confined glucose oxidase (GOX) at low concentration. A chemical pathway is proposed to functionalize and stabilize porous silicon structures that are primordial for further effective molecular confinement. The procedure avoids the preliminary thermal oxidation of the PSi surface and consists of a direct surface oxidation during the silanization process, an amino activation by a linker that also prevents further oxidation, and the binding of the GOX enzyme. Functionalization and protein confinement are monitored by the narrow resonance peaks in the near-infrared region (700–1000 nm) of the engineered meso- and macroporous microcavities. Protein penetration along the entire, large pore sized structure is demonstrated. The protein retains its native form within the properly functionalized PSi structures, which are ideal for molecular sensing also due to their high quality factor. A detection resolution of 25 nM GOX has been determined, thus demonstrating the high quality sensing of our functionalized porous silicon microcavity structures.