Design of molecular devices based on metalloproteins: a new approach

In this study, cytochrome c and azurin proteins were immobilized onto a porous silicon (PS) surface using the self-assembly technique. The heterostructures were maintained at ambient conditions for several days. Experimental results showed long term stability of proteins in solid state working as electron-transfer devices. Atomic force microscopy showed similar roughness of the surface for both protein heterostructures (14.5 and 11.3 nm, respectively) and globular morphology. Analysis of samples, using scanning electron microscopy, revealed a porous surface of 20–24 nm, whereas cross-section indicated a thickness between 3.6 and 3.8 μm. The fluorescence peak at room temperature, corresponding to blue emission, was observed at 362–550 nm. This is due to the quantum confinement effect through the silicon. Raman measurement showed one Raman’s peak, confirming that the prepared sample retained the crystallinity of bulk silicon; immobilization of proteins produced loss of crystallinity. Reflection spectra revealed the PS, changes in the refractive index profile at the interface of the PS, and the modified surface.