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Apatite films have been grown by a method involving both physical and chemical processes. The spontaneous nucleation of apatite crystals on the surface of Ti/Si and Si substrates was activated by applying positive constant potentials. The surface morphology and microstructure of these films have been studied. Several apatite-like nanocrystals have been observed in the bulk by high-resolution transmission electron microscopy. We also observed ordered structures with atomic resolution on the surface using atomic force microscopy. The results of the combined characterization suggest that this is a useful technique for low-temperature deposition of thin apatite films on both semiconductor and metallic substrates.

A novel deposition technique for the bio-functionalization by amine groups of surfaces of materials is presented. The process is based on the activation at high temperature of 3-aminopropyltrietoxysilane (3-APTS) molecules in vapor phase immediately before impinging on the substrate. Materials such as silicon, porous silicon, and titanium were chosen to demonstrate the validity of the process on surfaces with very different chemical properties. The effect of the activation process on the surface was evaluated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and x-ray diffraction (XRD). In addition, the reactivity under mild reaction conditions of the functionalized surfaces was determined by using a fluorescent reagent that specifically reacts with amine groups. From the experimental results it can be concluded that the proposed activation method induces amino-group fixation on the surface of materials, ranging from semiconductors to metals and insulating materials.

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