Diamond Based Biosensors: Surface-Fluid Interaction Issues

The interaction of nanocrystalline (NCD) and microcrystalline (MCD) p-type semiconducting diamond surfaces with phosphate buffer saline (PBS), simulated body fluid (SBF) and bovine serum albumin (BSA) solutions under applied electric potentials is the main subject of this work. The effect of these fluids on the electrical resistivity of the diamond surface is evaluated. Furthermore, the interaction effects of these surfaces with BSA containing SBF solution during 30 days, is addressed.The electrical measurements have shown that the electrical current passing through the NCD samples is influenced by the fluid's ionic composition, whereas no variation was detected for the MCD samples. Both NCD and MCD surfaces favor the formation of a deposit layer after 30 days in contact with SBF+BSA solution. This deposit is mainly composed of Ca, P, Mg and O, containing also a significant concentration of BSA proteins.