Interfacing boron doped diamond and biology: An insight on its use for bioanalytical applications

Boron doped diamond (BDD) films are promising materials for electroanalysis and bioelectroanalysis. This contribution gives a short review on BDD functionalization by chemical and biochemical entities and on the applications of BDD electrodes to electroanalysis of chemical compounds of biological interest. This review is illustrated by the developments on BDD interfaces in both these areas carried out in our group. BDD electrodes were prepared by means of microwave plasma-assisted CVD onto silicon substrate giving rise to H-terminated BDD films. Anodic polarization of BDD electrodes in aqueous media generates hydrophilic oxidized surfaces and extended electrochemical window in aqueous media. We took advantage of this enlarged electrochemical window together with the hydroxylated surface for the functionalization of BDD electrode surfaces with biomolecules and for bioelectroanalysis. We have designed a novel route of BDD functionalization using OH terminations of the anodized surface. The modification of the BDD surface with biotin groups will be presented here as biologically active model. Furthermore, as the anodic potential window of BDD increases upon electrochemical activation, 2'-deoxyguanosine (1.2 V vs. Ag/AgCl) and 2'-deoxyadenosine (1.5 V vs. Ag/AgCl) could be detected electrochemically with an acceptable signal to noise ratio. The electrochemical signature of each oxidizable base was assessed using differential pulse voltammetry (DPV). These experiments pointed towards adsorption of the oxidized products, which were investigated macroscopically by DPV and at the microscopic level by SECM (scanning electrochemical microscopy).