Selective growth of carbon nanotubes on boron-doped diamond for electrochemical biosensor application

A method for selective and direct growth of multi-wall carbon nanotubes (MWCNTs) on boron-doped diamond (BDD) was developed using electrostatic self-assembly of catalytic nanoparticles via a conventional photolithography method. As catalysts, stainless steel 316L (SUS316L) nanoparticles consisting of catalytic ions such as Fe and Ni were introduced. As-grown MWCNTs had a porous random-network structure that was suitable for electrochemical biosensor application. The electrochemical properties of the electrodes were characterized using cyclic voltammetry and electrochemical impedance spectroscopy. The effective surface area of the as-developed BDD/MWCNT electrode was larger than that of the BDD electrode and its electron transfer resistance was about 40 Ω, which is around 16 times higher than that of the BDD electrode. To evaluate the biosensing performance, glucose was chosen as a target analyte. The BDD/MWCNT electrode exhibited a higher sensitivity of 7.2 μA mM^-1 cm^-2 (R = 0.9943) with a wider linear range than did the BDD electrode, because of the synergistic effect between the MWCNTs and BDD.