Nitrogen incorporated nanodiamond film with ‘ridge’ surface morphology for detection of bio-analyte

Abstract

A planar electrode consisting of a nanodiamond film on a silicon substrate was fabricated using microwave plasma enhanced chemical vapor deposition technique. Nitrogen incorporation was achieved by the introduction of N 2 gas along with H 2 and CH 4 gases in the plasma. The electrochemical response of the electrode was evaluated by studying the Fe(CN) 6 3-/4- redox couple. Cyclic voltammetry was also used to study the detection of dopamine (DA), which is an important neurotransmitter, in 0.1 M phosphate buffered saline (PBS) at the physiologic pH of 7.4. The nitrogen incorporated nanodiamond electrode showed a linearly increasing peak oxidation current with increasing dopamine concentration at a scan rate of 100 mV/s. Also, a linear relationship between the peak oxidation current for 1 mM DA vs √(scan rate) was observed which is consistent with semi-infinite linear diffusion limited mass transport mechanism. In addition to the well-defined dopamine/o-quinone redox peaks, we also detected another pair of peaks corresponding to the leucodopaminechrome/dopaminechrome redox couple. These results have been achieved using ‘as-deposited’, hydrogen terminated, nitrogen incorporated nanodiamond electrode without any surface modification or pretreatment.