Abstract
Abnormal dopamine level in human body is related to some diseases. However, traditional dopamine sensing methods were confronted with problems such as interference and biofilm-fouling. This study adopted electrochemical method to detect dopamine, and the electrode we used was conductive nitrogen-incorporated ultrananocrystalline diamond (NUNCD) films which were prepared through the biased enhanced growth method. The synthesis conditions for NUNCD were 1400 W plasma power, -300 V applied bias at the substrate, 50 torr chamber pressure, and deposition for 1 hour. The best resistivity of the film was about 63.15 μΩ·cm. For the dopamine detection in the phosphate buffer solution, the detection limit was about 0.32 μM. In addition, detection of dopamine in the presence of ascorbic acid and uric acid were performed and it is found that the detection limit was not affected by the interference of biomolecules and the electrode showed good selectivity. In fetal bovine serum, the electrode also performed excellently with a detection limit of about 0.39 μM. We also built up calibration curves and equations to calculate the content of the dopamine in a blind sample. By substituted the current, obtained from the result of differential pulse voltammetry, into the equation and calculated the dopamine level, we found the dopamine concentration calculated from the equation has the same level with the value we added. Recovery of the electrode is about 90-120%, indicating that the NUNCD film has great potential to be used as an electrode for dopamine sensing.