A facile and green synthesis was employed to synthesize water-soluble carbon dots that were shown to be uniform monodisperse spheres with an average diameter of approximately 4 nanometers. Because of their strong adsorption, the carbon dots were assembled on a glassy carbon electrode without a bridging agent. The modified electrode was employed for the sensitive determination of dopamine. In 0.1 mole per liter phosphate buffer at pH 6.0, the peak currents of dopamine increased at the modified electrode. A calibration curve for dopamine was obtained from 1.5 × 10 7 to 1.5 × 10 4 mole per liter with a limit of detection of 2.6 × 10 8 mole per liter. The sensor was employed to determine dopamine in human plasma without interferences from uric acid and ascorbic acid. The carbon dot modified electrode also exhibited Downloaded by [University of Colorado -Health Science Library] at 21:37 30 March 2015 2 high stability and excellent precision. The results demonstrate the facile fabrication of a carbon dot-based sensor and a sensitive method for the determination of dopamine.