With citric acid as carbon source and different amino acids as nitrogen source,the nitrogen-doped carbon was synthesized by one-step hydrothermal method under the condition of no catalyst.The pre-experiments show that arginine-doped carbon dots(CDs-Arg) with relatively high fluorescence quantum yield (33.25％) were picked out for further study.Furthermore,we studied the physical and chemical properties of CDs-Arg through a series of spectral,electric potential,particle size,X ray and elemental analysis experiments.At the same time,the stabilities of the nanoparticles towards different pH,temperatures,excitation lasers or redox conditions were studied.And the MTr and in vivo distribution experiments were also conducted for the toxicity and metabolism studies.The experimental results showed that the arginine doped carbon dots has high fluorescence efficiency,good stability,and extremely low toxicity.And the water-soluble small particles of CDs-Arg nanoparticles showed that the nanoparticles can be excreted through the glomerulus.These results show that the CDs-Arg Nanoparticles are biocompatible nanoparticles and have potential applications in biological imaging and can serve as a monitor of drug metabolism.