Objective: To optimize the synthesis process of octadecylamine-fluorescein isothiocynate (ODA-FITC)

and evaluate its application. Method: ODA-FITC was synthesized by coupling reaction with ODA and FITC as raw materials

and the reaction process was monitored by thin layer chromatography. Its structure was verified by nuclear magnetic resonance spectroscopy

and the optimum synthesis process was obtained with the solvent

time

temperature and feed ratio as the investigation factors and with yield as the indicator. ODA-FITC was then used as a fluorescence marker for nanostructured lipid carriers(NLC) by solvent diffusion method. The ligated intestinal circulation model was established to observe the absorption and distribution of NLC in small intestine and evaluate its application. Result: The optimum reaction conditions were as follows:the molar ratio of ODA to FITC was 2:1

the solution was anhydrous ethanol

after reaction for 48 h at 60℃. Under such conditions

the yield was high

reaching (72.0±3.9)%

and the absorption and distribution of its marked nanoparticles in intestinal villus can be accurately evaluated. Conclusion: The synthesis method has complete reaction and high yield

with simple operation and high repeatability. Synthetic ODA-FITC can be used to intuitively evaluate the in vitro and in vivo conditions of nanoparticles.