Abstract: OBJECTIVE To prepare the appropriate mesoporous silica nanoparticles (MSNs) and investigate the influence of Chinese materia medica with properties of invigorating blood circulation and eliminating blood stasis on the distribution of MSNs-NH₂ in mice. METHODS MSNs were prepared using Stober method. The particle size， polydispersity index (PDI) and Zeta potential of MSNs were measured with different molar ratios of tetraethyl orthosilicate (TEOS) and sodium hydroxide (NaOH). The preparation procedure was optimized for further amino functionality on the surface of MSNs. The structure and morphology of the obtained MSNs-NH₂ were characterized by dynamic light scattering (DLS)， fourier transform infrared spectroscopy (FT-IR) and transmission electron microscope (TEM). Mice were orally administrated with Ligusticum chuanxiong Hort， Salvia miltiorrhiza Bge or Hirudenipponica Whitman decoction daily， respectively. Mice orally administrated with normal saline was used as the control group. Ten days later， Cy7-labeled MSNs-NH₂ was intravenously injected into mice via the tail vein for in vivo imaging. RESULTS Appropriate MSNs were prepared with the molar ratio of TEOS and NaOH being 20. After the surface of MSNs was functionalized with amino groups， the particle size of the MSNs-NH₂ was determined to be 136.8 nm with PDI of 0.17 and the Zeta potential of the MSNs-NH₂ was 16 mV. Chinese materia medica with properties of invigorating blood circulation and eliminating blood stasis had effect on the distribution of MSNs-NH₂in mice. The fluorescence signals of all experimental groups were mainly located in the liver and spleen， and the fluorescence signals of the group treated with Chinese materia medica that supposed to invigorate blood circulation and eliminate blood stasis were stronger than those of control group. In addition， the fluorescence signals of Ligusticum chuanxiong Hort group hit the peak earlier than that of Salvia miltiorrhiza Bget group. Besides， other organs showed no significant fluorescence except for lung in Ligusticum chuanxiong Hort group at 24 h post injection. CONCLUSION By adjusting the molar ratios of TEOS and NaOH， the size of MSNs could be effectively controlled. MSNs-NH₂ could be used as a probe to study the relationship between traditional Chinese medicine (TCM) and nanoparticles (NPs). Oral administration of Chinese materia medica with invigorating blood circulation and eliminating blood stasis had effect on the distribution location and peak time of MSNs-NH₂ in mice.