Silica-coated fluorescent nanoparticles functionalized with amine-or ester-po ly(amido-amide)(PAMAM) were synthesized and characterized by TEM

FTIR，TGA and z eta potential measurements.The efficiency of cellular uptake of nanoparticles，the cytotoxicity of nanoparticles toward 9L cell

and the distribution of nanoparticles in 9L cell were investiga ted by transmission electron microscopy (TEM)

confocal laser scanning microscop y (CLSM)

CCK-8 assay and flow cytometry analysis.TEM revealed the average siz e of nanoparticles was about 60 nm and the zeta potential of nanoparticles modif i ed with amine groups was +19.08

with ester groups was negative-9.01 at physio log ical pH

respectively.FTIR and TGA results also testified that the two kind of s ilic a-coated fluorescent nanoparticles were respectively functionalized by amine- an d ester- PAMAM. CLSM demonstrated that most nanoparticles were distributed in cyt oplasm and were entrapped in endosomes.CCK-8 analysis showed that both nanopart icles had no apparent toxicity.Flow cytometry analysis indicated that the cellu lar uptake of nanoparticles by 9L cells was a concentration- and time- depende nt endocytic process

and the uptake of amine functionalized nanoparticles was mor e efficient than that of ester functionalized nanoparticles.