Hi Subhadeep,

What is the size of your fluorescent lablelled nanoparticles?

Grow the cells on coverslip. Next day, pretreat the cells in the presence and absence of 1-2uM cytochalasin D (phagocytosis/actin polymerization inhibitor) for 1 hour. Then incubate the cells with your nanoparticles for 2-4 hours. Remove the media, wash 3 times with PBS, fix the cells with 2% PFA for 15 min at  RT, wash again with PBS and mount the coverslip (minimise the exposure to light). Or you can use FM™ 4-64FX which stains the plasma membrane to visualize your nano particle in the vesicles stained by this dye. 

Hope this will help.

Thank u for your kind support... I have a dye name "Phodro Red Dextran",it emits red fluorescence. Please suggest suitable process regarding this. My nanoformulation(

 I am using PMA differentiated THP-1 cell line. 

In this case, you can just add Phodro-Red Dextran as well as your nano particle at the same time, incubate the cells as mentioned above and process for imaging. Look for co-localisation of dextran and green-colored nano particle. 

Macrophage start doing phagocytosis as early as 15 min.

What should be the ideal incubation period of the both?

Can i dilute Phodro Red Dextan in complete RPMI 1640?

It will be better if you will use PBS.