I was trying to dye hematite-TPM (3-methacryloxypropyl trimethoxysilane (TPM) encapsulates 600 nm hematite cube) with Bodipy dye by swelling the particle with THF and dye mixture, then deswell, the fluorescence of the particle is slowly dimming and only last half minute when excited. Does anyone know what may be the reason of the quench? Is there something wrong of the bodipy dye with TPM or with hematite cube? I have searched some literature, says that nanoparticles will quench fluorescence, but the size of nanoparticle are way smaller than 600 nm in my case. I would be appreciated if anyone can give some clues.