Size-dependent distribution of fluorescent thiol-organosilica particles in popliteal lymph nodes of mice

•The distribution of particles in popliteal lymph nodes of mice was assessed.•120 and 380 nm particles mainly distributed in the marginal sinus/below the capsule.•840, 1700, and 2800 nm particles mainly distributed in the medullary area.•Particles are distributed in a size-dependent manner in lymph nodes.•120 nm particles may be useful in treating cancer with early lymph node metastasis.