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

Cancer cells tend to stay in the marginal sinus when they metastasize to lymph nodes. This study aimed to elucidate the distribution of particles in lymph nodes for the development of novel therapeutic approaches to early cancer with lymph node metastasis. We subcutaneously administered five different sizes of fluorescent thiol-organosilica particles (120, 380, 840, 1700, and 2800 nm) into the footpads of mice, and observed and analyzed the distributions of particles in the popliteal lymph nodes 24 h later in vivo, histologically, and three-dimensionally. The distributions of particles varied according to size, with particles measuring 120 and 380 nm being more significantly distributed in the marginal sinus, and particles measuring 840, 1700 and 2800 nm being more distributed in the medullary area. These results suggest that thiol-organosilica particles measuring 120 and 380 nm may be useful in the treatment of early cancer with lymph node metastasis