LYMPH-NODE LOCALIZATION OF BIODEGRADABLE NANOSPHERES SURFACE-MODIFIEDWITH POLOXAMER AND POLOXAMINE BLOCK-COPOLYMERS

Studies were performed to develop a sub-100 nm biodegradable colloidal system for the efficient delivery of drugs and diagnostic agents to t he lymphatic system. Nanospheres of poly(lactide-co-glycolide) were pr epared by interfacial polymer deposition. The nanospheres were coated with block co-polymers in order to modify their surface characteristic s. Radiolabelling of the nanospheres for in vivo tracing was achieved by the incorporation of the lipophilic complex In-111-oxine during nan osphere preparation. In vitro stability of the radiolabelled nanospher es was determined in rat serum at 37 degrees C. The lymphatic distribu tion of the nanospheres was determined after subcutaneous administrati on to the rat. Lymphatic uptake of all coated systems was enhanced com pared to the uncoated nanospheres, and a maximal uptake of 17% of the administered dose in the regional lymph nodes was achieved. These obse rvations suggest that the nanospheres are suitable for diagnostic and therapeutic applications in clinical and experimental medicine.