Fluorophore Localization Determines the Results of Biodistribution of Core-Shell Nanocarriers

INTRODUCTION: Biodistribution of nanocarriers with a structure consisting of core and shell is most often analyzed using methods based on labeling subsequent compartments of nanocarriers. This approach may have serious limitations due to the instability of such complex systems under in vivo conditions. METHODS: The core-shell polyelectrolyte nanocarriers were intravenously administered to healthy BALB/c mice with breast cancer. Next, biodistribution profiles and elimination routes were determined post mortem based on fluorescence measurements performed for isolated blood, tissue homogenates, collected urine, and feces. RESULTS: Despite the surface PEGylation with PLL-g-PEG, multilayer polyelectrolyte nanocarriers undergo rapid degradation after intravenous administration. This process releases the shell components but not free Rhodamine B. Elements of polyelectrolyte shells are removed by hepatobiliary and renal clearance. CONCLUSION: Multilayer polyelectrolyte nanocarriers are prone to rapid degradation after intravenous administration. Fluorophore localization determines the obtained results of biodistribution and elimination routes of core-shell nanomaterials. Therefore, precise and reliable analysis of in vivo stability and biodistribution of nanomaterials composed of several compartments requires nanomaterials labeled within each compartment.