RESUMEN
Improving our understanding of how design choices in materials synthesis impact biological outcomes is of critical importance in the development of nanomedicines. Here, we show that fluorophore labeling of polymer nanomedicine candidates significantly alters their transport and cell association in multi-cellular tumor spheroids and their penetration in breast cancer xenografts, dependent on the type of the fluorophore and their positioning within the macromolecular structure. These data show the critical importance of the biomaterials structure and architecture in their tissue distribution and intracellular trafficking, which in turn govern their potential therapeutic efficacy. The broader implication of these findings suggests that when developing materials for medical applications, great care should be taken early on in the design process as relatively simple choices may have downstream impacts that could potentially skew preclinical biology data.