Barrier-to-Design Codes for Organ-Targeted Nanomedicine: A Framework Linking Barrier Phenotypes to Nano-Bio Interface Design and Translational Validation.

Organ-targeted nanomedicine is often defined by anatomical destination, yet delivery performance is determined by the biological barriers, disease-associated remodeling, and nano-bio interface interactions encountered before therapeutically relevant cells are reached. Whole-organ accumulation, tissue fluorescence, or bulk biodistribution can demonstrate tissue arrival, but stronger targeting claims require evidence matched to the intended delivery task, including barrier crossing or penetration, spatial localization, target-cell exposure, cargo release, target engagement, functional activity, and safety. We introduce the Barrier-to-Design Codes framework, a conceptual approach that links measurable barrier phenotypes to conditional material and nano-bio interface parameters, claim-matched validation evidence, failure boundaries, and translational gates. The framework complements existing reporting, delivery-system design, and translational frameworks by treating the barrier phenotype-rather than the organ label or material class-as the primary unit of analysis. It integrates five linked domains: barrier architecture, pathological remodeling, acquired nano-bio interface behavior, including protein adsorption and immune recognition, validation, and translation. Using the blood-brain barrier, lymph nodes and immune organs, liver and metabolic organs, skin and mucosal barriers, and cartilage/extracellular-matrix niches as representative systems, we examine how particle size, charge, stiffness, ligand density, coating, release, protein adsorption, and immune recognition can acquire different functional meanings across barrier contexts. The framework separates transferable reasoning principles from non-transferable platform assumptions and requires organ-level signals to be resolved through barrier-matched models, spatial and cell-resolved exposure, pharmacokinetic/pharmacodynamic interpretation, functional response, manufacturing control, and repeat-dose safety. The Barrier-to-Design Codes framework is not a nanomaterial taxonomy, scoring system, or universal design prescription. Its intended value lies in reducing unsupported targeting claims, improving alignment between design hypotheses and validation evidence, and supporting more interpretable and translation-aware decisions, while remaining open to prospective empirical testing and refinement.