Why Magnetic Nanoparticles Still Struggle to Translate: A Systematic Analysis of Structural Gaps in Nanobiotechnology

This review offers an in-depth look at the diagnostic and therapeutic potential of MNPs as superparamagnetic and high-surface-area-to-volume entities, considering their applications in MRI, magnetic hyperthermia, and targeted drug delivery. Based on an integrative approach, which includes systematic searches in 3 main bibliographic databases, 870 articles, semantic network analysis, Retrieval-Augmented Generation (RAG), and gap classification (Miles’ taxonomy), our analysis identifies a constant gap between lab performances and in vivo applications, described through eight critical challenges. The development of MNP-based biotechnologies is largely hindered by open issues in terms of safety, standardization, and control of the nanobio interface, mainly incomplete physicochemical characterization and poor methodological harmonization, because the high sensitivity of MNPs to synthesis routes and scale is a major bottleneck for GMP-compatible translation. Moreover, the analysis of in vivo data suggests that, on average, less than 1% of the injected dose accumulates in solid tumors, whereas a substantial fraction is diverted to non-target organs, particularly those associated with the mononuclear phagocyte system, reinforcing concerns regarding off-target sequestration, incomplete clearance, and long-term safety. Other critical challenges include complex interactions with biofluids, lack of unifying conceptual frameworks, limited experimental validation, underexploited methodological integration, and geographical and biological biases. Consequently, successfully overcoming these challenges will require the early and deliberate integration of rigorous materials engineering, mechanistic biological insight, and application-oriented validation for robust, reproducible, and translatable magnetic nanoplatforms.