Prussian blue and its analogue nanoparticles: Appealing nanotheranostics for malignant tumor

Accurate diagnosis and therapy lie at the heart of cancer research, representing a primary goal for many research groups. Prussian blue (PB), the earliest known synthetic coordination compound dating back to 1706, is a timeless and captivating transition metal coordination material that remains at the forefront of cutting-edge research even after more than 300 years since its invention. Although bulk PB received U.S. Food and Drug Administration (FDA) approval as early as 2010 for decorporation therapy against radionuclide poisoning (specifically ²⁰¹Tl and ¹³⁷Cs), its clinical applications remained limited for years. The advent of nanoscience and nanotechnology has revolutionized the potential of PB through nanocrystallization, endowing it with outstanding physicochemical properties, including potent catalytic performance, high photothermal conversion ability, desirable imaging features, alongside versatile surface modifiability, efficient drug loading, and favorable biocompatibility/biodegradability. Consequently, considerable progress has been made in employing PB and its analogues (PBA) nanoparticles (NPs) for tumor therapy and diagnostics. In this context, a review was conducted on the fabrication methods and surface engineering approaches used to customize the dimensions, morphology, and properties of PB/PBA NPs. Following that, the state-of-the-art cancer therapies of PB/PBA NPs were scrutinized, encompassing phototherapy, catalytic therapy, chemotherapy, and immunotherapy, etc. Specifically, the use of PB/PBA NPs in mono/multimodal imaging for cancer theranostics was also reviewed. Furthermore, the key scientific issues, technical challenges requiring remediation, and prospects for the clinical transformation of PB/PBA NPs were simultaneously discussed.