Gold@MnFe-Prussian Blue Analog Yolk@Shell Nanoparticles for Light-Triggered and pH-Sensitive Drug Release.

Yolk@shell nanostructures have emerged as promising platforms for biomedical applications due to their unique architecture, which combines the high surface area and loading capacity of hollow nanoparticles with the structural stability and functional versatility of core@shell systems. In this work, we report the synthesis of multifunctional Au@MnFe-Prussian Blue Analog (PBA) yolk@shell nanostructures through a two-step process: initial formation of Au@PBA core@shells, followed by selective leaching of the inner PBA shell. This process not only generates a well-defined internal cavity of ∼75 nm, enhancing drug-loading capacity, but also induces partial etching of the gold core and its redeposition onto the PBA shell. This redistribution of gold leads to the emergence of absorbance in the near-infrared (NIR) region, enabling efficient photothermal conversion. Meanwhile, the MnFe PBA shell offers pH-sensitive properties and excellent biocompatibility. Using doxorubicin (DOX) as a model chemotherapeutic, the system exhibits a loading efficiency of ∼50% and a pH-dependent release profile, with enhanced release (∼150%) under NIR irradiation. In vitro studies demonstrate effective cellular uptake and synergistic cytotoxicity upon combined chemo- and photothermal treatment. This study reveals the significant potential of Au@MnFe PBA yolk@shell architectures for controlled drug delivery.