Assembly mechanism-instructed precision nanocarriers: Esox lucius apoferritin for hydrophilic or hydrophobic drug loading and smart release.

Ferritin (Fn) nanocages offer significant potential as drug delivery vehicles due to their biocompatibility, well-defined structure, and inherent targeting capabilities. In this study, we isolated Fn from the liver of Esox lucius and prepared its apo-form (apo-Fn) to engineer its reversible disassembly/reassembly for drug encapsulation. We demonstrated that apo-Fn undergoes controlled disassembly under mild acidic conditions (pH 2.0-4.0) or 4 M urea, and efficiently reassembles upon neutralization or urea removal. Thermal treatment below 55 °C also facilitated reversible structural transitions. Based on these properties, three loading strategies were developed. The temperature-gradient method was optimal for hydrophilic drugs (doxorubicin and phenytoin), while the urea-gradient method achieved 42.18% encapsulation for hydrophobic paclitaxel. The resulting formulations showed uniform size, colloidal stability, and minimal leakage at pH 7.4, but exhibited rapid release at acidic pH 5.0. Furthermore, apo-Fn showed high biocompatibility (> 90% cell viability) and exerted intrinsic anti-inflammatory effects by modulating macrophage polarization. This study highlights piscine apo-Fn as a promising platform for targeted drug delivery.