Efficient encapsulation of Fe₃O₄ nanoparticles into genetically engineered hepatitis B core virus-like particles through a specific interaction for potential bioapplications.

Self-assembly of viral coating proteins encapsulating functional nanoparticles provides a new class of biomaterials with robust chemical and physical properties for potential applications in functional imaging, and therapeutic or diagnostic agent delivery. Herein, a straightforward method is demonstrated for efficient encapsidation of magnetic nanoparticles into the engineered virus-like particle (VLP) through the affinity of histidine tags for the nickel- nitrilotriacetic acid (NTA) chelate. Monodispersed, uniformly sized, magnetic core-containing VLPs are obtained at high efficiency (>85%) and used as the cellular T2 contrast agents for MR imaging applications thanks to their biocompatibility, higher cellular uptake, as well as higher r2 values.