Unlocking Nature’s\nPotential: Ferritin as a\nUniversal Nanocarrier for Amplified Cancer Therapy Testing via 3D\nMicrotissues

In the existing development of extensive drug screening\nmodels,\n3D cell cultures outshine conventional 2D monolayer cells by closely\nimitating the in vivo tumor microenvironment. This makes 3D culture\na more physiologically relevant and convenient system in the regime\nof preclinical drug testing. In the nanomedicinal world, nanoconjugates\nas nanocarriers are largely hunted due to their capability of precisely\nbinding to target cells and distributing essential dosages of therapeutic\ndrugs with enhanced safety profiles. Thus, for boosted drug availability,\nthe evolution from conventional drug treatment to combination therapies\nand last switching to drug carriers has gained significant progression\nin cancer cure. In contrast to conventional engineered nanoparticles,\nherein, we successfully designed biomolecule (ferritin)-based drug\nnanoconjugates effective both as a single drug (valproic acid-VPA)\nand twin-drug (valproic acid/doxorubicin-Dox) carriers, which dramatically\nenhance the proficiency of the tumor therapeutic modality. To question\nthe reported adjuvant drug property of VPA, we progressed utilizing\nat first VPA alone as an effective yet exclusive tumor therapy when\ndelivered via some carrier molecule, in particular protein. Subsequently,\nwe paralleled this comprehensive investigation output to compare and\ntest the coloading strategy of drugs and observe the synergistic and/or\nadditive behavior of VPA in conjugation with other anticancer agents\n(Dox) while given via a carrier molecule. To approach this, VPA and/or\nDox molecules were encapsulated into the ferritin (F) cavity using\na thermosensitive synthesis method by maintaining the temperature\nat 60 °C. The successful encapsulation of drugs in the protein\nnanocage was confirmed through various characterization techniques.\nThe F-VPA/F-VPA-Dox nanoconjugates exhibited similar morphology and\nstructural characteristics to the hollow ferritin cage and showed\nsignificant cytotoxicity than the naked drugs when tested on physiologically\nrelevant 3D spheroid models. Precisely, our first designed carrier\nnanoconjugate, i.e., F-VPA, offered more than a 3-fold increased intratumoral\ndrug concentration than free VPA and significantly suppressed tumor\ngrowth after a single-dose treatment. However, our second modeled\ncarrier nanoconjugate, viz. F-VPA-Dox, revealed an extended median\nsurvival period and lesser toxicity when administered at a much more\neffective dose (∼3–5 μM), in 3D tumor spheroid\nmodels of various cancer cell lines. All in all, importantly, ferritin\nnanoconjugates exhibited an enhanced tumor inhibition rate with a\nsingle-dose treatment, which further confirms the benefits of the\nactive targeting property of these nanocarriers. Moreover, these nanocarriers\nalso offer to deliver a significant dose of the therapeutic drug into\ntumor cells, alongside tremendous biocompatibility and safety profiles\nin numerous tumor 3D spheroid models.