To develop positively charged human ferritin nanoparticles capable of modulating the surface properties of adenovirus vectors via electrostatic interaction-mediated self-assembly in order to enhance the cellular delivery efficiency of adenovirus vectors.

Based on structure-guided rational design, combinatorial amino acid mutations were introduced into wild-type human ferritin heavy chain (hF-wt) to generate a panel of positively charged ferritin mutants [(+)hFm]. The particle size and electrostatic binding capacity of (+)hFm were characterized using dynamic light scattering (DLS) and agarose gel electrophoresis, respectively, to identify the optimal (+)hFm that could self-assemble into nanoparticles and exhibit a high affinity for negatively charged biomacromolecules. Furthermore, the properties of the complex formed by the adenovirus type 5 vector (Ad5) and (+)hFm[Ad5@(+)hFm] were determined. The efficacy with which target transgene expressions were enhanced and the potential cytotoxicity of Ad5@(+)hFm were subsequently evaluated in HeLa cells.

The positively charged ferritins constructed by combinatorial amino acid mutations successfully self-assembled into nanoparticles with size distributions ranging from 10 to 70 nm. Among these mutants, (+)hFm-2 showed strong electrostatic binding to plasmid DNA at a migration retardation rate of up to 95.59%. At a molar ratio of 1:1000 [Ad5 to(+)hFm-2], the two components formed a complex with modulated surface properties, which significantly improved Ad5-mediated transgene expressions in the cellular model without inducing detectable cytotoxicity.

The positively charged engineered ferritin variant (+)hFm-2 can efficiently bind to Ad5 via electrostatic interaction, enhance Ad5-mediated transgene expressions, and possess high biocompatibility.