Modular antibody-functionalized poly(β-amino ester) polyplexes: Colloidal and interfacial design for targeted mRNA...

The rational design of polymer-nucleic acid nanoparticles requires precise control over colloidal stability, interfacial structure, and assembly under biologically relevant conditions. Here, we report a hierarchically assembled, antibody-functionalized polyplex nanoplatform for targeted messenger RNA (mRNA) delivery. A biodegradable cationic poly(β-amino ester) (PβAE-447) enables efficient condensation of in vitro-transcribed mRNA into nanoscale polyplexes. To enhance stability and introduce modular functionality, polyplexes were coated with a poly(γ-glutamic acid)-avidin (PGA-avidin) corona, forming a core-shell structure that suppresses aggregation and provides a chemically addressable interface. Biotinylated antibodies were conjugated via avidin-biotin interactions, enabling modular targeting without altering the nanoparticle core. The resulting nanoparticles exhibit controlled size, charge reversal, and buffering behavior in the endosomal pH range. Using CCR4-IRES-ZsGreen mRNA, antibody-functionalized nanoparticles demonstrated receptor-dependent uptake and expression in human T cells. Although delivery efficiency varied with biological conditions, the system reveals a balance between transfection efficiency and cytocompatibility. The reported study establishes a modular design framework for polymer-mRNA nanoparticles with tunable interfaces, supporting targeted and non-viral gene delivery applications.