Fluorinated Guanidino‐Polyamine Conjugates with Ribonuclease Activity – Toward a Therapeutic Tool for Multi‐Drug Therapy

The development of multifunctional carriers for gene delivery is a critical challenge in modern therapeutics, particularly in the context of multi-drug therapy (MDT). In this study, we report the synthesis and characterization of fluorinated guanidino-polyamine conjugates based on low-generation polyamidoamine (PAMAM) dendrimers and low molecular weight polyethyleneimine (PEI) polymers. These conjugates are designed to act as both efficient transfection agents and artificial ribonucleases, providing a dual-function approach to gene therapy. The functionalization with fluorinated guanidino groups enhances DNA condensation, facilitates intracellular delivery, and enables tracking via ¹⁹F MRI. Potentiometric and kinetic studies demonstrate their phosphodiesterase activity on a model compound, with PAMAM G4 derivatives exhibiting the highest catalytic efficiency. Biolayer interferometry and transfection experiments confirm mRNA cleavage activity, leading to reduced gene expression. Additionally, transfection studies with plasmid DNA (pDNA) indicate high gene delivery efficiency, surpassing conventional PEI-based systems while maintaining low cytotoxicity. These findings suggest that the conjugates presented herein, and in particular those derived from low-generation PAMAM dendrimers, can serve as promising multifunctional carriers for a combined diagnostic and MDT, offering a new strategy for synergistic gene delivery and RNA degradation.