Synthetic Redox-Responsive Nanocomplexes Facilitate Spatially Controlled mRNA Release and Tumor-Selective Expression

The refinement of dynamic molecular mechanisms regulating mRNA release kinetics represents a critical frontier in advancing the synthetic mRNA delivery systems. This study details the synthesis of an intriguing ROS-responsive cationic block copolymer (pM-pBD) via reversible addition-fragmentation chain transfer (RAFT) polymerization, employing biocompatible 2-methacryloyloxyethyl phosphorylcholine (MPC) and charge-reversible (2-acryloyl)ethyl(boronic acid benzyl)diethylammonium bromide (BD) as monomeric precursors. The synthesized copolymer facilitates electrostatic-driven self-assembly with anionic mRNA. Mechanistically, the pBD block exhibits ROS-mediated charge transition, enabling stimulus-dependent molecular decomposition and promoting mRNA payload liberation, thereby establishing spatial regulation of translational activity. Furthermore, intracellular ROS modulation experiments revealed that systemic ascorbic acid administration selectively enriches reactive oxygen species within tumor microenvironments. This redox microenvironment significantly amplifies pM-pBD nanocomplex-mediated mRNA expression by an order of magnitude across multiple carcinogenic cell lines, validating the ROS-responsive characteristics of our rationally designed delivery platform. In vivo studies demonstrated the highest mRNA expression levels in tumors when aided by ascorbic acid adjuvants, despite lower tumor accumulation of mRNA compared to renal and hepatic sequestration post intravenous administration of the pM-pBD nanocomplex. This spatial expression pattern correlates with ascorbic acid-mediated intratumoral ROS accumulation, which promotes cargo release and subsequent protein synthesis of approximately 6.4-fold enhancement. Our approach, integrating redox-responsive polymer design with organ-specific pharmacological modulation, signifies a transformative advancement in targeted nucleic acid delivery. By merging stimulus-responsive materials science with tumor microenvironment biology, this methodology provides a foundation for spatially controlled mRNA expression, presenting an innovative strategy for precision oncology applications.