In the field of systemically applied, nucleic acid-based drugs, polyplexes are interesting candidates for therapeutic systems. In this study, we synthesized a multifunctional triblock copolymer via reversible addition−fragmentation chain transfer (RAFT) block copolymerization. Due to three orthogonal reactive functionalities (an azide end group, a reactive disulfide block (P(PDSM)), and a reactive ester block (P(PFPMA))), the synthesized polymer system is highly adaptable and can be modified in a tailor-made fashion. After modification with N,N-dimethyl ethylendiamine (DMEDA), the synthesized cationic triblock copolymers form polyplexes with pDNA, even at low N/P ratios. The polyplexes can be stabilized further by crosslinking, having a size range of 113−151 nm in 10 mM NaCl, with high uniformity and low size distribution. ζ measurements indicate a good shielding of the charged polyplex core. Additionally, no significant cytotoxicity of the polyplexes is found. First transfection experiments are positive, but the gene transfer efficiency needs to be improved further. Because of its high modifiability, the presented triblock copolymer system is a good candidate for an adjustable pDNA transport system.

Reversible addition–fragmentation chain transfer polymerization with a low‐temperature initiator can be used to synthesize multifunctional block copolymers for polyplex formation. Utilizing three methacrylate monomers (triethylene glycol methyl ether methacrylate (MEO3MA), pyridyldisulfideethyl methacrylate (PDSM), N,N‐dimethylethylenediamine methacrylate (DMAEMA)) and an azide bearing chain transfer agent for polymerization, the resulting triblock‐copolymers possess two orthogonally reactive functionalities (a block with reactive disulfide side chains and an azide end‐group) and two additional functional blocks for i) solubilization and ii) polyplex formation. Thereby, the MEO3MA block provides solubility in aqueous media and the DMAEMA block, having a tertiary amine in the side chain, allows polyplex formation with polyanionic biomacromolecules like DNA or RNA. Due to the reactive disulfide block the polyplexes can be (reversibly) crosslinked with dithiols. Because of the manifold of possibilities to modify the pDNApolyplexes, this polymers system is an interesting candidate for active‐targeting and codelivery approaches.