pH-sensitive zwitterionic polycarboxybetaine as a potential non-viral vector for small interfering RNA delivery

Zwitterionic materials for nucleic acid delivery and therapeutic applications

Nucleic acid therapeutics have demonstrated substantial potential in combating various diseases. However, challenges persist, particularly in the delivery of multifunctional nucleic acids. To address this issue, numerous gene delivery vectors have been developed to fully unlock the potential of gene therapy. The advancement of innovative materials with exceptional delivery properties is critical to propel the clinical translation of nucleic acid drugs. Cationic vector materials have received extensive attention, while zwitterionic materials remain relatively underappreciated in delivery. In this review, we outline a diverse range of zwitterionic material nucleic acid carriers, predominantly encompassing zwitterionic lipids, polymers and peptides. Their respective chemical structures, synthesis approaches, properties, advantages, and therapeutic applications are summarized and discussed. Furthermore, we highlight the challenges and future opportunities associated with the development of zwitterionic vector materials. This review will aid to understand the zwitterionic materials in aiding gene delivery, contributing to the continual progress of nucleic acid therapeutics.

Advanced Strategies for Overcoming Endosomal/Lysosomal Barrier in Nanodrug Delivery

Nanocarriers have therapeutic potential to facilitate drug delivery, including biological agents, small-molecule drugs, and nucleic acids. However, their efficiency is limited by several factors; among which, endosomal/lysosomal degradation after endocytosis is the most important. This review summarizes advanced strategies for overcoming endosomal/lysosomal barriers to efficient nanodrug delivery based on the perspective of cellular uptake and intracellular transport mechanisms. These strategies include promoting endosomal/lysosomal escape, using non-endocytic methods of delivery to directly cross the cell membrane to evade endosomes/lysosomes and making a detour pathway to evade endosomes/lysosomes. On the basis of the findings of this review, we proposed several promising strategies for overcoming endosomal/lysosomal barriers through the smarter and more efficient design of nanodrug delivery systems for future clinical applications.

Thermo-Responsive Polyion Complex of Polysulfobetaine and a Cationic Surfactant in Water

Poly(4-((3-methacrylamidopropyl)dimethylammonium)butane-1-sulfonate) (PSBP) was prepared via controlled radical polymerization. PSBP showed upper critical solution temperature (UCST) behavior in aqueous solutions, which could be controlled by adjusting the polymer and NaCl concentrations. Owing to its pendant sulfonate anions, PSBP exhibited a negative zeta potential of −7.99 mV and formed a water-soluble ion complex with the cationic surfactant cetyltrimethylammonium bromide (CTAB) via attractive electrostatic interaction. A neutral PSBP/CTAB complex was formed under equimolar concentrations of the pendant sulfonate group in PSBP and the quaternary ammonium group in CTAB. Transmittance electron microscopic images revealed the spherical shape of the complex. The stoichiometrically neutral-charge PSBP/CTAB complex exhibited UCST behavior in aqueous solutions. Similar to PSBP, the phase transition temperature of the PSBP/CTAB complex could be tuned by modifying the polymer and NaCl concentrations. In 0.1 M aqueous solution, the PSBP/CTAB complex showed UCST behavior at a low complex concentration of 0.084 g/L, whereas PSBP did not exhibit UCST behavior at concentrations below 1.0 g/L. This observation suggests that the interaction between PSBP and CTAB in the complex was stronger than the interpolymer interaction of PSBP.

Zwitterionic Phospholipidation of Cationic Polymers Facilitates Systemic mRNA Delivery to Spleen and Lymph Nodes

Polymers represent a promising therapeutic platform for extrahepatic messenger RNA (mRNA) delivery but are hampered by low in vivo efficacy due to polyplex serum instability and inadequate endosomal escape following systemic administration. Here, we report the rational design and combinatorial synthesis of zwitterionic phospholipidated polymers (ZPPs) via cationic polymer postmodification by alkylated dioxaphospholane oxides to deliver mRNA to spleen and lymph nodes in vivo. This modular postmodification approach readily produces tunable zwitterionic species for serum resistance and introduces alkyl chains simultaneously to enhance endosomal escape, thereby transforming deficient cationic polymers to efficacious zwitterionic mRNA carriers without the need to elaborately synthesize functional monomers. ZPPs mediated up to 39 500-fold higher protein expression than their parent cationic counterparts in vitro and enabled efficacious mRNA delivery selectively in spleen and lymph nodes following intravenous administration in vivo. This zwitterionic phospholipidation methodology provides a versatile and generalizable postmodification strategy to introduce zwitterions into the side chains of cationic polymers, extending the utility of cationic polymer families for precise mRNA delivery and demonstrating substantial potential for immunotherapeutic applications.