Supercharged coiled-coil protein with N-terminal decahistidine tag boosts siRNA complexation and delivery efficiency of a lipoproteoplex

Short interfering RNA (siRNA) therapeutics have soared in popularity due to their highly selective and potent targeting of faulty genes, providing a non-palliative approach to address diseases. Despite their potential, effective transfection of siRNA into cells requires the assistance of an accompanying vector. Vectors constructed from non-viral materials, while offering safer and non-cytotoxic profiles, often grapple with lackluster loading and delivery efficiencies, necessitating substantial milligram quantities of expensive siRNA to confer the desired downstream effects. We detail the recombinant synthesis of a diverse series of coiled-coil supercharged protein (CSP) biomaterials systematically designed to investigate the impact of two arginine point mutations (Q39R and N61R) and decahistidine tags on liposomal siRNA delivery. The most efficacious variant, N8, exhibits a twofold increase in its affinity to siRNA and achieves a twofold enhancement in transfection activity with minimal cytotoxicity in vitro. Subsequent analysis unveils the destabilizing effect of the Q39R and N61R supercharging mutations and the incorporation of C-terminal decahistidine tags on α-helical secondary structure. Cross-correlational regression analyses reveal that the amount of helical character in these mutants is key in N8's enhanced siRNA complexation and downstream delivery efficiency.

Elevating nucleic acid delivery via a stable anionic peptide-dextran ternary system

Nucleic acid-based therapies hold promise for treating previously intractable diseases but require effective delivery vectors to protect the therapeutic agents and ensure efficient transfection. Cationic polymeric vectors are particularly notable for their adaptability, high transfection efficiency, and low cost, but their positive charge often attracts blood proteins, causing aggregation and reduced transfection efficiency. Addressing this, we designed an anionic peptide-grafted dextran (Dex-LipE5H) to serve as a cross-linkable coating to bolster the stability of cationic polymer/nucleic acid complexes. The Dex-LipE5H was synthesized through a Michael addition reaction, combining an anionic peptide (LipE5H) with dextran modified by divinyl sulfone. We demonstrated Dex-lipE5H utility in a novel ternary nucleic acid delivery system, CDex-LipE5H/PEI/nucleic acid. CDex-LipE5H/PEI/nucleic acid demonstrated lower cytotoxicity and superior anti-protein absorption ability compared to PEI/pDNA and Dex-LipE5H/PEI/pDNA. Most notably, the crosslinked CDex-LipE5H/PEI/pDNA demonstrated remarkable transfection performance in HepG2 cells, which poses significant transfection challenges, even in a medium with 20% serum. This system's effective siRNA interference performance was further validated through a PCSK9 gene knockdown assay. This investigation provides novel insights and contributes to the design of cost-effective, next-generation nucleic acid delivery systems with enhanced blood stability and transfection efficiency.

Self-Assembly of Peptide-Lipid Nanoparticles for the Efficient Delivery of Nucleic Acids

A transfection formulation is successfully developed to deliver nucleic acids by adding an auxiliary lipid (DOTAP) to the peptide, and the transfection efficiency of pDNA reaches 72.6%, which is close to Lipofectamine 2000. In addition, the designed KHL peptide-DOTAP complex exhibits good biocompatibility by cytotoxicity and hemolysis analysis. The mRNA delivery experiment indicates that the complex had a 9- or 10-fold increase compared with KHL or DOTAP alone. Intracellular localization shows that KHL/DOTAP can achieve good endolysosomal escape. Our design provides a new platform for improving the transfection efficiency of peptide vectors.

Fabrication of zein-based hydrophilic nanoparticles for efficient gene delivery by layer-by-layer assembly

As a natural biological macromolecule, zein has broad application prospects in drug delivery due to its unique self-assembly properties. In this work, zein/sodium alginate (Zein/SA) nanocomposites were prepared by a pH-cycle method, Then Zein/SA/PEI (ZSP) nanocomposites were prepared by efficient layer-by-layer assembly method, ZSP nanocomposite of higher transfection performance was further labeled by folic acid (FA). After characterizing the physicochemical properties of ZSP by various methods, the potential of ZSP as a gene delivery vehicle was explored in vitro. The results showed that ZSP had good dispersibility and stability, the diameter distribution was in the range of 124-203 nm, and it had a typical core-shell structure, which could effectively condensate DNA and protect it from nuclease hydrolysis. ZSP exhibited proton buffering capacity similar to PEI, lower cellular toxicity, lower protein adsorption and erythrocyte hemolysis effect than PEI. ZSP/pDNA complexes could be taken up by cells and exhibited higher transfection efficiency than PEI/DNA complexes at the same weight ratio. The transfection efficiency of the complex in HeLa and 293T cells can be improved by FA labeling, especially in HeLa cells. These results provide new perspective for the design and development of efficient zein-based gene delivery systems.