pH-responsive Multi-PEGylated dual cationic nanoparticles enable charge modulations for safe gene delivery

Area of Science:

• Biotechnology and Gene Therapy
• Polymer Chemistry
• Nanomedicine

Background:

• Cytotoxicity of polycations in gene therapy is a major hurdle, often caused by membrane destabilization.
• Polyethylene glycol (PEG) shielding is used to prolong the circulation of nonviral gene delivery vectors.
• Intelligent polycations with environment-sensing charge modulation are needed to minimize toxicity and boost gene expression.

Purpose of the Study:

• To design and characterize a novel di-cationic block copolymer for gene delivery with reduced cytotoxicity.
• To engineer a polycation capable of pH-mediated endosomal escape via charge interactions.
• To create a versatile scaffold for attaching functional moieties like PEG for enhanced gene expression.

Main Methods:

• Synthesis of a di-cationic block copolymer: poly(aspartate-hydrazide)-block-poly(L-lysine).
• Complexation of the polymer with plasmid DNA (pDNA) to form two-layered nanoparticles.
• Evaluation of pH-mediated charge transition and endosomal membrane disruption.
• Assessment of cytotoxicity and gene expression enhancement in cellular models.

Main Results:

• The designed copolymer exhibits pH-dependent charge modulation, transitioning from neutral to charged.
• Nanoparticles effectively disrupt endosomal membranes through charge interactions, facilitating endosomal escape.
• The system demonstrated negligible cytotoxicity compared to conventional polycations.
• Enhanced gene expression was observed, attributed to efficient endosomal escape and reduced toxicity.

Conclusions:

• The novel poly(aspartate-hydrazide)-block-poly(L-lysine) copolymer represents an intelligent nonviral vector for gene therapy.
• The pH-mediated endosomal escape mechanism based on charge interactions offers a safer alternative to the proton-sponge effect.
• This approach is a significant step towards engineering advanced nonviral vectors with improved safety and efficacy profiles.