Rational design of diblock copolymer enables efficient cytosolic protein delivery

Area of Science:

• Biomaterials Science
• Nanotechnology
• Drug Delivery

Background:

• Polymer-mediated protein delivery is a promising strategy for protein therapeutics.
• Efficient cytosolic delivery remains a challenge for many protein-based therapies.
• Existing delivery systems often struggle with protein binding, endosomal escape, and targeted delivery.

Purpose of the Study:

• To design and synthesize a novel diblock copolymer for efficient in vitro and in vivo cytosolic protein delivery.
• To investigate the copolymer's ability to bind proteins, facilitate endosomal escape, and trigger intracellular release.
• To evaluate the copolymer's potential for targeted delivery and therapeutic applications.

Main Methods:

• Design and synthesis of a diblock copolymer with a protein-binding/endosomal escape block (PBA/DMAP) and a PEG block.
• Optimization of copolymer composition, sequence, and length to identify the optimal variant (BP20).
• In vitro nanoparticle formation, protein loading, cytosolic delivery assessment (enzymes, toxic proteins, RNP), and cell line studies.
• In vivo tumor-targeted delivery studies using folic acid (FA)-modified PEG block and Saporin, assessing tumor growth suppression.

Main Results:

• The optimized diblock copolymer (BP20) efficiently formed stable nanoparticles with various proteins.
• BP20 mediated effective cytosolic delivery of enzymes, toxic proteins, and CRISPR/Cas9 ribonucleoproteins (RNP) to multiple cell lines.
• FA-modified BP20 demonstrated tumor-targeted delivery in vivo, significantly suppressing tumor growth via Saporin delivery.

Conclusions:

• The designed diblock copolymer represents a robust platform for cytosolic protein delivery.
• This novel polymeric vehicle shows significant potential for both biological research tools and therapeutic applications.
• The study provides a blueprint for designing advanced polymeric systems for intracellular protein delivery.