[Small interfering RNA delivery mediated by mPEG-PCL-g-PEI polymer nanoparticles]

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Gene Delivery

Background:

• Small interfering RNA (siRNA) holds promise for gene therapy but requires efficient and safe delivery vectors.
• Polyethyleneimine (PEI) is a common non-viral vector, but its high cytotoxicity limits clinical applications.
• Developing novel copolymers that combine the benefits of stealth polymers like polyethylene glycol (mPEG) and polycaprolactone (PCL) with the gene-complexing ability of PEI is crucial.

Purpose of the Study:

• To synthesize novel mPEG-PCL-g-PEI ternary copolymers.
• To characterize the synthesized copolymers and their ability to form nanoparticles with siRNA.
• To evaluate the in vitro efficacy and cytotoxicity of these nanoparticles as siRNA delivery vectors.

Main Methods:

• Synthesis of mPEG-PCL-OH via ring-opening polymerization.
• Chemical modification of mPEG-PCL-OH to mPEG-PCL-NHS.
• Grafting of branched PEI onto mPEG-PCL-NHS to form mPEG-PCL-g-PEI.
• Characterization using FTIR, NMR, and GPC.
• Formation and characterization of mPEG-PCL-g-PEI/siRNA nanoparticles (size, zeta potential).
• In vitro cytotoxicity assessment using MTT assays.
• Evaluation of gene silencing efficiency via cell transfection assays.

Main Results:

• Successful synthesis and characterization of mPEG-PCL-g-PEI copolymers.
• Formation of siRNA nanoparticles with sizes ranging from 50-200 nm and positive zeta potential.
• Significantly lower cytotoxicity of mPEG-PCL-g-PEI/siRNA nanoparticles compared to PEI/siRNA nanoparticles (P < 0.05).
• Effective down-regulation of firefly luciferase gene expression at N/P ratios from 50 to 150, with maximal inhibition at N/P ratio of 125 (P < 0.01).

Conclusions:

• The synthesized mPEG-PCL-g-PEI copolymers are effective siRNA delivery vectors.
• These novel copolymers exhibit significantly reduced cytotoxicity compared to traditional PEI vectors.
• mPEG-PCL-g-PEI shows great potential as a safe and efficient non-viral vector for gene silencing applications.