Introduction: Gene therapy offers a promising approach for treating various diseases, yet its success hinges on efficient and safe gene delivery systems. Poly(β-amino esters) (PBAE) is an excellent non-viral gene carrier which has the advantages of easy synthesis and various chemical structure. However, there are some obvious shortcomings, such as cytotoxicity and limited penetration in tissues. To address these issues, we developed PEGylated PBAE (PBAE-E) with tailored chain lengths and contents to enhance both transfection and biocompatibility.

Methods: We synthesized PBAE-E by incorporating short-chain PEG into the PBAE structure via Michael addition polymerization. The materials were characterized using 1H-NMR and FT-IR. PBAE-E nanoparticles were formed by complexing with the GFP plasmid and were analyzed for size, morphology (DLS, TEM), and DNA encapsulation (agarose gel electrophoresis). In vitro transfection was assessed in multiple cancer cell lines, and cytotoxicity was evaluated using the MTT assay. In vivo imaging of mouse vaginas was used to investigate whether the introduction of PEG chains could increase the mucosal permeability of nanoparticles.

Results: PBAE-E was synthesized successfully, as confirmed by 1H-NMR and FT-IR. PBAE-E could compact the plasmid into spherical nanoparticles with a diameter of about 250 nm. PBAE-E nanoparticles demonstrated improved transfection efficiency and reduced cytotoxicity compared to unmodified PBAE. Notably, PBAE-E4-5 and PBAE-E9-5 exhibited the best performance. In vivo imaging in mice revealed an enhanced mucosal permeability of PBAE-E, suggesting improved tissue penetration.

Conclusion: Our study demonstrates that PEG-modified PBAEs can significantly enhance plasmid transfection efficiency and biocompatibility compared to unmodified PBAEs. The PEGylation strategy provides a promising avenue for improving non-viral gene therapy.