Dual Functionalized Polyethylenimine With PH-responsive PEG And Tetraphenylene For Gene Delivery

Cationic gene carriers have spurred intensive interests in view of their non-immunogenicity,good water-solubility and ease in DNA encapsulation in recent years.Branched polyethyleneimine(PEI)with high amino density is particularly popularity with many important functionalities,such as intriguing cell internalization,prompt endosome escape and efficient transfection activity,regarded as the“gold standard”.Nevertheless,PEI also conduces to poor stability,severe protein adsorption and unfavorable biocompatibility due to excessive positive charge,remaining to be further optimized.In this work,PEI was coated with a PEG shell through a Schiff-base linkage,followed by the electrostatic incorporation of tetraphenylene(TPE),characterized as a lipophilic and aggregation-induced-emissive fluorophore,to get PEI-PEG/TPE polyplex micelle,ensemble of pH-responsive PEG detachment and functional TPE incorporation.The molecular structures were characterized by ~1H-NMR and FT-IR.Fluorescence spectrum demonstrated the successful preparation of PEI-PEG/TPE polyplex.Next,PEI-PEG/TPE was complexed with pDNA to study its properties as gene vectors.Gel electrophoresis assay and resistance to protein absorption assay indicated the important role of PEG and TPE in promoting colloidal stabilities and reducing protein adhesion.Moreover,PEG segments were designed to enable selective detachment from polyplex in acidic milieu,thus improving cell uptake,endosome escape and the pDNA release.Of note,the destabilization potency to the endosome membrane could be further facilitated with the aid of lipophilic TPE.Eventually,the proposed polyplex was validated to provide efficient gene expression and appreciable safety profile by in vitro/in vivo transfection and cytotoxicity experiments.