Polyamidoamine Dendrimer Grafted with an Acid-Responsive Charge-Reversal Layer for Improved Gene Delivery.

We report on a heterogeneous dendrimer (G3-acetal-NH2) derivative possessing an acid-responsive charge-reversal layer. The synthesis of G3-acetal-NH2 starts with a polyamidoamine (PAMAM) G3 core and follows the aza-Michael addition with N-(2-(1-(allyloxy)ethoxy)ethyl)acrylamide (AEEAA) synthesized by us and the thiol-ene click chemistry with cysteamine hydrochloride in sequence. The surface of this newly formed dendrimer can turn from amine-terminated to hydroxyl-terminated due to the cleavage of the acetal groups in a weakly acidic environment. This charge conversion from 34.3 ± 2.7 mV to 18.0 ± 0.3 mV in 24 h at pH 5.3 enables its capacity as a therapy delivery vehicle. G3-acetal-NH2 with a positively charged surface can condense pMAX GFP plasmid at similar weight ratios as native G4-NH2 (above 2:1), allowing for its protected uptake into cells and endosomal escape. While in the endosome, the drop in vesicle pH cleaves the acetal bond, releasing the genetic payload and limiting its recondensation by the reduction in the dendrimer surface charge. When the vector/plasmid weight ratio was 2:1, G3-acetal-NH2 improved transfection of pMAX GFP plasmid by 5-fold over native G4-NH2 in NIH3T3 cells in terms of GFP protein expression. Taken together, we show that this surface charge conversion performance makes the synthesized heterogeneous dendrimer an improved vehicle for gene transfection. PMID: 32820887 [PubMed - as supplied by publisher]
Source: Biomacromolecules - Category: Biochemistry Authors: Tags: Biomacromolecules Source Type: research