Poly(ethylene glycol)-block-poly(2-aminoethyl methacrylate hydrochloride)-Based Polyplexes as Serum-Tolerant Nanosystems for Enhanced Gene Delivery

Abstract

Incorporation of poly­(ethylene glycol) (PEG) into polyplexes has been used as a promising approach to enhance their stability and reduce unwanted interactions with biomolecules. However, this strategy generally has a negative influence on cellular uptake and, consequently, on transfection of target cells. In this work, we explore the effect of PEGylation on biological and physicochemical properties of poly­(2-aminoethyl methacrylate) (PAMA)-based polyplexes. For this purpose, different tailor-made PEG-b-PAMA block copolymers, and the respective homopolymers, were synthesized using the controlled/“living” radical polymerization method based on activators regenerated by electron transfer atom transfer radical polymerization. The obtained data show that PEG-b-PAMA-based polyplexes exhibited a much better transfection activity/cytotoxicity relationship than the corresponding non-PEGylated nanocarriers. The best formulation, prepared with the largest block copolymer (PEG45-b-PAMA168) at a 25:1 N/P ratio, presented a 350-fold higher transfection activity in the presence of serum than that obtained with polyplexes generated with the gold standard bPEI. This higher transfection activity was associated to an improved capability to overcome the intracellular barriers, namely the release from the endolysosomal pathway and the vector unpacking and consequent DNA release from the nanosystem inside cells. Moreover, these nanocarriers exhibit suitable physicochemical properties for gene delivery, namely reduced sizes, high DNA protection, and colloidal stability. Overall, these findings demonstrate the high potential of the PEG45-b-PAMA168 block copolymer as a gene delivery system.

Natural steroid-based cationic copolymers cholesterol/diosgenin-r-PDMAEMAs and their pDNA nanoplexes: impact of steroid structures and hydrophobic/hydrophilic ratios on pDNA delivery

“…1,2 Although many cationic polymer carriers have been developed to realize efficient gene transfection, some defects, such as low solution stability, poor serum compatibility, high cytotoxicity and low cellular uptake, have still largely restricted their practical applications. 3 To overcome the defects, it was disclosed that conjugation/modication of cationic polymers on their backbones/side chains with biocompatible building blocks: polyethylene glycol (PEG), [4][5][6] carbohydrates, 7,8 zwitterionic molecules 9 and natural products, 10 was an efficient way to reduce cytotoxicity and improve bioavailability. Meanwhile, researchers made great efforts to elucidate the structure-function relationships of cationic polymers so as to obtain the optimal balance between gene transfection efficiency and cytotoxicity.…”

Gene Therapy in Cancer Treatment: Why Go Nano?

“…In an effort to improve the capacity of polymeric nanoparticles to overcome the intracellular barriers and consequently increase the transfection efficacy, Santo et al constructed poly(2-aminoethyl methacrylate) (PAMA)-based polyplexes covered with PEG and evaluated the efficiency of in COS-7 and HepG2 cell lines. The results showed that the nanosystem covered with PEG increased the transfection activity and decreased the cytotoxicity [232]. Zhupanyn and co-workers evaluated the application of PEIs nanoparticles conjugated with extracellular vehicle (ECV) to deliver siRNA in different cell lines.…”

Cationic Nanostructures for Vaccines Design

“…immunizations (4 weeks apart) with a very low dose (1 microgram) of the plasmid PCV-tat delivered by these nanoparticles followed by one or two protein boosts induced significant antigen-specific humoral and cellular responses and greatly increased Th1-type T cell responses and CTLs against HIV-1 Tat [ 242 ]. Along similar lines, PEG was covalently bound to the cationic polymer poly (2-aminoethyl methacrylate hydrochloride) in order to improve the stability of nanstructures in vivo [ 243 ]. Figure 13 shows the core–shell microparticles obtained by Castaldello and coworkers, 2006, incorporating both functionalities, cationic charge and the stability, in aqueous medium imparted by PEG [ 242 ].…”