Synthesis and Application of Low Molecular Weight PEI‐Based Copolymers for siRNA Delivery with Smart Polymer Blends

Abstract

Polyethylenimine (PEI) is a commonly used cationic polymer for small‐interfering RNA (siRNA) delivery due to its high transfection efficiency at low commercial cost. However, high molecular weight PEI is cytotoxic and thus, its practical application is limited. In this study, different formulations of low molecular weight PEI (LMW‐PEI) based copolymers polyethylenimine‐g‐polycaprolactone (PEI–PCL) (800 Da–40 kDa) and PEI–PCL–PEI (5–5–5 kDa) blended with or without polyethylene glycol‐b‐polycaprolactone (PEG–PCL) (5 kDa‐4 kDa) are investigated to prepare nanoparticles via nanoprecipitation using a solvent displacement method with sizes ≈100 nm. PEG–PCL can stabilize the nanoparticles, improve their biocompatibility, and extend their circulation time in vivo. The nanoparticles composed of PEI–PCL–PEI and PEG–PCL show higher siRNA encapsulation efficiency than PEI–PCL/PEG–PCL based nanoparticles at low N/P ratios, higher cellular uptake, and a gene silencing efficiency of ≈40% as a result of the higher molecular weight PEI blocks. These results suggest that the PEI–PCL–PEI/PEG–PCL nanoparticle system could be a promising vehicle for siRNA delivery at minimal synthetic effort.

Efficient and Targeted siRNA Delivery to M2 Macrophages by Smart Polymer Blends for M1 Macrophage Repolarization as a Promising Strategy for Future Cancer Treatment

“…The disappearance of diacrylate peaks in the product at 6.37, 6.09, and 5.59 ppm was used as a benchmark for coupling. Our group recently demonstrated that blending of PEI–PCL–PEI with Man-PEG–PCL (2 kDa–2 kDa) showed beneficial effects in terms of cellular uptake efficiency in vitro and allowed for modification with targeting ligands . In this study, the A–B–A copolymer was blended with commercially available C–B-structured Man-PEG–PCL to gain receptor binding specificity toward CD206.…”

“…PEI (5 kDa)−PCL (5 kDa)−PEI (5 kDa) Synthesis. Similarly as described by Jin et al, 24 100 mg of polyethylenimine (PEI, branched, M n = 5 kDa) (Sigma-Aldrich, Taufkirchen, Germany) and 50 mg of polycaprolactone-diacrylate (PCL-diacrylate, M n = 5 kDa, Sigma-Aldrich, Taufkirchen, Germany)) were separately dissolved in 5 mL of N,N′-dimethylformamide (DMF) (Sigma-Aldrich, Taufkirchen, Germany). The obtained PEI solution was preheated to 40 °C in an oil bath.…”

“…Our group recently demonstrated that blending of PEI−PCL−PEI with Man-PEG−PCL (2 kDa−2 kDa) showed beneficial effects in terms of cellular uptake efficiency in vitro and allowed for modification with targeting ligands. 24 In this study, the A−B−A copolymer was blended with commercially available C−B-structured Man-PEG−PCL to gain receptor binding specificity toward CD206. Compared with C−B−A-structured systems, such as PEG−PCL−PEI, bNP systems can be adjusted easily for CD206 binding by changing polymer ratios without the necessity to start a new synthesis.…”

Nontoxic, Biodegradable Hyperbranched Poly(β-amino ester)s for Efficient siRNA Delivery and Gene Silencing

“…29 Recently, a linear pBAE based on spermine and 1,4-butanediol diacrylate reported higher cellular uptake efficiency than Lipofectamine and 58.5% GFP knockdown efficiency in H1299 cells at low N:P ratios, albeit with a high siRNA dose of 100 nM. 31 This might be attributed to the small size and high rigidity of siRNA, reducing the multivalency of electrostatic interactions and influencing the self-assembly process between cationic polymers and siRNA. 32,33 To maximize siRNA complexation ability, efforts have been made such as incorporating hydrophobic features to improve siRNA complexation, particle stability, and silencing efficiency.…”

Tuning the charge density and crosslinking of precise amphiphilic oligo(ethanamino)amides for efficient and biocompatible gene delivery

“…However, the high charge density of PEI also introduces instability under serum and physiological fluids, 10,11 resulting in poor biocompatibility. [12][13][14][15] In recent years, Wagner and co-workers have developed a library of oligomers through a solid phase peptide synthesis strategy based on artificial amino acids, such as succinoyltetraethylene pentamine (Stp), succinoyl-pentaethylene hexamine (Sph), etc. 16,17 The artificial amino acid fragments Stp (Fig.…”