Linear Well-Defined Polyamines via Anionic Ring-Opening Polymerization of Activated Aziridines: From Mild Desulfonylation to Cell Transfection

Functionalized Polyamine Synthesis with Photoredox Catalysis

Polyamines, such as putrescine and spermidine, are pivotal in various biological processes across living organisms. Despite their significance, structurally modified polyamines offer a less-explored avenue for discovering bioactive compounds. The limitation is attributed to the synthetic difficulty of accessing functionalized polyamines. In this study, we accomplished photoredox-catalyzed functionalization of polyamines to diversify their structure. The rapid functionalization allows attaching fluorophores to the target polyamine, facilitating the development of molecular probes for advancing chemical biology studies.

Cationic ring-opening polymerization of N-benzylaziridines to polyamines via organic boron

This communication reports the synthesis of cyclic polyamines via the cationic ring-opening polymerization (CROP) of N-benzylaziridines initiated by tris(pentafluorophenyl)borane. The debenzylation of these polyamines afforded water-soluble polyethylenimine derivatives. The electrospray ionization mass spectrometry and density functional theory results revealed that the CROP proceeded via the activated chain end intermediates.

pH-Regulated Single and Double Charge Inversions on PEI-Coated Surfaces

The pH-regulated charge inversions on polyethylenimine (PEI)-coated surfaces are indispensable to their applications in biomaterials and nanomaterials. Various PEI-coated surfaces, where single charge inversion happens, have been extensively investigated, while the surfaces where double charge inversion appears are less reported. Here, using a molecular theory, we systematically study the pH-regulated charge density of PEI-coated surfaces. The results suggest whether single or double charge inversion happens depends on PEI affinity to the surface and the bare surface charge density. The region of double charge inversion is much smaller than that of single charge inversion, revealing the reason why double charge inversion is less observed in experiments. Besides, the charge inversions are significantly influenced by the solution condition. The present work provides a useful guideline to the selection of the coated materials and the parameters of PEI solution in the design of PEI-coated surfaces aiming to promote their applications in multifunctional nanomaterials.

Linear Poly(ethylenimine-propylenimine) Random Copolymers for Gene Delivery: From Polymer Synthesis to Efficient Transfection with High Serum Tolerance

Naturally occurring oligoamines, such as spermine, spermidine, and putrescine, are well-known regulators of gene expression. These oligoamines frequently have short alkyl spacers with varying lengths between the amines. Linear polyethylenimine (PEI) is a polyamine that has been widely applied as a gene vector, with various formulations currently in clinical trials. In order to emulate natural oligoamine gene regulators, linear random copolymers containing both PEI and polypropylenimine (PPI) repeat units were designed as novel gene delivery agents. In general, statistical copolymerization of 2-oxazolines and 2-oxazines leads to the formation of gradient copolymers. In this study, however, we describe for the first time the synthesis of near-ideal random 2-oxazoline/2-oxazine copolymers through careful tuning of the monomer structures and reactivity as well as polymerization conditions. These copolymers were then transformed into near-random PEI-PPI copolymers by controlled side-chain hydrolysis. The prepared PEI-PPI copolymers formed stable polyplexes with GFP-encoding plasmid DNA, as validated by dynamic light scattering. Furthermore, the cytotoxicity and transfection efficiency of polyplexes were evaluated in C2C12 mouse myoblasts. While the polymer chain length did not significantly increase the toxicity, a higher PPI content was associated with increased toxicity and also lowered the amount of polymers needed to achieve efficient transfection. The transfection efficiency was significantly influenced by the degree of polymerization of PEI-PPI, whereby longer polymers resulted in more transfected cells. Copolymers with 60% or lower PPI content exhibited a good balance between high plasmid-DNA transfection efficiency and low toxicity. Interestingly, these novel PEI-PPI copolymers revealed exceptional serum tolerance, whereby transfection efficiencies of up to 53% of transfected cells were achieved even under 50% serum conditions. These copolymers, especially PEI-PPI with DP500 and a 1:1 PEI/PPI ratio, were identified as promising transfection agents for plasmid DNA.

Synthesis of bottlebrush polymers based on poly(N-sulfonyl aziridine) macromonomers

We synthesized bottlebrush polymers with polyaziridine brushes and a polynorbornene backbone by a grafting-through approach. The polyaziridine macromonomer aggregates in solution, but these aggregates disperse over the course of the polymerization.

Synthesis and characterization of novel poly(sulfone siloxane)s with good solubility and recyclability based on siloxane units

A controllable circulation between poly(sulfone siloxane)s (PSS) and sulfone-containing cyclosiloxane monomers (SCS) was acheived in the presence of KHSO4.

Catalyst-free aziridine-based step-growth polymerization: a facile approach to optically active poly(sulfonamide amine)s and poly(sulfonamide dithiocarbamate)s

Step-growth polymerization of chiral bis(N-sulfonyl aziridine)s with diamines or bis(dialkyldithiocarbamate) in the absence of a catalyst allows the facile synthesis of optically active polysulfonamide derivatives.

Organocatalytic sequential ring-opening polymerization of cyclic ester/epoxide and N-sulfonyl aziridine: metal-free and easy access to block copolymers

Sequential ring-opening polymerization of ε-caprolactone (ε-CL)/propylene oxide (PO) and N-sulfonyl aziridine switched by tosyl isocyanate (TSI) allows the metal-free synthesis of polysulfonamide-based copolymers.