Naturally occurring hemin, an iron‐containing porphyrin, and its synthetic derivatives were used as atom transfer radical polymerization (ATRP; see picture) catalysts. The effects of the halide salt concentration, attachment of poly(ethylene glycol) moieties, and hydrogenation of the hemin vinyl groups on the catalyst performance were studied.

The field of RNA interference depends on the development of safe and efficient carriers for short interfering ribonucleic acid (siRNA) delivery. Conventional cationic monomers for siRNA delivery have utilized the nitrogen heteroatom to produce cationic charges. Here, we polymerized cationic sulfonium (meth)acrylate by activators regenerated by electron transfer (ARGET) atom transfer radical polymerization (ATRP) to form polymers with narrow molecular weight distributions for siRNA delivery. The tertiary sulfonium species was stable toward dealkylation in water but less stable in the polar aprotic solvent dimethyl sulfoxide. Block copolymers poly(ethylene oxide) with poly(meth)acrylate containing sulfonium moieties were prepared as an siRNA delivery platform. Results suggested block copolymers were biocompatible up to 50 μg/mL in vitro and formed polyplexes with siRNA. Additionally, block copolymers protected siRNAs against endonuclease digestion and facilitated knockdown of glyceraldehyde 3-phosphate dehydrogenase (Gapdh) mRNA expression in murine calvarial preosteoblasts. The versatility, biocompatibility, and cationic nature of these tertiary sulfonium groups are expected to find widespread biological applications.

Natürlich vorkommendes Hämin, ein Eisen‐koordiniertes Porphyrinmolekül, und seine synthetischen Derivate wurden als Katalysatoren für die radikalische Atomtransferpolymerisation (ATRP; siehe Bild) verwendet. Die Effekte der Halogensalzkonzentration, der angehängten Polyethylenglykol‐Einheiten und der hydrierten Häminvinylgruppen auf die katalytische Aktivität wurden untersucht.