Hemin‐Doped, Ionically Crosslinked Silicone Elastomers with Peroxidase‐Like Reactivity

Abstract The encapsulation of hemin in polymer systems represents a powerful tool for the preparation of synthetic enzymes. Reported systems largely focus on the creation of hydrogels or microreactors that require a degree of modification to the hemin molecule itself. The straightforward synthesis of hydrophobic hemin‐aminosilicone crosslinked silicone elastomers is described with peroxidase like reactivity. Elastomers are formed from purely ionic interactions between commercial aminoalkylsilicones and native hemin, which acts as a crosslinker. Elastomers prepared from ethylene diamine‐based silicones are robust elastomers in which hemin is retained, while hemin can leach monoamine analogues into the adjacent aqueous environment. The system is easily tunable, allowing for precise control of the hemin concentration and the physical properties of the elastomer. Upon exposure to peroxide‐containing solutions, elastomers readily oxidize the substrate 3′,3′,5′,5′‐tetramethylbenzidine at the interface. Elastomers containing excess amine show greater catalytic efficiency due to the coordination of the amines to the iron center of hemin, which is known to be activating. The reaction can be followed using UV‐visible spectroscopy; rates of reaction and Michaelis–Menten parameters are derived.