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.

Insertion of Hemin into Metal–Organic Frameworks: Mimicking Natural Peroxidase Microenvironment for the Rapid Ultrasensitive Detection of Uranium

“…Hemin, the active site of various proteins, is a promising substitute for natural peroxidases . The “bottom-up” approach for the fabrication of such a hemin-based peroxidase mimetic catalyst allowed researchers to not only mimic catalytic function but also the active site of natural peroxidases, offering a more in-depth understanding of the genesis of the natural enzyme. Unfortunately, the requirement for structurally and chemically reproducing the active sites of natural enzymes makes the mimetic process challenging. , So far, to address this problem, various hemin-contained peroxidase mimetics have been developed. ,− But common approaches to the manufacture of these hemin-contained artificial enzymes relied on the use of biological macromolecules, such as DNA, , proteins, and polypeptides, − as the backbone to mimic the microenvironment of the natural peroxidase active center, still facing the vulnerability of biological macromolecules.…”

A Versatile Chemoenzymatic Nanoreactor that Mimics NAD(P)H Oxidase for the In Situ Regeneration of Cofactors

“…The use of hemin as active catalytic core of biomimetic NOx systems has been demonstrated to be successful for the oxidation of NADH [10–12] . Hemin is an organometallic iron (III) porphyrin that requires embedment into stabilizing scaffolds due to its inherent hydrophobicity and concomitant low stability in aqueous systems [13, 14] . Although hemin‐based materials effectively peroxidize enzymatic cofactors, they have shown strong limitations when coupled to enzymes.…”

“…[10][11][12] Hemin is an organometallic iron (III) porphyrin that requires embedment into stabilizing scaffolds due to its inherent hydrophobicity and concomitant low stability in aqueous systems. [13,14] Although hemin-based materials effectively peroxidize enzymatic cofactors, they have shown strong limitations when coupled to enzymes. To the best of our knowledge, there are no examples in which the full recycling system, i.e., DHs plus artificial heminbased NOx mimetics, has been proven effective.…”

A Versatile Chemoenzymatic Nanoreactor that Mimics NAD(P)H Oxidase for the In Situ Regeneration of Cofactors

“…The use of hemin as active catalytic core of biomimetic NOx systems has been demonstrated to be successful for the oxidation of NADH [10–12] . Hemin is an organometallic iron (III) porphyrin that requires embedment into stabilizing scaffolds due to its inherent hydrophobicity and concomitant low stability in aqueous systems [13, 14] . Although hemin‐based materials effectively peroxidize enzymatic cofactors, they have shown strong limitations when coupled to enzymes.…”