A novel nanoplatform encapsulating glucose oxidase for spectrophotometric biosensing of hydrogen peroxide and glucose

Abstract

In this work, we were inspired from the role of chelation of Fe³⁺–catechol in inter-protein interactions and the production of adhesives by marine mussels, and used dopamine (DA) as an anchor to connect the enzyme glucose oxidase (GOx) to Fe₃O₄ magnetic nanoparticle cores via the formation of Fe(OH)₃ shells. Because of the tendency of catechol and similar ligands such as DA to coordinate with the Fe³⁺ surface sites, a tight binding of DA to the Fe₃O₄–Fe(OH)₃ core–shell was easily accomplished. Accordingly, we formulated an Fe³⁺–polyDA framework to encapsulate GOx; we specifically produced Fe₃O₄–Fe(OH)₃@GOx–polyDA by carrying out an in situ polymerization of DA covalently linked to GOx on the Fe(OH)₃ shells of magnetic nanoparticles. The Fe³⁺–polyDA framework stabilized the structure of the encapsulated GOx layer and increased its thermal stability, operational stability and recyclability, while preserving its activity. The prepared Fe₃O₄–Fe(OH)₃@GOx–polyDA probe displaying enzyme-like characteristics was used as a multifunctional platform in a sensitive and selective spectrophotometric biosensor, with N,N-diethyl-p-phenylenediamine sulfate (DPD) as a redox indicator, for sub-micromolar detection of hydrogen peroxide and glucose via an enzymatic cascade reaction.