Two-phase synthesis of hydrophobic ionic liquid-capped gold nanoparticles and their application for sensing cholesterol

• A novel cholesterol biosensor was constructed based on ChOx-IL-capped-AuNPs/GCE.
• IL-capped-AuNPs was synthesized using two-phase synthesis and employed as a conducting matrix to immobilize ChOx.
• Direct electrochemistry of ChOx on the electrode was obtained.
• The ChOx-IL-capped-AuNPs/GCE exhibit remarkable performance for cholesterol detection.

A novel scheme for fabrication of hydrophobic ionic liquid-capped gold nanoparticles (IL-capped AuNPs) modified electrode is presented and its application potential for cholesterol biosensor is investigated. Highly stable gold nanoparticles were characterized by UV–vis absorption spectroscopy and transmission electron microscopy (TEM). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) indicated that IL-capped AuNPs nanocomposites showed excellent electrical conductivity. Furthermore, cholesterol oxidase (ChOx) was directly immobilized on the IL-capped AuNPs nanocomposite, and then the direct electrochemistry of ChOx on the modified glass carbon electrode (GCE) was obtained. As a new platform in cholesterol analysis, ChOx-IL-capped AuNPs/GCE exhibited a linear response to cholesterol in the range of 0.1–50 μM with a detection limit of 0.033 μM. Therefore, hydrophobic ionic liquid-capped gold nanoparticles would serve as a good candidate material to construct the related enzyme biosensors.

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