Facile synthesis of enzyme-inorganic hybrid nanoflowers and its application as a colorimetric platform for visual detection of hydrogen peroxide and phenol.

This study reports a facile approach for the synthesis of horseradish peroxidise (HRP)-inorganic hybrid nanoflowers by self-assembly of HRP and copper phosphate (Cu3(PO4)2·3H2O) in aqueous solution. Several reaction parameters that affect the formation of the hybrid nanoflowers were investigated and a hierarchical flowerlike spherical structure with hundreds of nanopetals was obtained under the optimum synthetic conditions. The enzymatic activity of HRP embedded in hybrid naonflowers was evaluated based on the principle of HRP catalyzing the oxidation of o-phenylenediamine (OPD) in the presence of hydrogen peroxide (H2O2). The results showed that 506% enhancement of enzymatic activity in the hybrid nanoflowers could be achieved compared with the free HRP in solution. Taking advantages of the structural feature with catalytic property, a nanoflower-based colorimetric platform was newly designed and applied for fast and sensitive visual detection of H2O2 and phenol. The limits of detection (LODs) for H2O2 and phenol were as low as 0.5 μM and 1.0 μM by the naked-eye visualization, which meet the requirements of detection of both analytes in clinical diagnosis and environmental water. The proposed method has been successfully applied to the analysis of low-level H2O2 in spiked human serum and phenol in sewage, respectively. The recoveries for all the determinations were higher than 92.6%. In addition, the hybrid nanoflowers exhibited excellent reusability and reproducibility in cycle analysis. These primary results demonstrate that the hybrid nanoflowers have a great potential for applications in biomedical and environmental chemistry.