Biocatalyst and Colorimetric/Fluorescent Dual Biosensors of H₂O₂ Constructed via Hemoglobin–Cu₃(PO₄)₂ Organic/Inorganic Hybrid Nanoflowers

Abstract

In this article, the three-dimensional hemoglobin (Hb)-Cu₃(PO₄)₂ organic/inorganic hybrid nanoflowers (Hb-Cu₃(PO₄)₂ HNFs) self-assembled by nanopetals were synthesized via a facile one-pot green synthetic method. The compositions and microstructure of the Hb-Cu₃(PO₄)₂ HNFs were well-characterized with X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and UV-vis spectrometry, respectively. The as-prepared Hb-Cu₃(PO₄)₂ HNFs were to be used as a biocatalyst to construct colorimetric/fluorescent dual biosensors. The experimental results show that the colorimetric/fluorescent dual biosensors exhibited two linear responses in the range of 2-10 ppb and 20-100 ppb for H₂O₂. The colorimetric and fluorescent detection limits were 0.1 and 0.01 ppb, respectively. Compared with the free Hb, the biocatalytic activity of the Hb-Cu₃(PO₄)₂ HNFs can be improved for 3-4 times under optimal conditions. The sensing performance of these Hb-Cu₃(PO₄)₂ HNF-based dual biosensors can be contributed such that the active sites of Hb molecules were more exposed on the surface of the Cu₃(PO₄)₂ nanopetals. Second, the unique nanopetal-assembled hybrid flowerlike structure was favorable to contact the detected substance with the biosensors. The dual biosensors were successfully applied for the determination of H₂O₂ in rainwater, tap water, and waste water samples. These results show that the dual biosensors had a potential application in the field of medical analysis, environmental monitoring, and food engineering.