Biocatalyst and Colorimetric/Fluorescent Dual Biosensors of H 2 O 2 Constructed via Hemoglobin-Cu 3 (PO 4 ) 2 Organic/Inorganic Hybrid Nanoflowers.

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 H2 O2 . 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 H2 O2 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.