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. 2015 Jun 8:5:11129.
doi: 10.1038/srep11129.

Multifunctional glucose biosensors from Fe₃O₄ nanoparticles modified chitosan/graphene nanocomposites

Wenjing Zhang  1 , Xiaojian Li  1 , Ruitao Zou  1 , Huizi Wu  1 , Haiyan Shi  1 , Shanshan Yu  1 , Yong Liu  2
Affiliations

Multifunctional glucose biosensors from Fe₃O₄ nanoparticles modified chitosan/graphene nanocomposites

Wenjing Zhang et al. Sci Rep. .

Abstract

Novel water-dispersible and biocompatible chitosan-functionalized graphene (CG) has been prepared by a one-step ball milling of carboxylic chitosan and graphite. Presence of nitrogen (from chitosan) at the surface of graphene enables the CG to be an outstanding catalyst for the electrochemical biosensors. The resulting CG shows lower ID/IG ratio in the Raman spectrum than other nitrogen-containing graphene prepared using different techniques. Magnetic Fe3O4 nanoparticles (MNP) are further introduced into the as-synthesized CG for multifunctional applications beyond biosensors such as magnetic resonance imaging (MRI). Carboxyl groups from CG is used to directly immobilize glucose oxidase (GOx) via covalent linkage while incorporation of MNP further facilitated enzyme loading and other unique properties. The resulting biosensor exhibits a good glucose detection response with a detection limit of 16 μM, a sensitivity of 5.658 mA/cm(2)/M, and a linear detection range up to 26 mM glucose. Formation of the multifunctional MNP/CG nanocomposites provides additional advantages for applications in more clinical areas such as in vivo biosensors and MRI agents.

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Figures

Figure 1
Figure 1. Formation of the Fe3O4/CG nanocomposites.
a Schematic synthesis of the CG. b A typical AFM image of the CG nanosheets. Arrow indicates presence of chitosan. c Schematic preparation of the Fe3O4/CG nanocomposites. d A typical AFM image of the Fe3O4/CG nanocomposites.
Figure 2
Figure 2. XPS spectra of the Fe3O4/CG nanocomposites.
a XPS survey spectrum of the Fe3O4/CG nanocomposites. b The high-resolution C1s spectrum. c The high-resolution Fe2p spectrum. d The high-resolution N1s spectrum.
Figure 3
Figure 3. Physicochemical characterization of the Fe3O4/CG nanocomposites.
a XRD patterns of the Fe3O4/CG. b Raman spectra of the CG and the Fe3O4/CG. c The FTIR spectrum of the Fe3O4/CG. d The TGA curve of the Fe3O4/CG.
Figure 4
Figure 4. Magnetic properties of the Fe3O4/CG nanocomposites.
a Digital photos of the Fe3O4/CG nanocomposite suspension with and without an exterior magnetic field. b magnetic hysteresis curve of the Fe3O4 and Fe3O4/CG nanomaterials. c T2 weighted MRI images of the CG and Fe3O4/CG nanomaterials.
Figure 5
Figure 5. Biosensor performance.
a Amperometric responses of the Fe3O4/CG -GOx electrode to successive additions of 5 mM of glucose at 0.5 V vs Ag/AgCl in 0.1 M PBS (pH = 7.4). b the calibration curve obtained for glucose detection.
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