Abstract
A simple two-step method was employed for preparing nano-sized gold nanoparticles-graphene composite to construct a GNPs-GR-SDS modified electrode. Hemoglobin (Hb) was successfully immobilized on the surface of a basal plane graphite (BPG) electrode through a simple dropping technique. Direct electrochemistry and electrocatalysis of the hemoglobin-modified electrode was investigated. The as-prepared composites showed an obvious promotion of the direct electro-transfer between hemoglobin and the electrode. A couple of well-defined and quasi-reversible Hb CV peaks can be observed in a phosphate buffer solution (pH 7.0). The separation of anodic and cathodic peak potentials is 81 mV, indicating a fast electron transfer reaction. The experimental results also clarified that the immobilized Hb retained its biological activity for the catalysis toward NO. The biosensor showed high sensitivity and fast response upon the addition of NO, under the conditions of pH 7.0, potential -0.82 V. The time to reach the stable-state current was less than 3 s, and the linear response range of NO was 0.72-7.92 μM, with a correlation coefficient of 0.9991.
Highlights
Graphene, a single layer of sp2-hybridized carbon atoms packed into a dense honeycomb two-dimensional lattice, has been the subject if intensive investigations by both the experimental and Sensors 2013, 13 theoretical scientific communities since the experimental observation of single layers by Novoselov and Geimin in 2004 [1,2,3]
These absorption changes indicate that the graphene-oxide plays an important role in dictating the size of gold nanoparticles
Plasmon resonance associated-absorption wavelengths will shift from blue to red, and reflected light will shift from red to blue, which results in further color changes of the gold nanoparticle solutions
Summary
A single layer of sp2-hybridized carbon atoms packed into a dense honeycomb two-dimensional lattice, has been the subject if intensive investigations by both the experimental and Sensors 2013, 13 theoretical scientific communities since the experimental observation of single layers by Novoselov and Geimin in 2004 [1,2,3]. Like carbon nanotubes (CNTs) and other nanomaterials, a key challenge in the synthesis and processing of bulk-quantity graphene sheets is aggregation due to the highly cohesive van der Waals energy (5.9 kJ·mol−1 carbon) [7] that adheres graphitic sheets to one another. To overcome this problem, graphene sheets have been prepared in the presence of a broad variety of reagents, including octadecylamine, polystyrene, poly (sodium 4-styrene sulfonate), alkali metal and even Au nanoparticles [8,9,10]. We demonstrate the direct electrochemistry and electrocatalysis of hemoglobin (Hb) immobilized in GNPs-GR-SDS films for the detection of NO
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