Non-Enzymatic Electrochemical Sensor Based on Sliver Nanoparticle-Decorated Carbon Nanotubes

Abstract

The authors report a non-enzymatic electrochemical sensor based on a sliver nanoparticle-decorated carbon nanotube (AgNPs-MWCNT). Highly-dispersed AgNPs were loaded on the MWCNT surface though a simple and facile two-step method. The morphology, components, and the size of the AgNPs-MWCNT nanocomposite were characterized by transmission electron microscopy, X-ray diffraction, and ICP analysis. Benefitting from the synergistic effect between the AgNPs and MWCNT, the AgNPs-MWCNT nanocomposite exhibited high electrocatalytic activity for H₂O₂; the AgNPs-MWCNT electrochemical sensor was prepared by coating the AgNPs-MWCNT nanocomposite on a glassy carbon electrode, and it showed a fast and sensitive response to H₂O₂ with a linear range of 1 to 1000 μM. The detection limit was 0.38 μM (S/N = 3). The sensor was applied to detect H₂O₂ in spiked human blood serum samples with satisfactory results.

Keywords: carbon nanotubes; hydrogen peroxide; nonenzymatic; sensor; silver nanoparticles.

Figure 1

Typical TEM images of the shortened MWCNTs (a and b) and the synthesized AgNPs-MWCNT nanocomposites (c and d).

Figure 2

XRD patterns of the shortened MWCNT (black) and AgNPs-MWCNT nanocomposite (red).

Figure 3

(a) Cyclic voltammograms of GCE, MWCNT/GCE, and AgNPs-CNT/GCE in N₂-saturated 0.1M PBS solution containing 5 mM H₂O₂, potential scan rate: 100 mV/s; (b) cyclic voltammograms of AgNPs-MWCNT/GCE in N₂-saturated 0.1M PBS in the presence of H₂O₂ with different concentrations (1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 mM), potential scan rate: 100 mV/s; (c) relationship between the reduction peak current and H₂O₂ concentrations. (d) Cyclic voltammograms of AgNPs-MWCNT/GCE in N₂-saturated 0.1 M PBS containing 1 mM H₂O₂ at different scan rates (40, 60, 80, 100, 120, 140, and 160 mV/s); (e) relationship between the peak current vs. square root of potential scan rate.

Figure 4

(a) The responsive currents of AgNPs-MWCNT/GCE in the presence of 1 mM H₂O₂ at different working potential from −0.1 to −0.6 V with 0.1 V interval; (b) typical amperommetric responses of AgNPs-MWCNT/GCE to the successive addition of H₂O₂ in 0.1 M PBS at working potential of −0.5 V; (c) the dependence of the responses of electrodes on H₂O₂ concentrations.

Figure 5

(a) Chronoamperometric curve (black) of the AgNPs-MWCNT/GCE in response to the successive addition of 0.1 mM H₂O₂, 5 mM ascorbic acid, 5 mM NaCl, 5 mM fructose, 5 mM sucrose, 5 mM glucose and 0.1 mM H₂O₂ in 0.1 M PBS at a working potential of −0.5 V; chronoamperometric curve (red) of the AgNPs-MWCNT/GCE in response to the successive addition of 1 mM H₂O₂, 5 mM ascorbic acid, 5 mM NaCl, 5 mM fructose, 5 mM sucrose, 5 mM glucose and 1 mM H₂O₂ in PBS at a working potential of −0.5 V. (b) Current responses of five equally fabricated sensors to 0.1mM H₂O₂. (c) Current responses of the AgNPs-MWCNT/GCE biosensor to 0.5 mM H₂O₂. Amperommetric measurements were performed in 5 days using the same sensor.