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. 2019 Jun 22;9(6):245.
doi: 10.3390/biom9060245.

Facile Preparation of Fe3O4/C Nanocomposite and Its Application for Cost-Effective and Sensitive Detection of Tryptophan

Jun Liu  1 , Shuai Dong  2 , Quanguo He  3 , Suchun Yang  4 , Mei Xie  5 , Peihong Deng  6 , Yonghui Xia  7 , Guangli Li  8
Affiliations

Facile Preparation of Fe3O4/C Nanocomposite and Its Application for Cost-Effective and Sensitive Detection of Tryptophan

Jun Liu et al. Biomolecules. .

Abstract

In this study, we reported facile synthesis of Fe3O4/C composite and its application for the cost-effective and sensitive determination of tryptophan (Trp) in human serum samples. Fe3O4/C composites were prepared by a simple one-pot hydrothermal method followed by a mild calcination procedure, using FeCl3∙6H2O as Fe3O4 precursor, and glucose as reducing agent and carbon source simultaneously. The Fe3O4/C composite modified glassy carbon electrode (Fe3O4/C/GCE) was prepared by drop-casting method. The microstructure and morphology of Fe3O4/C composite was characterized by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Due to large specific surface area and synergistic effect from Fe3O4 nanoparticles and carbon coating, Fe3O4/C composite showed excellent electrocatalytic activity toward the oxidation of Trp. As a result, the proposed Fe3O4/C/GCE displayed superior analytical performances toward Trp determination, with two wide detection ranges (1.0-80 μM and 80-800 μM) and a low detection limit (0.26 μM, S/N = 3). Moreover, successful detection of Trp in human serum samples further validate the practicability of the proposed sensor.

Keywords: Fe3O4/C composite; second derivative linear scan voltammetry; tryptophan; voltammetric detection.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
XRD patterns of pure Fe3O4 NPs (curve a) and Fe3O4/C composite (curve b).
Figure 2
Figure 2
SEM images of pure Fe3O4 nanoparticles (a,b) and Fe3O4/C composite nanoparticles (c,d).
Figure 3
Figure 3
Electrochemical active areas of different electrodes were investigated by CV in 0.1 M PBS containing 0.5 mM of K3[Fe(CN)6].
Figure 4
Figure 4
CV (a) and second derivative linear scan voltammetry (SDLSV) (b) responses of 10 μM Trp on bare GCE, Fe3O4/GCE, and Fe3O4/C/GCE. Supporting electrolyte: 0.1 M PBS (pH 6.5); Scanning rate: 0.1 V/s.
Figure 5
Figure 5
Effect of solution pH on the electrochemical responses of 10 μM Trp. (a) CV curves in different pH PBS. (b) Effect of solution pH on the anodic peak currents (black line) and the anodic peak potentials (blue line). Supporting electrolyte: 0.1M PBS; Scanning rate: 0.1 V/s; Accumulation potential: 0.2 V; Accumulation time: 210 s.
Figure 6
Figure 6
Effect of scanning rate (v) on the electrochemical responses of 10 μM Trp. (a) CVs curves of 10 μM Trp on Fe3O4/C/GCE recorded at various scanning rates (v); (b) Linear relationship between the anodic peak currents (ipa) and scanning rates (v); (c) Linear relationship between the anodic peak potentials (Epa) and Napierian logarithm of scanning rates (lnv).
Scheme 1
Scheme 1
Schematic diagram of the electrochemical mechanism of Trp oxidation.
Figure 7
Figure 7
Effect of accumulation potential (a) and accumulation time (b) on the anodic peak currents of 10 μM Trp.
Figure 8
Figure 8
curves of Trp with the concentrations ranging from 1 μM to 80 μM (a) and from 80 μM to 800 μM (b); Calibration curves between the anodic peak currents (ipa) and Trp concentrations (cTrp) in the range of 1–80 μM (c) and 80–800 μM (d). Supporting electrolyte: 0.1M PBS (pH 6.5); Scanning rate: 0.1 V/s; Accumulation potential: 0.2 V; Accumulation time: 210 s.
Figure 9
Figure 9
Response anodic peak currents of 10 μM Trp for ten successive measurements (n = 10).
See this image and copyright information in PMC

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