Abstract
As a well-known toxic pollutant, sulfide is harmful to human health. In this study, a simple and sensitive amperometric inhibitive biosensor was developed for the determination of sulfide in the environment. By immobilizing nanoporous gold (NPG) on glassy carbon electrode (GCE), and encapsulating horseradish peroxidase (HRP) onto NPG, a HRP/NPG/GCE bioelectrode for sulfide detection was successfully constructed based on the inhibition of sulfide on HRP activity with o-Phenylenediamine (OPD) as a substrate. The resulted HRP/NPG/GCE bioelectrode achieved a wide linear range of 0.1–40 μM in sulfide detection with a high sensitivity of 1720 μA mM−1 cm−2 and a low detection limit of 0.027 μM. Additionally, the inhibition of sulfide on HRP is competitive inhibition with OPD as a substrate by Michaelis-Menten analysis. Notably, the recovery of HRP activity was quickly achieved by washing the HRP/NPG/GCE bioelectrode using differential pulse voltammetry (DPV) technique in deaerated PBS (50 mM, pH 7.0) for only 60 s. Furthermore, the real sample analysis of sulfide by the HRP/NPG/GCE bioelectrode was achieved. Based on above results, the HRP/NPG/GCE bioelectrode could be a better choice for the real determination of sulfide compared to inhibitive biosensors previously reported.
Highlights
horseradish peroxidase (HRP) was successfully assembled onto nanoporous gold (NPG) to form a HRP/NPG biocomposite[15], and the HRP/NPG biocomposite was immobilized on glassy carbon electrode (GCE) to construct a HRP/NPG/GCE bioelectrode
The electrochemical determination of the NPG/GCE electrode and the HRP/NPG/GCE bioelectrode were recorded in deaerated PBS (50 mM, pH 7.0) using cyclic voltammetry (CV) technique at a scan rate of 50 mV s−1, Figure 2. (A) CVs of NPG/GCE electrode and HRP/NPG/GCE bioelectrode in deaerated PBS (50 mM, pH 7.0); (B) differential pulse voltammetry (DPV) of HRP/NPG/GCE bioelectrode at different conditions: (a) in deaerated PBS (50 mM, pH 7.0); (b) the same as (a) with the presence of 100 μM OPD and 0.1 mM H2O2; (c) the same as (b) with 10 μM sulfide
The HRP/NPG/GCE bioelectrode exhibited much higher sensitivity than previous reported inhibitive biosensors as shown in Table 2, which was attributed to the competitive inhibition on HRP by sulfide with OPD as a substrate. These results indicated that the HRP/NPG/GCE bioelectrode showed higher sensitivity, wider linear range, and lower detection limit than most inhibitive biosensors for sulfide detection reported in previous works (Table 2)
Summary
The morphology of NPG/GCE electrode (Fig. 1A) and HRP/NPG/GCE bioelectrode (Fig. 1B) were characterized by scanning electron microscope (SEM). When 10 μM sulfide was added, a remarkably decreased peak current density was observed as shown in Fig. 2B-c, confirming the inhibition of sulfide on HRP activity These results indicated that the inhibitive biosensor construction was feasible using the HRP/NPG/GCE bioelectrode. NH4+ (1 mM), Mg2+ (1 mM), Zn2+ (0.5 mM), K+ (1 mM), Fe3+ (0.5 mM), Fe2+ (1 mM), SO42− (1 mM), Cl− (1 mM), citrate (1 mM), and CN− (20 μM) were added respectively in deaerated PBS (50 mM, pH 7.0) containing 10 μM sulfide 100 μM OPD with 0.1 mM H2O2 to detected the anti-interference ability of the HRP/NPG/GCE bioelectrode. OPD and 0.1 mM H2O2 with different sulfide concentrations; (B) The inhibition rate of sulfide versus the concentration of sulfide
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
