An effective electrochemical biosensing platform for the detection of reduced glutathione

Figures & data

Figure 1. Schematic representation of the fabrication of a GSH biosensor.

Figure 2. Electrodeposition of Pt-NPs onto bare GCPE with cyclic voltammetry in 0.1 M KCl, at a potential ranging between − 0.70 V and + 0.80 V at 50 mV.s^{− 1} for 50 cycles.

Figure 3. Differential pulse voltammograms of (a) background for GSH-Px(immob)/GCPE, (b) 100 μM GSH/50 μM H₂O₂ GSH-Px(immob)/GCPE, (c) 100 μM GSH/50 μM H₂O₂ for Pt-NP-modified GSH-Px(immob)/GCPE. Conditions: 50 mM, pH 7.0 phosphate buffer solution, T = 25°C.

Figure 4. Nyquist plots of the response of the biosensing electrode at different stages in the electrode assembly process: bare GCPE (X); GSH-Px(immob)/GCPE (■) and GSH-Px(immob)/Pt-NP/GCPE (▲). All spectra were recorded in the presence of 1 mM [Fe(CN)₆]^3−/4− in 0.05 M PBS (pH 7.5), as a redox-active indicator. Frequency range: 10⁴ to 0.01 Hz, 0.05 V amplitude.

Figure 5. Differential pulse voltammetric responses of 100 μM GSH/50 μM H₂O₂ on the biosensor response at various amounts of enzyme: (a) 1.0 U, (b) 2.0 U, (c) 5.0 U, (d) 10.0 U, and (e) 15.0 U. Conditions: phosphate buffer solution system (50 mM, pH 7.0), potential range of 0 V and + 0.7 V. Inset: the curve showing the effect of optimum enzyme amount of GSH-Px(immob)/Pt-NP/GCPE.

Figure 6. Differential pulse voltammetric responses of different GSH/H₂O₂ ratios on the biosensor response; (a) 0.1/1 GSH/H₂O₂, (b) 0.5/1 GSH/H₂O₂, (c) 1/1 GSH/H₂O₂, (d) 2/1 GSH/H₂O₂, (e) 5/1 GSH/H₂O₂, and (f) 10/1 GSH/H₂O₂. Conditions: phosphate buffer solution system (50 mM, pH 7.0), [GSH] = 50.0 μM; potential range of 0 V and + 0.7 V, T = 25°C. Inset: Effect of the GSH/H₂O₂ ratio in the performance of the GSH biosensor.

Table I. A comparison of the analytical characteristics of differently modified electrochemical biosensors for the detection of GSH.

Biosensor	Analyte	Linear range (μM)	RSD (%)	R^2	Operational stability	References
GSH-Px immobilized EDAC^a/PGE^b	GSH	19–140	7.0	0.9993	No significant decrease after 2 months	Rover et al., 2001
Os-gel^c-HRP^d/GSH-SOx^e bilayer-modifed GCE	GSH GSSG	1–200	1.1	−	−	Mao and Yamomoto
GR^f-SOx/Chit^g/SGR^h bienzymatic	GSH GSSG	200–1000	1.9	0.9862	11% decrease after 3 h	Timur et al., 2008
GSH-Px/Pt-NP/GCPE	GSH	10–250	2.92	0.9968	2% decrease after 1 week	This work

^aEDAC: 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride

^bPGE: Pyrolytic graphite electrode

^cOs-gel: Osmium-Polyvinylpyridine Gel Polymer

^dHRP: Horseradish peroxidase

^eSOx: Sulfhydryl oxidase

^fGR: Glutathione reductase

^gChit: Chitosan

^hSGR: Spectrographic graphite rods

Rover L, Tatsuo Kubota L, Fenalti Höehr N. 2001. Development of an amperometric biosensor based on glutathione peroxidase immobilized in a carbodiimide matrix for the analysis of reduced glutathione from serum. Clin Chim Acta. 308:55–67.

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Timur S, Odacı YY, Dincer A, Zihnioglu F, Telefoncu A. 2008. Biosensing Approach for Glutathione Detection Using Glutathione Reductase and Sulfhydryl Oxidase Bienzymatic System. Talanta 817: 239–246.

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