Electrochemical glucose biosensor based on nickel oxide nanoparticle-modified carbon paste electrode

Figures & data

Figure 1. (A) CVs of 1 mmol L^–1 Fe(CN)₆^3–/4– on the various NiONPs–CPEs with the mass ratios of NiONPs to graphite powder were 1:2 (a), 1:3 (b), 1:4 (c), and 1:5 (d) (Scan rate: 50 mV s^–1), (B) the plot of the peak current vs. H₂O₂ concentration for the various NiONPs‐CPEs in 0.1 M PBS (pH 7.0) at 0.4 V vs. Ag/AgCl.

Table I. Comparisons of electrochemical characteristics of the NiONPs–CPEs were prepared at the various mass ratio of NiONPs/graphite toward the redox probe of Fe(CN)₆^3–/4– (scan rate = 50 mVs^–1).

The mass ratio of NiONPs to graphite	Epa/V	Epc/V	ΔEp/V	Ipa/μA	Ipc/μA
1:2	0.245	0.147	0.098	16.44	14.66
1:3	0.254	0.147	0.107	20.51	21.47
1:4	0.256	0.149	0.107	20.13	20.35
1:5	0.281	0.139	0.142	15.86	15.46

Figure 2. (A) CVs of the UCPE (a) and NiONPs–CPE (b) at scan rate 10 mVs^–1, (B) the plot of the peak current vs. the square root of the scan rate for NiONPs‐CPE (inset: CVs at different scan rates) in 0.1 mol L^–1 KCl solution containing 1 mmol L^–1 Fe(CN)₆^3–/4–.

Figure 3. The Nyquist curves of the (a) UCPE and (b) NiONPs–CPE in 0.1 mmol L^–1 KCl solution containing 1 mmolL⁻¹ Fe(CN)₆^3–/4–.

Figure 4. (A) CVs of the UCPE and NiONPs–CPE in the absence and presence of 1 mmol L^–1 H₂O₂ (scan rate = 50 mVs^–1) in 0.1 mmol L^–1 PBS (pH 7.0). (B) Amperometric responses of the UCPE and NiONPs–CPE for the oxidation of H₂O₂ in 0.1 M PBS (pH 7.0) at 0.4 V vs. Ag/AgCl.

Figure 5. The effect of working potential on the amperometric response of H₂O₂ in 0.1 mmol L⁻¹ PBS (pH 7.0).

Figure 6. The sensitivity of the GOD–NiONPs–CPE as a function of buffer pH in 0.1 mmol L^–1 PBS at 0.4 V vs. Ag/AgCl.

Figure 7. (A) Calibration curve of the GOD–NiONPs–CPE for glucose in 0.1 M PBS (pH 7.0) at 0.4 V vs. Ag/AgCl. (inset: linear working ranges plots), (B) Substrate concentration/current response vs. substrate concentration plot (Hanes–Woolf plot).

Figure 8. Amperometric responses of the glucose biosensor upon addition of AA (0.1 mmol L^–1, DA (0.1 mmol L^–1), and UA (0.1 mmol L^–1) in 0.1 M PBS (pH 7.0) at 0.4 V vs. Ag/AgCl.

Table II. Effects of interferences on glucose response.

Interfering species	Concentration^a (mmol L^–1)	Interference^b (%)
L-ascorbic acid	0.1	1.56
Dopamine	0.1	1.54
Uric acid	0.1	0.76

^aThe electrochemical cell concentration of interfering species.

^b% interference = (i_x − i₀)/i₀ × 100; i₀: The amperometric response of buffer solution containing 0.1 mmol L^–1 glucose solution and i_x: The amperometric response of buffer solution containing 0.1 mmol L^–1 glucose and interfering species with above concentration.

Table III. The determination of glucose levels in human serum samples.

Serum samples	Glucose concentration (mmol L^–1)
	Provided by the hospital	Determined by proposed biosensor*
1	3.61	3.50 ± 0.6
2	4.61	4.93 ± 0.9
3	5.00	5.14 ± 0.4
4	7.44	7.53 ± 1.0

*Average of three measurements.