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Original article
13 (
1
); 3255-3265
doi:
10.1016/j.arabjc.2018.11.001

Square wave voltammetric determination of anticancer drug flutamide using carbon paste electrode modified by CuO/GO/PANI nanocomposite

, ,
 Department of Chemistry, Shahid Bahonar University of Kerman, Kerman, Iran
 Young Researchers Society, Shahid Bahonar University of Kerman, Kerman, Iran

⁎Corresponding author at: Imam Khomeini Highway- Pajuhesh Square- Shahid Bahonar University of Kerman, the Faculty of Science, Department of Chemistry, Iran. moslem_afzali@yahoo.com (Moslem Afzali)

Received: , Accepted: ,
© The Author(s) 2018
Disclaimer:
This article was originally published by Elsevier and was migrated to Scientific Scholar after the change of Publisher.

Peer review under responsibility of King Saud University.

Abstract

The electrochemical behavior of flutamide was investigated using a carbon paste electrode (CPE) modified by CuO nanoparticles/graphene oxide/polyaniline (CuO/GO/PANI) nanocomposite. Square wave and differential pulse voltammetry were studied in different concentrations of flutamide. Square wave voltammetry which is a rapid and sensitive method for reversible systems was used to determine flutamide. Based on the studies carried out by the present method, the electrode has an excellent electrochemical activity to the flutamide oxidation. Under the optimized experimental conditions, the sensor showed excellent linearity from 0.050 to 200.0 nM with a detection limit of 14.0 pM; the best values obtained already for flutamide. The modified electrode was applied for the determination of flutamide in human urine and pharmaceutical samples with satisfy results.

Keywords

Flutamide
CuO/GO/PANI nanocomposite
Carbon paste electrode
Square wave voltammetry
1

1 Introduction

Flutamide, 4‐nitro‐3‐trifluoromethyl‐isobutilanilide (Scheme 1), is a nonsteroidal antiandrogen (NSAA) drug that has been used for the treatment of prostate cancer Koch et al. (2015), Ahmadi et al. (2015) and sold under the brand name of “Eulexin” among people (Elks, 2014). Also, flutamide which can be considered as a selective competitor for the androgen receptor (AR) compete with some androgens like testosterone and dihydrotestosterone (DHT) for binding to ARs in the prostate gland tissue (Hatanaka et al., 2015; Bhatia et al., 2014). So, it inhibits their effects and prevents the growth of prostate cancer cells. Flutamide is a prodrug to a more active form Matsumoto et al. (2016). So, its measurement is important. Various methods have been presented for flutamide determination such as liquid chromatography (Minato et al., 2015), electrospray ionization mass spectroscopy (ESI-MS) tandem mass (Khan et al., 2015), High performance liquid chromatography (HPLC) (Zheng-hua, 2013), spectrophotometry (Fathima et al., 2015), polarography (Pecková et al., 2012). Despite their advantages, these methods suffer from different problems. HPLC can be costly, requiring large quantities of expensive organics (Hassanein et al., 2018). The stray light of UV–Vis spectrophotometer could affect the spectra measurement accuracy of absorption in substance because the stray light will decrease linearity range and reduce the absorbency of substance it measures. Moreover, the electronic circuit design and the quality of spectrometer will increase noises which may be coupled into the measurement signal, hence influencing the measurement accuracy and reduce the sensitivity of the instrument (Sochor et al., 2010; Talsky et al., 1978). Polarography method uses a dropping mercury electrode that is hazardous to the environment (Heyrovsky, 2014). Among all the mentioned methods, electrochemically studies offer a sensitive, rapid, low cost and simple method such as differential pulse polarography (Yilmaz et al., 2014). However, differential pulse voltammetry (DPV) and square‐wave voltammetry (SWV) have widely applied in the determination of pharmaceuticals (Deroco et al., 2014; Eisele et al., 2013; Madrakian et al., 2014; Švorc et al,. 2014). Normal and differential pulse techniques have advantages, but SWV is faster than them which can be performed in a matter of seconds (Mirceski et al., 2013) and also is highly applicable to reversible systems (Lovrić, 2010).

The chemical structure of flutamide.
Scheme 1 The chemical structure of flutamide.

Nowadays, nanoparticles are very attractive for researchers due to their charming and significant attributes comparing with the bulk materials (Reddy, 2017). Having controlled size, large surface area and high surface energy, nanoparticles have been widely applied as modifier in sensors construction. Many nanoparticles such as titanium dioxide, iron oxides, platinum, palladium, gold and silver nanoparticles can affect the modified electrodes response, also, improve their electrical and thermal properties and so, their sensitivity, selectivity, and accuracy (Kurbanoglu and Ozkan, 2017). In the meantime, CuO nanoparticles, the semiconductor material with a band gap of about 3.65–3.72 eV, has found many usages in several fields (Verma et al., 2018) such as sensors (Yang et al., 2017), catalysts (Yan et al., 2017) and solar cells (Abraham et al., 2018).

Carbon materials including carbon nanotubes, graphene, active carbon and carbon nanofibers are typical materials for the electrochemical sensors due to their high specific surface area and excellent conductivity (Chen et al., 2017). Among these materials, graphene oxide (GO) having superior mechanical strength, electrical and good thermal conductivity has attracted great interest in recent years (Rezaeifar et al., 2018) for fuel cells (Klingele et al., 2017), gas sensors (Kumar et al., 2017); nanocatalysts (Bahadorikhalili et al., 2018) and chemical sensors (Guler et al., 2018). The chemical structure of graphene oxide composed of hexagonally arrayed sp2 carbon atoms surrounded by sp3 carbon with many functional groups makes it practical and water-soluble (Mirmotallebi et al., 2018).

Polyaniline (PANI), one of the attractive conducting polymers, has been utilized in many fields such as electrochemical sensors due to its beneficial attributes including environmental stability, facile synthesis and low cost (Chu et al., 2017; Gharbani, 2017). The combination of the GO with PANI can develop novel electrode materials with excellent electrochemical properties. Sha and et al. reported a graphene-polyaniline based electrochemical sensor for non-enzymatic detection of urea. They achieved good selectivity and stability for electrochemical determination of urea with a modified glassy carbon electrode (Sha et al., 2017). The fabrication of graphene oxide/polyaniline/polyvinyl alcohol (GO/PANI/PVA) nanofibers was performed via electrospinning technique by Rose and co-workers. The electrochemical efficiency of the GO/PANI/PVA nanofibers was studied through cyclic voltammetry (CV) studies (Rose et al., 2018). Herein, we have reported a novel electrochemical sensor for flutamide determination through the sensitive technique, square wave voltammetry, using CuO/GO/PANI nanocomposite modified CPE. The fabricated sensor was utilized for the determination of trace amounts of flutamide in pharmaceutical and urine samples.

2

2 Materials and methods

2.1

2.1 Apparatus

Electrochemical experiments were performed using a potentiostat/galvanostat (SAMA500, I. R. Iran) interfaced to computer control for data acquisition and potential. A three-electrode configuration was utilized for all measurements containing CuO/GO/PANI-modified carbon paste electrode as a working electrode, Ag/Agcl as a reference electrode and a platinum wire as an auxiliary electrode. An electrochemical cell was used for aqueous solutions. All analyses were performed at room temperature and under N2 atmosphere. pH values were measured by a Metrohm 827 pH meter (Herisau, Switzerland). Digital balance with a precision of 0.0001 was used to carry out analytical measurements. The micropipette was supplied from Gilson (Villiers-le-Bel, France). The obtained nanomaterials were analyzed by a Bruker Tensor 270 Fourier-transform infrared spectrometer, the Xpert MPD X-ray diffractometer (Philips, Netherlands), EM-900 transmission electron microscopy (Zeiss, Germany) and Mira III scanning electron microscopy (Tescan, Czech Republic).

2.2

2.2 Reagents

Flutamide (C11H11F3N2O3), Graphite powder (<300 μm, 99.99%) and ethanol were purchased from Aldrich (Steinheim, Germany). The 0.1 M standard stock solution of flutamide was prepared by dissolving flutamide powder in ethanol (purity > 99.8%). Phosphate buffer solution (PBS) was prepared using sodium dihydrogen phosphate (NaH2PO4) and disodium hydrogen phosphate (Na2HPO4) supplied from Merck (Darmstadt, Germany). Also, graphite powder and paraffin oil were purchased from Merck. All solutions were prepared with distilled water. The tablet of flutamide (250 mg, Rouz Darou Company) was obtained from a local pharmacy. Sulfuric acid (98%), copper sulfate, potassium permanganate, hydrogen peroxide, hydrochloric acid, iron (III) chloride and sodium nitrite were from Merck and used without any purification. Aniline was supplied from Merck and purified by distillation before using under high purity N2.

2.3

2.3 Synthesis of CuO nanoparticles

The synthesis of CuO nanoparticles was performed by dissolving 4.0 g of copper sulfate (CuSO4·5H2O) in 100 mL water and adjusting pH on 12 by adding 0.3 M NaOH solution. After 4 h stirring at 80 °C, the product was collected by centrifugation and washed three times using deionized water. It was then moved into an oven and dried under 80 °C, finally annealed at 120 °C for 7 h in the oven. The obtained powder was investigated by scanning electron microscopy (SEM).

2.4

2.4 Synthesis of graphene oxide

The preparation of GO was done by the modified Hummer’s method (Shahriary and Athawale, 2014). Firstly, 70 mL of concentrated H2SO4, 2 g of graphite powder and 1.5 g of NaNO3 were added into a 250 mL flask, and the mixture was cooled to 0 °C in an ice bath. 9 g of KMnO4 was slowly added into the flask, and the solution was kept under 10 °C using the ice bath for 2 h, then was warmed to 32 °C with continuous stirring for 8 h. Afterward, the mixture was cooled to room temperature, and 6 mL of 30% H2O2 was added to it. The resulting product was collected by centrifugation, washing with 37% HCl and deionized water and drying at 70 °C in an oven for 24 h.

2.5

2.5 CuO/GO/PANI nanocomposite synthesis

The CuO/GO/PANI nanocomposite was prepared by a simple in-situ polymerization method in the presence of GO and CuO. In a typical process, 1 mL of aniline and 0.3 g of CuO powder obtained from previous step were dispersed in 20 mL of 0.5 M HCl, 15 mL of 0.5 M FeCl3 was added and sonicated for 20 min. Then, 0.1 g of GO dispersed in 20 mL distilled water and 2.5 g of ammonium persulfate (APS) in 20 mL of 0.5 M HCl solution were added to this solution and stirred for 12 h at room temperature. The final compound was centrifuged, washed with ethanol 3 times and dried at 80 °C for 12 h in an oven. The structure and morphology of the composite were analyzed by FT-IR, XRD, EDX, TEM and SEM.

2.6

2.6 Fabrication of the modified carbon paste electrode

The type of working electrode modifier can be effective in electrochemical flutamide measurements. 0.17 g of graphite powder and 0.03 g of CuO/GO/PANI nanocomposite were mixed and eroded for 15 min. Then, three drops of paraffin oil were added to it. So, the modified carbon paste electrode was polished on a thick paper. The proposed sensor was named CuO/GO/PANI/CPE for analyzing flutamide according to the general procedure.

2.7

2.7 General procedure

For voltammetric measurement, 10.0 mL of phosphate buffer (0.1 M) at pH 7.0 and flutamide stock solution in the range of 0.050–200.0 nM were added in the electrochemical cell by micropipette and then the CuO/GO/PANI-CPE was prepared and located in the sample solution which was stirred gently for 5 min. Two equal values of flutamide were injected to the 0.1 M buffer solution (pH 7.0) at a scan rate of 50 mV s−1 to determine flutamide through differential pulse and square wave voltammetry methods. As can be seen from Fig. 1, the cathodic peak appears at a potential value of -0.18 V. The results proved that square wave voltammetry has a higher sensitivity than DPV. So, experiments were performed with SWV technique.

The comparison of the square wave and differential pulse voltammetry techniques for the determination of flutamide using CuO/GO/PANI-modified CPE.
Fig. 1 The comparison of the square wave and differential pulse voltammetry techniques for the determination of flutamide using CuO/GO/PANI-modified CPE.

3

3 Results and discussion

3.1

3.1 Nanocomposite characterization

The morphology and the average diameter of the CuO nanoparticles were investigated by SEM shown in Fig. 2. The image illustrates that the nanoparticles with an average size of 50 nm and uniform spherical shape are obtained where the absence of aggregates is observed.

The SEM image of the obtained CuO nanoparticles.
Fig. 2 The SEM image of the obtained CuO nanoparticles.

The SEM and TEM images of the prepared nanocomposite are exhibited in Fig. 3a and b, respectively. It can be seen that GO nanosheets have layered morphology, PANI with a mass structure is formed and accumulated on the surface of GO sheets and CuO nanoparticles are also dispersed in the bulk of the polymer. According to these results the proposed mechanism for composite formation is as follows: at first, aniline adsorbed to CuO nanoparticles because of their high surface energy, then FeCl3 began to oxidize aniline monomer and turn it into the oligomer. After adding GO, oligomers tend to be adsorbed to the surfaces of GO, so oligomers were more oxidized by APS and long chains of PANI were formed on the surface of GO sheets. Whereas GO nanosheets comprise many reactive oxygen-containing functional groups and large surface area, provides many active sites for polymerization and the growth of polymer at the surface of nanosheets.

(a) SEM and (b) TEM images of the CuO/GO/PANI nanocomposite.
Fig. 3 (a) SEM and (b) TEM images of the CuO/GO/PANI nanocomposite.

The chemical structure of GO, PANI, GO/PANI and CuO/GO/PANI nanocomposite was characterized by FT-IR and illustrated in Fig. 4. The characteristic peaks of GO at 1730, 1410, 1580 and a broad peak at 3432 cm−1 related to stretching of C⚌O and C—O bonds of COOH groups, the stretching of aromatic C⚌C and the O—H bond of carboxylic groups, respectively are observed in Fig. 4a. According to Fig. 4d, in the FT-IR spectrum of the nanocomposite C⚌O and C—O peaks are disappeared. The bands at 1318 and 1200 cm−1 in PANI spectrum presented in Fig. 4b are attributed to the C—N stretching vibration of benzenoid and C⚌N stretching of quinoid, respectively. Compared with pure PANI spectrum, the peaks corresponded to the C⚌C stretching of quinoid and benzenoid rings appeared at 1590, and 1489 cm−1 (Chu et al., 2017) have shifted to 1628 and 1517 cm−1 in the GO/PANI (Fig. 4c) and CuO/GO/PANI nanocomposite spectrums. This shift is probably due to the interaction between PANI and GO, and electron transfer between them, confirming PANI has successfully formed on the surfaces of the GO sheets. Also, two peaks at 605 and 1638 cm−1 related to stretching vibration and symmetrical stretching of Cu—O, respectively are also observed in the CuO/GO/PANI nanocomposite spectrum.

The FT-IR spectra of (a) GO, (b) PANI, (c) GO/PANI and (d) CuO/GO/PANI nanocomposite.
Fig. 4 The FT-IR spectra of (a) GO, (b) PANI, (c) GO/PANI and (d) CuO/GO/PANI nanocomposite.

The XRD patterns of GO and CuO/GO/PANI are shown in Fig. 5. As can be seen in Fig. 5a, the sharp diffraction peak of GO corresponding to an interlayer distance of 0.932 nm has appeared at 2θ = 10.4°. This interlayer distance compared to that of graphite (0.335 nm) is larger, indicating the full oxidation of graphite to GO due to the introduction of oxygen-containing functional groups (Wu et al., 2012). The peaks at 2θ = 32.8, 35.5, 38.8, 47, 53, 58.2 and 68.5° in Fig. 5b comply with standard XRD data for the (1 1 0), (−1 1 1), (1 1 1), (−2 0 2), (0 2 0), (2 0 2) and (1 1 3) planes of CuO with monoclinic phase (JCPDS no. 05-0661), respectively. The peaks placed at 2θ = 20 and 25.4° are assigned to PANI and implies the existence of both amorphous and crystalline portions (Chu et al., 2017).

The XRD pattern of the (a) GO and (b) CuO/GO/PANI nanocomposite.
Fig. 5 The XRD pattern of the (a) GO and (b) CuO/GO/PANI nanocomposite.

The elemental composition of the prepared nanocomposite was also investigated by EDX analysis, and the results are shown in Fig. 6. This analysis confirms the presence of Cu, O and C in the nanocomposite

The EDX spectrum of the CuO/GO/PANI nanocomposite.
Fig. 6 The EDX spectrum of the CuO/GO/PANI nanocomposite.

3.2

3.2 Electrochemical characterization

The square wave voltammogram of 200.0 nM flutamide in 0.1 M phosphate buffer solution at pH 7.0 in the presence of modified electrode was investigated and compared with the bare CPE for determination of flutamide. It was found that (Fig. 7) the reduction of flutamide took place at −0.28 V, −0.26 V, −0.22 V, −0.18 V in the presence of CPE, CuO/CPE, PANI/CPE, CuO/PANI/CPE and CuO/GO/PANI/CPE, respectively. The results showed that the modified electrodes caused to increase the cathodic peak current and electron transfer rate.

SW voltammograms of 200.0 nM flutamide in 0.1 M PBS (pH 7.0) obtained with different modified electrode.
Fig. 7 SW voltammograms of 200.0 nM flutamide in 0.1 M PBS (pH 7.0) obtained with different modified electrode.

Electrochemical properties of the bare and modified electrode were investigated by cyclic voltammetry. 0.1 mM [Fe(CN)6]3−/4− was prepared and diluted with 0.1 M KCl solution at pH 7.0 for studying the modified electrode mass process. According to Fig. 8, the cathodic peak current of CuO/GO/PANI/CPE was higher than the others and have excellent electrical conductivity. Various scan rates (1–800 mV s−1) were investigated on the modified electrode (Fig. 9). The results showed that anodic peak potential (190 mV) and cathodic one (100 mV) related to ferri/ferrocyanide [Fe(CN)6]3−/4− redox couple with a potential separation (ΔEp) of 90 mV is more than the theoretical value (ΔEp = 59/n mV) predicted for a reversible system. Therefore, the modified electrode showed quasi-reversible behavior. Fig. 9 inset indicates the linear relationship between anodic and cathodic peak currents, and the square root of scan rate (ν ½) with correlation coefficients (R2) of 0.9951 and 0.9937 approves the diffusion controlled electron transfer. For obtaining the effective surface area of the unmodified and modified electrodes, we used the Randles-Sevcik equation (Charoenkitamorn et al., 2018). From the slope of the Ipa vs. υ1/2 and the number of transferred electrons (n = 1), the active surface areas of electrodes: CuO/GO/PANI/CPE, CuO/PANI/CPE, PANI/CPE, CuO/CPE CPE for 0.1 mM [Fe(CN)6]3−/4− and 0.1 M electrolyte solution of KCl were calculated 0.096, 0.090, 0.081, 0.071 and 0.070 cm2, respectively. So, CuO/GO/PANI nanocomposite causes to increase the active surface of the electrode. According to the results, the modified electrode (CuO/GO/PANI/CPE) surface area was 1.37 times larger than the unmodified electrode (CPE).

The cyclic voltammograms of (a) bare (b) CuO/CPE (c) CuO/GO/PANI/CPE in the presence of 0.1 mM [Fe(CN)6]3−/4− and 0.1 M KCl at the scan rate of 800 mV s−1 at pH 7.0.
Fig. 8 The cyclic voltammograms of (a) bare (b) CuO/CPE (c) CuO/GO/PANI/CPE in the presence of 0.1 mM [Fe(CN)6]3−/4− and 0.1 M KCl at the scan rate of 800 mV s−1 at pH 7.0.
Cyclic voltammograms of CuO/GO/PANI/CPE in 0.1 mM [Fe(CN)6]3−/4− and 0.1 M KCl at different scan rates (down to up: 1, 50, 100, 200, 400, 600, 800 mV s−1). Inset: linear relationships of anodic and cathodic peak currents versus square root of the scan rate (ν 1/2).
Fig. 9 Cyclic voltammograms of CuO/GO/PANI/CPE in 0.1 mM [Fe(CN)6]3−/4− and 0.1 M KCl at different scan rates (down to up: 1, 50, 100, 200, 400, 600, 800 mV s−1). Inset: linear relationships of anodic and cathodic peak currents versus square root of the scan rate (ν 1/2).

For the quasi-reversible system, the standard rate constant, k0, can be calculated by Nicholson equation (Herr et al., 2014; Hwang et al., 2018). The equivalent parameter (ψ) for the peak difference of 90 mV with α = 0.5 was obtained to be 0.77. So, the rate constant value (k0) for the reduction and oxidation processes is found to be 5.43 × 10−3 cm s−1 at the CuO/GO/PANI/CPE. The obtained k0 for CuO/GO/PANI/CPE is higher than the gained values for CuO/CPE (2.70 × 10−3 cm s−1), PANI/CPE (4.15 × 10−3 cm s−1) and CuO/PANI/CPE (4.84 × 10−3 cm s−1). The results showed the fast kinetics of CuO/GO/PANI/CPE in comparison with other electrodes due to the modification of the electrode with CuO/GO/PANI nanocomposite.

3.3

3.3 The effect of scan rate

To evaluate the scan rate effect on the peak potential and cathodic current which play a significant role in the electrochemical investigations, cyclic voltammograms were recorded for the modified CPE in PBS (pH 7.0). As evident in Fig. 10, various scan rates (10–150 mV s−1) were studied and indicated that with increasing the scan rate, the reduction peak current of flutamide was increased without moving to more negative values along with a parallel increase in the peak current. Fig. 10 inset shows the linearity between reduction peak current and the square root of scan rate (ν ½). So, the results demonstrate that the redox process nature is diffusion controlled. Hence, the scan rate of 50 mV s−1 was selected due to the fine sensitivity achieved for the determination of flutamide.

Cyclic voltammograms of flutamide at different scan rates (down to up: 10, 20, 50, 80, 100 and 150 mV s−1) on CuO/GO/PANI/CPE in PBS (0.1 M) at pH 7.0 for quantification of flutamide. Inset: Relationships of the reduction peak current with the square root of the scan rate (up) and scan rate (down).
Fig. 10 Cyclic voltammograms of flutamide at different scan rates (down to up: 10, 20, 50, 80, 100 and 150 mV s−1) on CuO/GO/PANI/CPE in PBS (0.1 M) at pH 7.0 for quantification of flutamide. Inset: Relationships of the reduction peak current with the square root of the scan rate (up) and scan rate (down).

3.4

3.4 The effect of the type and pH of supporting electrolyte

The nature and pH of the supporting electrolyte such as borate, Robinson, phosphate and acetate were evaluated. As shown in Fig. 11, phosphate buffer solution had a higher cathodic peak current than the others. So, this buffer solution was selected for future experiments.

The effect of supporting electrolyte nature on the reduction current of flutamide.
Fig. 11 The effect of supporting electrolyte nature on the reduction current of flutamide.

The effect of buffer solution pH on the electrochemical current of flutamide was studied. Electrochemical analyses were carried out in phosphate buffer (0.1 M) with various pHs (3.0–9.0). As can be seen in Fig. 12, with increasing pH from 3.0 to 9.0 (left to right), the reduction peak potential moves to more negative amounts. The best pH for the determination of flutamide was found to be 7.0. Fig. 12 inset clearly shows the linear relation between the peak potential (Ep) and pH with the equation of Ep = −0.0564 pH + 0.1857 and correlation coefficient (R2) of 0.9935. The slope of −56.4 mV/pH corresponds with the obtained slop from Ep = (−0.0592 m/n) pH + b, where m is the number of protons and n is the number of transferred electrons involving in the electrochemical procedure, respectively. These results indicate equal number of protons and electrons involved in the electrode reaction. In the flutamide reduction mechanism demonstrated previously (Teppner et al., 2016; Brahman et al., 2012) four electrons and protons are involved as depicted in Scheme 2. P.K. Brahman et al. described reduction mechanism of flutamide (Brahman et al., 2012) but in our work hydroxylamine could be oxidized and returned to primary material production.

The SW voltammograms of flutamide at different pH of supporting electrolyte (PBS: 0.1 M) (from left to right: 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0). Inset: linear relationship between reduction peak potential and pH.
Fig. 12 The SW voltammograms of flutamide at different pH of supporting electrolyte (PBS: 0.1 M) (from left to right: 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0). Inset: linear relationship between reduction peak potential and pH.
The electrochemical mechanism of flutamide.
Scheme 2 The electrochemical mechanism of flutamide.

3.5

3.5 Analytical performance

The efficiency of the proposed method such as linearity, limit of detection and repeatability were studied under the optimized conditions. Linearity was evaluated on the various concentrations of flutamide (0.050–200.0 nM) by DPV and SWV technique using the CuO/GO/PANI/CPE. As depicted in Fig. 13A, DP voltammograms increased with increasing the concentration of flutamide and Fig. 13B indicates two linear relationships between Ipc and the concentration of flutamide for the range of 0.050–1.0 nM and 1.0–200.0 nM with a regression coefficient of 0.8906 and 0.9199, respectively but the results showed that SW voltammograms (Fig. 14) had higher sensitivity reduction peak current and good linear response (Inset of Fig. 14) with the correlation coefficient (R2) of 0.9989 and 0.9965, respectively than DP voltammograms for flutamide determination. The limit of detection (LOD) was obtained 14.0 pM according to the equation of 3Sb/m (Sb is a standard deviation of blank sample and m is the slope of calibration curve) for six replicate runs of phosphate buffer solution without the presence of flutamide. The relative standard deviations (RSDs) of the modified electrode for six successive measurements of 10.0 nM and 100.0 nM were obtained ±3.1% and 1.56%, respectively. So, the results showed a satisfactory precision of the proposed method.

(A) DPV of flutamide at variuse concentration of flutamide (down to up: 0.05, 0.50, 1.0, 10.0, 50.0, 100.0, 150.0 and 200.0 nM). (B) Two linear relationship at the concentration of 0.05 to1.0 nM and 1.0 to 200.0 nM flutamide.
Fig. 13 (A) DPV of flutamide at variuse concentration of flutamide (down to up: 0.05, 0.50, 1.0, 10.0, 50.0, 100.0, 150.0 and 200.0 nM). (B) Two linear relationship at the concentration of 0.05 to1.0 nM and 1.0 to 200.0 nM flutamide.
SWV of flutamide at different concentration of flutamide (down to up: 0.05, 0.50, 1.0, 10.0, 50.0, 100.0, 150.0 and 200.0 nM). Inset: two linear relationship at the concentration of 0.05–1.0 nM and 1.0–200.0 nM flutamide.
Fig. 14 SWV of flutamide at different concentration of flutamide (down to up: 0.05, 0.50, 1.0, 10.0, 50.0, 100.0, 150.0 and 200.0 nM). Inset: two linear relationship at the concentration of 0.05–1.0 nM and 1.0–200.0 nM flutamide.

3.6

3.6 Effect of interfering compounds

The interferences of some organic compounds (Glucose, Dopamine, Uric acid, Riboflavin, Ascorbic acid) and inorganic ions (Na+, K+, I−, Cl−) on the quantification of flutamide were investigated using the general procedure which listed in Table 1. The experiment results indicated that by adding excess amounts of the interferences to a 50 nM flutamide (up to 500-fold for organic and 1000-fold for inorganic compounds), they did not significantly influence on the reduction peak current of flutamide. As shown, the proposed sensor exhibited excellent selectivity to flutamide so that it could be applied for the determination of flutamide in pharmaceutical and urine samples.

Table 1 Effect of interferences for flutamide determination.
Co-existing species Molar ratio of the species to flutamide Recovery (%)
Glucose 250 102.0
Dopamine 100 100.5
Uric acid 500 101.3
Riboflavin 200 99.50
Ascorbic acid 150 101.5
Na+, K, I−, Cl− 1000 100.8

3.7

3.7 Determination of flutamide in real samples

Recovery and accuracy of the proposed method were also evaluated. Urine sample and 250 mg tablet of flutamide were tested for the practical application of our proposed sensor. For the preparation of real samples and determination of them with SWV technique, one flutamide tablet was pulverized, and a portion of powder was weighed and then dissolved in water. The solution was filtered, and undissolved contents were removed. The filtrate and washing aqueous solution was collected in a 100 mL volumetric flask. Then, 1.0 mL of tablet solution was cast into a 9.0 mL PBS (0.1 M) at pH 7.0 general procedure was performed. The urine sample of a healthy volunteer to study standard solution of flutamide was collected and then centrifuged at 4000 rpm for 10 min. Supernatants and sediment were separated and 5 mL of residual aqueous solution was added to 5 mL of PBS (0.1 M) at pH 7.0 in the electrochemical cell. So, the standard addition method was applied, and certain values of standard solution of flutamide were injected into the urine sample and PBS solution. The results are summarized in Table 2. Good accuracy and recovery with satisfactory results confirm that the method is applicable for the determination of flutamide.

Table 2 Determination of flutamide in two real samples using the present method.
Sample Certified amount Added amount Found amounta Recovery (%)
Flutamide tablet 250 (mg per tablet) – 255 ± 3.0 (mg per tablet) 102.0
– 0 –
Urine sample 10.0n M 10.3n M 103.3
100.0n M 101.0 nM 101.0
a Mean ± standard deviation (n = 3).

3.8

3.8 Comparison of the proposed method with other previously reports

Other electrochemical methods for the determination of flutamide were also reported already (Ensafi et al., 2016; Urbanová et al., 2017; Temerk et al., 2016; Švorc et al., 2017). So, the performance of the proposed sensor was compared with other utilized electrodes and different voltammetry methods. The results shown in Table 3 illustrate that the CuO/GO/PANI/CPE applied successfully with a wider linear range and lower limit of detection than the others for quantification of flutamide. Also, the proposed method was compared with HPLC recently report for the determination of flutamide (Abdelwahab et al., 2018). The main disadvantages of their method were being costly and required large quantities of expensive organics. In comparison, wider linear range, lower LOD and higher sensitivity were obtained through our proposed method.

Table 3 Comparison of the proposed method with other previously reports.
Electrode/method Linear range LOD Ref
Pencil graphite electrode/differential pulse voltammetry 0.10–100.0 nM 34.0 pM Ensafi et al. (2016)
Glassy carbon electrode/linear sweep voltammetry 0.009 to 14.7 µM 6.0 nM Urbanová et al. (2017)
Graphite electrodes/square wave voltammetry 3.98 × 10−7–6.36 × 10−6 M 1.55 × 10−8 M Temerk et al. (2016)
Boron-doped diamond electrode/square wave voltammetry 4.80–35.5 µM 0.18 µM Švorc et al. (2017)
Carbon paste electrode/square wave voltammetry 0.050–200.0 nM 14.0 pM This work

4

4 Conclusion

A novel electrochemical sensor based on CuO/GO/PANI nanocomposite modified CPE was reported for rapid determination of flutamide. The mentioned nanocomposite was synthesized, characterized and utilized to enhance the electrode sensitivity and electrochemical signals. Previously, other studies had been reported for determination of flutamide with different competence figures, but we tried to present a novel sensor with better properties than the others. The CuO/GO/PANI/CPE sensor was applied through differential pulse and square wave voltammetric techniques for flutamide determination in different concentration solutions and rendered not only excellent sensitivity and acceptable repeatability for flutamide, but also a wide linear range and low detection limit. Also, this simple and inexpensive method was employed successfully for flutamide determination in human urine and pharmaceutical samples so that it can be an applicable technique for analytical purposes.

Acknowledgement

The authors would like to express their sincere appreciation to the founders of Shahid Bahonar University of Kerman, Mr. Alireza Afzalipour and his wife, Mrs. Fakhereh Saba, for their foresight and generosity in training future generations of doctors, engineers and scientists. Also, the authors would like to acknowledge their thanks to Dr. Parviz Dabiri for his generous support for the research activities of the chemistry and nano laboratories in Shahid Bahonar University of Kerman.

References

  1. , , , . Determination of flutamide and two major metabolites using HPLC–DAD and HPTLC methods. Chem. Cent. J.. 2018;12(1):4.
    [Google Scholar]
  2. , , , , . Dye sensitized solar cells using catalytically active CuO-ZnO nanocomposite synthesized by single step method. Spectrochim. Acta Part A: Mol. Biomol. Spectrosc.. 2018;200:116-126.
    [Google Scholar]
  3. , , , , , , . Synthesis of Ag nanoparticles for the electrochemical detection of anticancer drug flutamide. Chin. J. Catal.. 2015;36(3):439-445.
    [Google Scholar]
  4. , , , , . Copper supported β-cyclodextrin functionalized PEGylated mesoporous silica nanoparticle-graphene oxide hybrid: An efficient and recyclable nano-catalyst for straightforward synthesis of 2-arylbenzimidazoles and 1, 2, 3-triazoles. Microporous Mesoporous Mater.. 2018;262:207-216.
    [Google Scholar]
  5. , , , , , , , , . Effects of the commercial antiandrogen flutamide on the biomarkers of reproduction in male Murray rainbowfish (Melanotaenia fluviatilis) Environ. Toxicol. Chem.. 2014;33(5):1098-1107.
    [Google Scholar]
  6. , , , , . Voltammetric determination of anticancer drug flutamide in surfactant media at polymer film modified carbon paste electrode. Colloids Surf., A. 2012;396:8-15.
    [Google Scholar]
  7. , , , , . Low-cost and disposable sensors for the simultaneous determination of coenzyme Q10 and α-lipoic acid using manganese (IV) oxide-modified screen-printed graphene electrodes. Anal. Chim. Acta. 2018;1004:22-31.
    [Google Scholar]
  8. , , , , , , . In situ one-pot preparation of reduced graphene oxide/polyaniline composite for high-performance electrochemical capacitors. Appl. Surf. Sci.. 2017;392:71-79.
    [Google Scholar]
  9. , , , , , , , . Synthesis and electrochromic properties of conducting polymers: Polyaniline directly grown on fluorine-doped tin oxide substrate via hydrothermal techniques. Sol. Energy Mater. Sol. Cells 2017
    [Google Scholar]
  10. , , , , , . Square-wave voltammetric determination of hydroxychloroquine in pharmaceutical and synthetic urine samples using a cathodically pretreated boron-doped diamond electrode. J. Electroanal. Chem.. 2014;719:19-23.
    [Google Scholar]
  11. , , , , , . Simultaneous square-wave voltammetric determination of paracetamol, caffeine and orphenadrine in pharmaceutical formulations using a cathodically pretreated boron-doped diamond electrode. Electroanalysis. 2013;25(7):1734-1741.
    [Google Scholar]
  12. , . The Dictionary of Drugs: Chemical Data: Chemical Data, Structures and Bibliographies. Springer; .
  13. , , , . Development of a cleanup and electrochemical determination of flutamide using silica thin film pencil graphite electrode functionalized with thiol groups. J. Iran. Chem. Soc.. 2016;13(9):1683-1690.
    [Google Scholar]
  14. , , , . Development of analytical methods for the determination of flutamide in bulk drug and its pharmaceutical formulation. Int. J. PharmTech Res.. 2015;8(7):146-153.
    [Google Scholar]
  15. , . Synthesis of polyaniline-tin (II) molybdophosphate nanocomposite and application of it in the removal of dyes from aqueous solutions. J. Mol. Liq.. 2017;242:229-234.
    [Google Scholar]
  16. , , , , . Electrochemical sensing of hydrogen peroxide using Pd@ Ag bimetallic nanoparticles decorated functionalized reduced graphene oxide. Electrochim. Acta 2018
    [Google Scholar]
  17. , , , , , . Fabrication of electrochemical sensor based on layered double hydroxide/polypyrrole/carbon paste for determination of an alpha-adrenergic blocking agent terazosin. Electroanalysis. 2018;30(3):459-465.
    [Google Scholar]
  18. , , , , , , , , , , . Rapid increase of spines by dihydrotestosterone and testosterone in hippocampal neurons: dependence on synaptic androgen receptor and kinase networks. Brain Res.. 2015;1621:121-132.
    [Google Scholar]
  19. , , , , , . Increasing the energy density of the non-aqueous vanadium redox flow battery with the acetonitrile-1, 3-dioxolane–dimethyl sulfoxide solvent mixture. J. Power Sources. 2014;265:317-324.
    [Google Scholar]
  20. , . Polarography, Encyclopedia of Applied Electrochemistry. Springer; . p. :1626-1629.
  21. , , , , . N-ferrocenylphthalimide; A single redox couple formed by attaching a ferrocene moiety to phthalimide for non-aqueous flow batteries. J. Power Sources. 2018;395:60-65.
    [Google Scholar]
  22. , , , , , . Detection of flutamide in pharmaceutical dosage using higher electrospray ionization mass spectrometry (ESI-MS) tandem mass coupled with Soxhlet apparatus. Anal. Chem. Res.. 2015;3:89-97.
    [Google Scholar]
  23. , , , , , , , . Sulfur doped reduced graphene oxide as metal-free catalyst for the oxygen reduction reaction in anion and proton exchange fuel cells. Electrochem. Commun.. 2017;77:71-75.
    [Google Scholar]
  24. , , , , , , , , . Anti-androgen flutamide suppresses hepatocellular carcinoma cell proliferation via the aryl hydrocarbon receptor mediated induction of transforming growth factor-β1. Oncogene. 2015;34(50):6092.
    [Google Scholar]
  25. , , , . Fabrication of chemiresistive gas sensors based on multistep reduced graphene oxide for low parts per million monitoring of sulfur dioxide at room temperature. Sens. Actuators, B. 2017;242:461-468.
    [Google Scholar]
  26. , , . Electrochemical carbon based nanosensors: A promising tool in pharmaceutical and biomedical analysis. J. Pharm. Biomed. Anal. 2017
    [Google Scholar]
  27. , . Square-wave Voltammetry, Electroanalytical Methods. Springer; . p. :121-145.
  28. , , , . Simultaneous determination of tyrosine, acetaminophen and ascorbic acid using gold nanoparticles/multiwalled carbon nanotube/glassy carbon electrode by differential pulse voltammetric method. Sens. Actuators, B. 2014;193:451-460.
    [Google Scholar]
  29. , , , , , . Use of pyruvate or succinate to enhance the efficacy of a hypoxia activated prodrug for the treatment of tumors. Google Patents 2016
    [Google Scholar]
  30. , , , , , . Development of analytical method for simultaneous determination of five rodent unique bile acids in rat plasma using ultra-performance liquid chromatography coupled with time-of-flight mass spectrometry. J. Chromatogr. B. 2015;1002:399-410.
    [Google Scholar]
  31. , , , , , , . Square-wave voltammetry: A review on the recent progress. Electroanalysis. 2013;25(11):2411-2422.
    [Google Scholar]
  32. , , , , . Characterization of three-dimensional reduced graphene oxide/copper oxide heterostructures for hydrogen sulfide gas sensing application. J. Alloy. Compd. 2018
    [Google Scholar]
  33. , , , , , , . Voltammetric determination of flutamide and its metabolite 4-nitro-3-trifluoromethylaniline at a hanging mercury drop minielectrode. Collect. Czech. Chem. Commun.. 2012;76(12):1811-1823.
    [Google Scholar]
  34. , . Green synthesis, morphological and optical studies of CuO nanoparticles. J. Mol. Struct.. 2017;1150:553-557.
    [Google Scholar]
  35. , , , , . Electrochemical determination of anticancer drug, flutamide in human plasma sample using a microfabricated sensor based on hyperbranchedpolyglycerol modified graphene oxide reinforced hollow fiber-pencil graphite electrode. Mater. Sci. Eng., C 2018
    [Google Scholar]
  36. , , , , , , . Electrochemical analysis of graphene oxide/polyaniline/polyvinyl alcohol composite nanofibers for supercapacitor applications. Appl. Surf. Sci. 2018
    [Google Scholar]
  37. , , , . Graphene-Polyaniline composite based ultra-sensitive electrochemical sensor for non-enzymatic detection of urea. Electrochim. Acta. 2017;233:44-51.
    [Google Scholar]
  38. , , . Graphene oxide synthesized by using modified hummers approach. Int. J. Renew. Energy Environ. Eng.. 2014;2(01):58-63.
    [Google Scholar]
  39. , , , , , , , , , , . Fully automated spectrometric protocols for determination of antioxidant activity: Advantages and disadvantages. Molecules. 2010;15(12):8618-8640.
    [Google Scholar]
  40. , , , , , . Advanced electrochemical platform for determination of cytostatic drug flutamide in various matrices using a boron-doped diamond electrode. Electrochim. Acta. 2017;251:621-630.
    [Google Scholar]
  41. , , , , , , . Sensitive electrochemical determination of amlodipine in pharmaceutical tablets and human urine using a boron-doped diamond electrode. J. Electroanal. Chem.. 2014;728:86-93.
    [Google Scholar]
  42. , , , . High-resolution, higher-order UV/VIS derivative spectrophotometry. Angew. Chem. Int. Ed. Engl.. 1978;17(11):785-799.
    [Google Scholar]
  43. , , , . Square wave cathodic adsorptive stripping voltammetric determination of the anticancer drugs flutamide and irinotecan in biological fluids using renewable pencil graphite electrodes. Electroanalysis. 2016;28(2):372-379.
    [Google Scholar]
  44. , , , , . Biomarkers of flutamide-bioactivation and oxidative stress in vitro and in vivo. Drug Metab. Dispos.. 2016;44(4):560-569.
    [Google Scholar]
  45. , , , , , . A facile graphene oxide based sensor for electrochemical detection of neonicotinoids. Biosens. Bioelectron.. 2017;89:532-537.
    [Google Scholar]
  46. , , , . Sputtering based synthesis of CuO nanoparticles and their structural, thermal and optical studies. Mater. Sci. Semicond. Process.. 2018;76:55-60.
    [Google Scholar]
  47. , , , , , , , . Hyperbranched-polymer functionalization of graphene sheets for enhanced mechanical and dielectric properties of polyurethane composites. J. Mater. Chem.. 2012;22(14):7010-7019.
    [Google Scholar]
  48. , , , , . In situ loading of highly-dispersed CuO nanoparticles on hydroxyl-group-rich SiO2-AlOOH composite nanosheets for CO catalytic oxidation. Chem. Eng. J.. 2017;316:1035-1046.
    [Google Scholar]
  49. , , , , , , . Nonenzymatic glucose sensing by CuO nanoparticles decorated nitrogen-doped graphene aerogel. Mater. Sci. Eng., C. 2017;78:210-217.
    [Google Scholar]
  50. , , , . Determination of the food dye carmine in milk and candy products by differential pulse polarography. J. Food Drug Anal.. 2014;22(3):329-335.
    [Google Scholar]
  51. , . Determination of related substances of flutamide by HPLC. Food and Drug. 2013;3:014.
    [Google Scholar]

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