ordered mesoporous carbon hybrid to detection of allopurinol in clinical samples

Journal Pre-proof Electrochemical sensor based on magnetite graphene oxide/ordered mesoporous carbon hybrid to detection of allopurinol in clinical samples Hediyeh Bagheri Ladmakhi, Fereshteh Chekin, Shahla Fathi, Jahan Bakhsh Raoof PII:

S0039-9140(20)30050-3

DOI:

https://doi.org/10.1016/j.talanta.2020.120759

Reference:

TAL 120759

To appear in:

Talanta

Received Date: 16 December 2019 Revised Date:

14 January 2020

Accepted Date: 17 January 2020

Please cite this article as: H.B. Ladmakhi, F. Chekin, S. Fathi, J.B. Raoof, Electrochemical sensor based on magnetite graphene oxide/ordered mesoporous carbon hybrid to detection of allopurinol in clinical samples, Talanta (2020), doi: https://doi.org/10.1016/j.talanta.2020.120759. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier B.V.

Electrochemical sensor based on magnetite graphene oxide/ordered mesoporous carbon hybrid to detection of allopurinol in clinical samples

Hediyeh Bagheri Ladmakhia, Fereshteh Chekina,*, Shahla Fathia, Jahan Bakhsh Raoofb, a

Department of Chemistry, Ayatollah Amoli Branch, Islamic Azad University, Amol, Iran

b

Electroanalytical Chemistry Research Laboratory, Department of Analytical Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar, Iran *Corresponding author. Tel: +981143217076; E-mail: [email protected]

1

ABSTRACT Allopurinol (ALO) is a radical scavenging clinical drug, a drug in the treatment of gout, an inhibitor of xanthine oxidase and an effective agent for anti-cancer purposes. The xanthine oxidase is thus essential, and the amount of ALO needs to be controlled more strictly. In this study, a new electrochemical sensor based on magnetite graphene oxide/ordered

mesoporous

carbon

(Fe3O4@GO/OMC)

hybrid

was

prepared

and

characterized. The results showed sphere shape Fe3O4 nanoparticles with a diameter in the range 17-22 nm on composite. Modification of

carbon paste electrode (CPE) with

Fe3O4@GO/OMC (Fe3O4@GO/OMC-CPE) allowed the ultrasensitive and selective detection of ALO at oxidation potential of 1.05 V with linear range of 0.05-7 µmol L-1, limit of detection of 47 nmol L-1 and sensitivity of 708 µA mmol-1 L. Also, the results demonstrate that charge transfer at the interface of Fe3O4@GO/OMC hybrid can provide a synergistic effect in comparison with Fe3O4@GO and OMC. The unique surface chemistry of Fe3O4@GO/OMC interface allows π–π stacking and electrostatic interactions with ALO. The advantages are the possibility to regenerate the surface of the sensor, its rapid and easy of production, as well as its applicability for detection of ALO in Tablets and human serum samples, making Fe3O4@GO/OMC-CPE promising interface for bio-electrochemical applications. Keywords: Allopurinol; Magnetite graphene oxide; Ordered mesoporous carbon; Sensor

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1. Introduction Allopurinol (1, 5-Dihydro-4H-Pyrazolo [3, 4-d] pyrimidin-4-one) is a drug commonly used in the treatment of chronic gout or hyperuricemia associated with leukaemia, radiotherapy, antineoplastic agents and treatment with diuretics conditions [1,2]. Allopurinol (ALO) is a structural isomer of hypoxanthine (a naturally occurring purine in the body) and acts to inhibit xanthine oxidase enzyme [3,4]. ALO prevents the oxidation of hypoxanthine to xanthine & xanthine to uric acid [5,6]. Xanthine oxidase is the enzyme required to produce uric acid by the breakdown of purine nucleotides. The uric acid itself, as well as the reactive oxygen species released during the enzymatic reaction, can have detrimental effects on the body [7]. Gout is a common condition that occurs due to elevated uric acid production via this mechanism. As a result, many drugs have been formed to combat gout, by inhibiting xanthine oxidase enzyme activity. Moreover, regulations of this enzyme have proven to be effective for anti-cancer purposes [8,9]. Different analytical approaches based on chromatography, capillary electrophoresis, spectrophotometric and electrochemical detection [10–18] have been developed for estimation of ALO in bulk drug, formulations and biological samples. Electrochemical sensors such as glassy carbon electrode modified with multiwall carbon nanotubemolecularly imprinted polymer (NMIP-MWCNT/GCE) [14], xanthin oxidase modified carbon paste electrode (XO/CPE) [19], carbon paste electrode based on the enhancement effect of cetyltrimethylammonium bromide (CTAB-CPE) [20], roughened pyrolytic graphite and glassy carbon electrode (PGE/GCE) [21] and glassy carbon electrode (GCE) [22] have been considered as feasible alternative analytical tools allowing direct sensing of ALO due to its intrinsic electrochemical activity. More recently, magnetite graphene oxide (Fe3O4@GO) nanocomposites basedelectrochemical sensors have shown to be well adapted for high sensitive sensing with a linear range of several orders of magnitude [23–25]. The Fe3O4@GO nanocomposites with the advantages of the magnetism and the conductivity could be easily adhered to the electrode surface to achieve the direct redox reactions and electrocatalytic behaviors of analytes adsorbed on the modified surface [26–28]. Moreover, the functional groups (COOH and OH) of GO allow it to conjugate with various molecules and act as an excellent performance carrier, while nanoparticles can be highly dispersed on its surface, and the charge transfer at 3

the interface of these hybrid materials can provide a synergistic effect to bring properties that are different from those of each individual component [29,30]. This unique surface chemistry of Fe3O4@GO nanocomposites allows for π–π stacking and electrostatic interaction to occur with drugs in electrochemical sensor applications [31-34]. Recent developments in designing structurally defined carbonaceous nanoporous materials, such as ordered mesoporous carbon (OMC), due to high surface area, (1000 m2 g1

), large pore volume (1cm3 g-1), and uniform mesoporous structures have shown potential for

various biomedical and biotechnological applications [35,36]. To the best of our knowledge, there has been no prior report on the electrocatalytic behavior of OMC conjugated with Fe3O4@GO nanocomposites.

In

this

work,

we investigate the

performance of

Fe3O4@GO/OMC modified sensor to detection of ALO. The proposed sensor offers a simple and fast way for ALO sensing in clinical samples within short analysis time, making the concept of interest. With a detection limit of 10 nmol L-1 and a liner range up to 7 µmol L-1, the sensor is well adapted for analyzing ALO concentration in serum plasma samples and Tablets.

2. Experimental 2.1. Materials Graphene oxide (GO) powder was purchased from Iranian Nanomaterials Pioneers. Allopurinol (C5H4N4O), Potassium hexacyanoferrate(II) ([K4Fe(CN)6]), phosphoric acid (H3PO4), sodium dihydrogen phosphate (NaH2PO4), disodium hydrogen phosphate (Na2HPO4), sodium phosphate (Na3PO4), graphite powder, potassium permanganate (KMnO4), hydrogen peroxide (H2O2), sulfuric acid (H2SO4) and iron(II) sulfate hepta hydrate (FeSO4⋅7H2O) were purchased from Sigma-Aldrich and used as received. Allopurinol Tablets were purchased from Hakim Pharmaceutical. Human plasma samples were kindly provided by the clinical laboratory tests, Ramsar. The samples were stored at 4°C.

2.2. Apparatus Electrochemical measurements were performed with a potentiostat/galvanostat (Sama 500-c Electrochemical Analysis system, Sama, Iran). A conventional three-electrode configuration consisting of Ag|AgCl|KCl as the reference electrode, a platinum wire as auxiliary electrode and CPE and Fe3O4@GO/OMC modified CPE as working electrodes 4

was

employed.

FE-SEM

images

were

obtained

using

an

electron

microscope

(MIRATESCAN-XMU, Czech Republic) combined with EDS (energy-dispersive X-ray Spectroscopy) machine equipped with a thermal field emission emitter and three different detectors. UV-Vis spectra of samples were recorded by UV-Vis spectrophotometer (UV1900, Shimadzu Co., Japan). Raman analysis was performed with a Takram P50C0R10 Raman spectrometer (Teksan, Iran) using a 532 nm laser and CCD array detector. X-ray diffraction measurement was recorded on a Bruker D8-Advance X-ray diffractometer (Germany).

2.3. Synthesis of Fe3O4@GO/OMC nanocomposite 10 mg of GO in 20 mL water was sonicated for 30 min and then 10 mL of FeSO4⋅7H2O solution (0.5 mol L-1) was added to GO suspension solution under vigorous stirring. The pH of solution was adjusted to 10 with NaOH, transferred to Teflon-lined stainless steel autoclave, and heated at 180 °C for 8 h. Ethanol and water were used to wash the sample and then the product (Fe3O4@GO) was dried at 60 °C overnight. To 1 mL of Fe3O4@GO (1 mg mL-1), 1 mL of OMC (1 mg mL-1) was added and the mixture was sonicated for 40 min at room temperature. Then the product (Fe3O4@GO/OMC) was washed with water and dried at 60 °C overnight. 2.4. Fabrication of Fe3O4@GO/OMC nanocomposite modified electrode The carbon paste electrode (CPE) was prepared based on our previous report [37,38]. The graphite powder plus paraffin hand-mixed until a uniformly wetted paste was obtained. Then the carbon paste was packed into a glass tube (with internal radius 3 mm). Electrical contact was made by a copper wire. The new surface of electrode was obtained by polishing it on a weighing paper. 1 mg of Fe3O4@GO/OMC nanocomposite was added to 1 mL of water and sonicated for 30 min. 5 µL of this solution was drop-casted onto the CPE and allowed to dry in an oven at 50 °C. 2.5. Analysis of serum plasma and Tablets 500 µL of human serum plasma or 1 mg of Tablet was transferred to the electrochemical cell containing 10 mL PBS (0.1 mol L-1; pH = 7.00) and the oxidation current was determined by DPV. Also, the samples were determined by UV-Vis spectroscopy at

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wavelength of 251 nm with diluting 500 µL or 0.5 mg of Tablet in 5 mL PBS (0.1 mol L-1; pH = 7.00). 3. Results and discussion 3.1. Characterization The morphology of GO, Fe3O4@GO and Fe3O4@GO/OMC is characterized with FESEM. As seen in Fig. 1, the GO is a wavy shape, thin layers and wrinkled edge (Fig. 1A). In contrast, the image of Fe3O4@GO (Fig. 1b) shows that GO sheets is decorated by sphere shape Fe3O4 nanoparticles with a diameter in the range 17-22 nm (Fig. 1c). This observation confirms the formation of Fe3O4@GO hybrid. The image of Fe3O4@GO/OMC shows that the GO nanosheets are covered by OMC structures and Fe3O4 nanoparticles (Fig. 1d). The EDS pattern shown in Fig. 1e indicates that the GO contains only C and O elements, while the EDS spectrum of Fe3O4@GO (Fig. 1f) contains C, O and Fe (38% W) elements. This result confirms the synthesis of magnetite GO. Fig. 1 Raman analysis of GO and Fe3O4@GO was also performed (Fig. 2A) and revealed the introduction of defects in the graphene framework after decoration of GO by Fe3O4 nanoparticles. The D and the G bands of GO are appeared at 1323 and 1577 cm-1 with the intensity ratio of D and G bands (ID/IG) of 1.14. The D and G bands of Fe3O4@GO are shifted to 1350 and 1603 cm-1, and the ID/IG of Fe3O4@GO is calculated to be 1.72, higher than that of GO after the decoration of Fe3O4 nanoparticles on GO nanosheets. It represents that GO has been partially reduced, and there are chemical interactions, but not only physical adsorption between Fe3O4 nanoparticles and GO carbon [40]. In the range below 700 cm-1, some bands including 115.1, 185.6, 421.6, 545.3 and 690.1 cm-1 appear in the spectrum of Fe3O4@GO attributed to the vibration modes of Fe-O and Fe-C bonds [41]. There is no observable Raman mode at 300 or 410 cm-1, indicating the absence of hematite phase in the composite [42]. Powder X-ray diffraction (XRD) is an effective method to investigate the inter layer changes and the crystalline properties of synthesized samples. Fig. 2B shows the XRD patterns of GO and Fe3O4@GO samples. As seen, the GO shows a very sharp diffraction peak at 9.8° corresponding to the (001) reflection. The diffraction peaks at 32.1°, 35.8°, 37.4°, 43.8°, 52.4°, 57.3° and 63.5 of Fe3O4@GO composite are in good agreement with the face-centered cubic spinel structure of Fe3O4 nanoparticles. Also, the diffraction peak of 001 6

at Fe3O4@GO shifted towards lower 2θ values, we suspect that the shift might be attributed to the functionalization of graphene oxide sheets by Fe3O4 nanoparticles. Figs. 2C and 2D show the cyclic voltammetric responses of modified CPE with different interfaces using [Fe(CN)6]3-/4- as the redox couple. The redox current increased considerably in the presence of Fe3O4@GO/OMC, being larger than those recorded for GO, Fe3O4, GO/OMC, Fe3O4@GO and OMC modified CP electrodes. The good electronic properties of both materials supporting rapid electron transfer are mostly likely responsible for the current enhancement. The 3D sphere-like architecture of the Fe3O4@GO/OMC results in an overall higher active surface being partially responsible for the higher current recorded. Indeed, the real electrochemical active surface area of the different interfaces, as determined by plotting the peak current as a function of the square root of the scan rate [39], allowed to estimate active surface areas of 0.07 cm2 for CPE, 0.14 cm2 for Fe3O4@GO-CPE, 0.16 cm2 for OMCCPE and 0.26 cm2 for Fe3O4@GO/OMC-CPE. Fig. 2 3.2. Electrochemical sensing of ALO The electrochemical behavior of Fe3O4@GO/OMC-CPE for 1.5 mmol L-1 ALO oxidation in 0.1 mol L-1 PBS (pH 7.00) was studied using cyclic voltammetry. As shown, the oxidation of ALO is wimpy and irreversibly with a peak potential of nearly 1055 mV vs. Ag/AgCl/KCl(3M) (Fig 3A, curve c) on the surface of bare CPE. The oxidation peak potential of ALO at the Fe3O4@GO/OMC-CPE (Fig. 3A, curve d) was shifted to less potential (1025 mV) with higher oxidation current in comparison with bare CPE. These data clearly showed that Fe3O4@GO/OMC hybrid has improved the electron transfer rate of ALO. The electrocatalytic response of bare CPE and CPE modified with GO, Fe3O4, GO/OMC, Fe3O4@GO, OMC and Fe3O4@GO/OMC interfaces was investigated toward the electrochemical oxidation of 2.5 mmol L-1 ALO in the 0.1 mol L-1 PBS (pH 7.00). As shown (Fig. 3B and Inset), the oxidation peak of ALO at Fe3O4@GO/OMC-CPE has higher current, indicating that the combination of Fe3O4@GO nanosheets and OMC has significantly improved performance toward ALO oxidation. The π–π stacking interactions as well as electrostatic interactions with ALO are most likely at the origin of this behavior. Indeed, the effect of pH on the electrochemical detection of ALO on Fe3O4@GO/OMC-CPE showed that the oxidation peak current increased gradually from 5.00 to 7.00 where it reached a maximum value. Therefore, pH 7.00 was chosen as the suitable pH for further studies. To evaluate the 7

behavior of ALO oxidation, the anodic peak potential, EP, was plotted versus the solution pH. The results demonstrated a plot with a linear regression of EP= 1.44-52.12×pH (R=0.991), indicating an electrode process with exchanged number of protons and electrons being the same according to Scheme 1. Scheme 1 The effect of scan rate on electrooxidation of ALO in the 0.1 mol L-1 PBS (pH 7.00) was investigated in addition (Fig. 3C). A linear relationship between the oxidation peak current and scan rate with regression of I (µA) = 1.0301 υ -2.1799 (R=0.992) is observed (Fig. 3C, Inset), indicating an adsorption-controlled electrochemical process. The adsorption behavior of ALO on Fe3O4@GO/OMC-CPE makes the accumulation potential (Eacc) and accumulation time (tacc) crucial parameters for detection. The accumulation potential between 0.2 V and 0.8 V was tested at accumulation time equal to 30 s (Fig. 3D). The highest oxidation peak current was achieved for accumulation potential equal to 0.5 V. The improvement in peak current height was also achieved with growing accumulation time (Fig. 3E). Increasing the time leads to an increase in peak current up to 60 s and then levels off due to the saturation of the electrode surface. Fig. 3 The Fe3O4@GO/OMC-CPE was further applied for the determination of ALO in PBS 0.1 mol L-1 (pH= 7.00). To assess whether the electrode can analyze quantitatively ALO oxidation, the change in peak current upon addition of increasing concentrations ALO using differential pulse voltammetry (DPV) was recorded (Fig. 4A). A linear relationship up to 7 µmol L-1 ALO was recorded with a correlation coefficient of 0.992, according to I (µA) = 3.14 + 0.71×[ALO] (µmol L-1) (Fig. 4B). The detection limit (LOD) for ALO was determined to be ≈47 nmol L-1. The LOD is comparable to that reported by other sensors (Table 1). Compared to other electrodes, the Fe3O4@GO/OMC-CPE shows lower LOD. It is however lower as compared to multiwall carbon nanotube-molecularly imprinted polymer modified glassy carbon electrode by Rezaei et al. [14] where a LOD of 6.67 nmol L-1. The ease and one step procedure of making Fe3O4@GO/OMC-CPE electrode, as shown in this work, might be however an advantage when it comes to sensing in clinical samples, with ALO concentrations in the low nmol L-1 region. The sensitivity (708 µA mmol-1 L) is markedly high making this sensor particular interest for sensing in biological fluids. Fig. 4 8

Table 1 The reproducibility of the electrode fabrication and use for ALO sensing is expressed in terms of relative standard deviation (RSD), which is found to be 6.7 % at ALO concentration of 10 µmol L-1 for five electrodes. The repeatability of the sensor response was evaluated by performing four determinations using a single sensor with the same ALO solution (5 µmol L1

). The RSD for these determinations was found to be 9%. Regeneration of the electrode

could be achieved upon immersion of the Fe3O4@GO/OMC-CPE in NaOH-H3PO4 (pH=12.0) solution for 30 min. The long-term stability of the sensor was in addition evaluated, showing a loss of 7 % when tested in 10 µmol L-1 ALO solution after the electrode was stored at 4 °C for 2 weeks. To evaluate the effect of potential interfering compounds such as ascorbic acid (AA), glutathione (Glu), cysteine (Cys), fructose (Fru), N-acetyl cysteamine (CA) and acetaminophen (AC) when present at equal concentration with ALO (Fig. 5A), the current response to 15 µmol L-1 ALO was determined (Fig. 5B) showing excellent selectivity.

3.3. ALO sensing in real samples The suitability of the proposed method for testing Tablet was analyzed using differential pulse voltammetry. The results obtained from the proposed method were compared statistically by t-test and variance ratio F-test, with the UV-Vis spectroscopy (Table 2). The calculated t and F values do not exceed the theoretical values at 95% confidence level. From the results it was found that the proposed method does not differ significantly in precision from the UV-Vis method (Figs. 5D and 5E). The accuracy of the proposed method was assessed by performing recovery experiments using the standard addition method. A known amount of pure ALO was added to the human blood serum (Fig. 5C). The obtained mean recoveries and relative standard deviations were in the ranges of 94.0–96.5 and 1.3–2.8%, respectively (Table 2). The results revealed that the proposed method can accurately determine any small changes of the drug concentration in the solutions. Fig. 5 Table 5 4. Conclusion

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A novel Fe3O4@GO/OMC hybrid has been successfully synthesized via a simple, fast and facile method. The results show sphere shape Fe3O4 nanoparticles with a diameter in the range 17-22 nm on composite. A sensitive, selective and precise electrochemical sensor was developed based on Fe3O4@GO/OMC hybrid film on a carbon paste electrode for the determination of ALO. The Fe3O4@GO/OMC-CPE displays ultrasensitive and selective detection of ALO at the oxidation potential of 1.05 V with linear range between 0.05-7.0 µmol L-1, limit of detection of 47 nmol L-1 and sensitivity of 708 µA mmol-1 L. The sensor combines the high electrical conductivity with the excellent catalytic activity of Fe3O4@GO/OMC hybrid which was used not only to enhance the sensor excellent selectivity but also to provide good stability of the sensor. The proposed method was compared statistically with the reference method for determination of ALO, finding that it does not differ significantly in precision and accuracy from the reference method. Additionally, Fe3O4@GO/OMC hybrid exhibited good performance for the determination of ALO in human serum samples, suggesting that the proposed method might be reliable and effective for ALO sensing in real samples. Acknowledgment The authors are sincerely thankful for the research facilities provided by the Ayatollah Amoli Branch of the Islamic Azad University.

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Figure captions Fig. 1. FE-SEM images of GO (a), Fe3O4@GO (b), Fe3O4@GO with larger dimension (c) and Fe3O4@GO/OMC (d); EDS of GO (e) and Fe3O4@GO (f). Fig. 2. (A) Raman spectra of GO and Fe3O4@GO; (B) XRD patterns of GO and Fe3O4@GO; (C) Cyclic voltammograms recorded on GO-CPE (a), Fe3O4-CPE (b) and GO/OMC-CPE (c); (D) Cyclic voltammograms recorded on Fe3O4@GO-CPE (a), OMC-CPE (b) and Fe3O4@GO/OMC-CPE (c) using [Fe(CN)6]3-/4- (5 mmol L-1)/PBS (0.1 mol L-1). Fig. 3. (A) Cyclic voltammograms of (a) CPE and (b) Fe3O4@GO/OMC-CPE in 0.1 mol L-1 PBS (pH 7.00) and 0.1 mol L-1 KCl and (c) as (a) and (d) as (b) in presence of 1.5 mmol L-1 ALO at scan rate of 100 mV s−1; (B) Cyclic voltammograms of (a) CPE, (b) Fe3O4@GOCPE, (c) OMC-CPE and (d) Fe3O4@GO/OMC-CPE in presence of 2.5 mmol L-1 ALO at scan rate of 100 mV s−1. Inset: Cyclic voltammograms of (a) GO-CPE, (b) Fe3O4-CPE and (c) GO/OMC-CPE in presence of 2.5 mmol L-1 ALO; (C) Cyclic voltammograms of 1.5 mmol L-1 ALO in 0.1 mol L-1 PBS (pH 7.00) and 0.1 mol L-1 KCl as supporting electrolyte at the surface of Fe3O4@GO/OMC-CPE at various scan rates: (a) 12, (b) 25, (c) 50, (d) 75 and (e) 100 mV s−1. Inset: Plot of peak currents vs. scan rates; (D) Dependence of accumulation potential for tacc = 30 s; (E) Dependence of accumulation time for Eacc = 0.5 V on oxidation peak current of 1.5 mmol L-1 ALO. Fig. 4. (A) Differential pulse voltammograms of Fe3O4@GO/OMC-CPE in 0.1 mol L-1 PBS (pH 7.00) in the presence of (a) 0.05, (b) 0.5, (c) 1.2, (d) 2, (e) 3, (f) 5 and (g) 7 µmol L-1 of ALO; (B) Plot of oxidation peak current vs. ALO concentration. Fig. 5. (A) DPV of a solution containing ascorbic acid (AA), cysteine (Cys) and ALO (15 µmol L-1 each); (B) The detected DPV current of Fe3O4@GO/OMC-CP electrodes in 0.1 mol L-1 PBS (pH 7.00) upon addition of ALO (15 µmol L-1) only and ALO (15 µmol L-1) with ascorbic acid (AA, 15 µmol L-1), cysteine (Cys, 15 µmol L-1), glutathione (Glu, 15 µmol L-1), N-acetyl cysteamine (CA, 15 µmol L-1), acetaminophen (AC, 15 µmol L-1) and fructose (Fru, 15 µmol L-1); (C) DPV of human serum upon addition of ALO (15 µmol L-1). (D) The UV-

16

Vis spectrum of ALO in 0.1 mol L-1 PBS (pH 7.00); (E) calibration curve of ALO determined by UV-Vis spectroscopy.

Scheme 1

17

Fig. 1

18

Fig. 2

19

Fig. 3

Fig. 4

20

Fig. 5 21

Table 1. Analytical parameters for voltammetric determination of ALO at different modified electrodes.

Electrode

Linear range (µ mol L-1)

LOD (nmol L-1)

Ref.

NMIP-MWCNT/GCE

0.01-1

6.88

[14]

XO/CPE

0.2-50

-

[19]

CTAB-CPE

0.6-60

97.20

[20]

-

50

[21]

150

500

[22]

PGE/GCE GCE

Fe3O4@GO/OMC-CPE 0.05-7.2

47

22

This work

Table 2. Determination of ALO in tablet and blood plasma samples at surface of Fe3O4@GO/OMC-CPE in 0.1 mol L-1 PBS solution (pH 7.00).

Sample

Spiked (mg)

Found (mg)

Mean

recovery (%)

Proposed method

UV method 99.4±0.9

Tablet

2.00

1.92

96.0±1.3

Plasma

1.00

0.94

94.0±2.1

Plasma

2.00

1.93

96.5±2.8

Theoretical values for t=2.31 and F=6.39 (p=0.05)

23

texp

2.37

Fexp

3.76


A novel Fe3O4@GO/OMC hybrid has been successfully synthesized via a simple, fast and facile method.
The results show sphere shape Fe3O4 nanoparticles with diameter ranging from 17 to 22 nm on composite.
A sensitive, selective and precise electrochemical sensor was developed based on Fe3O4@GO/OMC hybrid to detection of ALO.


The Fe3O4@GO/OMC-CPE displays linear range 0.05-7.0 µM, limit of detection of 47 nM and sensitivity of 708 µA mM-1.


The proposed method was compared statistically with the reference method .
Additionally, Fe3O4@GO/OMC hybrid exhibited good performance for the determination of ALO in human serum samples.
The proposed method might be reliable and effective for ALO sensing in real samples.

Declaration of interests ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☐The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: