**6. Comparative study**

Because of the biologically harmful and toxicologically relevant of BPA even at low doses, researchers are competing to develop a new electrochemical sensor to track low BPA levels. **Table 3** illustrates a comparison of the analytical performances between our BPA sensor based on RGO nanocarbon transducer (Au/RGO/ Fe(III)TMPP) and other recently reported BPA sensors. Alam et al. reported graphene oxide and β-cyclodextrin functionalized multiwalled carbon nanotubes (GO-MWCNT-βCD) for the detection of BPA at nanomolar level (6 nM) with good reproducibility (n = 3) and a two-step linear response from 0.05 to 5 μM and 5– 30 μM [44]. The GO-MWCNT-βCD modified screen-printed electrode (SPE) showed the highest oxidation peak current of 49.4 μA at Epa of 595 mV for BPA, which is at least 1.6 times higher than other modified SPEs. This was explained by the synergistic effect between GO, MWCNT and βCD leading to a fast electron transfer kinetics, consequently an amplified signal detection of BPA. Wan et al. reported an eco-friendly electrochemical sensor based on Multi-Walled Carbon Nanotubes (MWCNT)/Polythiophene(PTh)/Pt nanocomposites-modified glassy carbon electrode for determination of BPA molecules in aqueous media [45]. The working electrode captures BPA electrochemically and consequently gets adsorbed on the MWCNT-PTh-Pt electrode surface electrode followed by electrochemical oxidation by differential pulse voltammetry (DPV) with the increased oxidation current at 0.5 V. This affinity was explained by the Pt nanocluster that acted as a suitable catalyst of MWCNT-PTh nanocomposite and enhanced the electrochemical detection signal of BPA. Moreover, this sensor platform revealed linear response for BPA detection from 0.005 to 0.4 μM in phosphate buffer saline (PBS) solution and the detection limit was found to be 0.003 μM (S/N = 3). Ponnaiah et al. designed a GCE modified with a new nanocomposite composed of ruthenium nanoparticles, polyaniline and graphitic carbon nitride (Ru<sup>0</sup> /PANI/g-C3N4) as an electrochemical


*Novel Sensor Based on Nanocarbon Transducer Functionalized by Iron (III) Porphyrin… DOI: http://dx.doi.org/10.5772/intechopen.98560*

### **Table 3.**

*Comparison of the detection method, detection limit, linear range and preparation method of the sensor of recently reported sensors and the present study for the determination of BPA.*

sensor for the detection of BPA [46]. The sensor system exhibits picomolar-level detection limits, good sensitivity and stability with a detection range from 0.01 to 1.1 μM. This result was explained by the synergistic effect of the nanocomposite: the high activity of ruthenium nanoparticles, the porous structure of the conducting PANI and the catalyst role of g-C3N4 that created an amplified detection system. Jiang et al. reported the development of electrochemical sensors based on carbon nanomaterials, i.e. nanodiamond (ND/GCE) and nanocarbon (NC/GCE) [47]. These carbon materials have achieved a good sensitivity towards BPA monitored by Square Wave Voltammetry (SWV) thanks to their low fouling properties and porous structures. The limit of detection of the proposed sensor was at the nanomolar level with an acceptable liner range from 0.1 to 80 μM. Tsekeli et al. reported the synthesis of silver nanoparticle-exfoliated graphite nanocomposite (AgNPs-EG) for the application of BPA sensor [48]. The AgNPs-EG nanocompositebased electrode has demonstrated antifouling property and acceptable affinity towards BPA with LOD of 0.23 μM and a linear range from 5.0 to 100 μM.

Compared with all these recently reported BPA sensors (**Table 3**), our work based on Au/RGO/Fe(III)TMPP sensor presents the best sensing platform because of its lower limit of detection in the picomolar level (2.1 10<sup>7</sup> μM) and wider linear range spreading from 10<sup>6</sup> to 10<sup>2</sup> μM. Hence, the sensor based on nanocarbon transducer functionalized by Fe(III)TMPP presented in this work is capable of measuring BPA at concentrations lower than the daily dose limits set by recent medical advice. In addition to a lower detection limit and wide detection range, our fabrication method is based only on drop-casting and drying, which is more facile and less time consuming than other methods. Furthermore, the modification of our sensor is based on non-covalent bonding which preserves the sp2 structures of each membrane, leading to a good stability of the BPA response signal. Another advantage of our proposed sensor was that, in our work, electrochemical impedance

spectroscopy was used to follow the detection signal of BPA, while it was rarely used compared to DPV and SWV methods to monitor the attachment of BPA on the sensor surface. The advantage of the EIS method compared to the most frequently used SWV and DPV methods is that it does not damage the electrode surface and also enables low detection limits [49].We envisage that such sensors are promising tools to face the challenges of the detection of BPA at trace level in aqueous media, as an alternative to the conventional test or central lab equipment.

The better sensing performance of our sensor based on Au/RGO/Fe(III)TMPP could be attributed to different aspects such as the architecture of the modified electrode that is based on Au/RGO nanocarbon transducer for immobilized Fe(III)TMPP to retain its stability and activity which can facilitate the reaction towards BPA. Moreover, the high electric conductivity of RGO nanocarbon material can create a novel nanocarbon transducer with higher kinetic charge transfer compared to usual used transducers which facilitates the mediation of electrocommunication between the BPA and the electrode.

## **7. Conclusions**

In this chapter, a label-free impedimetric sensor using Au/RGO nanocarbon transducer functionalized by Fe(III)TMPP has been successfully designed for the detection of trace BPA. The Au/RGO/Fe(III)TMPP electrode was fabricated by loading RGO and Fe(III)TMPP membrane on Au transducer, respectively. The Au/RGO/ Fe(III)TMPP sensor has demonstrated an amplified response towards BPA compared to that of Au/Fe(III)TMPP electrode. This enhancement was attributed to the Au/ RGO nanocarbon transducer which acted as a charge transfer catalyst and good platform for the attachment of Fe(III)TMPP via *π*- *π* staking. The suggested Au/ RGO/Fe(III)TMPP has offered a few advantages compared to the previously reported strategy for the determination of BPA, including excellent low LOD (2.1 10<sup>13</sup> M) and wide linear dynamic range with a simple and efficient fabrication method. The findings from this study will be valuable for constructing highly sensitive sensors based on modified Au/RGO nanocarbon transducer to detect various substances with low concentration and trace amount.

### **Author details**

Zouhour Hsine\* and Rym Mlika Laboratory of Interfaces and Advanced Materials, Faculty of Science of Monastir, University of Monastir, Monastir, Tunisia

\*Address all correspondence to: zouhourhsine1@gmail.com

© 2021 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Novel Sensor Based on Nanocarbon Transducer Functionalized by Iron (III) Porphyrin… DOI: http://dx.doi.org/10.5772/intechopen.98560*
