A facile green synthesis of a perovskite-type nanocomposite using Crataegus and walnut leaf for electrochemical determination of morphine

Highlights

• Crataegus and walnut leaf were used for green synthesis of TbFeO₃/CuO.

• The new nanocomposite was applied for modification of SPE.

• Determination of morphine was performed using TbFeO₃/CuO/SPE.

• The Present electrode exhibited a minimum detection limit of 0.01 μM.

Abstract

In this study, we addressed a selective and sensitive electrochemical approach for detecting morphine (MO) using the TbFeO₃/CuO nanocomposite. Crataegus and walnut leaf as the environmentally friendly agents were used to synthesis TbFeO₃/CuO and energy disperse spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM), as well as vibrating-sample magnetometer (VSM) were employed for characterizing the products. In addition, chronoamperometry, cyclic voltammetry (CV) and differential pulse voltammetry (DVP) were applied to examine the electrochemical behavior of MO. According to analysis, this new modified electrode had higher peak currents for MO oxidation than the unmodified SPE and the analytical curve for MO detection exhibited a wide linear response in the range between 0.07 and 300.0 μM for MO. Moreover, the limit of detection (LOD) of 10 nM for MO was achieved. Finally, TbFeO₃/CuO/SPE showed successful utilization for detecting MO in the real samples, with a good recovery in the range between 96% and 104.3%.

Introduction

As one of the alkaloids derived from the poppy plant, MO has been introduced as the first real drug worldwide. Furthermore, it is a phenanthrene derivative present in nature, which applies a direct function at the pain regulating receptors in the nervous system, which is known as opioid receptors. Distribution of such receptors is observed across the central nervous system (CNS) with the increased concentration in the nuclei of the periaqueductal gray area (PAG), tractus solitarius, thalamus, substantia gelatinosa (SG), as well as the cerebral cortex of the spinal cord [1,2].

In clinical medicine, MO has been proposed to be a gold criterion or benchmark of analgesic utilized for relieving chronic pains in cases of cancer. The MO is also employed as the starting compound to synthesize other opioids like oxymorphine, heroin, and hydro morphine, whose analgesic effects and addiction have been reported to be so strong that should be regarded as abused medicines. Put differently, MO is toxic in case of overdosing and may impact diverse immune functions and disrupt respiratory rate and CNS, and lower blood pressure [3,4]. The above issues necessitate the design of one of the selective, simplified, and sensitive methods for precise monitoring of MO in multiple biological and drug specimens. For this reason, numerous experts applied various kinds of analytical approaches to detect MO like gas chromatography-mass spectroscopy (GC/MS) [5], high-performance thin-layer chromatography (HPTLC) [6], ELISA [7], chemiluminometric [8], high-performance liquid chromatography (HPLC) [9], electrochemical [10], and spectroscopy [11]. Nevertheless, several approaches suffer from shortcomings such as lower sensitivity, larger volumes of the sample, time-consuming and difficult process of the sample pre-treatment [12,13]. Consequently, researchers have shown the significance of the electrochemical approaches because of their affordability, portability, and higher sensitivity and selectivity. Nonetheless, electro-catalytic activities of the bare electrode have been not acceptable and incorporation of the nanomaterials in the sensors remarkably improved the signal transduction because of specific physicochemical and electronic features [[14], [15], [16], [17], [18]].

The chemical modification of conventional electrodes is a promising method for overcoming these problems. Based on the researches, the chemically modified electrodes, which use diverse nanomaterials, contribute highly to the improvement of sensitivity and selectivity of drug detection through the electrochemical technique [[19], [20], [21]].

According to the studies, rare earth NPs like Cerium (Ce), Terbium (Tb) and Europium (Eu) play important roles in several fields. In addition, they possess specific 4f-electron structures, larger atomic magnetic moments, as well as stronger spin-orbit coupling [[22], [23], [24]]. Because of the specific features of 4f and 5d electron orbitals, researchers dealt with the development of the new nanocomposites based on the rare earth elements for modifying electrochemical sensors with similar functionalities of the noble metal such as Pt, Au, Ru and Pd. Therefore, as a feasible alternative, one of the noticeable modifiers in several electrochemical applications would be the doping of metal oxide NPs with the rare earth elements [25]. It was found that perovskite-type oxides (ABO₃), in particular, as the nanomaterials, could be important materials for diverse applications in electrochemical sensors, catalysis, and fuel cells. Moreover, they exhibited major physicochemical features like higher electronic conductivity, variability in the content of oxygen, electrically active structures, magnetic and chemical and thermal stability [26,27]. In addition, these nanomaterials may promote the catalytic functions and make the strongly sensitive sensors to be employed in electrochemical sensing [28,29].

Additionally, because of the simple synthesis and acceptable electrical conductivity, the CuO NPs may be regarded as the most attractive substances to be combined with the perovskite-type oxides [30]. Hence, it was expected that combining CuO with TbFeO₃ exhibited higher electrochemical activities and greater selectivity and sensitivity for the determination of MO.

The green synthesis of the NPs has shown itself as one of the environmental-friendly, non-toxic, inexpensive, and clean approaches that could be implemented at room temperature and pressure. Moreover, it could be viewed as one of the alternatives for the synthesis of bio-compatible NPs.

As mentioned earlier, this study reports the green synthesis of TbFeO₃/CuO nanocomposites by using sol-gel and sonochemistry methods. We used Crataegus as a natural fuel to control the morphology of final perovskite material (TbFeO₃) nanoparticles. CuO nanoparticles were synthesized via the co-precipitation method using a walnut leaf. The study also addressed the electrochemical performance of the SPE modified with the TbFeO₃/CuO in the presence of morphine. MO was detected in the drug formulation, serum and urine samples for showing the sensor applicability. Results showed a very good recovery for real samples. Finally, acceptable relative standard deviation (RSD) values indicated the best repeatability of the TbFeO₃/CuO/SPE.