Ultrasound assisted synthesis of silver titanate for the differential pulse voltammetric determination of antibiotic drug metronidazole

Highlights

• Perovskite-type Ag₂TiO₃ was prepared by a simple ultrasonication method.

• The as-synthesized Ag₂TiO₃ modified electrode was optimized for the loading catalyst, pH, scan rate, peak current, and peak potential at the electrochemical determination of MTZ.

• The fabricated sensor shows an extensive linear response from 0.1 to 104.3 μM with a low detection limit of 0.011 μM.

• MTZ was successfully applied in real samples with good sensitivity and appropriate results.

Abstract

Highly electroactive transition metal oxides have been received great potential in antibiotic drug electrochemical sensors due to excellent features including ease of preparation, a large number of active sites, good conductivity, high stability, and selectivity. In this work, the perovskite-type silver titanate (Ag₂TiO₃) was synthesized by ultrasound-assisted coprecipitation method. The structural and morphology were examined using typical analytical techniques such as X-ray diffraction (XRD) Fourier transform infrared spectroscopy (FT-IR), Raman spectrometry, field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) analyzes confirmed the purity and the chemical composition of as-prepared Ag₂TiO₃. The Brunauer−Emmett−Teller analysis (BET) of as-synthesized Ag₂TiO₃ displayed a specific surface area of 48.485 m² g⁻¹ resulted in improved charge transfer resistance (R_ct) of 695 Ω. The cyclic voltammetry (CV) analysis revealed the superior electrochemical performance of Ag₂TiO₃ than other electrodes towards metronidazole (MTZ) detection. Under optimized differential pulse voltammetric (DPV) studies, the modified electrode exhibits a wide linear range of 0.1–104.3 μM with the lowest detection limit of 0.011 μM and a sensitivity of 0.371 μA μM⁻¹ cm⁻². Furthermore, the fabricated sensor displayed excellent cyclic stability, reproducibility, repeatability, and noticeable selectivity in potentially effective interfering compounds for the detection of MTZ. The constructed electrode delivered good sensitivity to MTZ in urine and tablet with acceptable recoveries.

Introduction

Nanomaterials have become an evergreen trend in the research arena due to their wide application in various fields [[1], [2], [3]]. Amongst, binary metal oxides (BMOs) with two-dimensional nanostructures have attracted more attention due to their unique physicochemical properties and potential applications. Especially BMOs are mainly utilized for qualitative and quantitative studies in diverse applications including bio-sensing (such as DNA, proteins, enzymes, metabolites, and antigens), chemical/gas detection, and optical sensing [4,5]. Perovskite nanostructures have established great recognition among researchers owing to their excellent electrochemical sensing capabilities with high sensitivity and selectivity. Most importantly, the cost-effectiveness of perovskite materials has brought them special considerations. In electrochemical sensing applications, different ABO₃ and A₂BO₃ perovskite-type nanostructures with various metal cations and metalized anion groups have been reported [6]. Titanium is an active periodic element, which has important uses in health and environmental applications. Several day-to-day products contain titanium oxide (TiO₂) as one of the main ingredients, such as talc, sunscreen, soap, toothpaste, food, paint, tablets, medicines, and other cosmetics [7]. In specific, TiO₂ has been widely used as a UV light-mediated efficient photocatalyst [8]. To improve the electrochemical sensing of TiO₂, researchers have tried different approaches, such as thin-film doped metal oxides [9], a synthetic technique based nanocomposite [10], protein immobilization [11], electrochemical detection [12,13], the introduction of a carbon source such as graphene [14] and addition of binding agent like nafion [15,16]. However, the application of TiO₂ based nanomaterials in the field of electrochemical sensing has not yet been revealed in the form of titanate. Titanate nanomaterials have superior physical and chemical properties, have good prospects, and can be used in photocatalysis [17], high energy lithium batteries [18], solar cells [19], supercapacitors [20], and electrochemical sensors [21] because of their extensive application as ferroelectric materials, they have attracted great consideration [[22], [23], [24]]. Previously, the titanate based perovskite nanomaterials have been reported, such as MnTiO₃ [25], CoTiO₃ [26], NiTiO₃ [27], SrTiO₃, BaTiO₃, CaTiO₃ were all of ABO₃ type [28,29]. Combining the titanate with precious metal nanoparticles can bring great potential in many applications [30]. Therefore, silver titanate (Ag₂TiO₃; ATO) has been selected as an electrode material since the electrochemical properties are yet to be studied.

Over the past decades, silver-doped metal oxide nanocomposites (for example Ag/MnO₂, Ag:NiO_x, Ag/ZnO, and Ag–Fe₂O₃) have been reported for various fields such as pseudocapacitor [31], photoreactor [32], photocatalysis [33], solar cell [34], and electrochemical sensor [35] applications and the performance has been improved by Ag particles. When compared to other conventional metal oxides, Ag incorporated metal oxides are expected to show enhanced behavior through the surface Plasmon's assistance [36,37]. Among them, the manufacturing and commercialization of devices are mainly related to electrochemical applications, such as redox reactions, detection, degradation, capacitance, and energy storage [[38], [39], [40]]. Electrochemical sensing technology uses different metal oxides-based electrode surface modifiers to increase its sensing performance [[41], [42], [43], [44]], even at trace levels, it can instantly detect the drugs and harmful substances present in the human body and environment.

Metronidazole (MTZ; 2-(2-methyl-5-nitroimidazole-1-yl)ethanol) is a well-known antibiotic drug, commonly used in humans to treat bacterial infections, specifically anaerobic bacteria, such as clostridium. MTZ is used as a growth additive for poultry and fish to remove parasites [45]. Owing to better water solubility, it is easily removed from the atmosphere and readily accumulates in the human/animal body. Due to its wider range of use, MTZ is dispersed in the body tissues (like bones, and bile) and body fluids (such as saliva, urine, blood, and breast milk) of humans and animals. The nitro anion free radicals in MTZ metabolites can interact and damage cell DNA [46]. The mediated requirement of MTZ in human serum is 2–8 μg mL⁻¹ or more, which should be regarded as excessive. Overdose and long-term use of MTZ may cause human ataxia, peripheral neuropathy, and seizures as well as animal fertility problems and cancer, which are not found in humans [47,48]. Because of the widespread and serious side effects of MTZ, sensitive low-level detection must be carried out for its presence in organisms and the environment. Among the various available methods, such as spectrophotometry [49], gas [50], and high-pressure liquid chromatography [51], chemiluminescence [52], and polarography [53]. Compare to the above methods, the electrochemical sensing platform is the most opt for the determination of MTZ [54,55], due to their cost-effective, simple fabrication step, fast kinetics, easy operating conditions, large surface to volume ratio, and higher sensitivity. Until now, from our knowledge, there are no reports available for the detection of MTZ using the novel ATO modified GCE.

Herein, we have prepared perovskite-type silver titanate (ATO) by an ultrasound-assisted coprecipitation route. The obtained ATO was examined by various spectroscopic methods. The ATO electrode was fabricated by a simple drop-casting method and applied for the electrochemical detection of antibiotic drug MTZ using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. As a result, the modified electrode displays higher electrocatalytic activity and thus enhanced electron transfer kinetics between the electrode surface and the MTZ. Besides, the constructed sensor showed a WLR, low LOD, excellent sensitivity, high selectivity, good stability up to 100 cycles, and satisfactory outcomes in tablet and urine samples towards the detection of MTZ.