## 1 Introduction
Analyzing antibiotics can be challenging due to the complexity of the samples being analyzed and the typically low concentrations at which these substances are found in these kinds of samples. This requires the use of highly sensitive analytical methods for monitoring these compounds at low concentration levels. In this context, sensitive analytical methods are required, not only for the quantitative determination of antibiotics in food and the environment but also for the detection of bacteria, screening compounds with antibacterial activity, and antibiotic susceptibility testing. Several separation methods exist, such as liquid chromatography (LC) [15], where detection limits have been obtained in the range of 1-10 ng/L in treated water, 0.8-10 ng/L in groundwater, and 0.8-25 ng/L in river water. Capillary electrophoresis (CE) [16] has also been used and low limits of detection of 4.1-6.3 ng/mL were obtained. Thin-layer chromatography (TLC) [17] is often used in conjunction with diode array detectors (DAD) [18] and mass spectrometry (MS) detectors [19] to accurately determine the presence of antibiotics, where the detection limits were found to be sufficiently low. Figure 1: Release of antibiotics into the environment and trophic chain [4]. It is worth mentioning that preconcentration techniques, such as solid-phase extraction [15; 19] and liquid-liquid extraction (LLE) [20], are often used with liquid chromatography, capillary electrophoresis, and other separation techniques before detection in order to lower the detection limits of antibiotics in complex matrices and improve the sensitivity of the assay. This step aimed at separating the target analytes from interferences is generally time-consuming and costly. In addition, preconcentration techniques are likely to eliminate other compounds whose analysis may be critical to the current or future evaluation of the sample (e.g., the presence of other contaminants, chemical tracers, metabolites, etc.). Alternatively, direct injection without complex sample preparation has been introduced for the rapid analysis of trace compounds in environmental and food matrices into high-performance liquid chromatography systems and became a widely utilized technique [21]. For instance, [PERSON] et al. [22] studied a direct injection method for the detection of veterinary antibiotics in freshwater and seawater using liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS). Although chromatography is a useful technique for determining the presence of antibiotics because of its automation, accurate quantification, simultaneous detection, and high specificity based on the structural information of the analytes, it is limited by several factors, including the high cost of time and equipment. Other precise methods for detecting antibiotics, such as capillary electrophoresis, fluorescence immunoassay, direct assay, and enzyme-linked immunosorbent assay, also require skilled personnel and complex sample preparation, which limits their widespread use [23]. Therefore, there is a pressing need for more accurate, simple, and cost-effective methods. Electrochemical sensors could potentially be used as a screening tool for quickly estimating antibiotic contamination in various samples. Electroanalytical chemistry is a well-established technique that offers high sensitivity and selectivity for the determination of antibiotics in complex matrices. In order to develop effective electrochemical sensors for therapeutic drug monitoring (TDM) that are also low-cost, we must carefully choose the electrode materials and coating layer materials for functionalization [24]. Due to their physical properties, nanoparticles have been incorporated into various matrices in order to expand their utility in nanomaterials and biomedical sensor applications as electrode surface modifiers, making them excellent candidates in fabricating nanoscale devices.