## 2 Nanoparticle-Modified Electrodes  
Nanoparticle-modified electrodes have shown promising results in the sensitive and selective electroanalytical determination of antibiotics. In recent papers, nanomaterials such as carbon nanotubes [49] and graphene oxide [50] have been used to modify electrodes, resulting in improved electrocatalytic properties and enhanced sensitivity and selectivity in electrochemical sensors. For example, [PERSON] at al. [49] developed a new method for detecting sulfamethazine (SMZ) in cow's milk using a glassy carbon electrode modified with graphene oxide and decorated with Cu-Ag core-shell nanoparticles. Electrodes modified with nanoparticles could be utilized in multiple electroanalytical applications of a broad range of antibiotics, including chloramphenicol [51], doxorubicin [52], pyrazinamide [53], streptomycin [54], and amoxicillin [55]. Some examples of electrode surfaces modified with nanoparticles that have been used in the determination of antibiotics are shown in Table 1.  
Figure 3: Common materials used as electrode modifiers [47]. These are just a few examples of nanoparticle-modified electrode surfaces that have been used for the electroanalytical determination of antibiotics. There are more examples of electrode surfaces modified with nanoparticles for the sensitive and selective electroanalytical determination of antibiotics. For instance, [PERSON] et al. developed a sensor using a nanocomposite of reduced graphene oxide and silver nanoparticles to detect the antibiotic chloramphenicol. This sensor was proved to be reproducible, stable, and selective over similar interfering substances in order to accurately detect chloramphenicol in milk samples [61]. [PERSON] et al. also reported the preparation of a paraffin composite electrode based on multi-walled carbon nanotubes (MWCNT) modified with antimony nanoparticles (SbNPs). The sensor was used to detect two antibiotics, sulfamethoxazole and trimethoprim, using differential pulse voltammetry in natural water samples. The sensor's structure and electrochemical properties were studied using field emission gun scanning electron microscopy and cyclic voltammetry, respectively [48]. These examples demonstrate the potential of using nanoparticles to modify electrode surfaces for the sensitive and selective electroanalytical determination of antibiotics, but there are many more. In one study, the development of an electrochemical sensor using platinum nanoparticles on carbon (PtNPs/C) for the detection of tetracycline is described. The sensor was first synthesized and characterized using X-ray diffraction and transmission electron microscopy. The researchers then studied how different experimental conditions, such as the number of platinum nanoparticles and the pH of the solution, affected the sensor's behavior. They used cyclic voltammetry and differential pulse voltammetry to investigate how tetracycline is electro-oxidized on the sensor and determined that the sensor was able to accurately detect tetracycline over a wide range of concentrations in urine samples. This suggests that the sensor may have the potential for use in clinical analysis and quality control [62]. In another study, [PERSON] et al. developed a copper nanoparticle-based film incorporating a cationic surfactant and graphene for determining the presence of gaifloxacin and perflocacin using differential pulse stripping voltammetry. The film's surface was analyzed using SEM and EDS, and it was found to have improved electrocatalytic properties due to the combination of copper nanoparticles, graphene, and CTAB surfactants. The modified electrode showed good performance in detecting the drugs, with linear responses at concentrations between 0.02-40 \(\mu\)M and 0.04-20 \(\mu\)M and detection limits of 0.0021 \(\mu\)M and 0.0025 \(\mu\)M, respectively. The sensors were also used to detect the drugs in shrimp and animal serum with successful results, suggesting that the film is a promising catalyst for electrocatalysis [65].