## 1 Introduction
### Modified Electrode Types
#### 1.1.4 Nanoparticle-Modified Electrodes [27; 44]  
Recently, the trend in electrochemical sensing is the utilization of nanomaterials, because they can offer the following advantages in electrode surface modification:  
1. Enhanced surface kinetics;
2. Large electroactive surface area and therefore accelerated electrochemical reactions;
3. Enhancement of analyte adsorption on the electrode surface and, consequently, lowered detection limits;
4. Nanoparticles give effective active functionalization sites towards analytes and usually have good stability as supporting platforms providing better selectivity than conventional electrodes. Electrochemical analysis based on screen-printed electrodes (SPEs) also shows an excellent miniaturized and portable alternative to conventional methods due to their disposable character, good reproducibility, and low-cost commercial availability [45; 46]. SPEs' applications have been widely extended, which makes it important to design functionalization strategies to improve their analytical response [45; 46]. In this sense, different types of nanoparticles (NPs) have been used to enhance the electrochemical features of SPEs. NPs' sizes (1-100 nm) provide them with unique optical, mechanical, electrical, and chemical properties that give the modified SPEs increased electrode surface area, increased mass-transport rate, and faster electron transfer [45; 46]. Recent progress in nanoscale material science has led to the creation of reproducible, customizable, and simple synthetic procedures to obtain a wide variety of shaped NPs [45; 46]. The success of SPCE fabrication is highly dependent on the composition of conductive ink, which consists of conductive materials, binders, and solvents; the substrate; and the fabrication techniques. Among the carbon-based materials, the most widely used for SPCE fabrication are graphite, graphene, and carbon nanotubes [45]. The solvents used for SPCE fabrication are varied and include water and various organic solvents. The main characteristics of the SPCE substrate should be inert in order to avoid any interferences during electrochemical measurements. Screen printing and inkjet printing techniques are preferred for SPCE fabrication due to their simplicity and the possibility for mass production [45; 46]. Thus, there has been increasing interest in modifying electrode surfaces with nanoparticles to enhance their performance in the determination of antibiotics. These modified electrodes can be used in various electroanalytical techniques, such as voltammetry and electrodes can be used in various electroanalytical techniques, such as voltammetry and amperometry, to detect a wide range of antibiotics. Despite the fact that nanomaterials can provide the above-mentioned advantages in the electrochemical sensing of antibiotics, their immobilization on the electrode surfaces and further functionalization with desired moieties is a quite challenging task. The success of these steps is basically a key factor in improving the electrode's performance. Additionally, electrochemical signal interferences from other compounds with similar chemical structures can limit the selectivity of these sensors. The methods that are currently being employed for electrode modification with nanomaterials include electrodeposition, physical adsorption, polymerization, through chemical bonding, etc., as seen in Figure 2.  
In recent years, there has been increasing interest in modifying electrode surfaces with nanoparticles to enhance their performance in the determination of antibiotics. These modified electrodes can be used in various electroanalytical techniques, such as voltammetry and amperometry, to detect a wide range of antibiotics. Thus, nanoparticle-modified electrodes have been shown to be effective for the detection of many different antibiotics, including penicillins, cephalospor, tetracyclines, and quinolones.