## 3 Molecular Imprinting by Electropolymerization
The development of the voltametric sensor involved the synthesis of an MIP film by CV directly on screen printed carbon electrode (SPCE) surface, using a solution containing dopamine as monomer, diclofenac sodium as template molecule and KCl as electrolyte. The electrodeposition was performed in a potential range between \(-0.5\) V and 1 V at a scan rate of 100 mV/s. Ultimately, the sensor was tested by DPV, and, according to the authors, the imprinting factor was 2.5. Furthermore, a LOD of 70 nM and a limit of quantification (LOQ) of 200 nM were obtained [81]. Another sensor based on Au nanoparticles and MIPs was introduced by [PERSON] and her group [82] for epinephrine detection. The authors used a three-electrode system consisting of GCE (working electrode), saturated calomel electrode (reference electrode) and a Pt electrode (counter electrode). The working electrode was modified previously with HAuCl\({}_{4}\), after which the electrodeposition was performed by applying a potential between \(-0.2\) and 1.2 V for 20 scan cycles in the presence of epinephrine and 3-thiophene boronic acid (3-TBA). CV and DPV techniques were used to evaluate the performance of the final sensor, in which case a detection limit of 7.6 \(\times\) 10\({}^{-8}\) M was recorded [82]. [PERSON] and his group [83] proposed a sensor for naloxone detection. In this respect, the MIP film was synthesized by electropolymerization on the screen-printed carbon electrode that was firstly modified with MWCNT. The MIP film was prepared by CV when applying a potential in a range between \(-0.2\) and 1 V, for 20 scan cycles at a scan rate of 100 mV/s, using a solution of 4-aminobenzic acid and naloxone in PBS. The performance of the sensor was further studied using DPV and a detection limit of 0.2 uM was acquired [83]. Three years later, [PERSON] and co-workers [84] also studied a sensor for naloxone detection, whereas the MIP film was deposited under similar conditions as described by [PERSON] et al. [83]. Yet, in this case, the SPCE surface was modified with Au nanoparticles and the CVs were obtained after applying a potential between \(-0.2\) and 1 V at a scan rate of 50 mV/s for 15 scan cycles. By doing so, a lower detection limit (0.16 uM) was achieved. Methylene is a synthetic drug, which produces psychotropic effects similar to extensor. Considering the side effects of this drug that include hypertension, paranoia and tachycardia, [PERSON] et al. [85] presented a method for preparing an MIP-based sensor for methylene detection. The film was deposited on screen-printed gold electrode by electropolymerization of 2-mercaptoethanolbenzamideimidazole (monomer) in presence of the template molecule (methylene). The process was performed by CV when applying a potential in a range between \(-0.2\) and 1.3 V for 15 scan cycles. A good performance of the sensor was obtained by SWV, in which case a detection limit of 1.1 uM was obtained. Moreover, the sensor also showed good stability and selectivity [85]. Melamine is a synthetic compound that can be used in the plastic industry as well as the milk industry. Considering the side effects of the melamine on human health (e.g., kidney problems, kidney stones), the monitoring of food is required. In this respect, [PERSON] and colleagues [86] developed an SPR sensor based on MIP films for melamine detection. The three-electrode system consisted of an optical fiber probe coated with Cr/Au film (working electrode), an Ag/AgCl electrode (reference electrode) and Pt electrode (counter electrode), while the MIP film was synthesized by electropolymerization of \(o\)-aminophen (functional monomer) in the presence of melamine, by applying a potential between \(-0.3\) and 1.2 V for 30 scan cycles at 50 mV/s. In order to estimate the performance of the sensor, several melamine solutions with different concentrations were used, leading to an LOD of 5.1 \(\times\) 10\({}^{-12}\) M, which indicated a good sensitivity of the sensor [89]. Two years later, [PERSON] et al.