# Functionalized Carbon-Based Electrochemical Sensors for Food and Alcoholic Beverages Safety
## 3 Carbon Nanomaterial-Based Electrochemical Sensors
### Graphene
As shown in Figure 5d, the CS-fishbone-shaped Fe\({}_{2}\)O\({}_{3}\) (ffe\({}_{2}\)O\({}_{3}\))-electrochemically reduced graphene oxide (ERGO), having a large surface area, excellent electronic conductivity, and high stability, was modified on the glassy carbon electrode for detecting GA to estimate the antioxidant capacity of wines. Under the optimal conditions, the good linear range and the low limit of detection of GA were obtained from 1 to 100 \(\upmu\)M and 0.15 \(\upmu\)M, respectively. In this work, ERGO and Hfe\({}_{2}\)O\({}_{3}\) hybrids have a significant synergistic amplification effect on enhancing the electrochemical performance of the electrode. Moreover, the good structural stability of the reported CS-fFe\({}_{2}\)O\({}_{3}\)-ERGO can avoid contamination of the detection system [101]. Similarly, [PERSON] et al. [107] reported an electrochemical sensor that was fabricated using SnO\({}_{2}\) decorated graphene (SnO\({}_{2}\)-RGO) composite, which exhibited excellent selectivity, reproducibility, and stability for caffeic acid (CA) detection in commercial red wine samples. Two-dimensional disulfide nanosheets, and particularly molybdenum disulfide (MoS\({}_{2}\)), have aroused tremendous research interest in electrochemical aptasensor applications under complicated conditions [115, 116]. However, the facile aggregation and low electronic conductivities of MoS\({}_{2}\) decrease the number of electroactive sites on the electrode surface, thereby restricting electron transfer and related electrochemical kinetics [117, 118]. A highly sensitive electrochemical sensor based on 2D nanocomposite for _trans_-resveratrol (TRA) was fabricated using graphene-molybdenum disulfide (Gr-MoS\({}_{2}\)), as shown in Figure 5e. Under optimized conditions, the prepared sensor showed a linear response in TRA concentration from 1.0 to 200 \(\upmu\)M with a limit of detection of 0.45 \(\upmu\)M due to the synergistic effect between Gr and MoS\({}_{2}\)[105]. Furthermore, [PERSON] et al. [103] reported reduced graphene oxide/molybdenum disulfide/polyaniline@gold nanoparticles/chitosan (RGO/MoS\({}_{2}\)/PANI@AuNPs/Cs), among which Cs acted as an aptasensor and AuNPs were dedicated to signal amplification, was constructed using facile hydrothermal and coating methods. The Au-S bonds formed on the surface of MoS\({}_{2}\) facilitate effective installation of the aptamer. As-developed RGO/MoS\({}_{2}\)/PANI@AuNPs/Apt exhibited a wide linear range from 0.01 fg mL\({}^{-1}\) to 1.0 fg mL\({}^{-1}\) and a remarkably low detection limit of 0.002 fg mL\({}^{-1}\) due to the synergistic effects among distinct components. In addition to coating catalysts on the surface of carbon electrodes, fabricating self-supported electrodes can effectively increase the contact between the detected substance and the sensor. Based on 3D printing technology, graphene-polylactic acid (graphene-PLA) electrodes were fabricated for detecting atropine in contaminated beverage samples, such as white wine, vodka, whisky, and energy drink. A linear concentration range between 5 and 60 \(\upmu\)M associated with a detection limit of 1 \(\upmu\)M was obtained using a SWV determination protocol [109]. Moreover, as shown in Figure 5f, a novel flexible electrochemical sensor using a direct laser-induced graphene (LIG) technique that transforms the commercial Kapton tape into 3D porous graphene was developed for sensitive detection of _trans_-tesveratrol (TRA) molecules in red wines. The prepared electrochemical sensor with excellent repeatability, stability, reproducibility, and reliability guaranteed an excellent linear response within the TRA concentration range from 0.2 to 50 \(\upmu\)M and a low limit of detection of 0.16 \(\upmu\)M. Furthermore, the developed sensor can be applied for the evaluation of TRA levels in red wines and grape skins with a satisfactory result [106]. Electrochemical sensors based on graphene composite materials have been widely studied in daily food safety and drug monitoring.