# Functionalized Carbon-Based Electrochemical Sensors for Food and Alcoholic Beverages Safety
## 3 Carbon Nanomaterial-Based Electrochemical Sensors
### Graphene  
Graphene is a 2D honeycomb lattice structure composed of a single layer of sp\({}^{2}\) hybridized carbon atoms. Graphene-based materials have been widely examined by researchers in experiments and theoretical studies due to, among other factors, their high chemical stability, thermal conductivity, and electron mobility [95,96]. As far as we know, graphene has shown great application potential in the fields of electronics, optics, magnetism, biomedicine, catalysis, and sensors [97,98]. In particular, graphene is very suitable for the development of sensing materials in electrochemical sensors by taking advantage of its large specific surface area and high electron mobility. In the following section, we illustrate the applications of graphene-based materials in the development of electrochemical sensors for food and beverage safety, as summarized in Table 3.  
Due to the 2D planar structure of graphene, the fabricated detection system can fully contact the detected substances, which is conducive to accelerating mass transfer and therefore realizing rapid detection. In addition, the detection requirements of different pollutants can be rationally met via grafting organic functional groups or compounding different metal nanomaterials. Recently, [PERSON] et al. [100] reported that oleamide-derivative decorated graphene can be directly coated on carbon electrodes and used to detect amino acids, such as L-histidine, L-tyrosine, L-ornithine, and L-lysine in wine (Figure 5a). In this work, the proposed sensors exhibited excellent sensitivity, reliability, and reproducibility for the quality determination of wines. Furthermore, an amperometric immunoassay for Saccharomyces cerevisiae was constructed using functionalizing and coupling approaches, as shown in Figure 5b. The immunosensor allowed the amperometric detection of the yeast in buffer solution and white wine samples in the range of 10-107 CFU mL\({}^{-1}\). Because this propionic acid-functionalized graphene oxide could provide a large number of adsorption and sensing sites, the immunosensor successfully detected Saccharomyces cerevisiae at the refermentation stage, exhibiting a low detection limit and high selectivity, and good reproducibility and storage stability [104]. The functionalized graphene is not merely able to serve as a platform for aptamer sequencing, but also as the signal-enlarging platform. [PERSON] et al. [102] reported an electrochemical apta-sensor based on hexamethylenediamine-functionalized GO as the signal-enlarging platform via carbodiimide amide-bonding. Aflatoxin B1 (AFB1) analyte molecule detection was accomplished in phosphate buffer saline (PBS) solution using methylene blue as a signaling fragment and FGO as the signal-enlarging platform. Under optimized conditions, a very low detection limit was obtained with the linear range of 0.05-6.0 ng mL\({}^{-1}\). Heteroatom doped graphene is one of the significant strategies for graphene properties' regulation. Nitrogen, phosphorus, oxygen, sulfur, and other atom-doped graphene have been extensively studied in the  
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