## 1 Introduction  
Listeriosis is a foodborne illness and the cause of approximately 23,000 infections in humans every year [1]. This disease is characterized by different clinical conditions such as gastroenteritis, meningoencephalitis, septicaemia, spontaneous abortion and serious infections in newborn babies. The groups most often affected are the young, the elderly, the immunocompromised, and pregnant women [2, 3]. Listeriosis is a major problem because it exhibits a high fatality rate (of up to 30%), requires hospital admission in more than 90% of cases, and has a neonatal death rate of 50% [4]. In 2017, 2480 confirmed cases of invasive listeriosis (0.48 cases per 100,000 population) were reported in the European Union, with a lethality rate of 13.8%, the highest among all foodborne illnesses [5]. In the United States approximately 1600 cases of severe forms of human listeriosis occur each year (with an incidence rate of 0.26 cases per 100,000 population), with a lethality rate of over 16% [6]. Moreover, there is an upward trend in the prevalence of the illness, both in Europe and the United States [5, 7]. The _Listeria_ family is made up of twenty different species [8]. _Listeria monocytogenes_ is the one responsible for the vast majority of cases of human listeriosis, although some cases of human disease caused by _Listeria ivanovii_ and _Listeria sealigeri_ have been described [9, 10]. _L. monocytogenes_ is divided into thirteen different serotypes based on somatic and flagellar antigens, of which three (1/2a, 1/2b, 4b) are responsible for more than 90% of the cases of human illness worldwide [11; 12]. _L. monocytogenes_ can persist for years on equipment and installations in food industry facilities. This is mainly due to its capacity to survive and multiply under food-related conditions that are stressful for other bacteria, such as refrigeration temperatures, drying out, heat, high salt concentrations and extreme pH values, in addition to its ability to form biofilms [13]. Biofilms are structured microbial communities enclosed in a self-produced matrix of hydrated extracellular polymeric substances (EPS) that adhere to an inert or living surface [14]. Cells in biofilms become more resistant than planktonic cells to different environmental stress factors such as sanitizing agents, facilitating bacterial survival. Furthermore, biofilms can be a continuous source of contamination when in contact with foodstuffs, which can trigger human disease [15; 16]. Previous studies have suggested that the physical and chemical properties of the substratum, its surface characteristics, and environmental conditions may alter the structure and composition of bacterial biofilms [17]. _L. monocytogenes_ can form biofilms on a range of surfaces [18], but in most previous research undertaken a single material has been used as a contact surface to study biofilms, most often glass, polystyrene or stainless steel. As far as we are aware, no previous studies have compared the architecture and viability of the biofilms formed by _Listeria_ spp. at refrigeration temperatures on glass, polystyrene, graphene and resin. In general, polystyrene, graphene and resin are considered to be hydrophobic materials, while glass is hydrophilic [17; 19; 20; 21]. Epoxy resins have been widely used for coatings, electronic materials, adhesives, and matrices for fibre-reinforced composites due to their outstanding mechanical properties, strong adhesive capacity, good ability to withstand heat, and high electrical and chemical resistance [22]. However, no previous studies have focused on the ability of pathogenic bacteria such as _Listeria_ spp. to form biofilms on this material. Graphene, regarded as the thinnest material in the world, is a two-dimensional monolayer of carbon atoms tightly packed into a flat hexagonal structure like a honeycomb lattice [23]. Graphene is characterized by both antibacterial activity and low toxicity to human cells [24].