## 1 Introduction  
Carbon-based nanomaterials (CBNs) are very promising functional materials with many advanced biomedical applications, including medical imaging and nanotnerqutics [1, 2, 3]. In fact, CBNs have been recently proposed as next-generation antimicrobials to combat infectious diseases such as the current Coronavirus disease 2019 (COVID-19) because they have unique biological properties such as antimicrobial activity against a broad range of microorganisms, the capacity of inducing tissue regeneration, and low risk of antimicrobial resistance [4]. The antimicrobial mechanism of CBNs is usually attributed to a combination of physical and chemical processes such as membrane structure disruption, microorganism entrapment, electron transfer, and/or oxidative stress by the action of reactive oxygen species (ROS) [5]. Moreover, they possess many other excellent physical and biological properties such as high thermal and electrical conductivity, excellent mechanical performance, immunomodulatory potential and can be combined with stem cellsin regenerative medicine [4; 6; 7; 8; 9; 10]. CBNs are a broad class of materials that involve single layer graphene, few-layer composed of 2-5 layers of graphene sheets packed together, and multi-layer graphene (2-10 layers), also called graphene nanoplatelets (GNPs) [11]. All these types of CBNs can also be produced in their oxidized form and have shown many different biological properties in terms of cytotoxicity, proliferative activity, and capacity of up-regulating genes in human keratinocytes HaCaT cells. Thus, CBNs such as few-layer graphene have shown to be less cytotoxic than few-layer graphene oxide (GO) in HaCaT cells [12]. Other CBNs in their oxidized form such as multi-layer GO, which contain hydroxyl (-OH), carboxyl (-COOH) and epoxy (-O-C) groups on the basal planes and at the edges of the GO nanosheets, has shown to be much more cytotoxic than few-layer GO, which has shown very weak cytotoxicity in a broad range of cell lines, including glioma and human skin HaCaT cells [13]. Furthermore, few-layer GO have shown anti-proliferative effects in several cell lines including the HaCaT cell line in contrast to multi-layer GO, which showed similar proliferative activity to an epidermal growth factor (EGF) [13]. In that study, multi-layer GO showed to be able to up-regulate four genes (_CAT, TGFB1, FN1,_ and _CDH1_) that are relevant in biomedicine [13]. Another CBN in the form of carbon filamentous hollow materials has recently been shown to be capable of up-regulating many more genes than other types of nanomaterials, silver nanoparticles, and thus showing the great potential of CBNs in the biomedical field [14].  
GNPs have shown excellent physical and biological properties such as antimicrobial activity [15; 16]. Despite the promising advantages of GNPs in the biomedical field, nanoscale materials may also present a potential hazard to human health, requiring extensive investigation into their in vitro and in vivo toxicity to guarantee safe use of this emerging nanotechnology. Thus, in this study, we analyze the cytotoxicity, proliferative activity, and the effect of GNPs on the expression of thirteen genes (_SODI, CAT, MMP1, TGFB1, GPX1, FN1, HAS2, LAMB1, LUM, CDH1, COLA1, FBN_, and VCAN_) in human keratinocytes HaCaT cells. These genes were chosen because they are highly associated with biochemical processes, including oxidative stress, extracellular matrix regulation, and the synthesis of proteins to maintain and repair tissues, which can provide valuable information to know the potential use of these CNBs in biomedical applications such as wound healing and skin tissue engineering. Furthermore, the toxicity of this advanced technology will be evaluated using the nematode _Caenorhabditis elegans_ in vivo model, which is a well-establish animal model with digestive, reproductive, endocrine, sensory and neuromuscular systems frequently used to study human development and disease [17; 18].