Bioinspired approaches of biomimetic and green chemistry based on graphene to address new challenges in health and environment

Graphene-based nanomaterials exhibit excellent optical, mechanical, and biological properties. They can be used as a substrate in the field of tissue engineering, due to their conductivity, allowing to study and guide neural growth and differentiation, as well as in the role of multimodal platform for nanomedicine applications and sustainable environmental management, taking advantage of their intrinsic nanozyme (enzyme-like) behavior. Here two case studies will be illustrated. The first one is about the very promising features of graphene oxide (GO) in regenerative medicine [1]. The nano-bio interface between the cell membrane and hybrids made of GO nanosheets functionalized with neurotrophin-mimicking peptides was scrutinized to exploit the theranostics (i.e., therapy + imaging/diagnostics) potential for targeting neurodegenerative diseases as well as angiogenesis. Indeed, neurotrophins, crucial for the functioning of the nervous system, are also known to regulate vascularization. The hybrid peptide-GO systems were assembled by spontaneous physisorption onto GO nanosheets of peptide sequences mimicking the Brain-Derived Neurotrophic Factor (BDNF), the NeuroTrophin 3 (NT3) and the Nerve Growth Factor (NGF), respectively. The interaction of peptide-GO nanoplatforms at the bio-interface with artificial cell membranes was analyzed both in 3D and in 2D, by utilizing model phospholipids self-assembled as small unilamellar vesicles (SUVs) or planar-supported lipid bilayers (SLBs), respectively. The experimental studies were paralleled by molecular dynamics (MD) computational analyses. Proof-of-work in vitro cellular experiments with undifferentiated neuroblastoma (SH-SY5Y), neuron-like, differentiated neuroblastoma (dSH-SY5Y), and human umbilical vein endothelial cells (HUVECs) were carried out to shed light on the capability of the pep-GO nanoplatforms to stimulate the neurite outgrowth as well as tubulogenesis and cell migration. The second case study concerns the synthesis, physicochemical and functional characterization of hybrid nanocomposites of 2D GO/palladium nanoparticles (PdNP) [2]. The physicochemical properties were scrutinized by using UV-visible and Raman spectroscopies, atomic force microscopy, zeta-potential and hydrodynamic light scattering. Theoretical DFT calculations paralleled the experimental studies. The GO/Pd hybrids were tested in terms of photocatalysis experiments of H2 evolution and photothermal response. The assessment of nanozyme features for the GO/Pd nanoplatforms unveiled a strong enhancement of hydrogen evolution and broad antioxidant activities, as revealed by photocatalysis experiments of glycerol photoreforming, MitoSOX and SOD-like activity, respectively. This work has been partially funded by the European Union (NextGeneration EU), through the MUR- PNRR project SAMOTHRACE (ECS00000022), the MUR, under Grant PRIN (project code: 2017WBZFHL), and the University of Catania (PIAno di inCEntivi per la RIcerca di Ateneo 2020/2022, Linea di intervento 2 GRABIO).