Biocompatible 2D Material Inks Enabled by Supramolecular Chemistry: From Synthesis to Applications

ConspectusThe emergence of two-dimensional (2D) materials, such as graphene, transition-metal dichalcogenides (TMDs), and hexagonal boron nitride (h-BN), has sparked significant interest due to their unique physicochemical, optical, electrical, and mechanical properties. Furthermore, their atomically thin nature enables mechanical flexibility, high sensitivity, and simple integration onto flexible substrates, such as paper and plastic.The surface chemistry of a nanomaterial determines many of its properties, such as its chemical and catalytic activity. The electronic properties can also be modified by surface chemistry through changes in charge transfer or by the presence of surface states. Surface defects and functional groups can act as trap sites for excitons, hence affecting the optical properties. Furthermore, surface chemistry determines the stability and dispersibility of nanomaterials in colloidal dispersions as well as their biocompatibility and toxicity. In addition, the surface chemistry dictates how nanomaterials interact with biological systems, influencing cellular uptake, immune response, and biodistribution, to name a few examples. It is, therefore, crucial to be able to produce 2D materials with tunable surface chemistry to match target applications.Because of their dimensionality, 2D materials can be easily functionalized with noncovalent and covalent approaches. This review delves into the role of supramolecular chemistry, which is based on noncovalent interactions, in achieving stable and highly concentrated water-based dispersions of 2D materials with specific surface chemistry.In particular, we provide an overview of the recent progress made by our group in the field of solution-processed 2D materials produced by liquid-phase exfoliation with pyrene derivatives used as supramolecular receptors. We highlight the relationship between the structure of the pyrene derivative stabilizer and the concentration, stability, and lateral size and thickness distributions of the produced nanosheets. Subsequently, we give a short overview of the applications enabled by the supramolecular approach in printed electronics, sensing, bioelectronics, and in the biomedical field. We show that the careful design of the pyrene derivative enables us to achieve excellent stability of the material in the cellular medium, which is essential to accurately assess biological effects. We also highlight seminal case studies on the use of cationic graphene in the therapeutics of lysosomal storage disorders, and on the use of TMD nanosheets for trained immunity and as immune-compatible nanoplatforms, traceable at the single-cell and tissue (suborgan) levels.This Account aims to provide a comprehensive guide for readers on the potential of the supramolecular approach for the design of 2D material dispersions with tailored surface chemistry. This approach is expected to be extremely attractive for many applications, from tissue engineering to energy storage devices, so we hope that this Account will drive further efforts and advancements in this field by ultimately leading to the integration of solution-processed 2D materials made by supramolecular chemistry into practical applications.