Leading-edge regenerative medicine can take advantage of improved knowledge of key roles played, both in stem cell fate determination and in cell growth/differentiation, by mechano-transduction and other physicochemical stimuli from the tissue environment. This prompted advanced nanomaterials research to provide tissue engineers with next-generation scaffolds consisting of smart nanocomposites and/or hydrogels with nanofillers, where balanced combinations of specific matrices and nanomaterials can mediate and finely tune such stimuli and cues. In this review, we focus on graphene-based nanomaterials as, in addition to modulating nanotopography, elastic modulus and viscoelastic features of the scaffold, they can also regulate its conductivity. This feature is crucial to the determination and differentiation of some cell lineages and is of special interest to neural regenerative medicine. Hereafter we depict relevant properties of such nanofillers, illustrate how problems related to their eventual cytotoxicity are solved via enhanced synthesis, purification and derivatization protocols, and finally provide examples of successful applications in regenerative medicine on a number of tissues.

Carbon nanomaterials are promising adsorbents for dye removal from wastewater also due to their possible surface functionalization that, in principle, can increase the adsorption rate and provide regeneration. To investigate the real advantages of functionalization, we synthesized and characterized through IR, TGA, TEM, XPS and DLS measurements a multi-walled carbon nanotube (MWCNT) derivative bearing benzenesulfonate groups (MWCNT-S). The obtained material demonstrated to have good dispersibility in water and better capability to adsorb methylene blue (MB) compared to the pristine MWCNT adsorbent. Adsorption kinetic studies showed a very fast process, with a constant significantly higher with respect not only to that of the unfunctionalized MWCNT adsorbent but also to those of widely used activated carbons. Moreover, the adsorption capacity of MWCNT-S is more than doubled with respect to that of the insoluble pristine MWCNT adsorbent, thanks to the dispersibility of the derivatives, providing a larger available surface, and to the possible electrostatic interactions between the cationic MB and the anionic sulfonate groups. Additionally, the reversibility of ionic interactions disclosed the possibility to release the adsorbed cationic pollutant through competition with salts, not only regenerating the adsorbent, but also recovering the dye. Indeed, by treating the adsorbed material for 1 h with 1 M NaCl, a regeneration capacity of 75% was obtained, demonstrating the validity of this strategy.

Carbon-based nanomaterials are increasingly investigated for water purification due to their high surface area, tunable reactivity, and versatile adsorption mechanisms. Among them, graphene and its derivatives have demonstrated superior performance over activated carbon and carbon nanotubes, although their use is often hindered by sheet aggregation and limited dispersibility. In this work, we report the synthesis and characterization of a sulfonated reduced graphene oxide derivative (rGO-S), obtained through a diazotization reaction with sodium sulfanilate. The covalent introduction of benzenesulfonate groups was confirmed by TEM, EDX, XPS, FTIR, and TGA, revealing a homogeneous functionalization and enhanced water dispersibility (0.49 mg/mL). rGO-S exhibited a highly negative zeta potential (−45.3 mV), preventing aggregation and increasing the number of accessible adsorption sites. Using methylene blue (MB) as a model cationic pollutant, adsorption studies demonstrated remarkable performance: equilibrium was reached in less than one minute, with kinetics best described by a pseudo-second-order model and a two-fold increase in adsorption capacity (326 mg/g) compared to pristine rGO. Moreover, rGO-S displayed efficient regeneration through ion-exchange with NaCl solutions, achieving up to 92% desorption in multiple cycles, in combination with ethanol, while maintaining stable adsorption capacity upon reuse. Selectivity tests against a mixture of dyes confirmed the preferential uptake of MB, highlighting the role of electrostatic interactions with sulfonate groups. Overall, the sulfonated graphene derivative combines fast kinetics, good efficiency, selectivity, and reusability, providing promising perspectives for scalable water treatment applications and pollutant recovery within a circular economy framework.