Functional graphene nanomaterials (FGNs) are fast emerging materials with extremely unique physical and chemical properties and physiological ability to interfere and/or interact with bioorganisms; as a result, FGNs present manifold possibilities for diverse biological applications. Beyond their use in drug/gene delivery, phototherapy, and bioimaging, recent studies have revealed that FGNs can significantly promote interfacial biointeractions, in particular, with proteins, mammalian cells/stem cells, and microbials. FGNs can adsorb and concentrate nutrition factors including proteins from physiological media. This accelerates the formation of extracellular matrix, which eventually promotes cell colonization by providing a more beneficial microenvironment for cell adhesion and growth. Furthermore, FGNs can also interact with cocultured cells by physical or chemical stimulation, which significantly mediate their cellular signaling and biological performance. In this review, we elucidate FGNs-bioorganism interactions and summarize recent advancements on designing FGN-based two-dimensional and three-dimensional architectures as multifunctional biological platforms. We have also discussed the representative biological applications regarding these FGN-based bioactive architectures. Furthermore, the future perspectives and emerging challenges will also be highlighted. Due to the lack of comprehensive reviews in this emerging field, this review may catch great interest and inspire many new opportunities across a broad range of disciplines.

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A green and facile method for preparing biopolymer functionalized reduced graphene oxide (RGO) by using mussel inspired dopamine (DA) as the reducing reagent and the functionalized molecule is proposed. In the study, GO is reduced by DA and DA is adhered to RGO by one-step pH-induced polymerization of DA (polydopamine, PDA), and then heparin or protein is grafted onto the PDA adhered RGO (pRGO) through catechol chemistry. The obtained pRGO, heparin grafted pRGO (Hep-g-pRGO), and BSA grafted pRGO (BSA-g-pRGO) exhibit fine 2D morphology and excellent stability in water and PBS solution. Furthermore, the biocompatibility of the biopolymer functionalized RGO are investigated using human blood cells and human umbilical vein endothelial cells (HUVECs). The biopolymer functionalized RGO exhibits an ultralow hemolysis ratio (lower than 1.8%), and the cellular toxicity assay suggests that the biopolymer functionalized RGO has good cytocompatibility for HUVEC cells, even at a high concentration of 100 mg mL À1 . Moreover, the high anticoagulant ability of Hep-g-pRGO indicates that the grafted biopolymer could maintain its biological activity after immobilization onto the surface of pRGO. Therefore, the proposed safe and green biomimetic method confers the biopolymer functionalized RGO with great potential for various biological and biomedical applications.

Carbon-based materials are considered to be active for electrochemical oxygen reduction reaction (ORR) to hydrogen peroxide (H2O2) production. Nevertheless, less attention is paid to the investigation of the influence of in-plane carbon lattice defect on the catalytic activity and selectivity toward ORR. In the present work, graphene precursors were prepared from oxo-functionalized graphene (oxo-G) and graphene oxide (GO) with H2O2 hydrothermal treatment, respectively. Statistical Raman spectroscopy (SRS) analysis demonstrated the increased in-plane carbon lattice defect density in the order of oxo-G, oxo-G/H2O2, GO, GO/H2O2. Furthermore, nitrogen-doped graphene materials were prepared through ammonium hydroxide hydrothermal treatment of those graphene precursors. Rotating ring-disk electrode (RRDE) results indicate that the nitrogen-doped graphene derived from oxo-G with lowest in-plane carbon lattice defects exhibited the highest H2O2 selectivity of >82% in 0.1 M KOH. Moreover, a high H2O2 production rate of 224.8 mmol gcatalyst –1 h–1 could be achieved at 0.2 VRHE in H-cell with faradaic efficiency of >43.6%. Our work provides insights for the design and synthesis of carbon-based electrocatalysts for H2O2 production.

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