A strong electrostatic MV(2+) -GQD nanocomposite provides an electrolyte-free flexible electrochromic device wih high durability. The positively charged MV(2+) and negatively charged GQD are strongly stabilized by non-covalent intermolecular forces (e.g., electrostatic interactions, π-π stacking interactions, and cation-π electron interactions), eliminating the need for an electrolyte. An electrolyte-free flexible electrochromic device fabricated from the GQD-supported MV(2+) exhibits stable performance under mechanical and thermal stresses.

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This study aimed to demonstrate that curcumin (Cur)-containing graphene composites have high anticancer activity. Specifically, graphene-derivatives were used as nanovectors for the delivery of the hydrophobic anticancer drug Cur based on pH dependence. Different Cur-graphene composites were prepared based on polar interactions between Cur and the number of oxygen-containing functional groups of respective starting materials. The degree of drug-loading was found to be increased by increasing the number of oxygen-containing functional groups in graphene-derivatives. We demonstrated a synergistic effect of Cur-graphene composites on cancer cell death (HCT 116) both in vitro and in vivo. As-prepared graphene quantum dot (GQD)-Cur composites contained the highest amount of Cur nano-particles and exhibited the best anticancer activity compared to the other composites including Cur alone at the same dose. This is the first example of synergistic chemotherapy using GQD-Cur composites simultaneous with superficial bioprobes for tumor imaging.

A band gap tuning of environmental-friendly graphene quantum dot (GQD) becomes a keen interest for novel applications such as photoluminescence (PL) sensor. Here, for tuning the band gap of GQD, a hexafluorohydroxypropanyl benzene (HFHPB) group acted as a receptor of a chemical warfare agent was chemically attached on the GQD via the diazonium coupling reaction of HFHPB diazonium salt, providing new HFHPB-GQD material. With a help of the electron withdrawing HFHPB group, the energy band gap of the HFHPB-GQD was widened and its PL decay life time decreased. As designed, after addition of dimethyl methyl phosphonate (DMMP), the PL intensity of HFHPB-GQD sensor sharply increased up to approximately 200% through a hydrogen bond with DMMP. The fast response and short recovery time was proven by quartz crystal microbalance (QCM) analysis. This HFHPB-GQD sensor shows highly sensitive to DMMP in comparison with GQD sensor without HFHPB and graphene. In addition, the HFHPB-GQD sensor showed high selectivity only to the phosphonate functional group among many other analytes and also stable enough for real device applications. Thus, the tuning of the band gap of the photoluminescent GQDs may open up new promising strategies for the molecular detection of target substrates.