Dye-containing wastewater is one of the major issues in water contamination, and its treatment remains a serious problem due to the low concentrations of dyes in polluted natural water and high cost for purification. Herein, we report the application of graphene oxides (GO) in the decontamination of ppm levels of methylene blue (MB) in an aqueous solution. During the dye removal process, GO adsorbs MB molecules via strong interactions including π–π stacking and electrostatic attraction, and facilitates the precipitation of GO/MB complexes, which can be readily removed from the solution. The adsorption progress follows the Langmuir isotherm model and the pseudo-second-order kinetic model. The thermodynamic parameters indicate that the adsorption progress is a spontaneous progress. By using our strategy, a dye removal rate as high as 95% has been achieved with a final dye concentration of only 0.25 ppm. In addition, 82% of the dye can be recycled through ethanol extraction from the collected GO/MB complexes. All the results demonstrate that GO nanosheets can effectively remove and recover ppm levels of cationic dye pollutants, represented by MB, showing the promising application of GO in ultra-low concentration dye containing wastewater treatment.

Although gold nanorods (GNRs) have been investigated extensively for optical hyperthermia therapies, the synthesis of rods is far from ideal. In this report, we optimized the synthesis of gold nanorods using hydroquinone as a reducing agent. Compared with the GNRs prepared by traditional ways, the as-synthesized rods have a flexibly tunable size and wider range of longitudinal surface plasmon resonance (LSPR). Furthermore, a series of small-length gold nanorods with length ranging from 30 to 90 nm were synthesized and they are more suitable for in vivo biomedical applications. Finally, we exploited a convenient approach for preparing water-soluble GNRs with less toxicity, better dispersion and flexible functionalization by exchanging hexadecyltrimethylammonium bromide (CTAB) on the surface of the rods with carboxylated bovine serum albumin (BSA) derivative, the BSA modified GNRs showed significant anticancer efficacy through near infrared (NIR) hyperthermia. We believe that the as-prepared gold nanorods will find promising applications in biomedical fields, especially in cancer therapy.