We report the first pyrrole-ring surface-functionalized graphene quantum dots (p-GQDs) prepared by a two-step hydrothermal approach under microwave irradiation in an ammonia medium. The most distinct feature of the functionalized GQDs is that both the excitation and emission wavelengths fall into the visible-light region. The p-GQDs are excited by visible light at λ_ex 490 nm (2.53 eV) to emit excitation-independent photoluminescence at a maximum wavelength of λ_em 550 nm. This is thus far the longest emission wavelength reported for GQDs. Stable photoluminescence is achieved at pH 4–10 with an ionic strength of 1.2 mol L⁻¹ KCl. These features make the p-GQDs excellent probes for bio-imaging and bio-labeling, which is demonstrated by imaging live HeLa cells.

A novel adsorbent was developed by coating yttrium hydroxide precipitate layer on cellulose fibre. This material takes up ca. 98% of 5 µg·L⁻¹ As(III) and As(V) at low pH (pH<7), while a favorable selectivity for As(V) was achieved within pH 11–12. In practice, a mini-column packed with Y(OH)₃ precipitate layer coated cellulose fibre particles was incorporated into a sequential injection system for selective uptake of arsenate at pH 11.5. The retained arsenate was afterwards recovered with 50 µL of 0.8 mol·L⁻¹ NaOH solution as eluent, followed by hydride generation in a reaction medium of 2.0 mol·L⁻¹ HCl and 1.0% NaBH₄ solution (W/V, in 0.5% NaOH) after pre-reduction of arsenate to arsenite by KI-ascorbic acid (5%, W/V), with detection by atomic fluorescence spectrometry. Total inorganic arsenic was quantitatively taken up at pH 6.0 by following the same procedure and arsenic speciation was performed by difference. With a sample volume of 1.0 mL, an enrichment factor of 16.4 was derived with a detection limit of 17 ng·L⁻¹ within a linear range of 0.05–2.0 µg·L⁻¹. A relative standard deviation (RSD) of 2.6% (0.5 µg·L⁻¹, n=11) was achieved. The procedure was validated by analyzing arsenic in a certified reference material GBW 09101 (human hair), and speciation of inorganic arsenic in natural water samples. The entire process requires no organic solvents, thus Y(OH)₃ coated cellulose fibre provides a green adsorbent.

WO₃ nanoparticles loaded in TiO₂ nanotube arrays, fabricated by a chemical bath deposition (CBD) technique in combination with a pyrolysis process, is uniform and the diameter can be easily adjusted by the deposition times. The resultant hybrid nanotubes array shows a multistage coloring electrochromic response at different potential bias. The formation of a 3-dimensional WO₃/TiO₂ junction promotes unidirectional charge transport due to the one-dimensional features of the tubes, which leads to the significant positive-shift onset potential of the cathodic reaction (ion insertion) and the highly increased proton storage capacity. Compared to non-decorated nanotube arrays, the enhanced electrochromic properties of longer lifetime, higher contrast ratio (bleaching time/coloration time), and improved tailored electrochromic behavior could be achieved using the composite films.

Graphene oxide (GO) nanosheets have been immobilized onto SiO₂ particles through electrostatic interactions by surface assembly. The surface-assembled composite material was characterized by means of SEM and FTIR and UV/Vis spectroscopy to reveal an assembling ratio of 2.3 % (w/w, GO/SiO₂). The GO/SiO₂ composites were subsequently used, for the first time, as adsorbents for the adsorption/isolation of proteins. Selective isolation of proteins of interest, namely, hemoglobin (Hb) in this case, from complex sample matrices, for example, human whole blood, could be obtained by carefully manipulating the adsorption/desorption process. At pH 7, an adsorption of 85 % was achieved for Hb (70 mg L⁻¹) in sample solution (1.0 mL) by the GO/SiO₂ composites (3.0 mg). The adsorption behavior was consistent with the Langmuir adsorption model, corresponding to a theoretical adsorption capacity of 50.5 mg g⁻¹ for Hb. The retained Hb could be readily recovered by using a Tris-HCl buffer at pH 8.9 to give a recovery of 80 %. Circular dichroism and specific activity investigations indicated that the GO/SiO₂ composites exhibited favorable biocompatibility, characterized by virtually no effect on the conformation and activity of Hb after adsorption/desorption. The composites were used for the selective isolation of Hb from human whole blood and achieved satisfactory results by assaying with sodium dodecyl sulfate polyacrylamide gel electrophoresis.