Zhengzhi Zeng

A facile chemical method to produce superparamagnetic graphene oxide-Fe3O4 hybrid composite and its application in the removal of dyes from aqueous solution

A superparamagnetic graphene oxide–Fe3O4 hybrid composite (GO–Fe3O4) was prepared via a simple and effective chemical method. Amino-functionalized Fe3O4 (NH2-Fe3O4) particles are firmly deposited on the graphene oxide sheets. The graphene oxide sheets could prevent NH2-Fe3O4 particles from agglomeration and enable a good dispersion of these oxide particles. The as-prepared GO–Fe3O4 hybrid composite had a much higher thermal stability than graphene oxide. The amount of NH2-Fe3O4 loaded on GO was estimated to be 23.6 wt% by atomic absorption spectrometry. The specific saturation magnetization (Ms) of the GO–Fe3O4 hybrid composite is 15 emu g−1. The magnetic GO–Fe3O4 composite has been employed as adsorbent for the magnetic separation of dye contaminants from water. The adsorption test of dyes (Methylene Blue (MB) and Neutral Red (NR)) demonstrates that it only takes 30 min for MB and 90 min for NR to attain equilibrium. The adsorption capacities for MB and NR in the concentration range studied are 167.2 and 171.3 mg g−1, respectively. The GO–Fe3O4 hybrid composite can be easily manipulated in magnetic field for desired separation, leading to the removal of dyes from polluted water. These GO–Fe3O4 hybrid composites have great potential applications in removing organic dyes from polluted water.

Spectroscopic studies on the interaction between an anticancer drug ampelopsin and bovine serum albumin

The interaction between bovine serum albumin (BSA) and the anticancer drug molecule ampelopsin (AMP) was investigated using fluorescence spectroscopy, circular dichroism (CD) spectra, and time-resolved spectra under simulated physiological conditions. Fluorescence data showed that the intrinsic fluorescence of BSA was strongly quenched by AMP in terms of a dynamic quenching process. Binding constants and binding sites were calculated. The thermodynamic parameters indicated that the hydrogen bonding and weak van der Waals force played a major role in the interaction. The site marker competitive experiments suggested that the binding site of AMP and BSA was probably located on site III. Based on the Försters theory, the average binding distance between AMP and BSA was obtained (r=5.47nm). The binding of AMP and BSA leaded to conformational changes of BSA according to synchronous fluorescence spectra, CD data and mean fluorescence lifetime values.

Gelatin functionalized graphene oxide for mineralization of hydroxyapatite: biomimetic and in vitro evaluation

We report a facile modification of graphene oxide (GO) by gelatin to mimic charged proteins present in the extracellular matrix during bone formation. The bioinspired surface of GO-gelatin (GO-Gel) composite was used for biomimetic mineralization of hydroxyapatite (HA). A detailed structural and morphological characterization of the mineralized composite was performed. Additionally, MC3T3-E1 cells were cultured on the GO-Gel surfaces to observe various cellular activities and HA mineralization. Higher cellular activities such as cell adhesion, cell proliferation, and alkaline phosphatase activity (ALP) were observed on the GO-Gel surface compared with the GO or glass surface. The increase of ALP confirms that the proposed GO-Gel promotes the osteogenic differentiation of MC3T3-E1 cells. Moreover, the evidence of mineralization evaluated by scanning electron microscopy (SEM) and alizarin red staining (ARS) corroborate the idea that a native osteoid matrix is ultimately deposited. All these data suggest that the GO-Gel hybrids will have great potential as osteogenesis promoting scaffolds for successful application in bone surgery.

Fluorescent graphene oxide composites synthesis and its biocompatibility study

In this research, we developed a “clean” and “wet” route to produce sandwich-like fluorescent CdQ2/GO composites sheets starting from graphene oxide (GO) and Cd2+ in water/ethanol solution in one pot. The as-prepared CdQ2/GO composites sheets were fully characterized by IR, XRD, TEM and TGA analysis. The CdQ2/GO composites exhibited a strong fluorescence emission centered at 500 nm. Both the solid sample and the water dispersion could demonstrate strong green fluorescence. When incubated with Hep G2 cells at 37 °C, the CdQ2/GO composites were found to adhere to the surroundings of the cell membrane, resulting in strong green fluorescence observed by laser confocal fluorescence microscopy. MTT assay experiment results showed that this kind of composite material had low cytotoxicity at the concentration of 400 μg mL−1. We believe this method and composite materials will open up a brand new avenue for wider applications of graphene-based materials in the detection of other types of biomarkers, biomolecular interactions, and fluorescence imaging in vitro and in vivo.

Facile synthesis of Pd-based bimetallic nanocrystals and their application as catalysts for methanol oxidation reaction

We employed an efficient and facile route to synthesise monodisperse Pd-based bimetallic nanocrystals (MPd: M = Cu, Co and Ni) via a controlled co-reduction of Pd(ii) chloride and M(ii) nitrate at 200-230 °C in the presence of oleylamine (OAm). These monodisperse Pd-based nanocrystals have small dimensions, unique structures and homogeneous morphology, thus exhibit efficient catalytic activities for methanol oxidation in alkaline solution, which is much better than commercial Pd/C with same amount of palladium. The catalytic activities of these nanocrystals followed the order of NiPd/C > CoPd/C > CuPd/C > commercial Pd/C, due to the different synergistic effects. Our results show that these Pd-based bimetallic nanocrystals can be promising as practical catalysts for methanol oxidation reactions and other catalytic reactions in further investigations.

Magnetic Fe3O4 nanoparticles coupled with a fluorescent Eu complex for dual imaging applications

Magnetic 8 nm Fe(3)O(4) nanoparticles (NPs) were synthesized and modified with dopamine (DPA) and polyethylene glycol (PEG) diacid. The water soluble Fe(3)O(4)-DPA-PEG NPs were then conjugated with the fluorescent Eu(iii) complex of tris(dibenzoylmethane)-5-amino-1,10-phenanthroline (BMAP), giving an Fe(3)O(4)-DPA-PEG-BMAP-Eu NP conjugate. The conjugate was both colloidally and chemically stable in phosphate buffered solutions and could be used as a probe for magnetic resonance and fluorescent imaging.

Fluorescent magnetic nanoparticles based on a ruthenium complex and Fe3O4

A fluorescent ruthenium (Ru) complex is coupled to magnetic Fe3O4 nanoparticles (NPs) via3-(3,4-dihydroxyphenyl) propanoic acid (DHPPA) and O,O′-bis(2-aminopropyl) polypropylene glycol-block-polyethylene glycol-block-polypropylene glycol (PPG-PEG-PPG-diamine). The resultant Ru–Fe3O4 NP conjugate shows excellent colloidal, photochemical and magnetic stability, and is promising as a dual functional probe for biological imaging applications.