Facile synthesis and optical properties of polymer-laced ZnO-Au hybrid nanoparticles

Photocatalytic Activity of Monosized AuZnO Composite Nanoparticles

Photocatalytic activity of monosized AuZnO composite nanoparticles with different compositions were synthesized by the one-pot polyol procedure, using the triblock copolymer poly(ethylene glycol)-block-poly(propylene glycol)-blockpoly(ethylene glycol) (PEO-PPO-PEO) as the surfactant. The structure and morphology of the composite nanoparticles were analyzed by X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), selected area electron diffraction (SAED), a transmission electron microscope (TEM) and high resolution transmission electron microscopy (HRTEM). The characterization showed that the AuZnO composite nanoparticles were spherical, with narrow particle size distribution and high crystallinity. The Fourier transform infrared spectroscopy (FTIR) study confirms the PEO-PPO-PEO molecules on the surface of the composite nanoparticles. The investigations by ultraviolet-visible light absorbance spectrometer (UV-Vis) and photoluminescence spectrophotometer (PL) demonstrate well the dispersibility and excellent optical performance of the AuZnO composite nanoparticles. Photocatalytic activity and reusability of the AuZnO nanoparticles in UV and visible light regions was evaluated by the photocatalytic degradation of Rhodamine B (RhB). The experimental results show that the AuZnO composite nanoparticles with a suitable amount of Au loading have stability and improved photocatalytic activity. AuZnO composite nanoparticles are effective and stable for the degradation of organic pollutants in aqueous solution.

Thickness Dependent Nanostructural, Morphological, Optical and Impedometric Analyses of Zinc Oxide-Gold Hybrids: Nanoparticle to Thin Film

The creation of an appropriate thin film is important for the development of novel sensing surfaces, which will ultimately enhance the properties and output of high-performance sensors. In this study, we have fabricated and characterized zinc oxide (ZnO) thin films on silicon substrates, which were hybridized with gold nanoparticles (AuNPs) to obtain ZnO-Au_x (x = 10, 20, 30, 40 and 50 nm) hybrid structures with different thicknesses. Nanoscale imaging by field emission scanning electron microscopy revealed increasing film uniformity and coverage with the Au deposition thickness. Transmission electron microscopy analysis indicated that the AuNPs exhibit an increasing average diameter (5–10 nm). The face center cubic Au were found to co-exist with wurtzite ZnO nanostructure. Atomic force microscopy observations revealed that as the Au content increased, the overall crystallite size increased, which was supported by X-ray diffraction measurements. The structural characterizations indicated that the Au on the ZnO crystal lattice exists without any impurities in a preferred orientation (002). When the ZnO thickness increased from 10 to 40 nm, transmittance and an optical bandgap value decreased. Interestingly, with 50 nm thickness, the band gap value was increased, which might be due to the Burstein-Moss effect. Photoluminescence studies revealed that the overall structural defect (green emission) improved significantly as the Au deposition increased. The impedance measurements shows a decreasing value of impedance arc with increasing Au thicknesses (0 to 40 nm). In contrast, the 50 nm AuNP impedance arc shows an increased value compared to lower sputtering thicknesses, which indicated the presence of larger sized AuNPs that form a continuous film, and its ohmic characteristics changed to rectifying characteristics. This improved hybrid thin film (ZnO/Au) is suitable for a wide range of sensing applications.

Synthesis of bi-phase dispersible core-shell FeAu@ZnO magneto-opto-fluorescent nanoparticles

Bi-phase dispersible core-shell FeAu@ZnO magneto-opto-fluorescent nanoparticles were synthesized by a modified nanoemulsion process using poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-PPO-PEO) as the surfactant. The morphology and crystal structure of the nanoparticles were studied by TEM/HRTEM and XRD. The nanoparticles manifest soft ferromagnetic and/or near superparamagnetic behavior with a small coercivity of ~19 Oe at room temperature. The corresponding magnetic hysteresis curves were elucidated by the modified Langevin equation. The FTIR study confirms the PEO-PPO-PEO molecules on the surface of the nanoparticles. The UV-vis and PL results reveal the well-behaved absorption bands including surface plasmon resonance and multiple visible fingerprint photoluminescent emissions of the nanoparticles dispersed in both hydrophilic and hydrophobic solvents. Moreover, the processes of solvent dispersion-collection of the nanoparticles were demonstrated for application readiness of such core-shell nanostructures.

Targeted photosensitizer nanoconjugates based on human serum albumin selectively kill tumor cells upon photo-irradiation

Small and non-toxic nanoconjugates RGD–HSA–Ce6 could provide targeted and effective photodynamic therapy of tumor cells.