Optical and bio-sensing characteristics of ZnO nanotubes grown by hydrothermal method

Nano-Al2O3 can mediate transduction-like transformation of antibiotic resistance genes in water

The prevalence of various antibiotic resistance genes (ARGs) and resistant bacteria has caused global public health risks. The carrier transport mediated by phages or membrane vesicles is an important way for horizontal transfer of ARGs. Nano metal oxide particles (NMOPs), which can enter cell through the cell membrane, may be used as the carriers of genes. However, whether they can be used as transmembrane delivery vectors for the horizontal ARG transfer remains unknown. Here, we set up a model of MONPs-mediated transfer of ARGs, and demonstrate that NMOPs, especially for nano-Al₂O₃, can act as carriers mediating the transduction-like ARG transformation in water. The highest transfer rate mediated by nano-Al₂O₃ is 4.53 × 10⁴ cfu/mmol, and it is 10⁴ times higher than that of control. Nano-Al₂O₃ can combine with plasmid coding for ARGs to form high-density package and prevent ARGs from degradation by endonuclease. The results of superresolution fluorescence microscopy and transmission electron microscopy show that nano-Al₂O₃ can carry ARGs for transmembrane transport. Genome-wide transcription microarray and qPCR indicate that SOS response was closely related to transduction-like ARG transformation mediated by nano-Al₂O₃. This study is the first to demonstrate that as a new transmembrane carrier, nano-Al₂O₃ can also cause ARGs diffusion in water.

Flower-Like ZnO Nanorods Synthesized by Microwave-Assisted One-Pot Method for Detecting Reducing Gases: Structural Properties and Sensing Reversibility

In this work, flower-like ZnO nanorods (NRs) were successfully prepared using microwave-assisted techniques at a low temperature. The synthesized NRs exhibited a smooth surface and good crystal structure phase of ZnO. The sharp peak of the XRD and Raman spectrum confirmed the high crystallinity of these ZnO NRs with a pure wurtzite structure. The nanorods were ~2 μm in length and ~150 nm in diameter, respectively. The electron diffraction pattern confirmed that the single crystal ZnO nanorods aligned along the [001] plane. The NRs were applied to fabricate a gas sensor for reducing gases such as CH4, CO, and H2. The sensor showed a good performance and sensitivity toward the target gases. However, its response toward CH4 and CO was higher compared to H2 gas. Although the operating temperature was varied from room temperature (RT) up to 350°C, the sensor did not show a response toward any of the target gases in the range of RT-150°C, but dramatic enhancement of the sensor response was observed at 200°C, and up to higher temperatures. This behavior was ascribed to the activity of the smooth surface and the reactivity of surface oxygen species with the targeted gases. The sensor response was measured at various gas concentrations, where the calibration curve was shown. The gas sensing mechanism was described in terms of the reaction of the gases with the transformed oxygen species on the surface of the oxides.

CdS-decorated ZnO nanorod heterostructures for improved hybrid photovoltaic devices

Cadmium sulfide (CdS)-decorated zinc oxide (ZnO) nanorod heterostructures have been grown by a combination of hydrothermal and pulsed laser deposition techniques. Hybrid photovoltaic devices have been fabricated with CdS modified and unmodified ZnO nanorods blended separately with regioregular poly(3-hexylthiophene) (P3HT) polymer as the active layer. The solar cell performance has been studied as a function of ZnO concentration and the casting solvent (chlorobenzene, chloroform, and toluene) in the unmodified ZnO:P3HT devices. The power conversion efficiency is found to be enhanced with the increase of ZnO concentration up to a certain limit, and decreases at a very high concentration. The surface modification of ZnO nanorods with CdS leads to an increase in the open circuit voltage and short-circuit current, with enhanced efficiency by 300% over the unmodified ZnO:P3HT device, because of the cascaded band structure favoring charge transfer to the external circuit.