Fabrication of ZnO Nanobrushes by H2-C2H2 Plasma Etching for H2 Sensing Applications.

Zinc oxide has widespread use in diverse applications due to its distinct properties. Many of these applications benefit from controlling the morphology on the nanoscale, where for example gas sensing is strongly enhanced for high surface-to-volume ratios. In this work the formation of novel ZnO nanobrushes by plasma etching treatment as a new approach is presented. The morphology and structure of the ZnO nanobrushes are studied in detail by transmission and scanning electron microscopy. It is revealed that ZnO nanobrush structures are fabricated by self-patterned preferential etching of ZnO microtetrapods in a hydrogen-acetylene plasma. The etching process was found to be most effective at 1% C2H2 admixture. Nanowire arrays are formed enabled by sidewall passivation due to a-C:H deposition. The nanobrush structures are further stabilized by simultaneous deposition of a SiOx layer from the opposite direction. Highly sensitive (gas response S = 148), selective, and fast (response time 15 s, recovery time 6 s) hydrogen sensors are fabricated from single nanobrushes. Single nanobrush sensors show enhanced sensing performance in increased gas response S of at least 10 times and improved response as well as recovery times when compared to nonporous single ZnO nanorod sensors due to the small diameters (≈50 nm) of the formed nanowires as well as the strongly enhanced surface-to-volume ratio of the nanobrushes by a factor of more than 10.

In vitro proinflammatory gene expression changes in human whole blood after contact with plasma-treated implant surfaces.

BACKGROUND: The aim of this in vitro study was to identify changes in gene expression of proinflammatory cytokines in human whole blood after contact with titanium implant surfaces after plasma treatment. MATERIALS AND METHODS: Grade 4 titanium dental implants were conditioned with low-pressure plasma (LPP) and atmospheric-pressure plasma (APP) and submerged in human whole blood in vitro. Unconditioned implants and blood samples without implants served as control and negative control groups, respectively. Sampling was performed at 1, 8, and 24 h. Changes in mRNA expression levels of interleukin 1-beta (IL1-ß) and tumor necrosis factor-alpha (TNF-α) were assessed using RT-qPCR. RESULTS: In the control group, significant increases in IL1-ß and TNF-α expression were observed. Significant decreases in the expression of IL1-ß and TNF-α were identified in blood with implants after plasma treatment. CONCLUSION: Differences in gene expression of proinflammatory cytokines after incubation of plasma-conditioned titanium implants can be assessed using human whole blood. The results of the present study indicate that plasma treatment (APP and LPP) of titanium dental implants leads to downregulation of proinflammatory cytokine gene expression, which might be beneficial in early osseointegration.