Novel plasma-based technologies that offer maximum efficiency at minimal environmental costs are expected to further promote the sustainable societal and economic development. Unique transfer of chemical reactivity and energy from gaseous plasmas to water takes place in the absence of any other chemicals, but results in a product with a notable transient broad-spectrum biological activity, referred to as plasma-activated water (PAW). These features make PAW a green prospective solution for a wide range of biotechnology applications, from water purification to biomedicine. Here, we present a succinct review of how novel, efficient methods based on non-equilibrium reactive plasma chemistries can be applied to low-cost natural water sources to produce a prospective product with a wide range of applications while at the same time minimising the process steps and dramatically reducing the use of expensive and/or hazardous reagents. Despite the recent exciting developments in this field, there presently is no topical review which specifically focuses on the underlying physics and chemistry related to plasma-activated water. We focus specifically on the PAW generation, origin of reactive species present in PAW, its related analytical chemistry and potentially different mechanisms that regulate the bio-activities of PAW in different biotech-applications and their roles in determining PAW efficacy and selectivity. We then review recent advances in our understanding of plasma-water interactions, briefly outlining current and proposed applications of PAW in agriculture, food and biomedicine. Finally, we outline future research directions and challenges that may hinder translation of these technologies into real-life applications. Overall, this review will provide much needed insights into the fundamental aspects of PAW chemistry required for optimization of the biochemical activity of PAW and translation of this environment- and human-health-friendly, and energy-efficient strategy into real life applications.

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Dengue virus (DENV) has become a global health threat with about half of the world’s population at risk of infection. Although the disease caused by DENV is self-limiting in the first infection, the antibody-dependent enhancement (ADE) effect increases the mortality in the second infection with a heterotypic virus. Since there is no specific efficient medicine in treatment, it is urgent to develop vaccines to prevent infection and disease progression. Currently, only a live attenuated vaccine, chimeric yellow fever 17D—tetravalent dengue vaccine (CYD-TDV), has been licensed for clinical use in some countries, and many candidate vaccines are still under research and development. This review discusses the progress, strengths, and weaknesses of the five types of vaccines including live attenuated vaccine, inactivated virus vaccine, recombinant subunit vaccine, viral vectored vaccine, and DNA vaccine.

Multiwall carbon nanotubes were dispersed in Nafion (MWCNTs-NA) solution and used in combination with bismuth (MWCNTs-NA/Bi) for fabricating composite sensors to determine trace Pb(II) and Cd(II) by differential pulse anodic stripping voltammetry (DPASV). The electrochemical properties of the MWCNTs-NA/Bi composites film modified glassy carbon electrode (GCE) were evaluated. The synergistic effect of MWCNTs and bismuth composite film was obtained for Pb(II) and Cd(II) detection with improved sensitivity and reproducibility. Linear calibration curves ranged from 0.05 to 100 mg/L for Pb(II) and 0.08 to 100 mg/L for Cd(II). The determination limits (S/N ¼ 3) were 25 ng/L for Pb and 40 ng/L for Cd, which compared favorably with previously reported methods in the area of electrochemical Pb(II) and Cd(II) detection. The MWCNTs-NA/Bi composite film electrodes were successfully applied to determine Pb(II) and Cd(II) in real sample, and the results of the present method agreed well with those of atomic absorption spectroscopy.

The propagation behavior of cold atmospheric pressure plasma jets has recently attracted lots of attention. In this paper, a cold He plasma jet generated by a single plasma electrode jet device is studied. The spatial-temporal resolved optical emission spectroscopy measurements are presented. It is found that the emission intensity of the He 706.5 nm line of the plasma behaves similarly both inside the syringe and in the surrounding air (plasma plume). It decreases monotonously, which is different from the emission lines, such as N2 337.1 nm line, N2+ 391.4 nm line, and O 777.3 nm line. For the discharge inside the syringe, the emission intensity of the He 706.5 nm line decays more rapidly than that of the other three spectral lines mentioned above. The N2 337.1 nm line behaves a similar time evolution with the discharge current. For the N2+ 391.4 nm line and the atomic O 777.3 nm line, both of them decay slower than that of the He 706.5 nm and the N2 337.1 nm. When the plasma plume propagates further away from the nozzle, the temporal behaviors of the emission intensities of the four lines tend to be similar gradually. Besides, it is found that, when the size of the plasma bullet appears biggest, the propagation velocity of the bullet achieves its highest value while the emission intensity of the N2+ 391.4 nm line reaches its maximum. Detailed analysis shows that the Penning effect between the metastable state Hem and the air molecules may play a significant role in the propagation of the plasma bullet in the open air.

Cold atmospheric-pressure plasma plumes are generated in the ambient air by a single-electrode plasma jet device powered by pulsed dc and ac sine-wave excitation sources. Comprehensive comparisons of the plasma characteristics, including electrical properties, optical emission spectra, gas temperatures, plasma dynamics, and bacterial inactivation ability of the two plasmas are carried out. It is shown that the dc pulse excited plasma features a much larger discharge current and stronger optical emission than the sine-wave excited plasma. The gas temperature in the former discharge remains very close to the room temperature across the entire plume length; the sine-wave driven discharge also shows a uniform temperature profile, which is 20–30 degrees higher than the room temperature. The dc pulse excited plasma also shows a better performance in the inactivation of gram-positive staphylococcus aureus bacteria. These results suggest that the pulsed dc electric field is more effective for the generation of nonequilibrium atmospheric pressure plasma plumes for advanced plasma health care applications.