Degradation and toxicity of bisphenol A and S during cold atmospheric pressure plasma treatment.

Bisphenols are widely recognised as toxic compounds that potentially threaten the environment and public health. Here we report the use of cold atmospheric pressure plasma (CAP) to remove bisphenol A (BPA) and bisphenol S (BPS) from aqueous systems. Additionally, methanol was added as a radical scavenger to simulate environmental conditions. After 480 s of plasma treatment, 15-25 % of BPA remained, compared to > 80 % of BPS, with BPA being removed faster (-kt = 3.4 ms-1, half-life = 210 s) than BPS (-kt = 0.15 ms-1, half-life 4700 s). The characterisation of plasma species showed that adding a radical scavenger affects the formation of reactive oxygen and nitrogen species, resulting in a lower amount of ˙OH, H2O2, and NO2- but a similar amount of NO3-. In addition, a non-target approach enabled the elucidation of 11 BPA and five BPS transformation products. From this data, transformation pathways were proposed for both compounds, indicating nitrification with further cleavage, demethylation, and carboxylation, and the coupling of smaller bisphenol intermediates. The toxicological characterisation of the in vitro HepG2 cell model has shown that the mixture of transformation products formed during CAP is less toxic than BPA and BPS, indicating that CAP is effective in safely degrading bisphenols.

Degradation of bisphenol A and S in wastewater during cold atmospheric pressure plasma treatment.

Developing novel, fast and efficient ecologically benign processes for removing organic contaminants is important for the continued development of water treatment. For this reason, this study investigates the implementation of Cold Atmospheric pressure Plasma (CAP) generated in ambient air as an efficient tool for the removal of Bisphenol A (BPA) and Bisphenol S (BPS)-known endocrine disrupting compounds in water and wastewater, by monitoring degradation kinetics and its transformation products. The highest removal efficiencies of BPA (>98%) and BPS (>70%) were obtained after 480 s of CAP exposure. A pseudo-first-order kinetic revealed that BPA (-kt = 4.4 ̶ 9.0 ms-1) degrades faster than BPS (-kt = 0.4 ̶ 2.4 ms-1) and that the degradation is also time- and CAP power-dependent, while the initial concentration or matrix type had a negligible effect. This study also tentatively identified three previously reported and one novel transformation product of BPA and four novel transformation products of BPS. Their postulated structures suggested similar breakdown mechanisms, i.e., hydroxylation followed by ring cleavage. The results demonstrate that CAP technology is an effective process for the degradation of both BPA and BPS without the need for additional chemicals, indicating that CAP is a promising technology for water and wastewater remediation worthy of further investigation and optimization.

Atmospheric pressure plasma jet-mouse skin interaction: Mitigation of damages by liquid interface and gas flow control.

The possible benefits of an atmospheric pressure plasma jet skin treatment have been tested in vivo on mouse skin. Many studies have been conducted in vitro on mouse skin cells, but only a few in vivo where, due to the complexity of the biological system, plasma can cause severe damages. For this reason, we investigated how kHz plasma generated in a jet that is known to inflict skin damage interacts with mouse skin and explored how we can reduce the skin damage. First, the focus was on exploring plasma effects on skin damage formation with different plasma gases and jet inclinations. The results pointed to the perpendicular orientation of a He plasma jet as the most promising condition with the least skin damage. Then, the skin damage caused by a He plasma jet was explored, focusing on damage mitigation with different liquid interfaces applied to the treatment site, adding N2 to the gas mixture, or alternating the gas flow dynamics by elongating the jet's glass orifice with a funnel. All these mitigations proved highly efficient, but the utmost benefits for skin damage reduction were connected to skin temperature reduction, the reduction in reactive oxygen species (ROS), and the increase in reactive nitrogen species (RNS).

Label-Free Mycotoxin Raman Identification by High-Performing Plasmonic Vertical Carbon Nanostructures.

Mycotoxins are widespread chemical entities in the agriculture and food industries that can induce cancer growth and immune deficiency, posing a serious health threat for humankind. These hazardous compounds are produced naturally by various molds (fungi) that contaminate different food products and can be detected in cereals, nuts, spices, and other food products. However, their detection, especially at minimally harmful concentrations, remains a serious analytical challenge. This research shows that high-performing plasmonic substrates (analytical enhancement factor = 5 × 107 ) based on plasma-grown vertical hollow carbon nanotubes can be applied for immediate detection of the most toxic mycotoxins. Due to excellent sensitivity allowing operation at ppb concentrations, it is possible to collect vibrational fingerprints of aflatoxin B1 , zearalenone, alternariol, and fumonisin B1 , highlighting the key spectral differences between them using principal component analysis. Regarding time-consuming conventional methods, including thin-layer chromatography, gas chromatography, high-performance liquid chromatography, and enzyme-linked immunosorbent assay, the designed surface-enhanced Raman spectroscopy substrates provide a clear roadmap to reducing the detection time-scale of mycotoxins down to seconds.

Unravelling the pathways of air plasma induced aflatoxin B1 degradation and detoxification.

Aflatoxins are considered to be a critical dietary risk factor for humans, with aflatoxin B1 (AFB1) identified by the WHO as one of the most potent natural group 1 carcinogen. Despite this, more than half of the world's population is chronically exposed, resulting in up to 170,000 annual cases of human hepatocellular carcinoma cancer. Here we report an easily implemented approach using non-equilibrium plasma for targeted degradation of AFB1. Apart from reaching the 100 % decontamination in less than 120 s of treatment, this is the first study that combines hypersensitive analytical methods such as high-resolution mass spectroscopy (HRMS) and nuclear magnetic resonance spectroscopy (NMR) to provide a detailed description of CAP mediated AFB1 degradation. We identify rapid scission of the vinyl bond between 8- and 9-position on the terminal furan ring of AFB1 as being of paramount importance for the suppression of toxic potential, which is confirmed by the examination of both cytotoxicity and genotoxicity. The plasma reactive species mediated degradation pathways are elucidated, and it is demonstrated that the approach not only renders AFB1 harmless but does so in order of magnitude less time than UV irradiation as one of the other non-thermal methods currently under investigation.

Mycotoxin Decontamination Efficacy of Atmospheric Pressure Air Plasma.

Mycotoxins, the toxic secondary metabolites of mould species, are a growing global concern, rendering almost 25% of all food produced unfit for human or animal consumption, thus placing immense pressure on the food supply chain. Cold Atmospheric pressure Plasma (CAP) represents a promising, low-cost, and environmentally friendly means to degrade mycotoxins with negligible effect on the quality of food products. Despite this promise, the study of CAP-mediated mycotoxin degradation has been limited to a small subset of the vast number of mycotoxins that plague the food supply chain. This study explores the degradation of aflatoxins, trichothecenes, fumonisins, and zearalenone using CAP generated in ambient air. CAP treatment was found to reduce aflatoxins by 93%, trichothecenes by 90%, fumonisins by 93%, and zearalenone by 100% after 8 minutes exposure. To demonstrate the potential of CAP-mediated mycotoxin degradation against more conventional methods, its efficiency was compared against ultraviolet C (UVC) light irradiation. In all cases, CAP was found to be considerably more efficient than UVC, with aflatoxin G1 and zearalenone being completely degraded, levels that could not be achieved using UVC irradiation.

Effective Fungal Spore Inactivation with an Environmentally Friendly Approach Based on Atmospheric Pressure Air Plasma.

Fungal contamination of surfaces is a global burden, posing a major environmental and public health challenge. A wide variety of antifungal chemical agents are available; however, the side effects of the use of these disinfectants often result in the generation of toxic residues raising major environmental concerns. Herein, atmospheric pressure air plasma generated by a surface barrier discharge (SBD) is presented as an innovative green chemical method for fungal inactivation, with the potential to become an effective replacement for conventional chemical disinfection agents, such as Virkon. Using Aspergillus flavus spores as a target organism, a comparison of plasma based decontamination techniques is reported, highlighting their respective efficiencies and uncovering their underpining inactivation pathways. Tests were performed using both direct gaseous plasma treatment and an indirect treatment using a plasma activated aqueous broth solution (PAB). Concentrations of gaseous ozone and nitrogen oxides were determined with Fourier-transform infrared spectroscopy (FTIR) and Optical emission spectroscopy (OES), whereas hydrogen peroxides, nitrites, nitrates, and pH were measured in PAB. It is demonstrated that direct exposure to the gaseous plasma effluent exhibited superior decontamination efficiency and eliminated spores more effectively than Virkon, a finding attributed to the production of a wide variety of reactive oxygen and nitrogen species within the plasma.

Mycotoxin Decontamination of Food: Cold Atmospheric Pressure Plasma versus "Classic" Decontamination.

Mycotoxins are secondary metabolites produced by several filamentous fungi, which frequently contaminate our food, and can result in human diseases affecting vital systems such as the nervous and immune systems. They can also trigger various forms of cancer. Intensive food production is contributing to incorrect handling, transport and storage of the food, resulting in increased levels of mycotoxin contamination. Mycotoxins are structurally very diverse molecules necessitating versatile food decontamination approaches, which are grouped into physical, chemical and biological techniques. In this review, a new and promising approach involving the use of cold atmospheric pressure plasma is considered, which may overcome multiple weaknesses associated with the classical methods. In addition to its mycotoxin destruction efficiency, cold atmospheric pressure plasma is cost effective, ecologically neutral and has a negligible effect on the quality of food products following treatment in comparison to classical methods.

Microplasma Induced Cell Morphological Changes and Apoptosis of Ex Vivo Cultured Human Anterior Lens Epithelial Cells - Relevance to Capsular Opacification.

Inducing selective or targeted cell apoptosis without affecting large number of neighbouring cells remains a challenge. A plausible method for treatment of posterior capsular opacification (PCO) due to remaining lens epithelial cells (LECs) by reactive chemistry induced by localized single electrode microplasma discharge at top of a needle-like glass electrode with spot size ~3 µm is hereby presented. The focused and highly-localized atmospheric pressure microplasma jet with electrode discharge could induce a dose-dependent apoptosis in selected and targeted individual LECs, which could be confirmed by real-time monitoring of the morphological and structural changes at cellular level. Direct cell treatment with microplasma inside the medium appeared more effective in inducing apoptosis (caspase 8 positivity and DNA fragmentation) at a highly targeted cell level compared to treatment on top of the medium (indirect treatment). Our results show that single cell specific micropipette plasma can be used to selectively induce demise in LECs which remain in the capsular bag after cataract surgery and thus prevent their migration (CXCR4 positivity) to the posterior lens capsule and PCO formation.