Search for: All records

One of the recently observed effects of plasma in medical applications is the physical effect, suggesting that the electromagnetic (EM) emission of cold atmospheric plasmas can lead to cell membrane oscillations and sensitization to the chemical active ingredient of treatments such as cancer drugs. This is a new aspect that must be considered along with the plasma chemical effects for the future dose definition which is the most urgent research topic of plasma medicine. However, unlike the reactive oxygen and nitrogen species generated from plasma chemistry which is well-known as playing a key role in apoptosis cancer cells, the EM emission power spectrum and emission mechanism are still unquantified. This makes the uncertainty of the physical dosage of the therapy and thus impedes the further understanding and optimization of the plasma therapy. In this paper, we compute the 3D spatial distribution of the power density spectrum of EM emission from a cold atmospheric helium plasma jet. The simulations indicate that the plasma oscillations following the plasma streamer propagation are the main source of EM emission, while the emissions of the bulk current caused by net charge movements and the bremsstrahlung due to charge collisions are negligible. The results are also verified by a microwave power measurement using a heterodyne frequency sweep. These findings will thus fill out the last missing piece of the jigsaw before the plasma medicine community can define the dose in the future.

 

In experiment and 2D3V PIC MCC simulations, the breakdown development in a pulsed discharge in helium is studied forU= 3.2 kV and 10 kV andP= 100 Torr. The breakdown process is found to have a stochastic nature, and the electron avalanche develops in different experimental and simulation runs with time delays ranging from 0.3 to 8μs. Nevertheless our experiments demonstrate that the breakdown delay time distribution can be controlled with a change of the pulse discharge frequency. The simulation results show that the breakdown process can be distinguished in three stages with (a) the ionization by seed electrons, (b) the ions drift to the cathode and (c) the enhanced ionization within the cathode sheath by the electrons emitted from the cathode. The effects of variation of seed electron concentrations, voltage rise times, voltage amplitudes and ion–electron emission coefficients on the breakdown development in the pulsed gas discharge are reported.

 

Cold atmospheric plasma (CAP), a near room temperature ionized gas, has shown potential application in many branches of medicine, particularly in cancer treatment. In previous studies, the biological effect of CAP on cancer cells and other mammalian cells has been based solely on the chemical factors in CAP, particularly the reactive species. Therefore, plasma medicine has been regarded as a reactive species-based medicine, and the physical factors in CAP such as the thermal effect, ultraviolet irradiation, and electromagnetic effect have been regarded as ignorable factors. In this study, we investigated the effect of a physical CAP treatment on glioblastoma cells. For the first time, we demonstrated that the physical factors in CAP could reinstate the positive selectivity on CAP-treated astrocytes. The positive selectivity was a result of necrosis, a new cell death in glioblastoma cells characterized by the leak of bulk water from the cell membrane. The physically-based CAP treatment overcomed a large limitation of the traditional chemically based CAP treatment, which had complete dependence on the sensitivity of cells to reactive species. The physically-based CAP treatment is a potential non-invasive anti-tumor tool, which may have wide application for tumors located in deeper tissues.

 

Over the last three decades, cold atmospheric plasma (CAP) has been heavily investigated in a wide range of biological applications, including wound healing, microorganism sterilization, and cancer treatment. Atmospheric pressure plasma jets (APPJs) are the most common plasma sources in plasma medicine. An APPJ’s size determines its application range and approach in treatment. In this study, we demonstrated the real-time recognition of an APPJ’s plasma plume output using computer vision (CV), dramatically improving the measurement speed compared to the traditional method of using the naked eye. Our work provides a framework to monitor an aspect of an APPJ’s performance in real time, which is a necessary step to achieving an intelligent CAP source. 

As the carriers and executors of algorithms, digital computers are limited by the density of semiconductors on chips, where the quantum uncertainty is significant at the nanometer scale. Based on the mathematical similarity between chemical pathway networks and artificial neural networks, a new construct to achieve artificial intelligence running on a matter is developed. A general theory is derived followed by an evaluation of its fitting capability and an example where a low‐temperature plasma is trained to play the board game Tic–Tac–Toe. The plasma can emit a spectrum representing its next move when we are feeding a gas combination carrying the board information. Finally, the fourth state of matter shows a significantly high winning rate against a random‐move player, reflecting its own strategies. This work reveals that any matter, with substantial chemical complexity, can process information based on particle collisions, like a programmable analog computer at the molecular level.

 

Cold atmospheric plasma (CAP) has been used for the treatment of various cancers. The anti-cancer properties of CAP are mainly due to the reactive species generated from it. Here, we analyze the efficacy of CAP in combination with temozolomide (TMZ) in two different human glioblastoma cell lines, T98G and A172, in vitro using various conditions. We also establish an optimized dose of the co-treatment to study potential sensitization in TMZ-resistant cells. The removal of cell culture media after CAP treatment did not affect the sensitivity of CAP to cancer cells. However, keeping the CAP-treated media for a shorter time helped in the slight proliferation of T98G cells, while keeping the same media for longer durations resulted in a decrease in its survivability. This could be a potential reason for the sensitization of the cells in combination treatment. Co-treatment effectively increased the lactate dehydrogenase (LDH) activity, indicating cytotoxicity. Furthermore, apoptosis and caspase-3 activity also significantly increased in both cell lines, implying the anticancer nature of the combination. The microscopic analysis of the cells post-treatment indicated nuclear fragmentation, and caspase activity demonstrated apoptosis. Therefore, a combination treatment of CAP and TMZ may be a potent therapeutic modality to treat glioblastoma. This could also indicate that a pre-treatment with CAP causes the cells to be more sensitive to chemotherapy treatment. 

CAP is an ionized gas generated under atmospheric pressure conditions. Due to its reactive chemical components and near-room temperature nature, CAP has promising applications in diverse branches of medicine, including microorganism sterilization, biofilm inactivation, wound healing, and cancer therapy. Currently, hundreds of in vitro demonstrations of CAP-based cancer treatments have been reported. However, preclinical studies, particularly in vivo studies, are pivotal to achieving a final clinical application. Here, we comprehensively introduced the research status of the preclinical usage of CAP in cancer treatment, by primarily focusing on the in vivo studies over the past decade. We summarized the primary research strategies in preclinical and clinical studies, including transdermal CAP treatment, post-surgical CAP treatment, CAP-activated solutions treatment, and sensitization treatment to drugs. Finally, the underlying mechanism was discussed based on the latest understanding. 

Abstract Plasma technology is actively used for nanoparticle synthesis and modification. All plasma techniques share the ambition of providing high quality, nanostructured materials with full control over their crystalline state and functional properties. Pulsed-DC physical/chemical vapour deposition, high power impulse magnetron sputtering, and pulsed cathodic arc are consolidated low-temperature plasma processes for the synthesis of high-quality nanocomposite films in vacuum environment. However, atmospheric arc discharge stands out thanks to the high throughput, wide variety, and excellent quality of obtained stand-alone nanomaterials, mainly core–shell nanoparticles, transition metal dichalcogenide monolayers, and carbon-based nanostructures, like graphene and carbon nanotubes. Unique capabilities of this arc technique are due to its flexibility and wide range of plasma parameters achievable by modulation of the frequency, duty cycle, and amplitude of pulse waveform. The many possibilities offered by pulsed arc discharges applied on synthesis of low-dimensional materials are reviewed here. Periodical variations in temperature and density of the pulsing arc plasma enable nanosynthesis with a more rational use of the supplied power. Parameters such as plasma composition, consumed power, process stability, material properties, and economical aspects, are discussed. Finally, a brief outlook towards future tendencies of nanomaterial preparation is proposed. Atmospheric pulsed arcs constitute promising, clean processes providing ecological and sustainable development in the production of nanomaterials both in industry and research laboratories.