Electric discharge during electrosurgery

New Hopes for Plasma-Based Cancer Treatment

Non-thermal plasma represents a novel approach in cancer treatment. Both direct and indirect plasma treatments are available, with clinical trials of direct plasma treatment in progress. Indirect treatments involve chemotherapy (i.e., plasma-activated medium) and immunotherapy. Recent studies suggest that integrated plasma treatments could be an extremely effective approach to cancer therapy.

The Emerging Role of Gas Plasma in Oncotherapy

Atmospheric pressure gas plasmas are emerging as a promising treatment in cancer that can supplement the existing set of treatment modalities and, when combined with other therapies, enhance their selectivity and efficacy against resistant cancers. With further optimisation in production and administration of plasma treatment, plasma-enabled therapy has a strong potential to mature as a tool for selectively curing highly resistant solid tumours. Although intense preclinical studies have been conducted to exploit the unique traits of plasma as an oncotherapy, few clinical studies are underway. This review identifies types of cancers and patient groups that most likely benefit from plasma oncotherapy, to introduce clinical practitioners to plasma therapy and accelerate the speed of translating plasma for cancer control in clinics.

Counting the electrons in a multiphoton ionization by elastic scattering of microwaves

Multiphoton ionization (MPI) is a fundamental first step in high-energy laser-matter interaction and is important for understanding the mechanism of plasma formation. With the discovery of MPI more than 50 years ago, there were numerous attempts to determine the basic physical constants of this process in direct experiments, namely photoionization rates and cross-sections of the MPI; however, no reliable data was available until now, and the spread in the literature values often reaches 2–3 orders of magnitude. This is due to the inability to conduct absolute measurements of plasma electron numbers generated by MPI, which leads to uncertainties and, sometimes, contradictions between MPI cross-section values utilized by different researchers across the field. Here, we report the first direct measurement of absolute plasma electron numbers generated at MPI of air, and subsequently we precisely determine the ionization rate and cross-section of eight-photon ionization of oxygen molecule by 800 nm photons σ₈ = (3.3 ± 0.3)×10⁻¹³⁰ W⁻⁸m¹⁶s⁻¹. The method, based on the absolute measurement of the electron number created by MPI using elastic scattering of microwaves off the plasma volume in Rayleigh regime, establishes a general approach to directly measure and tabulate basic constants of the MPI process for various gases and photon energies.

Aqueous Plasma Pharmacy: Preparation Methods, Chemistry, and Therapeutic Applications

Plasma pharmacy is a subset of the broader field of plasma medicine. Although not strictly defined, the term aqueous plasma pharmacy (APP) is used to refer to the generation and distribution of reactive plasma-generated species in an aqueous solution followed by subsequent administration for therapeutic benefits. APP attempts to harness the therapeutic effects of plasma-generated oxidant species within aqueous solution in various applications, such as disinfectant solutions, cell proliferation related to wound healing, and cancer treatment. The subsequent use of plasma-generated solutions in the APP approach facilitates the delivery of reactive plasma species to internal locations within the body. Although significant efforts in the field of plasma medicine have concentrated on employing direct plasma plume exposure to cells or tissues, here we focus specifically on plasma discharge in aqueous solution to render the solution biologically active for subsequent application. Methods of plasma discharge in solution are reviewed, along with aqueous plasma chemistry and the applications for APP. The future of the field also is discussed regarding necessary research efforts that will enable commercialization for clinical deployment.