Session UR4: Plasma Biomedicine II

Live

Endotoxins are a pyrogen class that are relatively stable and difficult to neutralize. Pyrogens have detrimental effects in pharmaceutical material, impact patient well-being, and can limit a material's viability for internal medicine applications. Chitosan is a naturally formed polymer that has many medical applications, but also a high affinity for endotoxin attachment as well as limitations with regard to high temperature degradation that make traditional depyrogenation methods ineffective. Plasma depyrogenation can be an alternative method to efficiently inactivate pyrogens without degrading the chitosan polymer. Plasma-based depyrogenation has been demonstrated previously, but the mechanisms that drive depyrogenation and development of a cost-effective system are in the preliminary stages. A dielectric barrier discharge is built to perform depyrogenation in a sealed environment. Experiments are performed with nitrogen-helium and nitrogen-oxygen mixtures. Preliminary results show the reduction of endotoxin units in chitosan powder. Limulus Amebocyte Lysate (LAL) assay was used for quantification of endotoxin units. Material modification due to plasma exposure is presented using FTIR spectroscopy. -/a   

Live

The COVID-19 pandemic and its rapid expansion led to a shortage of PPE and an immediate lack of facepiece respirators (FPR) forcing reuse of contaminated single-use N95 and FFP3 masks. Shortage and reuse have led to deaths of over 1000 medical personnel as of May 18$^{\mathrm{th}}$ and a second wave looms over the horizon. Here we present a plasma-enabled technology that can contribute in the fight against the pandemic. FPR sterilization is a field emerging as an attempt to stem the tide of FPR shortages and increasing waste from PPE. We describe the development of an air-fed dielectric barrier discharge plasma-based method of simple extremely low-cost FPR sterilization. While ozone as a passive sterilizing method has been implemented in the past, where material is placed in a container filled with ozone, a flow-through forced convective design has proven more than 400{\%} as efficient a sterilization method on beta10-bacteria. Effectiveness against differing pathogens (viral, bacterial, and fungal) as well as ozone production measurements using transient UV absorption and FTIR spectroscopy were also performed. Repurposing a plasma globe toy's circuitry as an ozone source achieves sterilization and lends itself to a cost-effective portable sterilization system.   

Live

It is well-known that reactive oxygen and nitrogen species (RONS) play a key role in plasma medicine applications. At the current stage, two critical points are required to be solved. First, due to the difference among cell responses during cold atmospheric plasma (CAP) treatments, an optimized RONS dosage must be found for each case to maximize the selectivity. Moreover, such optimized dosages can be dynamic during treatments. Therefore, the second point is to develop a self-adaptive plasma treatment that can automatically optimize the plasma parameters and its chemistry in real-time. To achieve these two goals, we developed a real-time RONS dosage diagnostics method for CAP plume based on the real-time measurement and reversed computation of the optical emission spectrum (OES). Due to the complexity of 800$+$ chemical reactions behind the OES, we developed a novel mutation-evolution algorithm of an artificial neural network to compute the species composition based on the OES signals. The well-trained neural network is thus not only able to be a core of future self-adaptive plasma treatments but also potentially to be a diagnostic for other types of plasmas, such as the pulsed arc for nanomaterial synthesis and electrical propulsion plumes.   

Live

Non-equilibrium atmospheric-pressure plasma (APP) has recently emerged as a novel tool in medicine and agriculture. Despite the promising potential of breakthrough applications using non-equilibrium APP, key species and action mechanisms remain unclear in most cases. One of the reasons is due to a lack of fundamental experiment on the interaction of plasma-generated reactive species with biomolecules such as proteins (peptide, amino acids), phospholipids, and enzymes. In this study, we focused on the interaction of APP with several standard amino acids such as tyrosine and have analyzed plasma-generated reactive species and amino-acid derivatives. In particular, composition of tyrosine derivatives generated by APP exposure strongly depended on reactive species which were transferred into solution. In the presentation, transports of reactive species from the gas phase to the liquid phase and reaction processes of the liquid-phase reactive species will be discussed.   

Live

Biological activity of plasma activated liquids by atmospheric pressure plasmas has been investigated to identify the composition and formation pathways of chemically active species formed in plasma, depending on the plasma source configuration. Two types of plasma devices operated at different voltage repetition frequency (60 Hz and 9 kHz) for the treatment of solutions were used, to elucidate the mechanism of the chemically active species formation by using liquid-chromatography mass-spectrometry (LC-MS/MS), nuclear magnetic resonance (NMR), and electron spin resonance (ESR) measurements. In plasma treated glucose solutions, the formation of intermediate products was analyzed. The cancer cells enhance glucose metabolism in a manner that is distinct from that of cells in normal tissues. Oncogenic mutations result in glucose uptake, exceeding the bioenergetic demands of cell growth. We will discuss the effect of plasma treated glucose solutions on the metabolic pathways responsible for the cancer cell death.   

Live

Plasma jets deliver large radical fluxes, including OH, and understanding radical interactions with biomolecules, in comparison with radiolysis studies, can help develop plasma medicine approaches. We used an environmentally isolated He-H2O RF plasma to supply fluxes dominated by H, OH and H2O2 to DNA in liquid. The plasma was situated remotely (\textgreater ~50~mm) and no charged species reach the liquid. Using this simplified plasma effluent chemistry, DNA fragmentation and denaturing was investigated using Gel Electrophoresis (GE). Significant double-stranded breaks occurred within 60~s and by 500~s, the average fragment size had decreased linearly from 50kbp to 5kbp, equivalent to an increase in number of fragments from 2000 to 15000. DNA exposure to H2O2 alone showed limited fragmentation. Simulation of species in liquid indicated a much shorter lifetime for H compared to OH, while H2O2 was long-lived. Thus, OH is most likely cause of rapid DNA fragmentation due to reaction with H atoms in the DNA sugar phosphate backbone. The measured OH flux into solution is 1x1014 OH s-1 therefore results in an estimated fragmentation rate, from GE, of 30~s-1, equivalent to \textgreater ~50 bonds broken s-1. This will be compared to rate coefficients from radiolysis.   

OH radical flux measurements in the far effluent of a He-H$_{\mathrm{2}}$O RF plasma jet.

The production of ROS continues to define a plasma's ability to induce change in biological material. The presence of gaseous H$_{\mathrm{2}}$O either inside the plasma or via downstream atmospheric interaction, inherently results in the formation of the most biologically reactive ROS, OH. The short-lived nature of radicals such as OH has led to the application of APPJs via a direct or `in contact' application. The work presented here illustrates the ability of a humidity-controlled APPJ to deliver a measurable OH flux of 1.9e19 m$^{\mathrm{-2}}$s$^{\mathrm{-1}}$ from a significantly remote distance of over 100 mm, modify protein and DNA via OH interaction at 50 mm and rapidly kill E.coli up to 150 mm. OH density measurements performed in the treated liquid via fluorimetry were found to depend heavily on He feed gas humidity. The enclosed system ensures a simple chemistry dominated by H$_{\mathrm{2}}$O$_{\mathrm{2}}$ and OH while maintaining low temperature interaction. Simulation of water dissociation products highlights the importance of H and H$_{\mathrm{2}}$O$_{\mathrm{2}}$ densities in the efficiency of OH delivery. The capacity to deliver short lived radicals long distances introduces APPJs to a wide range of treatments previously thought inapplicable.