Enhanced Generation of Reactive Species by Cold Plasma in Gelatin Solutions for Selective Cancer Cell Death

Abstract

Atmospheric pressure plasma jets generate reactive oxygen and nitrogen species (RONS) in liquids and biological media, which find application in the new area of plasma medicine. These plasma-treated liquids demonstrated recently to possess selective properties on killing cancer cells and attract attention towards new plasma-based cancer therapies. These allow for local delivery by injection in the tumor but can be quickly washed away by body fluids. By confining these RONS in a suitable biocompatible delivery system, great perspectives can be opened in the design of novel biomaterials aimed for cancer therapies. Gelatin solutions are evaluated here to store RONS generated by atmospheric pressure plasma jets, and their release properties are evaluated. The concentration of RONS was studied in 2% gelatin as a function of different plasma parameters (treatment time, nozzle distance and gas flow) with two different plasma jets. Much higher production of reactive species (H 2 O 2 and NO 2-) was revealed in the polymer solution than in water after plasma treatment. The amount of RONS generated in gelatin is greatly improved with respect to water, with concentrations of H 2 O 2 and NO 2between 2 and 12 times higher for the longest plasma treatments. Plasma-treated gelatin exhibited the release of these RONS to a liquid media, which induced an effective killing of bone cancer cells. Indeed, in vitro studies on Sarcoma Osteogenic (SaOS-2) cell line exposed to plasma-treated gelatin lead to timedependent increasing cytotoxicity with the longer plasma treatment time of gelatin. While SaOS-2 cell viability decreased down to 12%-23% after 72 hours for cells exposed to 3-min treated gelatin, viability of healthy cells (hMSC) was preserved (around 90%), establishing the selectivity of the plasma-treated gelatin on cancer cells. This sets the basis for designing improved hydrogels with high capacity to deliver RONS locally to tumors.

Biomolecules as Model Indicators of In Vitro and In Vivo Cold Plasma Safety

“…The biological effects of plasma and plasma generated chemistry are dependent on the surrounding liquid environment [15][16][17][18]. In fact, studies have indicated immense variability in the biological effects attributed to cold plasma, depending on both the composition of the sample substrate and that of the ionized gas.…”

Tiny Cold Atmospheric Plasma Jet for Biomedical Applications

“…Cold plasma has received considerable attention for its potential biomedical applications, including blood coagulation, wound healing, sterilization/inactivation, skin regeneration, oral health, and cancer therapy [4,32,33]. The efficiency of plasma for biomedical applications mainly relies on the ROS/RNS generated in it [34,35]. As shown in Figures 2d, 4b, and 5b, the tiny plasma jet is an ideal ROS/RNS source, and ROS/RNS intensity increases when the plasma jet is used nearer to tissues and conductive materials.…”

Intracellular Responses Triggered by Cold Atmospheric Plasma and Plasma-Activated Media in Cancer Cells

“…In contrast, CAP-treated foetal bovine serum (FBS), acting as a model for complex bio-fluids, shows not only cytotoxic effects but also exhibits increased mutagenic potential [18]. Compared to water, a higher production of reactive species (H 2 O 2 and NO 2 − ) can be detected in 2% gelatine polymer solution after CAP treatment, with RONS amounts generated in up to 12-times higher concentration, thus resulting in its higher efficiency to kill U-2 OS bone cancer cells [19]. Likewise, CAP treated DMEM shows increased effect on proliferation and apoptosis of A431 and HaCaT cutaneous squamous carcinoma cells, compared to CAP treated PBS, though intracellular ROS levels are more increased in the latter [20].…”