Fluorescein-agarose gel as a tissue model to visualize and measure local CAP-induced acidification

International audienceCold Atmospheric Plasmas (CAPs) have been shown to lower the pH of the treated target. CAP-induced acidification can have beneficial effects on the treated tissue (e.g. disinfection and healing). Conversely a tissue hyper acidification can lead to permanent damages with dramatic consequences. Before starting in vivo plasma treatments, preliminary tests should be carried in order to tune the acidifying effect induced by CAP exposition. Here we propose a tissue model that can be a useful tool to visualize and measure pH changes induced by plasma treatment

A fluorescent method to measure plasma-induced surface acidification on tissue models

National audienc

Cold atmospheric plasma-induced acidification of tissue surface: visualization and quantification using agarose gel models

International audienc

Cold atmospheric single plasma jet for RONS delivery on large biological surfaces

International audienceSeveral attempts have been made to deliver reactive oxygen and nitrogen species (RONS) produced by non-thermal plasma onto large surfaces in a controllable way compatible with skin treatments. In this paper, the effect of pulse frequency, in the range 0.5–20 kHz, on the discharge behavior was studied on skin tissue models to evaluate potential treatment changes. This has been done through electrical characterization, visualization of the helium flow (by Schlieren technique), produced plasma jet modifications (ICCD imaging) and RONS measurements. The results show that, in addition to its well known important role in the production of the chemical species, the applied discharge frequency plays a very significant role in the size of the treated surface. An enhancement of NO*, OH* and O* production in the gas phase at the higher frequency is reported and assigned to the stronger mixing of the helium flow with ambient air. The efficacy of plasma jet on transporting RONS on/into agarose gel and pig skin has been evaluated. The distribution of the reactive species on the target, or passing through, is strongly dependent on the discharge frequency and consequently induces pH variations. The present study supports a new way for enlarging the treated surface by using a simple jet at high frequency in the 20 kHz range, leading, with appropriate gas flow and distance to target, to conditions of RONS production that are compatible with potential uses for biomedical or cosmetic applications

Low pressure plasma processing of collagen membranes for anti-cancer drug delivery

International audienceFor targeting the cancer cells, a low pressure ICP reactor was utilised to fabricate a drug delivery system. On the surface of biocompatible collagen membranes, thin plasma polymer coatings were deposited to encapsulate an anticancer drug carboplatin and impart different biologically active functionalities. The characteristics of the deposited films were analysed by FTIR and XPS and the overall functionalities were tested by in vitro and in vivo experiments on the cancer cells lines on the cancer nodules respectively. Preliminary results of fabricated drug delivery systems showed the inhibition of cancer cell proliferation in vitro as well as tumour growth in mice models by 2.8 folds in mass compared to the control cas

Plasma/target interactions in non-thermal atmospheric plasma biomedical applications: a challenge and key issue

International audienceThe last decade has seen an impressive increase of the research dedicated to the biomedical applications of low temperature plasmas, especially with plasma sources working at atmospheric pressure. In this new trend, beside decontamination/sterilization and surface treatment that have already a quite long story through low-pressure plasma research and developments, medical applications are tacking an increasing place underlined by the actual numerous clinical trials. Medical applications of low temperature plasmas now concern a very wide range of domains, including primary haemostasis and blood coagulation, dental care, skin decontamination and hygiene, wound and ulcer treatment, dermatology, cancer treatment. Biological applications are also now extended to agriculture and, more recently, to cosmetic. Despite the huge number of in vitro and in vivo experiments there are still numerous challenges to overcome linked to the nature of the encountered target (biological tissues and materials, organs and their direct environment, liquids) that have a direct effect on the produced plasma itself and on the generated species. It is clear that the extremely strong coupling between the characteristics of the plasma and those of the target, as already shown, will play a very important role in the results observed during the treatments. A variation in the chemical or physical characteristics of the target will involve significant differences in the gas flow, the local temperature, or the induced electric field, resulting de facto in variations in the production of the reactive species. It also concerns the transposition of the results between the in vitro and the in vivo experiments that are carried out under extremely different conditions, especially concerning the equivalent electric circuit of the reactor / plasma / biological target assembly. These problems directly affect the identification of the processes involved and currently limit the possibility of a definition of a "dose" in plasma treatments. Recently, study reported led to reflections on non-sustainable tumor response. The loss of effectiveness under long-term plasma treatment of cancer tissue opens questions about plasma application and protocol. It must be considered that the treated area is morphologically and chemically changing over the time, from activated surrounding to more normal tissues that are less humid and bacteriologically cleaner. This aspect is particularly important for the development of efficient systems and protocols in plasma cancer treatment but also for any other plasma therapeutically approaches. It induce a in real-time in situ control of plasma production and at longer term a protocol adaptation taking into account the biological target evolution. Some progress are already done in that domai