A low power atmospheric plasma source for accelerated blood coagulation

The development of a biomedical tool able to locally accelerate blood coagulation (BC), especially in patients following an anticoagulant therapy, is a very attractive and challenging goal. In this contribution we present the main features of the Plasma Coagulation Controller (PCC) device, a cold atmospheric pressure plasma source based on the Dielectric Barrier Discharge (DBD) scheme, specifically designed for accelerating blood coagulation. The device is controlled by a microcontroller and can explore different operational parameters in terms of discharge repetition rate (1-20 kHz) and applied voltage (2-8 kV). Effective current measured on a metallic target is of the order of 1 mA and, thus, suitable for application on human body. Helium is used as a working gas though some tests have been performed in Argon for investigating mechanisms behind plasma-living matter interaction. The presence in the PCC plasma jet of reactive oxygen and nitrogen species (ROS and RONS) and of metastable excited states is revealed through emission spectroscopic measurements. The analysis of the rotational OH- and N2 spectra allowed also the estimate of their rotational temperatures, ranging around 300 K. Interestingly, ROS and RONS produced by the PCC are able to induce the production of reactive species in cells, as shown in biological tests performed on human fibroblasts, where it was observed a significant increase in the levels of ROS and NO (nitric oxide) compared to the untreated samples. This might give an insight into the molecular mechanism behind the cellular response to the plasma. The ability of PCC device to accelerate BC has been investigated through in-vitro and in-vivo tests. In-vitro tests have been performed on blood samples from patients following anticoagulant therapy and exposed either to air (control samples) or to direct plasma jet for different time points. PCC exposure strongly stimulated formation of blood clots that have been successively analyzed by histological methods. A Western Blot has been also performed in order to investigate the relative activation of proteins involved in BC, as well as of enzymes involved in the reactive species' disposal. In vivo tests have been performed on Male Wistar rats; in particular, the bleeding was induced by a deep cut on both hindlimbs at the same time, and only one was treated by the PCC. The BC was accelerated in the treated area compared to the other side. Finally, the disinfectant effect of the plasma produced with PCC has been tested by treating different bacteria strains (E. coli, S. aureus and P. aeruginosa). Bacteria viability drops under 50% after only 15s of plasma exposure, and keeps decreasing over time until reaching almost 100% of inactivation after 2min. Taken together, our data suggest that the PCC is able to reduce the BC time possibly through the production of reactive species.