Volume 10, Issue 2, June 2015
Index of content:
- In Focus Plasma Medicine
10(2015); http://dx.doi.org/10.1116/1.4905666View Description Hide Description
The application of low temperature plasmas in biology and medicine may lead to a paradigm shift in the way various diseases can be treated without serious side effects. Low temperature plasmas generated in gas mixtures that contain oxygen or air produce several chemically reactive species that have important biological implications when they interact with eukaryotic or prokaryotic cells. Here, a review of the effects of low temperature plasma generated by the plasma pencil on different cancerous cells is presented. Results indicate that plasma consistently shows a delayed killing effect that is dose dependent. In addition, there is some evidence that apoptosis is one of the pathways that leads to the death of the cells, indicating that plasma initiates cell signaling pathways.
How do plasma-generated OH radicals react with biofilm components? Insights from atomic scale simulations10(2015); http://dx.doi.org/10.1116/1.4904339View Description Hide Description
The application of nonthermal atmospheric pressure plasma is emerging as an alternative and efficient technique for the inactivation of bacterial biofilms. In this study, reactive molecular dynamics simulations were used to examine the reaction mechanisms of hydroxyl radicals, as key reactive oxygen plasma species in biological systems, with several organic molecules (i.e., alkane, alcohol, carboxylic acid, and amine), as prototypical components of biomolecules in the biofilm. Our results demonstrate that organic molecules containing hydroxyl and carboxyl groups may act as trapping agents for the OH radicals. Moreover, the impact of OH radicals on N-acetyl-glucosamine, as constituent component of staphylococcus epidermidis biofilms, was investigated. The results show how impacts of OH radicals lead to hydrogen abstraction and subsequent molecular damage. This study thus provides new data on the reaction mechanisms of plasma species, and particularly the OH radicals, with fundamental components of bacterial biofilms.
Dielectric barrier discharge plasma treatment of ultrahigh molecular weight polyethylene in different discharge atmospheres at medium pressure: A cell-biomaterial interface study10(2015); http://dx.doi.org/10.1116/1.4907755View Description Hide Description
Nonthermal plasma activation of ultrahigh molecular weight polyethylene (UHMWPE) is performed in different discharge atmospheres (helium, nitrogen, argon, and air) using a parallel-plate dielectric barrier discharge reactor at medium pressure. Obtained samples are characterized via water contact angle, x-ray photoelectron spectroscopy (XPS), and atomic force microscopy. Plasma treatments were found to significantly alter the samples' surface chemical and physical characteristics. Before conducting a biocompatibility study, the influence of postplasma sterilization processes (ethanol rinsing/UV exposure) on the plasma treatment effects were studied. XPS studies showed that samples' surface chemical composition is least affected by UV exposure, thus making this process the most adequate for sterilization. In-vitro evaluation of biocompatibility was carried out by studying human foreskin fibroblast interaction with untreated and plasma treated surfaces. Cell attachment and viability on all plasma treated UHMWPE were found to be significantly higher in comparison to plain UHMWPE; this was further confirmed by the overall cell morphology. This increased cell viability on treated samples can be explained by the increased wettability on these samples. In this study, a somewhat higher cell proliferation was observed on argon plasma treated surface (water contact angle = 52°) after 7 days culture.
Angiogenic tube formation of bovine aortic endothelial cells grown on patterns formed by H2/He plasma treatment of the plasma polymerized hexamethyldisiloxane film10(2015); http://dx.doi.org/10.1116/1.4913375View Description Hide Description
Angiogenesis, the process to generate new vessels, is necessary for normal development in children as well as the wound healing and the tumor growth in adults. Therefore, it is physiologically and/or pathophysiologically significant to monitor angiogenesis. However, classical in vitro methods to evaluate angiogenesis take a long time and are expensive. Here, the authors developed a novel method to analyze the angiogenesis in a simple and economical way, using patterned films. In this study, the authors fabricated a plasma polymerized hexamethyldisiloxane (PPHMDSO) thin film deposited by capacitively coupled plasma chemical vapor deposition system with various plasma powers. The patterned PPHMDSO film was plasma treated by 10:90 H2/He mixture gas through a metal shadow mask. The films were characterized by water contact angle, atomic force microscopy, x-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy analyses. Our results show that the PPHMDSO film suppresses the cell adhesion, whereas surface modified PPHMDSO film enhances the cell adhesion and proliferation. From cell culture experiments, the authors found that the patterned film with 300 μm line interval was most efficient to evaluate the tube formation, a sapient angiogenic indicator. This patterned film will provide an effective and promising method for evaluating angiogenesis.