Effect of argon plasma abutment activation on soft tissue healing: RCT with histological assessment

OBJECTIVE

To assess the peri-implant soft tissue profiles between argon plasma treatment (PT) and non-treated (NPT) healing abutments by comparing clinical and histological parameters 2 months following abutment placement.

MATERIALS AND METHODS

Thirty participants were randomly assigned to argon-plasma treatment abutments group (PT) or non-treated abutments (NPT) group. Two months after healing abutment placement, soft peri-implant tissues and abutment were harvested, and histological and clinical parameters including plaque index, bleeding on probing, and keratinized mucosa diameter (KM) were assessed. Specialized stainings (hematoxylin-eosin and picrocirious red) coupled with immunohistochemistry (vimentin, collagen, and CK10) were performed to assess soft tissue inflammation and healing, and the collagen content keratinization. In addition to standard statistical methods, machine learning algorithms were applied for advanced soft tissue profiling between the test and control groups.

RESULTS

PT group showed lower plaque accumulation and inflammation grade (6.71% vs. 13.25%, respectively; p-value 0.02), and more advanced connective tissue healing and integration compared to NPT (31.77% vs. 23.3%, respectively; p = 0.009). In the control group, more expressed keratinization was found compared to the PT group, showing significantly higher CK10 (>47.5%). No differences in KM were found between the groups.

SIGNIFICANCE

PT seems to be a promising protocol for guided peri-implant soft tissue morphogenesis reducing plaque accumulation and inflammation, and stimulating collagen and soft tissue but without effects on epithelial tissues and keratinization.

Effect of Plasma Argon Pretreatment on the Surface Properties of AZ31 Magnesium Alloy

Climate change has evidenced the need to reduce carbon dioxide emissions into the atmosphere, and so for transport applications, lighter weight alloys have been studied, such as magnesium alloys. However, they are susceptible to corrosion; therefore, surface treatments have been extensively studied. In this work, the influence of argon plasma pretreatment on the surface properties of an AZ31 magnesium alloy focus on the enhancement of the reactivity of the surface, which was examined by surface analysis techniques, electrochemical techniques, and gravimetric measurements. The samples were polished and exposed to argon plasma for two minutes in order to activate the surface. Contact angle measurements revealed higher surface energy after applying the pretreatment, and atomic force microscopy showed a roughness increase, while X-Ray photoelectron spectroscopy showed a chemical change on the surface, where after pretreatment the oxygen species increased. Electrochemical measurements showed that surface pretreatment does not affect the corrosion mechanism of the alloy, while electrochemical impedance spectroscopy reveals an increase in the original thickness of the surface film. This increase is likely associated with the high reactivity that the plasma pretreatment confers to the surface of the AZ31 alloy, affecting the extent of oxide formation and, consequently, the increase in its protection capacity. The weight loss measurements support the effect of the plasma pretreatment on the oxide thickness since the corrosion rate of the pretreated AZ31 specimens was lower than that of those that did not receive the surface pretreatment.

The Effect of Argon Plasma Surface Treatment on Poly(lactic-co-glycolic acid)/Collagen-Based Biomaterials for Bone Tissue Engineering

Nonunion bone fractures can impact the quality of life and represent a major economic burden. Scaffold-based tissue engineering has shown promise as an alternative to bone grafting. Achieving desirable bone reconstruction requires appropriate surface properties, together with optimizing the internal architecture of 3D scaffolds. This study presents the surface modification of poly(lactic-co-glycolic acid) (PLGA), collagen, and PLGA-collagen via an argon plasma treatment. Argon plasma can modify the surface chemistry and topography of biomaterials and improve in vivo integration. Solvent-cast films were prepared using 1,1,1,3,3,3-hexafluoro-2-propanol and characterized via differential scanning calorimetry, thermogravimetric analysis, contact angle measurement, and critical surface tension analysis. For PLGA films, the water contact angle dropped from 70° to 42°, whereas the diiodomethane contact angle reduced from 53° to 32° after the plasma treatment. A set of PLGA-collagen formulations were loaded with nanohydroxyapatite (nHA) and polyethylene glycol (PEG) to enhance their osteoconductivity and hydrophilicity. Then, 3D scaffolds were fabricated using a 3D Bioplotter and characterized via Fourier-transform infrared (FTIR) spectroscopy. A bicinchoninic acid assay (BCA) was used to compare the protein release from the untreated and plasma-treated scaffolds into phosphate-buffered saline (PBS). The plasma-treated scaffolds had a lower protein release, and the difference compared to the untreated scaffolds was statistically significant.

Lung Decortication With Argon Plasma Energy for the Treatment of Chronic Pleural Empyema

Lung decortication for the treatment of chronic pleural empyema remains a technically challenging procedure that is associated with bleeding and air leak. The recent advent of pure argon plasma has provided thoracic surgeons with an electrically neutral energy source for dissection and coagulation of pulmonary tissue with minimal depth of necrosis. In this article, we describe the technique of lung decortication with argon plasma energy (PlasmaJet, Plasma Surgical, Roswell, GA, USA) for the treatment of chronic pleural empyema. With appropriate application, the PlasmaJet can facilitate the removal of fibrous cortex with satisfactory hemostasis and aerostasis. Argon plasma energy can potentially be a useful adjunct in lung decortication. Controlled trials are needed to determine its role in the surgical management of advanced pleural empyema.

Effect of argon plasma on repair bond strength using nanofilled and microhybrid composites

OBJECTIVES

To evaluate the effect of atmospheric pressure plasma (PLA), sandblasting (SAN), silanization (SIL) and hydrophobic bonding resin (HBR) on the micro-shear bond strength (MSBS) of fresh nanofilled (NF) or microhybrid (MH) composites to water-aged nanofilled composite.

MATERIALS AND METHODS

NF plates were fabricated and stored in distilled water for 4 months. The aged plates were assigned to the groups (n = 6): 1- untreated; 2- SAN + SIL + HBR; 3- HBR; 4- PLA + HBR; 5- SAN + HBR; 6- SAN + PLA + HBR; and 7- PLA. Two fresh composite cylinders were constructed on each plate with NF or MH composites and tested after 24 h or 1 year of water-storage, using the MSBS testing. Data were analyzed by three-way ANOVA and Tukey test (α = 0.05).

RESULTS

NF yielded better outcomes than MH at 24 h, which was not observed at 1 year. HBR showed the highest MSBS results, while untreated and PLA groups yielded the lowest one. MSBS reduced for all groups after 1 year.

CONCLUSIONS

Only HBR can obtain good MSBS results, while PLA alone was not beneficial. After 1 year, a reduction in repair MSBS was observed and the type of composite did not influence the results.

CLINICAL RELEVANCE

The repair technique can be simplified with the use of only an adhesive and macromechanical retentions in the old composite, regardless the type of fresh composite.

Experience with PlasmaJet™ in debulking surgery in 87 patients with advanced-stage ovarian cancer

OBJECTIVE

The aim was to evaluate the effectiveness and safety of PlasmaJet™ in cytoreductive surgery in patients with advanced-stage ovarian cancer.

METHODS

All patients between September 2013 and January 2018 undergoing surgical cytoreduction for advanced-stage ovarian cancer with the help of PlasmaJet™ were identified and analyzed retrospectively.

RESULTS

Eighty-seven patients diagnosed with advanced-stage ovarian cancer underwent surgery with PlasmaJet™. Primary debulking surgery was performed in 15 cases. Fifty-seven patients underwent interval debulking after neoadjuvant chemotherapy. Secondary and tertiary debulking was done in, respectively, 11 and three patients, and one patient underwent quaternary debulking using PlasmaJet™. In all 87 patients but one, complete resection of all macroscopic disease was obtained. PlasmaJet™ was used to remove carcinomatosis on the peritoneum, bowel serosa, intestinal mesentery, and lesions in the upper abdomen (diaphragm and liver surface). No damage to the bladder or ureter was noted in relation to the use of PlasmaJet™. Three patients developed a bowel leakage postoperatively. In one of these patients, PlasmaJet™ was used to treat tumoral implants in the affected region.

CONCLUSIONS

Our series suggests that the use of PlasmaJet™ is efficient and safe in obtaining complete resection of all macroscopic tumoral lesions in advanced-stage ovarian cancer.

Argon plasma effects on maize: pesticide degradation and quality changes

BACKGROUND

During planting, storage and transportation of maize excessive amounts of pesticides are used to ensure production, resulting in pesticide residues on the maize that can threaten human health. Plasma, compared with other technologies, has been widely regarded as a green, safe and promising technology for surface decontamination to ensure maize safety and quality.

RESULTS

The aim of this study is to discuss plasma effects on the degradation of chlorpyrifos and carbaryl on maize surface and the changes of treated maize quality. Results achieved the largest degradation efficiency of chlorpyrifos and carbaryl, up to 91.5% and 73.1%, respectively. The physical changes of maize were observed by scanning electron microscopy (SEM), showing a decrease in contact angle, an increase in surface free energy and polar component, leading to improved hydrophilicity of the treated maize. There was no significant change of vitamin B₂ content of maize. A significant increase of acid value and decrease of moisture content and starch content were observed within acceptable limits.

CONCLUSION

It is reasonable to believe that argon plasma treatment enhances the edible safety of maize while maintaining maize quality. © 2019 Society of Chemical Industry.

A retrospective comparative study of argon plasma versus polypectome snare tip coagulation: effect on recurrence rate after resection of large laterally spreading type lesions

Background

Endoscopic mucosal resection (EMR) is an established technique for treating large laterally spreading type (LST) lesions ≥20 mm. The aim of our study was to compare the use of argon plasma (APC) versus snare-tip coagulation on the recurrence rate of large LST lesions.

Methods

All patients with large LST lesions resected by EMR between January 2006 and December 2014 were enrolled. After piecemeal resection, patients underwent either APC or snare-tip coagulation of the rim of the resection area and any residual adenomatous tissue. Follow up included colonoscopy and biopsies. Medical records, including characteristics of patients and polyps, complications and recurrence were retrieved and collected.

Results

One hundred one patients were included in the final analysis. They were divided into the APC group (n=50) and the snare-tip coagulation group (n=51). The 2 groups were similar concerning patients’ characteristics, size of polyps and histology. Post-polypectomy coagulation syndrome was observed in 8 patients (7.9%) (APC group: n=5 and snare tip group: n=3). EMR-related bleeding occurred in 9 patients (8.9%) (APC group: n=4 and snare tip group: n=5). Total recurrence rate was 14.85% (16% and 13.7% in APC and snare-tip groups, respectively, P=0.34).

Conclusion

The effectiveness of snare-tip coagulation is comparable with that of APC with respect to recurrence rate after resection of large LST lesions. It thus represents a cost-effective alternative to APC.

Argon Plasma Treatment to Tune Perovskite Surface Composition for High Efficiency Solar Cells and Fast Photodetectors

The surface composition of perovskite films is very sensitive to film processing and can deviate from the optimal, which generates unfavorable defects and results in efficiency loss in solar cells and slow response speed in photodetectors. An argon plasma treatment is introduced to modify the surface composition by tuning the ratio of organic and inorganic components as well as defect type before deposition of the passivating layer. It can efficiently enhance the charge collection across the perovskite-electrode interface by suppressing charge recombination. Therefore, perovskite solar cells with argon plasma treatment yield enhanced efficiency to 20.4% and perovskite photodetectors can reach their fastest respond speed, which is solely limited by the carrier mobility.

Surface heparinization and blood compatibility modification of small intestinal submucosa (SIS) for small-caliber vascular regeneration

OBJECTIVES

This study aims to investigate the small intestinal submucosal (SIS) surface after heparinization with the hypothermia plasma technique, to improve the blood compatibility of SIS, and to explore the possibility of construction of small-caliber vascular grafts with modified SIS scaffolds in vivo.

METHODS

SIS films prepared from jejunums of pigs were processed for surface treatment at different time periods with the argon plasma initiation technique under vacuum, and were then immediately immersed in 4% (m/v) heparin sodium solution for 24-h heparinization. The surface morphologies of heparinized SIS were observed under a scanning electron microscope (SEM). The antithrombogenicity of the modified SIS films was tested by measuring the water contact angle, blood coagulation time, activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT), and observation of platelet adherence by SEM. Heparinized SIS films were sewn into a small caliber (3-mm) tube and implanted into the defect of a canine femur by anastomosis as a vascular graft. The efficiency of the SIS graft was evaluated according to the patency for the circulation of blood with Doppler color ultrasonography and hematoxylin-eosin staining.

RESULTS

Heparinized SIS showed a significantly different surface morphology compared with that of untreated SIS. The SIS surface resembles wrinkled film, but the heparinized SIS surface is uniformly coated with microdots, and appears to have a layer of heparin adhesion.

CONCLUSION

Heparin was attached to the SIS surface after hypothermia plasma treatment. Hydrophilicity and antithrombogenicity of heparinized SIS were clearly increased. The heparinized SIS vascular graft showed great potential for replacement of defective small-caliber vessels.

Atmospheric Pressure Plasma Jet Treatment of Poly-ε-caprolactone Polymer Solutions To Improve Electrospinning

An atmospheric pressure plasma jet (APPJ) specifically designed for liquid treatment has been used in this work to improve the electrospinnability of a 5 w/v % solution of poly-ε-caprolactone (PCL) in a mixture of chloroform and N,N-dimethylformamide. Untreated PCL solutions were found to result in nonuniform fibers containing a large number of beads, whereas plasma-treated solutions (exposure time of 2-5 min) enabled the generation of beadless, uniform nanofibers with an average diameter of 450 nm. This enhanced electrospinnability was found to be mainly due to the highly increased conductivity of the plasma-modified PCL solutions. Consequently, more stretching of the polymer jet occurred during electrospinning, leading to the generation of bead-free fibers. Plasma treatment also results in an increased viscosity and decreased pH values. To explain these observed changes, optical emission spectroscopy (OES) has been used to examine the excited species present in the APPJ in contact with the PCL solution. This study revealed that the peaks attributed to H, CH, CH₂, and C₂ species could be responsible for the degradation of solvent molecules and/or PCL structures during the plasma treatment. Size exclusion chromatography and X-ray photoelectron spectroscopy results showed that the molecular weight and the chemical composition of PCL were not significantly affected by the APPJ treatment. Plasma exposure mainly results in the degradation of the solvent molecules instead of modifying the PCL macromolecules, preserving the original polymer as much as possible. A hypothesis for the observed macroscopic changes in viscosity and pH values could be the generation of new chemical species such as HCl and/or HNO₃. These species are characterized by their high conductivity, low pH values, and strong polarity and could enhance the solvent quality for PCL, leading to the expansion of the polymer coil, which could in turn explain the observed enhanced viscosity after plasma modification.

The inactivation of Staphylococcus aureus biofilms using low-power argon plasma in a layer-by-layer approach

The direct application of low power argon plasma for the decontamination of pre-formed Staphylococcus aureus biofilms on various surfaces was examined. Distinct chemical/physical properties of reactive species found in argon plasmas generated at different wattages all demonstrated very potent but very different anti-biofilm mechanisms of action. An in-depth analysis of the results showed that: (1) the different reactive species produced in each plasma demonstrated specific antibacterial and/or anti-biofilm activity; and (2) the commonly associated etching effect could be manipulated and even controlled, depending on the experimental conditions. Under optimal experimental parameters, bacterial cells in S. aureus biofilms were killed (> 99.9%) by plasmas within 10 min of exposure and no bacteria nor biofilm regrowth from argon discharge gas treated biofilms was observed for 150 h. The decontamination ability of plasmas for the treatment of biofilm related contaminations on various materials was confirmed and an entirely novel layer-by-layer decontamination approach was designed and examined.

Efficacy of Tissue Tolerable Plasma (TTP) against Ixodes ricinus

The efficacy of Tissue Tolerable Plasma (TTP) against ticks was tested, as data from the literature has demonstrated its efficacy against other acari. The study was carried out by using the KINPen09 (Argon as carrier gas) on Ixodes ricinus (n=24). Treatment times of 1 and 3 minutes led to a reversible inactivation of the ticks. After 5 min of treatment, they died. Thanks to the acaricidal effect of TPP, a new treatment strategy using the KINPen09 for tick-infested pets is now available.

In vitro efficacy of cold atmospheric pressure plasma on S. sanguinis biofilms in comparison of two test models

Dental plaque critically affects the etiology of caries, periodontitis and periimplantitis. The mechanical removal of plaque can only be performed partially due to limited accessibility. Therefore, plaque still represents one of the major therapeutic challenges. Even though antiseptic mouth rinses reduce the extent of biofilm temporarily, plaque removal remains incomplete and continuous usage can even result in side effects. Here we tested argon plasma produced by kinpen09 as one option to inactivate microorganisms and to eliminate plaque. S. sanguinis biofilms cultivated in either the European Biofilm Reactor (EUREBI) or in 24 well plates were treated with argon plasma. In both test systems a homogeneous, good analyzable and stable biofilm was produced on the surface of titan plates within 72 h (>6,9 log10 CFU/ml). Despite the significantly more powerful biofilm production in EUREBI, the difference of 0.4 log10 CFU/ml between EUREBI and the 24 well plates was practically not relevant. For that reason both test models were equally qualified for the analysis of efficacy of cold atmospheric pressure plasma. We demonstrate a significant reduction of the biofilm compared to the control in both test models. After plasma application of 180 s the biofilm produced in EUREBI or in 24 well plates was decreased by 0.6 log10 CFU/ml or 0.5 log10 CFU/ml, respectively. In comparison to recently published studies analyzing the efficacy of kinpen09, S. sanguinis produces a hardly removable biofilm. Future investigations using reduced distances between plasma source and biofilm, various compositions of plasma and alternative plasma sources will contribute to further optimization of the efficacy against S. sanguinis biofilms.

Pilot-study on the influence of carrier gas and plasma application (open resp. delimited) modifications on physical plasma and its antimicrobial effect against Pseudomonas aeruginosa and Staphylococcus aureus

INTRODUCTION

Physical plasma is a promising new technology regarding its antimicrobial effects. This is especially accounting for treatment of bacterial infection of chronic wounds. Plasma can be generated with different carrier gases causing various biological effects. Screening of different carrier gases and plasma generation setups is therefore needed to find suitable compositions for highly effective antimicrobial plasma treatments and other applications.

METHOD

The plasma source used was a radio-frequency plasma jet which generates tissue tolerable plasma (TTP). The study compared the antimicrobial efficacy of air, argon, or helium plasma alone or admixed with 0.1%, 0.5%, and 1% oxygen against Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus). Treatment took place in an environmentally open and delimited system. Therefore, bacteria were plated on agar and treated with plasma in a punctiform manner. The resulting inhibition zones were measured and the reduction factors were calculated by colony counting, respectively.

RESULTS

For S. aureus and P. aeruginosa, inhibition zones and overall reduction of colony forming units (CFU) on the agar plate were observed while an accumulative reduction of CFU dominated for S. aureus. The highest antimicrobial effect was shown in form of an inhibition zone for argon plasma with 0.1% oxygen admixture for both species. S. aureus was more sensitive for helium plasma with >0.1% oxygen admixture compared to P. aeruginosa which in turn was more sensitive for argon plasma with and without oxygen. The efficacy of air plasma was very low in comparison to the other gases. The treatment in a closed system predominantly enhanced the antimicrobial effect. The effect intensity varied for each treatment time and gas mixtures.

DISCUSSION

As expected, the antimicrobial effect mostly increased when increasing oxygen admixture to the carrier gases. The variation in bacterial growth and inhibition after exposure to different plasma gas compositions could be due to a varying generation of reactive oxygen species or radiation.

CONCLUSION

The applied plasma in a "closed system" accumulates bactericidal plasma species and might increase antimicrobial efficacy in clinical settings as in wound management involving multi-drug resistant bacteria.