Application of Pinhole Plasma Jet Activated Water against Escherichia coli, Colletotrichum gloeosporioides, and Decontamination of Pesticide Residues on Chili (Capsicum annuum L.)

Plasma activated water (PAW) generated from pinhole plasma jet using gas mixtures of argon (Ar) and 2% oxygen (O2) was evaluated for pesticide degradation and microorganism decontamination (i.e., Escherichia coli and Colletotrichum gloeosporioides) in chili (Capsicum annuum L.). A flow rate of 10 L/min produced the highest concentration of hydrogen peroxide (H2O2) at 369 mg/L. Results showed that PAW treatment for 30 min and 60 min effectively degrades carbendazim and chlorpyrifos by about 57% and 54% in solution, respectively. In chili, carbendazim and chlorpyrifos were also decreased, to a major extent, by 80% and 65% after PAW treatment for 30 min and 60 min, respectively. E. coli populations were reduced by 1.18 Log CFU/mL and 2.8 Log CFU/g with PAW treatment for 60 min in suspension and chili, respectively. Moreover, 100% of inhibition of fungal spore germination was achieved with PAW treatment. Additionally, PAW treatment demonstrated significantly higher efficiency (p < 0.05) in controlling Anthracnose in chili by about 83% compared to other treatments

Improvement of Biological Properties of Natural Hemostatic Agent by Plasma Technology

The aim of this study was to evaluate the effect of non-thermal plasma treatment on the biological properties of a natural hemostatic agent. The results show that plasma treatment can enhance the biodegradability property of the hemostatic agent by increasing the degradation rate of the specimen up to 94.26% within 7 days. Furthermore, the plasma-treated specimen also exhibited good biocompatibility based on the cell viability test of the fibroblast cells. The cell growth and cell proliferation on this sample were found to be helpful for the wound healing process. With appropriate degradable and biocompatible properties, this modified agent could be beneficial for better control over bleeding during surgery. Research on the physical and mechanical properties are on to develop novel hemostatic products to match the requirements as far as biomedical applications are concerned

Effect of Water-Resistant Properties of Kraft Paper (KP) Using Sulfur Hexafluoride (SF₆) Plasma Coating

Sulfur hexafluoride (SF6) plasma at different pressures, powers, and times was used to treat Kraft paper (KP) to enhance its water resistance. The KP was treated with SF6 plasma from 20–300 mTorr of pressure at powers from 25–75 Watts and treatment times from 1–30 min at 13.56 MHz. The prepared papers were characterized by contact angle measurement and water absorption. The selected optimum condition for the plasma-treated KP was 200 mTorr at 50 Watts for 5 min. Advancement with the change in treatment times (3, 5, and 7 min) on the physical and mechanical properties, water resistance, and morphology of KP with SF6 plasma at 200 mTorr and 50 Watts was evaluated. The changes in the chemical compositions of the plasma-treated papers were analyzed with an XPS analysis. The treatment times of 0, 3, 5, and 7 min revealed fluorine/carbon (F/C) atomic concentration percentages at 0.00/72.70, 40.48/40.97, 40.18/37.95, and 45.72/39.48, respectively. The XPS spectra showed three newly raised peaks at 289.7~289.8, 291.5~291.7, and 293.4~293.6 eV in the 3, 5, and 7 min plasma-treated KPs belonging to the CF, CF2, and CF3 moieties. The 5 min plasma-treated paper promoted a better interaction between the SF6 plasma and the paper yielded by the F atoms. As the treatment time for the treated KPs increased, the contact angle, water absorption time, and Cobb test values increased. However, the thickness and tensile strength did not show remarkable changes. The SEM images revealed that, as the treatment time increased, the surface roughness of the plasma-treated KPs also increased, leading to improved water resistance properties. Overall, the SF6 plasma treatment modified the surface at the nano-layer range, creating super-hydrophobicity surfaces

Potential of Nonthermal Atmospheric-Pressure Dielectric Barrier Discharge Plasma for Inhibition of <i>Athelia rolfsii</i> Causing Southern Blight Disease in Lettuce

Athelia rolfsii is one of the most destructive and aggressive fungal pathogens worldwide and causes southern blight disease of lettuce. A nonthermal atmospheric-pressure dielectric barrier discharge (DBD) plasma has attracted interest as an alternative control method to chemical usage because of its antimicrobial activity. Exposure of A. rolfsii to DBD plasma for 5, 10, 15, and 20 min resulted in in vitro fungal inhibition of mycelial discs and sclerotia. The results showed that DBD plasma exposure for 10 min completely inhibited fungal growth of mycelial discs, whereas exposure for over 20 min was required to inhibit the hyphal growth of sclerotia. Scanning electron microscopy (SEM) observations of mycelia and sclerotia abnormalities revealed laceration and damage of both mycelia and sclerotia. In addition, disease incidence and severity were reduced in mycelial and sclerotia inoculation following DBD plasma exposure for 15 and 20 min, respectively, compared with the positive control. In conclusion, the DBD plasma demonstrates antifungal activity against A. rolfsii via inhibition of fungal growth and reduction in disease incidence and severity. Therefore, DBD plasma has the potential to be applied in controlling southern blight disease of lettuce

Gliding arc discharge non-thermal plasma for retardation of mango anthracnose

The effects of non-thermal plasma (NTP) using a gliding arc (GA) discharge was studied with harvested Nam Dok Mai mangoes to determine the rate of retardation of anthracnose disease (Colletotrichum gloeosporioides). Different fluxes of argon (Ar) gas (3–5 L/min) and treatment times (5–7 min) with NTP delayed mycelium growth as well as decreasing fungal spore survival and anthracnose severity. A GA discharge at 5 L/min Ar for 7 min had a significantly higher (p ≤ 0.05) inhibition of C. gloeosporioides mold growth on potato dextrose agar and mango fruit at 30 °C together with reducing the number of fungi spores in suspension. Hydroxyl radicals (OH ● ) together with hydrogen peroxide (H₂O₂) may be responsible for the suppression of the postharvest anthracnose disease with mangoes

Non-thermal plasma for elimination of pesticide residues in mango

The effects of non-thermal plasma (NTP) on elimination of pesticide residues and on quality changes of mango (cv. Nam Dok Mai) were investigated. Varied flow rate of Ar gas (2, 5 and 8 L/min) and time dependent degradations of chlorpyrifos and cypermethrin as a result of NTP treatments using a gliding arc (GA) discharge for 5 or 10 min were studied. Results showed that the NTP treatment for 5 min at 5 L/min Ar flow rate successfully decreased the concentrations of chorpyrifos by 74.0% and cypermetrin by 62.9%. There were significant (p ≤ 0.05) decreases in titratable acidity and total phenolic content and increases in carotenoid content for the treated mangoes. However, total soluble solid, color and texture parameters were not significantly different (p > 0.05). The emission signal of hydroxyl (OH) radicals at 309 nm was also obtained to monitor that the system was working properly

Plasma surface modification of two-component composite scaffolds consisting of 3D-printed and electrospun fiber components from biodegradable PLGA and PLCL

In this study, two-component, morphologically composite scaffolds consisting of a 3D-printed component and an electrospun fiber component were fabricated and treated with a nitrogen-argon (N2-Ar) plasma to enhance their surface properties. The 3D-printed component provided mechanical strength, while the electrospun fibrous component acted as a mimic to the extracellular matrix to improve cell-substrate interactions. Two biodegradable polyesters, poly(L-lactide-co-ε-caprolactone) (PLCL) and poly(L-lactide-co-glycolide) (PLGA), were used to create the scaffolds. The resulting 3D/E/N2-Ar scaffolds were characterized in terms of surface properties (morphology, chemical compositions, wettability, roughness, crystallinity), degradation, mechanical properties, and cell cytotoxicity, cell attachment and proliferation, LDH release and cell apoptosis. Results showed that the plasma treatment significantly increased the surface roughness, wettability, and hydrophilicity of the scaffolds. The 3D-printed component provided sufficient mechanical support, while the electrospun fiber component promoted cell attachment and proliferation. Following plasma treatment, the water contact angle of the scaffolds was greatly reduced from 124.0 ± 1.8° (PLCL) and 119.6 ± 1.4° (PLGA), to 0° and persisted even after 168 days. Human Schwann cells (SCs) showed excellent viability on both 3D/E/N2-Ar and 3D/E scaffolds were in excess of 95%. Cells cultivated on the 3D/E/N2-Ar scaffolds, with higher surface roughness, displayed significant increase in attachment and proliferation and a higher presence of healthy cells when compared with untreated 3D/E scaffolds. Both PLCL and PLGA scaffolds showed potential for use in biomedical applications. Although PLGA performed slightly better in terms of cell behavior, PLCL exhibited a slower degradation rate and higher tensile strain. These results demonstrate the potential of these designed scaffolds to support cell regeneration in clinically relevant devices such as nerve guide conduits and nerve protectant wraps