Effect Of Non-thermal Atmospheric Plasma Research Articles

Inhibitory effects of non-thermal atmospheric plasma on Yersinia enterocolitica and Staphylococcus aureus in the Korean traditional non-fermented kimchi “Geotjeori”

Food-borne bacteria have frequently been detected in kimchi, a representative and traditional fermented ethnic food of Korea. This study investigated the effect of atmospheric dielectric barrier discharge (DBD) plasma treatment (1.1 kV, 43 kHz, N2: 1.5 m/s, 5–60 min) on reduction of Yersinia enterocolitica and Staphylococcus aureus and on quality parameters in Geotjeroi, a non-fermented kimchi. A decrease of 0.12/0.09, 0.19/0.19, 0.34/0.45, 0.64/0.72, and 1.13/1.12 log10 CFU/g was observed by 5, 10, 20, 30, and 60 min of DBD plasma, respectively. D-value of 52.83 and 51.95 min was determined for Y. enterocolitica (R2 = 0.99) and S. aureus (R2 = 0.98) using the first order kinetics model. The quality parameters (pH, Brix, and hardness) were not significantly different (P > 0.05) between treated and untreated Geotjeori. Moreover, a decrease of >1 log10 CFU/g, for both bacteria was observed without any change in the quality of Geotjeori. These findings imply that DBD plasma treatment enhances Geotjeori safety and protects product from microbial risk.

Investigation of Fludioxonil Reduction Using Non-Thermal Atmospheric Plasma through Experimental Simulation

In this study, the effect of non-thermal atmospheric plasma (NTAP) treatment on the reduction of residual fludioxonil (C12H6F2N2O2, 4-(2,2-difluoro-1,3-benzodioxol-4-yl)-1H-pyrrole-3-carbonitrile) was investigated through experimental simulation. Fludioxonil is known for its high residual concentration on fruits and vegetables. To simulate residual fludioxonil reduction in the storage location prior to consumption of fruits or vegetables by consumers, we designed an experimental setup utilizing a gas distribution system and a cylindrical dielectric barrier discharge (DBD) plasma source. A cylindrical DBD plasma source was adopted to produce the plasma activated chemical species (O3). To evaluate the effect of plasma treatment on the reduction of residual fludioxonil, experiments were performed under three different conditions: varying concentrations and treatment times of O3, as well as the surface roughness of microscope slide glass. Based on the results, 10 min plasma treatment with an O3 concentration of 11.89 μL/L, which showed a 58.5% reduction rate, is recommended. The O3 concentration has a higher priority than the treatment time for reduction rates of residual fludioxonil.

Low-Dose Non-Thermal Atmospheric Plasma Promotes the Proliferation and Migration of Human Normal Skin Cells

(1) Background: The purpose of this study was to investigate the effects of low-dose non-thermal atmospheric plasma (NTP) on the proliferation and migration of human immortalized keratinocytes (HaCaT cells) and its molecular mechanisms. (2) Methods: The effects of NTP on HaCaT cells were detected by cell viability, wound healing assay, cell cycle, mitochondrial membrane potential detection, and western blot, and the role of reactive oxygen species (ROS) content in low-dose NTP was explored. (3) Results: Results showed that the proportion of cells in G1-S phase transition, cell migration ability, and the expression of Cyclin D1 and STAT3 reached the peak at 10 s treatment group, while the cell viability and the expression of PI3K, AKT, mTOR, ERK, WNT, and β-catenin proteins reached the peak at 15 s treatment group. (4) Conclusions: These results manifested that ROS produced by low-dose NTP promoted the proliferation of HaCaT cells by activating the PI3K/AKT/mTOR signaling pathway and also promoted the migration by activating the WNT/β-catenin signaling pathway. Therefore, these results will be useful for the application of low-dose NTP in the treatment of wound healing.

Effect of nonthermal atmospheric plasma on bond strength of composite resin using total-etch and self-etch adhesive systems.

The aim of this study was to assess the impact of nonthermal atmospheric plasma (NTAP) on the bond strength of composite resin following plasma application at different steps of dentin bonding in total-etch and self-etch adhesive systems. Ninety extracted third molars were taken, and the occlusal surfaces were removed until the exposure of the dentin. Samples were distributed into two main groups: Group T: total-etch adhesive system and Group S: self-etch adhesive system. Groups are further subdivided (n = 10) based on plasma application at different steps of dentin bonding. T1: surface etching with 37% phosphoric acid and bonding agent application. T2: plasma application and bonding agent application. T3: plasma application, etching, and bonding agent application. T4: etching, plasma application, and bonding agent application. T5: etching, plasma application, bonding agent application, and again plasma application. S1: self-etch bonding agent application. S2: plasma application and bonding agent application. S3: Bonding agent application and plasma application. S4: plasma application, bonding agent application, and again plasma application. For all the samples, composite resin buildup was done, and shear bond strength (SBS) was measured. The contact angle was measured at different steps of dental adhesive systems. Two-way analysis of variance and the post hoc Tukey's test were used for analysis, regarding P < 0.05 as statistically significant. Among all groups of total-etch and self-etch adhesives, Group T4 (48.81 Mpa) and Group S2 (36.59 Mpa), respectively, have demonstrated significantly greater bond strength values than the corresponding control groups. NTAP enhanced the composite resin's SBS when plasma treatment was done before bonding agent application and significantly reduced the contact angles of the distilled water.

Nonthermal Plasma Treatment Can Eliminate Sandblasting Procedure For Zirconia-Resin Cement Bonding.

To evaluate the effects of nonthermal atmospheric plasma (NTAP) treatment, alone or combined with sandblasting and/or primer application, on the bonding of zirconia ceramics to resin cement. Materıals and Methods: A total of 420 discs of Y-TZP (2 x 15 x 12 mm) were prepared and randomly divided into 10 groups according to surface treatment, as follows: Z (control), SB (sandblasting), Pr (primer), SBPr (sandblasting + primer), P (NTAP), SBP (sandblasting + NTAP), PrP (primer + NTAP), SBPrP (sandblasting + primer + NTAP), PPr (NTAP + primer), and SBPPr (sandblasting + NTAP + primer). After surface treatments, the surface roughness values were evaluated using a profilometer, and the contact angle measurements were performed using a goniometer. Surface characterizations of the groups were analyzed using scanning electron microscopy and x-ray photoelectron spectroscopy analyses. Shear bond strength tests were performed after adhesive cementation in 20 specimens per group, with half (n = 10) subjected to thermocycling (5,000 cycles, 5°C to 55°C). The failure mode was recorded by examining each specimen using a stereomicroscope. One-way and two-way ANOVA followed by Student-Newman-Keuls test (α = .05) were used to analyze the data statistically. Untreated zirconia surfaces (without sandblasting) were found to have a higher wettability and oxygen ratio after NTAP treatment. The clinical application order of NTAP is an important factor, and the best combination for bonding quality was NTAP treatment followed by primer application on untreated zirconia (group PPr), rather than on a sandblasted surface. Conclusıon: NTAP application may be a promising surface treatment method for adhesive cementation of zirconia ceramics as an alternative to sandblasting. To achieve strong adhesion, NTAP should be applied before primer aplication.

Effects of non-thermal atmospheric plasma on protein.

Currently, the advancement in non-thermal atmospheric plasma technology enables plasma treatments on some heat-sensitive targets, including biological substances, without unspecific damage caused by thermal effect. The significant effects of non-thermal atmospheric plasma modulating biological events have been demonstrated by considerable studies. Protein, one of the most important biomolecules, participates in the majority of the life-sustaining activities in all organisms, whose functions are derived from the diverse biochemical properties of amino acid compositions and four-tiered protein structure hierarchy. Therefore, the knowledge of how non-thermal atmospheric plasma affects protein greatly benefits the understanding and application of the non-thermal atmospheric plasma's effect in biological area. In this review, we summarize recent research progress on the effects of non-thermal atmospheric plasma, particularly its reactive species, on biochemical and biophysical characteristics of proteins at different structural levels that leads to their functional changes. Moreover, the physiological effects of non-thermal atmospheric plasma at cellular or organism level driven by the manipulations on protein and their relative application prospects are reviewed. Despite the exceptional application potential, the exploration of the non-thermal atmospheric plasma's effect on protein still confronts with difficulties due to the limited knowledge of the underlying mechanisms and the complexity of non-thermal atmospheric plasma operation systems, which requires further studies and standardization of non-thermal atmospheric plasma treatments.

Effect of nonthermal atmospheric plasma, grape seed extract, and bromelain on immediate bonding of composite to bleached and microabraded surfaces

Background:Tooth whitening procedures such as bleaching and microabrasion alters the enamel surface and thus reduce the composites’ bond strength. Hence, various surface treatments were introduced to overcome this problem.Aim:To assess the effect of nonthermal atmospheric plasma (NTAP), grape seed extract (GSE) and bromelain on the shear bond strength (SBS) of the composite after bleaching and microabrasion.Materials and Methods:Eighty extracted maxillary anterior teeth were distributed into two groups. Group 1: bleaching and Group 2: Microabrasion and further subdivided into four subgroups (n = 10) based on the form of surface treatment employed. Group A: no surface treatment, Group B: bromelain, Group C: GSE, Group D: NTAP. Composite resin was bonded to the labial surface and placed in artificial saliva for 24 h. SBS testing was done for all the samples.Statistical Analysis:Analysis was performed using two-way analysis of variance and post hoc Tukey's test with P < 0.05 considered statistically significant.Results:Group 1D revealed the highest bond strength (35.4 Mpa) and Group 1A showed the least bond strength values (15.7 Mpa). Among the bleaching groups, significant difference was observed between all the subgroups except Group 1A and 1B (P = 0.972). In microabrasion group, significant difference was observed between Group 2A and 2D (P = 0.0001), Group 2B and 2D (P = 0.0010), and Group 2C and 2D (P = 0.0001).Conclusions:Following bleaching, NTAP application and GSE significantly improved the SBS of composite resin. Application of NTAP to microabraded surfaces increased the bond strength of composite resin.

Evaluation of the protective effects of non-thermal atmospheric plasma on alveolar bone loss in experimental periodontitis.

The inhibition of bone destruction is one of the main goals of periodontitis treatment. The aim of this study was to investigate the protective effects of non-thermal atmospheric plasma (NTAP) on alveolar bone loss radiographically, histomorphometrically, and histologically in experimental periodontitis in rats. A total of twenty-eight rats were randomly divided into three groups: control group (CG) (n = 8), periodontitis group (PG) (n = 10), and NTAP group (NTAPG) (n = 10). In PG and NTAPG, experimental periodontitis was created with ligating. The kINPen 11 plasma jet was applied around the ligatured teeth in NTAPG. The samples from each group were radiographically assessed with microcomputed tomography (micro-CT); then, histological (presence of osteoclasts and inflammatory cells) and immunohistochemical (immunoreactive of OCN and ALP) findings were compared. The results revealed a significant increase in alveolar bone loss in the PG compared with CG and NTAPG (p < 0.05). Inflammation, alveolar resorption, and cement damage were reduced significantly in the group treated with NTAP compared to the PG (p < 0.05). Significantly higher levels of osteoclasts were detected in the PG in comparison with both CG and NTAPG (p < 0.05). The lowest osteocalcin and ALP values were determined in PG, and the differences between PG and both groups were also significant (p < 0.05). Within the limitations of the present study, we can say that NTAP may enhance the bone remodeling process by inhibiting inflammation and preventing alveolar bone destruction. NTAP has clinical potential for accelerating and treating periodontitis with the inflammatory response modulation, osteoblast differentiation, and alveolar bone loss reduction.

Effect of Non-thermal Atmospheric Plasma on Viability and Histamine-Producing Activity of Psychotrophic Bacteria in Mackerel Fillets.

Non-thermal atmospheric plasma (NTAP) has gained attention as a decontamination and shelf-life extension technology. In this study its effect on psychrotrophic histamine-producing bacteria (HPB) and histamine formation in fish stored at 0–5°C was evaluated. Mackerel filets were artificially inoculated with Morganella psychrotolerans and Photobacterium phosphoreum and exposed to NTAP to evaluate its effect on their viability and the histidine decarboxylase (HDC) activity in broth cultures and the accumulation of histamine in fish samples, stored on melting ice or at fridge temperature (5°C). NTAP treatment was made under wet conditions for 30 min, using a dielectric barrier discharge (DBD) reactor. The voltage output was characterized by a peak-to-peak value of 13.8 kV (fundamental frequency around 12.7 KHz). This treatment resulted in a significant reduction of the number of M. psychrotolerans and P. phosphoreum (≈3 log cfu/cm2) on skin samples that have been prewashed with surfactant (SDS) or SDS and lactic acid. A marked reduction of their histamine-producing potential was also observed in HDC broth incubated at either 20 or 5°C. Lower accumulation of histamine was observed in NTAP-treated mackerel filets that have been inoculated with M. psychrotolerans or P. phosphoreum and pre-washed with either normal saline or SDS solution (0.05% w/v) and stored at 5°C for 10 days. Mean histamine level in treated and control groups for the samples inoculated with either M. psychrotolerans or P. phosphoreum (≈5 log cfu/g) varied from 7 to 32 and from 49 to 66 μg/g, respectively. No synergistic effect of SDS was observed in the challenge test on meat samples. Any detectable amount of histamine was produced in the meat samples held at melting ice temperature (0–2°C) for 7 days. The effects of NTAP on the quality properties of mackerel’s filets were negligible, whereas its effect on the psychrotrophic HPB might be useful when time and environmental conditions are challenging for the cool-keeping capacity throughout the transport/storage period.

Effect of Non-Thermal Atmospheric Plasma on Micro-Tensile Bond Strength at Adhesive/Dentin Interface: A Systematic Review.

Objective: The objective of this review was to evaluate the effect of non-thermal atmospheric plasma (NTAP) on adhesives resin–dentin micro-tensile bond strength (μTBS) in previously published studies. Methods: Electronic search was conducted using the Medline, Cochrane library, and Scopus databases. The included studies were laboratory studies that investigated the effect of NTAP on adhesives μTBS to coronal dentin. Studies that evaluated the effect of NTAP on bond strength to indirect substrates, enamel or root dentin, were excluded. The methodological quality of included studies was assessed. Results: Thirteen studies were included in this systematic review. All the included studies were considered to have a medium risk of bias. NTAP significantly improved μTBS at 24 h or after short-term aging in five studies (38.5%) and both immediate and after long-term aging in 5 studies (38.5%). In two studies (15.4%), NTAP resulted in a short-term material-dependent effect that was not stable after long-term aging. Interestingly, in one study (7.7%), NTAP had a positive effect only in the etch-and-rinse (ER) mode after long-term aging. Conclusion: Within the limitations of this systematic review, NTAP application could enhance resin–dentin μTBS of ER adhesives or universal adhesives (UAs) applied in the ER mode. In the ER mode, the rewetting step after NTAP seems to be unnecessary. Because of the limited information currently available in the literature, further studies are required to evaluate the effect of the NTAP application on self-etch (SE) adhesives or UAs applied in the SE mode.

Effect of nonthermal atmospheric plasma on the shear bond strength of composite resin after using different tooth-whitening systems: An in vitro study.

Aim:We aimed to evaluate the effect of nonthermal atmospheric plasma (NTAP) on the bond strength of composite resin after using different tooth-whitening systems.Methods:Eighty maxillary central incisors (n = 80) were divided into two groups based on the tooth-whitening procedure used – Group 1: bleaching (Pola Office, USA), Group 2: microabrasion (Opalustre, Australia). The samples were subdivided into four groups depending on the surface treatments – Group A: control (no surface treatment), Group B: plasma, Group C: antioxidant (sodium ascorbate), and Group D: buffering agent (sodium bicarbonate). After the surface treatments, the specimens were stored in artificial saliva for 24 h and composite resin was bonded to the labial surface of the teeth perpendicular to the long axis. The samples were then subjected to shear bond strength test under the universal testing machine.Statistical Analysis:The results received from shear bond strength analysis were subjected to statistical analysis using a two-way ANOVA test, independent t-test, and Tukey's multiple post hoc tests. The P value set was <0.05.Results:The highest mean bond strength value was seen in Group 2B (NTAP treatment after microabrasion) followed by Group 1B (NTAP treatment after bleaching). Mean shear bond strength values have suggested a statistically significant difference between all the other groups (P < 0.05) except between Groups 1A, 2A and 1D, 2D.Conclusions:Within the limitations of the current in vitro study, bleaching and microabrasion followed by surface treatment using NTAP showed the highest bond strength than other groups.

Effect of nonthermal atmospheric plasma on the push-out bond strength of epoxy resin-based and bioceramic root canal sealers: An in vitro study.

Aim:The aim of this study was to evaluate the effect of nonthermal atmospheric plasma (NTAP) on the bond strength of epoxy resin-based and bioceramic root canal sealers.Materials and Methods:Freshly extracted forty (n = 40) single-rooted mandibular premolar teeth were divided into four groups (n = 10) based on the sealer used and NTAP application – Group 1: Epoxy resin-based sealer (AH Plus) without NTAP application, Group 2: Epoxy resin-based sealer (AH Plus) with NTAP application for 30 s, Group 3: Bioceramic sealer (BioRoot RCS) without NTAP application, and Group 4: Bioceramic sealer (BioRoot RCS) with NTAP application for 30 s. After NTAP application in Groups 2 and 4, all the samples were obturated using sealers according to their grouping protocols. Two-millimeter slices were obtained from each sample using hard tissue microtome, which were subjected to push-out bond strength (PBS) under the universal testing machine. Data were subjected to statistical analysis using one-way analysis of variance followed by the Post hoc tukey test. The level of statistical significance was set at P < 0.05.Results:The PBS values were observed to be significantly higher in bioceramic sealer with NTAP application (Group 4) followed by epoxy resin-based sealer with NTAP application (Group 2).Conclusion:NTAP application enhanced the PBS of bioceramic (BioRoot RCS) and epoxy resin-based (AH Plus) sealers compared to their control groups.

Effect of Non-Thermal Atmospheric Plasma on Food-Borne Bacterial Pathogens on Ready-to Eat Foods: Morphological and Physico-Chemical Changes Occurring on the Cellular Envelopes.

Currently, there is a need for new technological interventions to guarantee the microbiological safety of ready-to-eat (RTE) foods. Non-thermal atmospheric plasma (NTAP) has emerged as a promising strategy for inactivating microorganisms on thermo-sensitive foods, and the elucidation of its mechanisms of action will aid the rational optimization and industrial implementation of this technology for potential applications in the food industry. In this study, the effectiveness of NTAP for inactivating strains of Salmonella Enteritidis, Salmonella Typhimurium, Escherichia coli O157:H7 and Listeria monocytogenes contaminating the surface of different sliced RTE foods (“chorizo”, salami, bacon, smoked salmon, tofu and apple) was investigated. In addition, to further assess the bacterial inactivation mechanisms of NTAP, the morphological and physico-chemical damages in bacterial cells were analyzed. NTAP was effective for the surface decontamination of all products tested and, especially, of cut apple, where the microbial populations were reduced between 1.3 and 1.8 log units for the two Salmonella strains and E. coli O157: H7, respectively, after 15 min of exposure. In the rest of foods, no significant differences in the lethality obtained for the E. coli O157:H7 strain were observed, with inactivation rates of between 0.6 and 0.9 log cycles after a 15-min treatment. On the other hand, the strains from the rest of pathogenic microorganisms studied were extremely resistant on tofu, where barely 0.2–0.5 log units of inactivation were achieved after 15 min of plasma exposure. S. Enteritidis cells treated for 10 min exhibited noticeable morphological and structural changes, as observed by transmission electron microscopy, which were accompanied by a loss in membrane integrity, with an increased leakage of intracellular components and uptake of propidium iodide and marked changes in regions of their FTIR spectra indicating major alterations of the cell wall components. Overall, this indicates that loss of viability was likely caused for this microorganism by a significant damage in the cellular envelopes. However, the plasma-treated cells of L. monocytogenes did not show such obvious changes in morphology, and exhibited less marked effects on the integrity of their cytoplasmic membrane, what suggests that the death of this pathogenic microorganism upon NTAP exposure is more likely to occur as a consequence of damages in other cellular targets.

Antibacterial effect of non-thermal atmospheric plasma against soft rot bacteria on paprika

Non-thermal atmospheric plasma (NTAP) was examined for its antibacterial activity of Pectobacterium carotovorum subsp. carotovorum on paprika. Bacterial populations were completely inhibited in response to NTAP treatment at 1000 W for 30 s–90 s. To further assess the mechanisms that NTAP treatment inactivates bacterial populations, the morphology and membrane damage of bacterial cells were analyzed. The bacterial cells treated with NTAP for 90 s at 1000 W exhibited noticeable disruption, hollowness, and roughness on the outer membrane surfaces accompanied by severe loss in membrane integrity, which indicates that cell death was caused by this significant membrane damage. NTAP treatment for 90 s induced DNA leakage from the Pcc membrane and caused significant DNA damage as assessed by qRT-PCR. On in vivo test, NTAP-treated paprika showed antibacterial effects by 40% compared to untreated samples. Our findings suggest the high applicability of NTAP in controlling postharvest bacteria and ensuring the preservation of paprika.

Prevention of Peritoneal Adhesions by Non-Thermal Dielectric Barrier Discharge Plasma Treatment on Mouse Model: A Proof of Concept Study

Purposes: Formation of peritoneal adhesions is a common consequence of abdominopelvic surgeries and remarkably increases the mortality and morbidity. Moreover, peritoneal adhesions linked to chronic abdominopelvic pain and infertility in women. Various attempts for prevention of peritoneal adhesions were reported. However, these methods either remain insufficient to prevent formation of peritoneal adhesions or carry some practical limitations and thus, there is a need for novel techniques that could effectively decrease the formation of peritoneal adhesions. The aim of the present prospective, randomized, controlled, and single blinded study was to evaluate the effect of non-thermal atmospheric plasma (NTAP) treatment on prevention of peritoneal adhesions. Materials and Methods: Sixteen male CD-1 mice were randomly divided into two groups: control and plasma. Excisional and abrasion adhesion models were generated on the peritoneal side wall and cecum, respectively. Ten days after creating adhesion models, mice were sacrificed and adhesion formations were evaluated macroscopically using Knightly’s and Linsky’s grading systems to assess the intensity and extent of adhesions, respectively. Zühlke’s grading system was used for microscopic assessment of adhesions. Results: The mean scores for peritoneum and cecum in control group according to Knightly’s grading system were determined as 3.3 and 2.6, respectively. In NTAP-treated group, Knightly’s score was determined as 1.6 and 0.5 for peritoneum and cecum, respectively. NTAP treatment reduced Linsky’s score from 3.8 to 1.3 and 2.1 to 1.1 on peritoneum and cecum. Finally, in microscopic evaluation, NTAP treatment reduced Zühlke’s score from 3.4 to 1.5 and 2.6 to 1.3 for peritoneum and cecum, respectively. Conclusions: The results of the present proof of concept study suggest that NTAP could be a novel method to reduce and/or prevent the formation of peritoneal adhesions after abdominopelvic surgeries.

Nonthermal atmospheric plasma enhances myoblast differentiation by eliciting STAT3 phosphorylation.

The use of nonthermal atmospheric plasma (NTP) in the biomedical field has recently expanded into cell death induction in cancer, infection prevention, inflammation treatment, and wound-healing enhancement. NTP has been demonstrated to enhance skin and muscle regeneration, but its effects on tissue regeneration, following deep tissue or muscle damage, remains underinvestigated. In this study, we determined the effects of NTP on muscle differentiation and the mechanisms of NTP's contribution to differentiation and regeneration. NTP treatment enhanced cell differentiation in primary normal human skeletal muscle myoblast cells and increased the relative expression of mRNA levels of MyoD which is one of the earliest markers of myogenic commitment, and myogenin, which are important transcription factors required for myogenic differentiation. Furthermore, NTP treatment induced increases in the levels of myosin heavy chain, a differentiated muscle-specific protein, and in myotube formation of myoblasts. We observed that signal transducer and activator of transcription 3 (STAT3) activation induced by NTP treatment affects the myogenic differentiation. In addition, STAT3 phosphorylation was also enhanced by NTP treatment in injured animal muscle. These findings indicate that NTP could enhance musculoskeletal differentiation by acting as an external stimulus for myoblast differentiation, suggesting its treatment potential in promoting regeneration of damaged muscle.-Park, J. K., Kim, Y. S., Kang, S. U., Lee, Y. S., Won, H.-R., Kim, C.-H. Nonthermal atmospheric plasma enhances myoblast differentiation by eliciting STAT3 phosphorylation.

Antifungal effect of non-thermal atmospheric plasma and its application for control of postharvest Fusarium oxysporum decay of paprika

Non-thermal atmospheric plasma (NTAP) has been shown to be effective for controlling postharvest fungi in vitro, but little is known regarding its mode of action, fungal response to NTAP, and the effect of its application on fresh produce. NTAP was evaluated for its in vitro and in vivo antifungal activity against Fusarium oxysporum on paprika. NTAP treatment resulted in complete inhibition of mycelial growth and spore germination of F. oxysporum, particularly at 1000 W for 90 s. To further investigate the mechanisms by which NTAP inhibits fungal growth, the membrane integrity and the expression of a membrane-related gene (SHO1) were tested, which indicated that NTAP treatment results in the loss of plasma membrane integrity and up-regulation SHO1. In vivo assays demonstrated that NTAP treatment for 90 s inhibited the growth of this fungal pathogens by approximately 50%. Color and hardness parameters had no significant changes during 14 days of storage after NTAP treatment. The mechanisms by which NTAP treatment decreased fungal growth on paprika were directly associated with the disruption of the fungal cell membrane. These findings suggest that application of NTAP as an antifungal is an effective approach for preserving paprika.

The effect of non-thermal atmospheric plasma on the production and activity of recombinant phytase enzyme

Atmospheric pressure cold plasma (ACP) is introduced as a useful tool in a variety of biological applications. Proteins are the most abundant macromolecules in living systems with a central role in all biological processes. These organic molecules are modified by ACP exposure that is responsible for many of ACP’s biological effects. This study evaluated the effect of ACP on the production of recombinant phytase in yeast Pichia pastoris (P. pastoris) as well as the structure and function of the phytase enzyme. The results indicated that yeast cells treated with ACP, directly or indirectly, produced higher amounts of recombinant phytase, which was associated with the time of ACP treatment. The exposure of commercial phytase solution with ACP caused a significant increase in the enzyme activity (125%) after 4 hours. Evaluation of the phytase solution by far- and near-UV circular dichroism (CD) and fluorescence analysis indicated that this protein maintained its secondary structure when exposed to ACP while the tertiary structure was slightly unfolded. The effects of heat and H2O2 on the phytase structure and function were compared with the effect of ACP treatment. The modification of Cys, Tyr and Trp amino acids upon reactive oxygen/nitrogen spices was simulated using a molecular dynamics approach. RMSF and RMSD analysis suggested that this structural alteration occurs owing to changes made by reactive species in accessible amino acids.

Effects of non-thermal atmospheric plasma treatment on dentin wetting and surface free energy for application of universal adhesives

The study aims to evaluate the effects of non-thermal atmospheric plasma (NTAP) treatments on dentin wetting and surface free energy (SFE) and compare the effects of NTAP treatment, etch-and-rinse, and self-etch protocols for application of universal adhesives. Mid-coronal dentin of intact third molars was used to measure contact angles of distilled water, ethylene-glycol, and diiodomethane and calculate SFE following different NTAP preset treatments (feeding gas consisting of pure He, He + 1% O2, He + 1.5% O2), power input (1 or 3W), and tip-to-surface distance (2, 4, or 8mm). Contact angles of reference liquids and SFE of dentin following He + 1.5% O2 at 3-W and 4-mm treatment was compared to phosphoric acid etching. Contact angles of Single Bond Universal (SBU; 3M ESPE) and Clearfil Universal Bond (CUB; Kuraray Noritake) were measured following NTAP, etch-and-rinse, and self-etch protocols. NTAP significantly reduced contact angles of reference liquids and increased dentin SFE compared to untreated dentin (p< 0.05). O2 intensified the effect of He NTAP (p< 0.05). NTAP and phosphoric acid increased dentin polarity and Lewis base surface characteristics. Phosphoric acid increased contact angles of adhesives compared to the self-etch protocol (p< 0.05). NTAP resulted in lower adhesive contact angles than phosphoric acid, the difference being statistically significant for CUB (p< 0.05). Compared to the self-etch protocol, NTAP slightly reduced CUB contact angle but not that of SBU (p> 0.05). He NTAP with and without O2 increased dentin wetting and SFE, surpassing the effect of phosphoric acid and lowering adhesive contact angles. NTAP produced no apparent micro-morphological changes on dentin surface comparable to acid etching. NTAP treatment of dentin prior to adhesive application increases dentin wetting and surface free energy facilitating better adhesive distribution on dentin surface compared to phosphoric acid etching and similar to the "self-etch" application protocol.

Antimicrobial Effect of Non-Thermal Atmospheric Plasma on Streptococcus Mutans -The Key Cariogenic Microorganism in Plaque Biofilm

Background: To evaluate the antimicrobial effect of non-thermal atmospheric plasma on mutans biofilms. Materials: A 100 µl culture of Streptococcus mutans poured into two 120 well flat base microtiter plates, allowed to adhere and incubated overnight using brain heart infusion (BHI). These 120 wells were grouped into four groups, group A-helium treated, group B-plasma treated, group C- chlorohexidine treated and group D-control group (untreated group) with a group size of 30 wells per group. Triphenyl tetrazolium chloride (TTC) essay & Colony Forming Units (CFU) counting was done to check the viability & survival of streptococcus mutans biofilms. Results: The results showed that there was a significant difference in the mean optical density (OD) among the four groups (p<0.001). Post-hoc analysis revealed that untreated samples and Helium had significantly higher mean OD than plasma and chlorhexidine groups. A similar result was also seen using the survival essay by CFU counting. Conclusion: Plasma utilizes the air from the atmosphere, thus rendering plasma a better reach in the oral cavity. This property of plasma can be efficiently used to neutralize Streptococcus mutans biofilms in the oral cavity.