Min Of Plasma Treatment Research Articles

Preventing thermal aggregation of ovalbumin through dielectric-barrier discharge plasma treatment and enhancing its emulsification properties

The impact of Dielectric-Barrier Discharge (DBD) plasma treatment on the prevention of heat-induced aggregation of Ovalbumin (OVA) and improvement in emulsification properties was investigated. Results highlighted the effective inhibition of thermal aggregation of OVA following exposure to plasma. Structural analysis revealed that the plasma-induced oxidation of sulfhydryl and intermolecular disulfide bonds played a pivotal role in inhibiting the thermal aggregation, considered by Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE), multiplies spectroscopy, and analysis of dynamic exchange of sulfhydryl-disulfide bonds. Meanwhile, the oxidation of exposed hydrophobic sites due to plasma treatment resulted in the transformation of the OVA molecule's surface from hydrophobic to hydrophilic, contributing significantly to the aggregation inhibition. Additionally, compared to an untreated sample of OVA, almost one-fold increase in emulsifying ability (EAI) and 1.5-fold in emulsifying stability (ESI) was observed after 4 min of plasma treatment. These findings demonstrated that plasma treatment not only enhanced the thermal stability of OVA, but also improved its emulsification properties.

Enhancing Essential Oil Extraction from Lavandin Grosso Flowers via Plasma Treatment.

This study explores the impact of plasma treatment on Lavandin Grosso flowers and its influence on the extraction of essential oils (EOs) via hydrodistillation. Short plasma treatment times enhance the yield of EO extraction from 3.19% in untreated samples to 3.44%, corresponding to 1 min of plasma treatment, while longer treatment times (10 min) show diminishing returns to 3.07% of yield extraction. Chemical characterization (GC/MS and ATR-FTIR) indicates that plasma treatments do not significantly alter the chemical composition of the extracted EOs, preserving their aromatic qualities. Investigations into plasma-surface interactions reveal changes at the nanometer level, with XPS confirming alterations in the surface chemistry of Lavandin Grosso flowers by reducing surface carbon and increasing oxygen content, ultimately resulting in an increased presence of hydrophilic groups. The presence of hydrophilic groups enhances the interaction between the surface membrane of the glandular trichomes on Lavandin Grosso flowers and water vapor, consequently increasing the extraction of EOs. Furthermore, microscopic SEM examinations demonstrate that plasma treatments do not affect the morphology of glandular trichomes, emphasizing that surface modifications primarily occur at the nanoscale. This study underscores the potential of plasma technology as a tool to enhance EO yields from botanical sources while maintaining their chemical integrity.

Reduction of antigenicity and emulsibility improvement of ovalbumin by dielectric-barrier discharge plasma treatment induced structure modification

The effects of Dielectric-Barrier Discharge (DBD) plasma treatment (40 kV, 1–4 min) on the structure, antigenicity and emulsibility of ovalbumin (OVA) were investigated. Plasma-induced structural changes of OVA were determined by SDS-PAGE, multi-spectroscopic, and LC-MS/MS analysis. Meanwhile, the reduction in antigenicity of OVA was evaluated by western blotting (WB) and enzyme-linked immunosorbent assay (ELISA) analysis. The results indicated effective elimination of the antigenicity of OVA was achieved after 4 min of plasma treatment. The immunoglobulin E (IgE) binding capacity of OVA was notably reduced by 90.80%, as evidenced by WB and ELISA analysis. Plasma-mediated oxidation led to the unfolding of OVA's structure, resulting in alterations to its conformational epitope, and the partial destruction of linear epitopes through polypeptide chain cleavage, thus contributing to the reduction in antigenicity. These findings were supported by the results of SDS-PAGE, multi-spectroscopic, and LC-MS/MS analysis. Furthermore, a significant increase (53%) in emulsifying ability and a one-fold improvement in emulsifying stability of OVA were achieved after 4 min of plasma treatment. The current study confirms that DBD plasma treatment not only reduces the allergenicity of OVA but also enhance its emulsibility through structural modification.

Plasma-induced nanogap narrowing and morphological transformation in gold nanoparticle assemblies.

The plasmonic properties of gold nanoparticle (AuNP) assemblies are critically influenced by the nanogaps between particles. Here, we demonstrate that plasma treatment effectively narrows these nanogaps and ultimately merges the nanoparticles. This process induces a sequential redshift, weakening, broadening, and an eventual blueshift of the plasmon coupling peak in UV-vis spectra, indicating transitions from classical to quantum regimes and finally to contact modes. Surface-enhanced Raman spectroscopy reveals an initial increase in intensity as the nanogaps narrow, followed by a decline as linker molecules are removed. Transmission electron microscopy images further show significant deformation of AuNPs after 5 min of plasma treatment. Based on these combined observations, we propose that the oxidative desorption of thiol linkers causes the collapse of self-assembled monolayers, leading to the gradual narrowing of nanogaps and eventual particle fusion. This plasma-induced transformation also enables the creation of novel AuNP shapes, such as nano-snowmen and particles with protruding morphologies, by merging heterodimers or core-satellite structures. Our findings not only deepen the understanding of plasma effects on nanoparticle assemblies but also expand the utility of plasma treatment for controlling nanogap distances and fabricating exotic nanoparticle shapes.

Multiple chemical warfare agent simulant decontamination by self-driven microplasma

Low-temperature plasma is a green and high-efficiency technology for chemical warfare agent (CWA) decontamination. However, traditional plasma devices suffer from the problems of high-power composition and large power-supply size, which limit their practical applications. In this paper, a self-driven microplasma decontamination system, induced by a dielectric-dielectric rotary triboelectric nanogenerator (dd-rTENG), was innovatively proposed for the decontamination of CWA simulants. The microplasma was characterized via electrical measurements, optical emission spectra and ozone concentration detection. With an output voltage of −3460 V, the dd-rTENG can successfully excite microplasma in air. Reactive species, such as OH, O(1D), H α and O3 were detected. With input average power of 0.116 W, the decontamination rate of 2-chloroethyl ethyl sulfide reached 100% within 3 min of plasma treatment, while the decontamination rates of malathion and dimethyl methylphosphonate reached (65.92 ± 1.65)% and (60.88 ± 1.92)% after 7 min of plasma treatment, respectively. In addition, the decontamination rates gradually decreased with the increase in the simulant concentrations. Typical products were identified and analyzed. This study demonstrates the broad spectrum and feasibility of the dd-rTENG-microplasma for CWA elimination, which provides significant guidance for their practical applications in the future.

Effects of Cold Plasma Treatment on Physical Modification and Endogenous Hormone Regulation in Enhancing Seed Germination and Radicle Growth of Mung Bean

This study investigated the effects of plasma duration and different reactive species ratios of cold atmospheric-pressure plasma treatment on both physical and endogenous hormone changes in enhancing the germination and growth of mung bean seeds. Seed germination and sprout stem length were significantly enhanced after plasma treatment. The germination rate increased eleven times after 12 h, while the radicles’ length increased ~3 times after 96 h with optimal plasma treatment parameters. SEM images showed that the plasmas directly induced gradual changes in the seed coating, including deformed and shrunken epidermis, and cracks with sizes varying from 0.2 to 1.5 µm after 4 min of plasma treatment. Water contact angle was reduced from 73° with untreated seed to almost 0° with 4 min treated seed. These effects could lead to better water absorption on the surface of treated seeds. We found that a plasma energy dosage of 0.08 Wh per seed and NO concentration between 20–95 ppm were the optimal enhancement conditions. We also showed that, for the first time, through delicate extraction, separation, and quantification processes, NO-induced upregulation of the natural growth hormone gibberellic acid could be the dominant phytochemistry pathway responsible for the enhancement effect.

Atmospheric pressure pin-to-plate cold plasma modification of high methoxyl apple pectin: Impact on functional properties

Modification of hydrocolloids by employing “green” processes such as cold plasma has gained attention in recent times. Apple pectin is a highly branched pectin, which leads to a low emulsification capacity. This study aims to understand the effect of cold plasma on the structural and functional properties of pectin, ranging from emulsification to antioxidant properties. In this study, atmospheric pressure cold plasma (230 V|3–15 min) was used for the modification of apple pectin (Degree of esterification (DE)∼68%). The viscosity-average-molecular weight decreased from 160677.4 to 98352.3 g mol −1 within 6 min of plasma treatment. A decrease in DE from 68 to 54% was observed after 15 min of treatment. An increase in galacturonic acid from 0.653 to 0.816 g g −1 and reducing sugars from 0.243 to 1.134% was noted after 15 min of treatment. The highest amount of unsaturated GalA residues (2.36 mmol/g) was formed after 12 min of treatment. The Ca 2+ sensitivity of the acid-sugar-pectin gels increased from 22.2 to 65.3 mPa s after 15 min of treatment. An increase in the whiteness index and a decrease in flow properties of the pectin powder were observed with the increasing duration of the treatment. This was well-evidenced in the Hausner's and Carr's indices, which increased from 1.23 to 1.48 and 0.24 to 0.35, respectively after 12 min of treatment. Prolonged treatments (>9min) negatively impacted emulsion stability. The DPPH radical scavenging activity and reducing power of pectin increased with the duration of plasma treatments for low concentrations of pectin (0.5–1.5%). The maximum DPPH radical scavenging activity (26.11%) was observed for 2% pectin dispersions, which were made from 12 min-plasma modified pectin. The future course of work can include the exploration of advanced applications of plasma-treated pectin in food matrices. • Cold plasma is a “green” method of pectin modification. • A decrease in degree of esterification and an increase in reducing sugars was observed. • Plasma modification decreased the viscosity and textural properties of pectin-sugar-acid gels. • An increase in emulsifying, foaming and antioxidant properties after the plasma treatment was identified.

Plasma Promotes Fungal Cellulase Production by Regulating the Levels of Intracellular NO and Ca2.

For the industrial-scale production of useful enzymes by microorganisms, technological development is required for overcoming a technical bottleneck represented by poor efficiency in the induction of enzyme gene expression and secretion. In this study, we evaluated the potential of a non-thermal atmospheric pressure plasma jet to improve the production efficiency of cellulolytic enzymes in Neurospora crassa, a filamentous fungus. The total activity of cellulolytic enzymes and protein concentration were significantly increased (1.1~1.2 times) in media containing Avicel 24–72 h after 2 and 5 min of plasma treatment. The mRNA levels of four cellulolytic enzymes in fungal hyphae grown in media with Avicel were significantly increased (1.3~17 times) 2–4 h after a 5 min of plasma treatment. The levels of intracellular NO and Ca2+ were increased in plasma-treated fungal hyphae grown in Avicel media after 48 h, and the removal of intracellular NO decreased the activity of cellulolytic enzymes in media and the level of vesicles in fungal hyphae. Our data suggest that plasma treatment can promote the transcription and secretion of cellulolytic enzymes into the culture media in the presence of Avicel (induction condition) by enhancing the intracellular level of NO and Ca2+.

Enhanced antibacterial activity of ZnO-PMMA nanocomposites by selective plasma etching in atmospheric pressure

We present an alternative route to enhance antibacterial activity of polymer matrix nanocomposites that incorporate biocidal nanomaterials, using open-air atmospheric pressure plasma etching. We applied He/O2 discharges to rapidly remove the upper organic layers of ZnO -PMMA nanocomposite coatings, thus increasing the surface concentration of ZnO. To quantify the ZnO concentration from SEM images on the surface of the nanocomposite material, we developed and employed a new nanometrology method based on local variances of pixel luminosities and found a rapid increase of surface fraction up to 30% for the first 2 min of plasma treatment. Plasma etching resulted in enhanced antibacterial activity against Gram-negative E. coli cells after 4 h incubation under dynamic conditions. The results revealed an almost exponential drop of bacterial concentration with ZnO surface fraction, thus confirming the direct correlation of antibacterial activity with the interfacial area of the biocidal nanomaterial.

Nitrogen-Doped Ti3C2Tx MXene Induced by Plasma Treatment with Enhanced Microwave Absorption Properties.

Ti3C2Tx has microwave absorption (MA) properties due to its dielectric loss, but the absence of magnetic loss capability of pure Ti3C2Tx causes unmatched impedance and unsatisfied MA performance. Modification of Ti3C2Tx with magnetic particles is an effective way to introduce the magnetic loss mechanism. However, these modified Ti3C2Tx particles have higher density and require complicated fabrication processes, restricting the industrial production and functional applications. Here, a low-temperature and simple method of radio-frequency N2 plasma treatment was adopted to modify Ti3C2Tx with N. More interestingly, the N-doped Ti3C2Tx flakes demonstrated magnetic properties and thus exhibited drastically enhanced MA properties. The minimum reflection loss (RLmin) of -59.20 dB at 10.56 GHz was achieved in N-doped Ti3C2Tx products after only 3 min of plasma treatment, remarkably higher than RLmin of -11.07 dB at 7.92 GHz for the pristine Ti3C2Tx. The main mechanism is due to the combination of dielectric loss, magnetic loss, and the good impedance matching in the N-doped Ti3C2Tx. Further prolonging the nitriding time induces much desorption of -F and the formation of TiO2, thus deteriorating the impedance matching and the MA properties.

Oxidation induced by dielectric barrier discharge (DBD) plasma treatment reduces IgG/IgE binding capacity and improves the functionality of glycinin

The effect of dielectric barrier discharge (DBD) plasma treatment times from 2 to 5 min at 40 kV on IgG/IgE binding capacity and functionality of soybean glycinin was examined. A substantial reduction in the binding capacity (91.64% for IgG and 81.49% for IgE) was obtained after 5 min of plasma treatment, as determined by western-blot and ELISA analyses. Further studies demonstrated that the elimination of antigenicity and allergenicity of glycinin was directly related to plasma-induced structural changes on two aspects. A conformational alteration caused by oxidation of peptide bond amino groups, accompanied with an oxidation of Trp, Tyr, and Phe amino acid residues, which was confirmed by surface hydrophobicity, multi-spectroscopic analysis, and amino acid analysis. The cleavage of polypeptide chains inevitably partially diminished the linear epitopes, resulting in a primary decline in IgG/IgE binding capacity. Additionally, an increase in the solubility from 10.78 ± 0.35 to 65.96 ± 1.86% and significant increase in the emulsifying ability from 21.08 ± 2.64 to 160.29 ± 4.12 m2/g were observed after treatment of the plasma for 2 min. The present results confirm the potential use of DBD for the production of hypoallergenic soy protein-based products and improving their technical functions such as solubility and emulsifying ability.

The Feasibility Study of Plasma-activated Water as a Physical Therapy to Induce Apoptosis in Melanoma Cancer Cells In-vitro.

Low-temperature plasma (LTP) has demonstrated great potential in biomedicine, especially in cancer therapy in-vivo and in-vitro. Plasma activated water (PAW) as an indirect plasma therapy is a significant source of reactive oxygen and nitrogen species (RONS) which play an important role in apoptosis induction in cancer cells. In this study, Helium (He) plasma jet operating in 0.75 W and 20 kHz as dissipated power and frequency, respectively, is used as the cold plasma source. The electrical, thermal, and spectroscopic properties of (He) plasma jet and pH as well as the conductivity and temperature of PAW samples, are investigated. The concentration of hydrogen peroxide (H2O2), nitrite (NO2-) and nitrate (NO-3), which are produced in water as long-lived anticancer RONS, was measured 471.6, 7.9 and 93.5 μM, respectively after 6 min of plasma treatment. Alamar Blue and flow cytometry assays were employed to investigate the B16F10 cancer metabolic activity and apoptosis. These data support that cold atmospheric plasma (CAP) can produce a certain concentration of anti-cancer agents in water and induce apoptosis in melanoma cancer cells due to RONSs via activating the caspase 3 pathway.

The role of cold atmospheric plasma (CAP) in the control of biofilms on titanium surfaces: A Literature review

Aim: Cold atmospheric plasma (CAP) is frequently used for the sterilization of biomaterials in the field of dentistry. The aim of this narrative review is to present the role of CAP in the control of biofilms on titanium surfaces. Materials and Methods: The PubMed, Scopus, and WOS databases were searched to identify scientific articles published between 2010 and 2020, with the keywords “biofilm,” “cold atmospheric temperature,” and “titanium,” using the logical operators AND and OR. Results: We found 8 articles in PubMed, 11 in Scopus, and 10 in WOS, including review articles and original studies, among others. All the articles were selected by two independent reviewers according to the eligibility criteria. Conclusions: Despite the restrictions of this review, CAP seems to have an effect on titanium surfaces in the oral area. Studies have shown that bacterial biofilms become inactive after 3 min of plasma treatment.

Effect of oxygen plasma treatment on the nanofiltration performance of reduced graphene oxide/cellulose nanofiber composite membranes

Graphene based nanosheets have been widely used as building blocks for fabrication of superior separation membrane for water processing. In particular, membranes made of reduced graphene oxide (rGO) show better stability compared with graphene oxide (GO). However, densely stacked of rGO often results in low water flux. In this study, cellulose nanofibers (CNFs) were incorporated into the rGO laminates by vacuum filtration of dilute GO/CNF solution and thermal reduction at 150 °C for 1.5 h. The resulting rGO/CNF membrane was treated with oxygen plasma for 1–4 min to create nanopores on the membrane surface for the purpose of enhancing nanofiltration performance. The results showed that the optimum membrane performance was obtained by using the equal amount of GO (31.83 mg m-2) and CNFs accompanied by 3 min of plasma treatment, exhibiting a pure water permeance of 37.2 ± 3.9 L m-2 h-1 bar-1 maintaining a rejection above 90% for Acid Fuchsin (1.2×1.1 nm), Rose Bengal (1.5×1.2 nm) and Brilliant Blue (2.2×1.7 nm).

PLASMA-ASSISTED ADVANCED OXIDATION PROCESS AND NOVEL MATERIALS FOR WATER AND WASTEWATER TREATMENT

The rapid growth in world population brings with it the need for improvement in the current technology for water purification, in order to provide adequate potable water to everyone. The plasma-based advanced oxidation process (AOP) is one of the most widely studied and best developed processes owing to its environmental compatibility, simple structure, efficiencies and ease of operation. In this study, a plasma-based AOP was stably generated using contact non-equilibrium low-temperature plasma and plasma synthesized composite nanomaterials (TiO2/Ag NPs) for water and wastewater purification. The degradation efficiency of the pollutants was determined by UV–Vis absorption spectroscopy. It was found that, due to the simultaneous production of highly reactive species, plasmas can efficiently eliminate pollutants that are difficult to remove using conventional methods. Aqueous solutions of various pollutants were treated by a low-pressure discharge. Experimental results indicated that CNP was effective for degradation azo dye pollutants (methylene blue (MB) and methyl orange MO) and antibiotics (ofloxacin (OFX) and ciprofloxacin (CFX)): МВ and МО were degraded by 98.5% and 97.0%, respectively after 3 min of plasma treatment; OFX and CFX were degraded by ~95.0% and 80.0%, respectively AOP by CNP indicated. The photodegradation of methylene blue catalyzed by plasma synthesized TiO2/Ag was studied under UV irradiation. The degradation (~91%) was obtained with 2.4 g/L TiO2/Ag within 90 min irradiation.

Purification of organic pollutants in cationic thiazine and azo dye solutions using plasma-based advanced oxidation process via submerged multi-hole dielectric barrier discharge

Due to industrialization and population growth, water shortage has emerged as a critical global issue. Pollution of existing water supplies is a critical part of this issue, and organic contaminants are one of the main causes of water pollution. The non-thermal plasma-based advanced oxidation process (AOP) is one of the most widely studied and best developed processes owing to its simple structure and ease of operation. In this study, a plasma-based AOP was stably generated using submerged multi-hole dielectric barrier discharge (DBD) and added to an aqueous solution. Using a plasma system, the complexity of the process for generating hydroxyl radicals (OH) can be simplified by allowing ozone, hydrogen peroxide, ultraviolet light (UV), and OH to be generated simultaneously in one device. The electrical properties and concentrations of the active species were analyzed to establish optimal plasma operating conditions. Among the organic pollutants, methylene blue (MB) and methyl orange (MO) were selected as experimental targets because they are representative cationic thiazine and azo dyes, respectively. The results were analyzed by measuring the absorbance of UV–Vis, total organic carbon (TOC), chromaticity, and changes in solution properties. The effects of hydroxyl radical (OH) scavengers (D-mannitol) on the MB and MO degradation rates were also investigated. Based on these results, degradation mechanisms of MB and MO are proposed. After 3 min of plasma treatment, the concentration, chromaticity, and TOC of MB and MO rapidly decreased. Consequently, we believe that plasma-based AOP using submerged multi-hole DBD has advantages as an alternative technology for treating organic pollutants.

Catalytic and Non-Catalytic Treatment of Industrial Wastewater under the Exposure of Non-Thermal Plasma Jet

Freshwater is only 2.5% of the total water on the Earth and rest is contaminated or brackish. Various physical and chemical techniques are being used to purify the contaminated water. This study deals with catalytic plasma treatment of contaminated water collected from different sites of Faisalabad-Pakistan. A non-thermal DC plasma jet technique was used to treat the water samples in the presence of TiO2 catalyst. The plasma-assisted catalytic treatment introduced some oxidative species (O3, H2O2, HO2−, OH−) in the water. These species reacted with pollutants and cause the degradation of harmful contaminants, especially dyes. The degradation of dye sample during plasma treatment was more pronounced as compared to other samples. pH, conductivity and TDS of dye containing sample decreased after catalytic plasma treatment. The degradation of organic pollutants increased due to presence of several oxidants, such as TiO2, ferrous ions and hydrogen peroxide. FT-IR analysis revealed the degradation of some functional groups during treatment process and confirmed the effectiveness of the process. The residue of the treated samples was consisted of amines, amides and N-H functional groups. XRD analysis showed the presence of Alite, Ferrite, aluminate, Si, S and some heavy metals in the residue. The effect of plasma treatment on activity of gram-negative Escherichia coli (E. coli) bacteria in water was also checked. The bacterial activity was reduced by almost 50% after 2 min of plasma treatment.

Plasma Enhanced Wet Chemical Surface Activation of TiO2 for the Synthesis of High Performance Photocatalytic Au/TiO2 Nanocomposites

To enhance the effectiveness of TiO2 as a photocatalyst, it was believed that the drawbacks of the large bandgap and the rapid electron-hole recombination can be overcome by coupling TiO2 with plasmonic metal nanoparticles. The incorporation of the nanoparticles onto the TiO2 surface requires a suitable procedure to achieve the proper particle adhesion. In this work, we propose a simple, clean, and effective surface activation of TiO2 using plasma enhanced wet chemical surface treatment. Under only 5 min of plasma treatment in a 3% NH3/3% H2O2 solution, gold nanoparticles were found better adhered onto the TiO2 surface. Hence, the methylene blue degradation rate of the Au/TiO2 under sunlight treated was improved by a factor of 3.25 times in comparison to non-treated Au/TiO2 and by 13 times in comparison to the bare rutile TiO2.

Dielectric barrier discharge (DBD) plasma induced flavonoid degradation kinetics and mechanism in water

In this work, we evaluated the degradation mechanism of standard flavonoids when treated with dielectric barrier discharge (DBD) plasma in water. Five different standard flavonoids were chosen for analysis, including apigenin, myricetin, kaempferol, rutin, and quercetin. All flavonoids were treated for 5 min, and the samples were collected at different time intervals. The degradation kinetics of DBD plasma-treated samples were analyzed using HPLC, which follows first-order reaction kinetics. Various degradation peaks were observed in the HPLC chromatogram that started appearing within 10 s of DBD plasma treatment and increased until 60 s–90 s, subsequently degraded completely within 5 min of plasma treatment. LC-MS analysis was performed for the quercetin fragments obtained at 7.54 min. Based on the obtained major molecular ion peak at m/z 152.98 And 196.96; a quercetin degradation mechanism is suggested. The effect of two different feed gases (clean dry air and N2) on flavonoid degradation was also evaluated.

An in vitro and in vivo study of plasma treatment effects on oral biofilms

ABSTRACTManagement of dental plaque/biofilms is critical to maintain oral health. The objective of this study is to investigate the treatment effects of non-thermal atmospheric gas plasmas on oral biofilm formation and recovery under in vitro and in vivo conditions. Streptococcus mutans biofilms, a significant contributor to tooth decay, were cultured and treated by plasma. It was found that plasma treatment not only significantly reduced the in vitro biofilms, but also increased the metabolic activity of the bacteria in the biofilms. As compared with untreated control group, the cell metabolic activity, as measured by MTT assay, increased by 273%, and the aconitase activity increased by 446% for the plasma-treated group. The increased metabolic activity of the plasma-treated biofilm bacteria enhanced their susceptibility to antibiotic and host defense. An in vivo animal model using a total of 60 female rats (19 days old) were used to evaluate the anti-caries effects on the molars by 2 min of plasma treatment. It was found that, 6 months after the plasma treatment, the decayed surfaces were reduced by 62.5% on the upper molars and by 31.6% on the lower molars as compared with the untreated upper and lower molars, respectively. These in vitro and in vivo data demonstrate that the physiological state change of the biofilm due to plasma treatment provided benefit to caries control and prevention.