Cold Atmospheric Pressure Plasma Research Articles

Time-dependent efficacy and safety of tooth bleaching with cold plasma and H2O2 gel

BackgroundHydrogen peroxide (H2O2) is the commonly used bleaching agent for teeth. But it is highly corrosive to teeth for the high concentration. The cold atmospheric pressure plasma has been witnessed a novel tooth bleaching technology and could help strengthen the bleaching effect when combined with H2O2. However, the efficacy and safety might highly correlated with processing time. The present study aims to evaluate the time-dependent efficacy and safety of tooth bleaching with cold plasma and H2O2 gel in vitro.MethodsThe H2O2 concentrations of the gel used in the study are 6%, 15%, 25% and 35%, respectively and the treatment time varies from 5 to 20 min. The tooth bleaching effect was evaluated by a Crystaleye Spectrophotometer and the overall change of the colorimetric value based on three independent measurements. Meanwhile, the microhardness, roughness and tooth temperature were evaluated. The surface morphology and the elemental composition were determined by scanning electron microscope and energy-dispersive X-ray spectroscopy.Results5 min bleaching treatment contributed to 60% of the bleaching effect maximum, the 10 min effect was close to 15 min effect. Meanwhile, the microhardness reduced and roughness increased under a treatment which was longer than 20 min. Tooth pulp chamber temperature was keeping in a safe range within 20 min treatment.Conclusion5–10 min was the best treatment time from which we can get an ideal tooth bleaching effect and less influence on tooth enamel and pulp tissue when using cold plasma and H2O2 gel.

Water Modification by Cold Plasma Jet with Respect to Physical and Chemical Properties

This work is devoted to unbuffered and buffered water treatment by means of atmospheric pressure cold plasma of electrical discharges. The interest in the activation of these two liquids by plasma-induced, gaseous-phase chemistry ranges over a wide area of potential applications and interdisciplinary scientific fields. These include biology, medicine, sanitation, environmental restoration, agriculture, etc. Atmospheric pressure cold plasma is here produced in the form of a plasma jet and set into physical contact with the liquid specimens. The operational window of the treatment, in terms of plasma reactivity, is determined by means of UV-NIR optical emission spectroscopy, and the treated liquids are probed in a variety of respects. Evaporation rate, temperature, acidity and basicity, resistivity, and oxidation-reduction potential are measured as a function of the treatment time, either in-situ or ex-situ. The formation of principal reactive oxygen species, i.e., •OH, H2O2 and O2•−, with a plasma jet mean power lower than 400 mW, is eventually demonstrated and their concentration is measured with original methods borrowed from the biology field. The experimental results are linked to reports published over the last ten years, which are compiled in a brief but meaningful review.

Technologies to decontaminate bacterial biofilm on hospital surfaces: a potential new role for cold plasma?

Healthcare-associated infections (HCAIs) are a major challenge and the near patient surface is important in harbouring causes such as methicillin-resistant Staphylococcus aureus (MRSA) and Clostridioides difficile. Current approaches to decontamination are sub-optimal and many studies have demonstrated that microbial causes of HCAIs may persist with onward transmission. This may be due to the capacity of these microbes to survive in biofilms on surfaces. New technologies to enhance hospital decontamination may have a role in addressing this challenge. We have reviewed current technologies such as UV light and hydrogen peroxide and also assessed the potential use of cold atmospheric pressure plasma (CAPP) in surface decontamination. The antimicrobial mechanisms of CAPP are not fully understood but the production of reactive oxygen and other species is believed to be important. CAPP systems have been shown to partially or completely remove a variety of biofilms including those caused by Candida albicans, and multi-drug-resistant bacteria such as MRSA. There are some studies that suggest promise for CAPP in the challenge of surface decontamination in the healthcare setting. However, further work is required to define better the mechanism of action. We need to know what surfaces are most amenable to treatment, how microbial components and the maturity of biofilms may affect successful treatment, and how would CAPP be used in the clinical setting.

Topically Confined Enhancement of Cutaneous Microcirculation by Cold Plasma

Introduction: We aim to explore potentials and modalities of cold atmospheric pressure plasma (CAP) for the subsequent development of therapies targeting an increased perfusion of the lower leg skin tissue. In this study, we addressed the question whether the microcirculation enhancement is restricted to the tissue in direct contact with plasma or if adjacent tissue might also benefit. Methods: A dielectric barrier discharge (DBD)-generated CAP device exhibiting an electrode area of 27.5 cm² was used to treat the anterior lower leg of ten healthy subjects for 4.5 min. Subsequently, hyperspectral imaging was performed to measure the tempospatially resolved characteristics of microcirculation parameters in superficial (up to 1 mm) and deeper (up to 5 mm) skin layers. Results: In the tissue area covered by the plasma electrode, DBD-CAP treatment enhances most of the perfusion parameters. The maximum oxygen saturation increase reached 8%, the near-infrared perfusion index (NIR) increased by a maximum of 4%, and the maximum tissue hemoglobin increase equaled 14%. Tissue water index (TWI) was lower in both the control and the plasma groups, thus not affected by the DBD-CAP treatment. Yet, our study reveals that adjacent tissue is hardly affected by the enhancements in the electrode area, and the effects are locally confined. Conclusion: Application of DBD-CAP to the lower leg resulted in enhancement of cutaneous microcirculation that extended 1 h beyond the treatment period with localization to the tissue area in direct contact with the cold plasma. This suggests the possibility of tailoring application schemes for topically confined enhancement of skin microcirculation, e.g., in the treatment of chronic wounds.

Changes in structure and emulsifying properties of coconut globulin after the atmospheric pressure cold plasma treatment

Atmospheric pressure cold plasma (ACP) treatment, a non-thermal sterilization technology with great potential in coconut milk, can maximize the retention of the taste and flavour. However, it is unavoidable to have an impact on the coconut milk components. In this study, coconut globulin (CG), a component important for coconut milk stability, was selected to explore the effect of the ACP treatment on the structure and emulsifying properties of CG. After the ACP treatment, the structure of CG unfolded, which was the increase in random coils and reduction in intrinsic fluorescence intensity. In addition, the carbonyl and S–S bond content increased, while the free –SH content decreased. Compared with untreated CG (440.57 nm), the particle size of CG after the ACP treatment decreased, especially at 60 kV 60 s (207.63 nm) and 60 kV 90 s (204.20 nm). Simultaneously, poor modification and excessive modification of CG have similar surface hydrophobicity and interfacial tension to untreated CG. Notably, moderate modification (60 kV 60 s and 60 kV 90 s) resulted in the unfolding of CG molecules and the exposure of hydrophobic groups, increasing their adsorption at the oil-water interface. As expected, the emulsifying ability and emulsifying stability of CG were significantly improved after the ACP treatment at 60 kV 60 s and 60 kV 90 s. In conclusion, moderate ACP treatment could improve the emulsifying properties of CG by modifying its structure. This study provides new insights into the effect of ACP on food components during liquid food sterilization.

Polymerization Process from the Cold Atmospheric Pressure Plasma Treatment of l-Cysteine Powder by Addition of DMSO and H2O2

Polymerization Process from the Cold Atmospheric Pressure Plasma Treatment of l-Cysteine Powder by Addition of DMSO and H2O2

Studies on a sinusoidally driven gas–liquid two-phase plasma discharge and its application to sterilization

Atmospheric pressure cold plasmas are widely used in the biomedical field as evidenced by developments in recent years. In this study, a quartz tube-guided gas–liquid two-phase discharge has been configured with a hollow needle-water structure. The power source for the device was sinusoidal, and switching between a gas–liquid miscible discharge and a pure gaseous discharge was simple. It was discovered that the gas–liquid discharge was beneficial in terms of reactant species generation and reaction efficiency in terms of processing water. The types of particles, the physicochemical properties, and the concentrations of reactive oxygen and nitrogen species in the discharge were studied spectroscopically. The discharge was discovered to have high levels of H2O2 and NO2−, and the activated water was proven to be effective at sterilizing samples that were contaminated with micro-organisms. Key experimental parameters including the driving voltage and the air flow rate were optimized to achieve the best sterilization conditions. The membrane potential changes in the treated bacteria were also studied to explore the causes of bacterial inactivation. The results showed that the device exhibited a strong bactericidal effect for the gas–liquid mixed phase discharge operating at 17 kV for 5 min with a gas flow rate of 0.3 SLM. In addition, the present device offers enhanced sterilization efficiency relative to the efficiency of conventional plasma sterilization equipment and, therefore, has a wide range of applications.

Redox Reactions of Biologically Active Molecules upon Cold Atmospheric Pressure Plasma Treatment of Aqueous Solutions.

Cold atmospheric pressure plasma (CAPP) is widely used in medicine for the treatment of diseases and disinfection of bio-tissues due to its antibacterial, antiviral, and antifungal properties. In agriculture, CAPP accelerates the imbibition and germination of seeds and significantly increases plant productivity. Plasma is also used to fix molecular nitrogen. CAPP can produce reactive oxygen and nitrogen species (RONS). Plasma treatment of bio-tissue can lead to numerous side effects such as lipid peroxidation, genotoxic problems, and DNA damage. The mechanisms of occurring side effects when treating various organisms with cold plasma are unknown since RONS, UV-Vis light, and multicomponent biological tissues are simultaneously involved in a heterogeneous environment. Here, we found that CAPP can induce in vitro oxidation of the most common water-soluble redox compounds in living cells such as NADH, NADPH, and vitamin C at interfaces between air, CAPP, and water. CAPP is not capable of reducing NAD+ and 1,4-benzoquinone, despite the presence of free electrons in CAPP. Prolonged plasma treatment of aqueous solutions of vitamin C, 1,4-hydroquinone, and 1,4-benzoquinone respectively, leads to their decomposition. Studies of the mechanisms in plasma-induced processes can help to prevent side effects in medicine, agriculture, and food disinfection.

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.

The Use of Cold Atmospheric Pressure Plasma for the Synthesis of Saccharide-Stabilized Re Nanostructures Enabling Effective Deactivation of Nitro-Based Antimicrobial Agents

Monosaccharide- and polysaccharide biopolymer-stabilized rhenium oxide nanoparticles (ReOxNPs) were effectively applied for deactivation of furazolidone (FRz) and chloramphenicol (ChRP) dissolved in solutions. The employed for that purpose monosaccharide- and polysaccharide biopolymer-stabilized ReOxNPs were synthesized in a two-step procedure. In the first step, the raw-ReOxNPs were produced using a cold atmospheric pressure plasma (CAPP)-based approach. In the second step, the raw-ReOxNPs were incorporated within either D-fructose or Arabic gum, acting as mono- and polysaccharide matrices. Optical and granulometric properties of the so-obtained stabilized ReOxNPs were revealed using several experimental techniques such as UV/Vis absorption spectrophotometry (UV/Vis), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), energy dispersive X-ray scattering (EDAX), attenuated total reflectance Fourier transform infrared spectroscopy (ATR FT-IR), X-Ray photoelectron spectroscopy (XPS), and dynamic light scattering (DLS). It was found that the produced raw-ReOxNPs, fructose-stabilized ReOxNPs, and Arabic gum-stabilized ReOxNPs were a blend of Re0 and different O-doped Re species, that were octahedral in shape and exhibited the size of 240.6, 461.8, and 7.54 nm, respectively, as was determined using DLS. The obtained ReOxNPs led to losses of FRz in 97, 91, and 62%, for raw-ReOxNPs, fructose-ReOxNPs, and Arabic-gum-stabilized ReOxNPs, respectively, as was estimated using high-performance liquid chromatography with a diode-array detector (HPLC–DAD). The applied approach led to the 100% conversion of ChRP by raw-ReOxNPs, while the saccharide-stabilized nanostructure turned out to be inefficient in reducing ChRP. The method described here might be applied as a tempting alternative to other methods used in the wastewaters purification processes.Graphical

Short-time cold atmospheric pressure plasma exposure can kill all life stages of the poultry red mite, Dermanyssus gallinae, under laboratory conditions

In the present study, the acaricidal effects of cold atmospheric pressure plasma treatment on poultry red mites of different developmental stages have been investigated under laboratory conditions using a dielectric barrier discharge system. A total of 1890 poultry red mites and 90 mite eggs, respectively, were exposed to the plasma under various parameter settings with a single plasma pulse generated using the gas mixture of the ambient air at atmospheric pressure. The results showed that all developmental stages of the poultry red mite could be killed by cold atmospheric pressure plasma treatment. Plasma exposure to mite eggs resulted in a complete 100% hatch inhibition regardless of the parameter settings. Post-exposure mortality rates of larvae, nymphs and adults showed significant differences after utilization of plasma at 10 W for 1.0 s. In addition, the mortality rate increased with progressing time after plasma exposure. An average mortality rate of 99.7% was observed after 12 h in all mites exposed to plasma, regardless of the selected plasma parameter, developmental stage, and nutritional status of the mites. Cold atmospheric pressure plasma has an acaricidal effect on all developmental stages of Dermanyssus gallinae, suggesting that it could be developed to an effective method for the control of poultry red mites in laying hen husbandry.

Continuous in-line decontamination of food-processing surfaces using cold atmospheric pressure air plasma

This study assessed a continuous in-line decontamination system for food contact surfaces and processing equipment that utilized cold atmospheric pressure plasma (CAP) generated from ambient air. The plasma system was evaluated against two common foodborne pathogens (Salmonella Typhimurium, Listeria monocytogenes) on stainless steel surfaces and against S Typhimurium on commercial poly[ether]-thermoplastic poly[urethane] (PE-TPU) conveyor belts, under simulated conditions of a food-processing facility. A significant level of microbial inactivation was achieved, up to 3.03 ± 0.18 and 2.77 ± 0.71 logCFU/mL reductions of L. monocytogenes and S. Typhimurium respectively within 10 s total treatment on stainless steel surfaces, and a 2.56 ± 0.37 logCFU/mL reduction of S. Typhimurium within 4 s total treatment on the PE-TPU material, according to a procedure based on the well-established EN 13697:2015 industrial protocol. CAP exposure was shown to have a minor impact on the morphology and composition of the treated surfaces. The results indicated that CAP can be applied for effective and continuous disinfection against common foodborne pathogens in food-processing facilities. Industrial relevanceLow temperature plasmas have shown great promise for microbial decontamination, yet industrial uptake of the technology has been limited due to scaling limitations. In this study, a prototype conveyor-based CAP decontamination system was developed and tested under realistic conditions expected within a food-processing facility. The results showed a high level of antimicrobial action against two common foodborne pathogens within a few seconds of CAP exposure, a timescale in line with industrial line processing speeds. Our findings demonstrated that CAP shows great promise for the continuous in-situ decontamination of food contact surfaces, with the potential to mitigate against the costly downtimes incurred in current production line practices implementing chemical disinfectants.

Spectroscopic Investigation of the Impact of Cold Plasma Treatment at Atmospheric Pressure on Sucrose and Glucose.

When exposing food and feedstuff to cold atmospheric pressure plasmas (CAPP), e.g., for decontamination purposes, possible unwanted effects on the contained nutrients might occur. In the present study, we thus concentrated on CAPP-induced degrading effects on different sugars, namely glucose and sucrose. The treatments were performed using admixtures of argon and synthetic air over durations of up to . Continuous degradation of sucrose and glucose was determined using ATR-FTIR and XPS analyses. OH stretching bands showed notable broadening in the ATR-FTIR spectra, which possibly indicates reduced crystallinity of the sugars caused by the CAPP treatment. In the fingerprint regions, most bands, especially the more intense C-O bands, showed decreases in peak heights. In addition, two new bands occurred after CAPP treatment. The bands were detectable in the range between 1800 and and potentially can be assigned to C=C and, after comparison with the results of the XPS measurements, O-C=O bindings. The XPS measurements also showed that the O-C=O bonds probably originated from earlier C-O bonds.

DNA-based surrogates for the validation of microbial inactivation using cold atmospheric pressure plasma and plasma-activated water processing

Cold atmospheric pressure plasma (CAPP) and plasma-activated water (PAW) are emerging nonthermal technologies. Due to the complexity of plasma-generated species as a function of plasma generation conditions, there is a need to develop process validation. This study aims to evaluate plasma interactions with DNA-based surrogates using infrared spectroscopy and gradient boosting decision tree, a machine learning algorithm, for data analysis to validate the decontamination effectiveness of CAPP and PAW. Chitosan-DNA films were developed and treated with CAPP or PAW. Changes in the spectral properties of DNA were characterized with Fourier-transform infrared spectroscopy (FTIR) and correlated to the dosage levels of CAPP and PAW and decontamination efficacy. Using the LightGBM algorithm, both plasma dosage and the inactivation efficacy against bacteria and biofilms were predicted with high accuracy (>89%) based on the spectral features of DNA. In summary, this study illustrates a novel approach for validating the decontamination efficacy of plasma processing.

Degradation of bisphenol A and S in wastewater during cold atmospheric pressure plasma treatment.

Developing novel, fast and efficient ecologically benign processes for removing organic contaminants is important for the continued development of water treatment. For this reason, this study investigates the implementation of Cold Atmospheric pressure Plasma (CAP) generated in ambient air as an efficient tool for the removal of Bisphenol A (BPA) and Bisphenol S (BPS)-known endocrine disrupting compounds in water and wastewater, by monitoring degradation kinetics and its transformation products. The highest removal efficiencies of BPA (>98%) and BPS (>70%) were obtained after 480 s of CAP exposure. A pseudo-first-order kinetic revealed that BPA (-kt = 4.4 ̶ 9.0 ms-1) degrades faster than BPS (-kt = 0.4 ̶ 2.4 ms-1) and that the degradation is also time- and CAP power-dependent, while the initial concentration or matrix type had a negligible effect. This study also tentatively identified three previously reported and one novel transformation product of BPA and four novel transformation products of BPS. Their postulated structures suggested similar breakdown mechanisms, i.e., hydroxylation followed by ring cleavage. The results demonstrate that CAP technology is an effective process for the degradation of both BPA and BPS without the need for additional chemicals, indicating that CAP is a promising technology for water and wastewater remediation worthy of further investigation and optimization.

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.

Oxidative modification in nuclear and mitochondrial DNA and its removal in A549 human lung cancer cells exposed to cold atmospheric-pressure plasma

Non-thermal atmospheric-pressure plasma has emerged as a useful tool in life science research and medicine. Plasma irradiation generates reactive oxygen and nitrogen species (RONS) that stimulate various cellular responses. In this study, we investigated oxidative damage to nuclear and mitochondrial DNA in A549 human lung cancer cells exposed to a helium atmospheric-pressure plasma jet (APPJ). APPJ irradiation decreased the viability of A549 cells and increased intracellular RONS levels. The formation of 8-oxoguanine (8-oxoG), a representative oxidized form of a DNA base, was observed in nuclear DNA. Pretreatment of A549 cells with an antioxidant reagent prior to APPJ irradiation suppressed the increase in 8-oxoG level. The 8-oxoG level gradually decreased during cell culture, suggesting that 8-oxoG was removed from nuclear DNA after APPJ irradiation. Formation of 8-oxoG was also observed in mitochondrial DNA, indicating the accumulation of RONS in mitochondria.

Mask disinfection using atmospheric pressure cold plasma

ObjectivesMask usage has increased over the last few years due to the COVID-19 pandemic, resulting in a mask shortage. Furthermore, their prolonged use causes skin problems related to bacterial overgrowth. To overcome these problems, atmospheric pressure cold plasma was studied as an alternative technology for mask disinfection. MethodsDifferent microorganisms (Pseudomonas aeruginosa, Escherichia coli, Staphylococcus spp.), different gases (nitrogen, argon, and air), plasma power (90-300 W), and treatment times (45 seconds to 5 minutes) were tested. ResultsThe best atmospheric pressure cold plasma treatment was the one generated by nitrogen gas at 300 W and 1.5 minutes. Testing of breathing and filtering performance and microscopic and visual analysis after one and five plasma treatment cycles, highlighted that these treatments did not affect the morphology or functional capacity of the masks. ConclusionConsidering the above, we strongly believe that atmospheric pressure cold plasma could be an inexpensive, eco-friendly, and sustainable mask disinfection technology enabling their reusability and solving mask shortage.

Study of unique aspects of oxidative-nitrosative environment in a radio frequency cold plasma device

The study reports unique aspects of oxidative and nitrosative environment and generation of radicals in a newly developed 13.56 MHz cold atmospheric pressure plasma jet (APPJ) device using optical emission spectroscopy (OES). Signature of generated species, species density, energy, their spatial variation and interaction with liquid medium are investigated. While techniques to achieve controlled generation of atomic oxygen and nitrogen in the same device are identified, distinct ability of pure argon APPJ to break oxygen molecules in air releasing atomic oxygen is an interesting finding. Boltzmann plot technique is used to determine the electron excitation temperature. Time averaged gas temperature is measured using mercury thermometer as well as matching simulated and experimental spectra of A-X band of OH radical. Electron density is determined from spectral broadening of Hα line. Formation of OH radical is detected via its signature A-X band. Measured electron density and electron excitation temperature are of the order of 1021 per m3, and 3 eV respectively at the nozzle exit. Standard test strips are used to investigate generation of H2O2, NO2 and NO3 radicals through interaction of the plasma jet with water as a function of time.

Characterization of N‐doped carbon quantum dots synthesized by DBD‐based cold atmospheric pressure plasma jet

AbstractThis study develops a new approach for the synthesis of fluorescent N‐doped carbon quantum dots (CQDs), using cold atmospheric pressure plasma jet. Herein, the CQDs were synthesized with two plasma exposure times of 30 and 60 min. The UV‐Vis absorption spectrum confirms the existence of carbonic core and surface functional groups. The Fourier transform infrared spectrum shows that carbonyl groups and amide groups exist on the surface of CQDs. Depending on the plasma exposure time, the mean average sizes of CQDs are 3.63 and 5.45 nm with strong photoluminescence emission. Generally, our results indicated that using different mechanisms for plasma discharge, lead to different physical and chemical properties of produced plasma and consequently of synthesized CQDs. The synthesized N‐doped CQDs exhibited strong fluorescence and higher quantum yield compared to previous reports.