Plasma Brush Research Articles

Application of a pm-rf-APGD-type plasma brush for deactivation of antibiotics from liquid solutions leads to impaired development of drug resistance by bacterial pathogens

The presence of antibiotics residuals in the natural environment contributes to development and spread of drug resistance determinants among bacteria, often including clinically significant human pathogens. To tackle with this threat, we constructed a plasma brush, generating pulse-modulated radio-frequency atmospheric pressure glow discharge (pm-rf-APGD), named pm-rf-APGD-type plasma brush, intended for degradation of biologically active pharmaceuticals from both single- and five-component solutions of ciprofloxacin (CFX), enrofloxacin (EFX), ofloxacin (OFX), doxycycline (DXC), and trimethoprim (TMP). The mean antibiotics removal efficiency, achieved mainly due to the action of reactive oxygen species (ROS), was 93.3 %. This removal efficiency corresponded to a mean 62.7% decrease in the antibacterial activities. We revealed the transformation products resulting from an oxygen attack and/or internal fragmentation of the treated pharmaceuticals. Based on a laboratory evolution study, bacterial exposure to the pm-rf-APGD-treated drug lead to significantly lower rates of antibiotic resistance development in juxtaposition with a long-term exposure to the sublethal dose of the active molecules. Thus, we anticipate a great potential of high-throughput, continuous flow, eco-friendly pm-rf-APGD-type plasma brush for routine decontamination processes in the future disposal pipelines of pharmaceuticals-containing wastewaters.

Boosted hydrophobic properties of leather surfaces by atmospheric pressure plasma brush reactor

In this article, we demonstrate the application of an atmospheric pressure plasma brush (APPB) reactor for improving the hydrophobic properties of leather surfaces treated with organo-silane precursors for the first time. A comprehensive investigation was conducted to analyze the influence of various process parameters, including plasma access current, treatment duration, nozzle height, and gas flow rate, on the observed outcomes effects. The dispersion of active particles in the APPB was scrutinized using an Optical Emission Spectrometer (OES), while the underlying reaction mechanism was elucidated through the integration of Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), cross-sectional Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM) analysis. The findings unveiled that the resultant polysiloxane polymers bestowed a remarkable degree of hydrophobicity upon the leather, persisting steadfastly even following a 90-day aging period (WCA >140°). This APPB treatment combined with organosilane strategy may open a new design avenue for the development of surface treatments for intricate and temperature-sensitive substrates materials.

A novel approach to expedite wound healing with plasma brush of cold flame.

Excessive or persistent infection is a major contributing factor in impeding chronic wound healing. Wound bed preparations using antiseptics do not necessarily target the entire bacterial spectrum, and the highly proliferating granulation tissue may be sensitive to the cytotoxic effects, impairing tissue repair. Non-thermal gas atmospheric pressure plasmas are partially ionized gases that contain highly reactive particles while the gas phase remains near room temperature, thus having the capability of accessing small irregular cavities and fissures and killing bacteria because of the diffusive nature of gas phase plasma species that are chemically reactive, providing an ideal approach to topical wound disinfection. A non-thermal plasma brush device of novel design has been developed that is suitable for clinical application in the disinfection of oral and wound bacteria. In vivo studies have indicated that the plasma brush treatment rendered no harmful effect on healthy skin or tissues, while it could improve wound healing in Pseudomonas aeruginosa biofilm infected wounds exposed to an optimized treatment with argon plus 1% nitrogen (Ar + N2) plasma.

Cold Atmospheric Plasma Brush Effect on Population Reduction of Different Bacterial Spectrums

Cold Atmospheric Plasma Brush Effect on Population Reduction of Different Bacterial Spectrums

Self‐enhanced plasma brush for therapeutic use in dermatology and its safety assessment

AbstractIn this study, a self‐enhanced plasma brush based on a single dielectric barrier discharge was developed by optimizing the load position for treatment in dermatology. The electrical, optical, and temperature characteristics of the fabricated reactor were investigated. Results show that the length and the width of the plasma brush could reach 20 and 15 mm, respectively. The electric field and the resulting discharge between the reactor and the human impedance model were enhanced and the discharging resistance decreased when introducing a human load. The plume temperature is around 24°C and the current flowing through the human model is lower than the threshold of perception current, which is friendly for human contact. The sterilization effects are verified by killing Escherichia coli.

Removal of clinically significant antibiotics from aqueous solutions by applying unique high-throughput continuous-flow plasma pencil and plasma brush systems

High demands of medical and husbandry sectors led to a massive annual production of 100,000 tonnes of various antibiotics on a global scale. Considering that an access to sublethal doses of these pharmaceuticals causes subsequent increase in resistance of virulent human bacterial pathogens, there is a substantial need for development of novel methods and techniques for degradation of antibiotics from aqueous solutions. Here, high-throughput continuous flow plasma pencil and plasma brush methodologies were developed and verified for their applicability for removal of antibiotics from solutions, as estimated by high-performance liquid chromatography coupled with diode-array detection (HPLC-DAD) or ultraperformance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). The removal efficiency of drugs treated by the plasma pencil was in the range from 3 to 24%, and was corresponded to with 1.39% to 10.76% losses in the antibacterial properties of the plasma-treated solutions. However, application of a unique plasma brush increased the antibiotics degradation rates significantly, now falling in the range from 29 to 67% that led to 12.06–81.59% decrease in the antimicrobial properties of the plasma-exposed antibiotics solutions. The deviations in the effectiveness of the plasma pencil and the plasma brush methods were assigned with the types and amounts of generated species. Various intermediate degradation products were also detected in the post-plasma solutions, which derived from the oxygen attack to nucleophilic sides of the antibiotic molecules. We assume that such novel high-throughput, continuous flow methodological setups may find application in hospitals as an end-of-pipe technology for routine elimination of pollutants before reaching municipal sewage treatment plants.

Nonthermal Plasma Brush Treatment on Titanium and Zirconia To Improve Periabutment Epithelium Formation.

The peri-implant soft tissue with inferior adhesion takes a long healing period to form, which is undesirable for the reaction around the peri-implant soft tissues. The aim of this study is to improve the physicochemical properties of titanium (Ti) and zirconia (ZrO2) implant abutments and shorten the formation period of periabutment epithelium tissue. A nonthermal atmospheric plasma brush (NTAPB, N) was employed for Ti and ZrO2 activation. The surface topographies, roughness, crystallinity, wettability, and chemical elements of the abutment materials were examined. The epithelial cell behavior analysis and tissue remodeling of the periabutment epithelial tissue were performed in vitro and in vivo. N-Ti and N-ZrO2 had a similar good surface wettability, with a 65 and 70% increase in oxygen content and a 70 and 75% decrease in carbon content, respectively. Both N-Ti and N-ZrO2 showed excellent adhesion, spread, and proliferation of epithelial cells in vitro, with improved adhesion molecule expression levels compared to untreated samples. N-Ti and N-ZrO2 abutments were placed in the implantation sites of rats. From week 2 to week 6 after implantation, N-Ti and N-ZrO2 had similar periabutment epithelium tissue formation, and both had increased plectin-positive and laminin γ2-positive cell numbers compared to Ti and ZrO2. The NTAPB shows promising abutment modification abilities. It promotes the expression levels of adhesion molecules and the epithelial cell performance, which later leads to a quicker formation and remodeling of the important periabutment epithelial tissue.

Influence of air addition on surface modification of polyethylene terephthalate treated by an atmospheric pressure argon plasma brush

An atmospheric pressure argon plasma brush with air addition is employed to treat polyethylene terephthalate (PET) surface in order to improve its hydrophilicity. Results indicate that the plasma plume generated by the plasma brush presents periodically pulsed current despite a direct current voltage is applied. Voltage−current curve reveals that there is a transition from a Townsend discharge regime to a glow one during one discharge period. Optical emission spectrum indicates that more oxygen atoms are produced in the plume with increasing air content, which leads to the better hydrophilicity of PET surface after plasma treatment. Besides, an aging behavior is also observed. The hydrophilicity improvement is attributed to the production of oxygen functional groups, which increase in number with increasing air content. Moreover, some grain-like structures are observed on the treated PET surface, and its mean roughness increases with increasing air content. These results are of great importance for the hydrophilicity improvement of PET surface with a large scale.

Influence of non-thermal plasma systems and two favorable surface treatments on the shear bond strength of PAEKs to composite resin

This study aimed to investigate the effect of non-thermal plasma systems with and without two favorable surface treatment techniques on the surface roughness (Ra) and shear bond strength (SBS) of polyaryletherketone (PAEK) polymers to veneering composite resin material. A total of 288 (n = 144 for each polymer) Polyetheretherketone (PEEK) and Polyetherketoneketone (PEKK) samples (7 73mm) were divided into the surface treatment methods (n = 16): untreated (CNT); dielectric barrier discharge air plasma treatment (DBD); atmospheric pressure plasma treatment with a plasma brush (APB); 98% sulfuric acid etching (SA); SA_DBD; SA_APB; tribochemical silica coating (TBC); TBC_DBD; TBC_APB. The Ra (n = 5) and scanning electron microscope (SEM) analyses (n = 1) were performed. A bonding agent was applied to the remaining samples (n = 10) and veneered with a composite resin. After storing in distilled water for 24 h at 37 °C, the SBS test was applied with a universal test machine, and the failure modes were examined with an optical microscope. The SBS and Ra data were statistically analyzed with Kruskal Wallis, two-way analysis of variance (ANOVA), and compared with Mann-Whitney_U and Tamhane tests (α = 0.05). The highest SBS value was observed in Groups SA (22.67 ± 1.48 MPa) for PEEK, Group TBC (18.91 ± 1.09 MPa) for PEKK polymer groups. The highest Ra values were determined in Group TBC_DBD for both polymers. While the TBC may enhance the SBS values of both polymers, the SA application is more effective for PEEK polymer regarding the SBS value. In contrast to the effect of DBD, APB application is beneficial for improving the bonding capacity of PAEKs.

Transient Electric Field Shaping With the Linear Combination of Configuration Field Method for Enhanced Spatial Control of Microwave Plasmas

The demonstration of enhanced spatial control of nanosecond microwave plasmas generated by the time reversal plasma source is presented in this paper. This new microwave plasma source relies on the spatio-temporal control of the electric field inside an all-metal plasma reactor by modifying the waveform of a high power microwave signal. More specifically, it originally used the spatio-temporal focusing capabilities of the time reversal method to focus a high electric field in a small location. However, a parasitic microwave breakdown can still occur at sharp corners or wedges inside the cavity due to the local enhancement of the residual electric field during time reversal focusing. Thus, it is proposed to use the linear combination of configuration field method to improve field control inside the reactor. Its transient electric field shaping capabilities turn out to be a good candidate for the development of a low pressure microwave “plasma brush”.

Immobilization of quaternary ammonium based antibacterial monomer onto dentin substrate by non-thermal atmospheric plasma.

Use of non-thermal atmospheric plasma (NTAP) brush on immobilization of dimethylaminohexadecyl methacrylate (DMAHDM) onto dentin bonding substrate, and resulting antibacterial activity against Streptococcus mutans were investigated. A bonding substrate with several-micron-demineralized layer was created from human dentin. DMAHDM was applied onto the demineralized layer with or without plasma exposure. Scanning electron microscopy (SEM) and Fourier transformed infrared (FTIR) spectroscopy were employed to verify immobilization/grafting of DMAHDM onto the substrate. Antibacterial activity of the resulting substrate was assessed by using colony-forming unit (CFU) and confocal scanning laser microscopy. Effects of saliva pellicle treatment and aging process on the above substrate were also evaluated. The SEM/FTIR results demonstrated that NTAP could induce DMAHDM immobilization onto dentin substrate, which was further verified via quantitative FTIR analysis. Comparing with non-plasma-treated, the plasmatreated substrate, with CFU 4 log lower, exhibited much stronger inhibitory effects, which were minimally affected by saliva or aging. The DMAHDM-immobilized dentin substrate showed effective and sustained antibacterial characteristics.

Deposition of stain resistance coating by non-thermal plasma brush application to dental whitening

A non-thermal plasma brush is employed to deposit stain-resistant SiO2-like coatings on resin composite fillings and bovine teeth. With post-treating by plasma, the hardness of the coating increases from H to 8H and the water contact angle decreases from 98.8° to 61.7°. The Fourier transform infrared spectroscopy (FTIR) results show that, after plasma post-treating, the Si–O–Si and Si–OH bonds of the coating increase. Scanning electron microscope (SEM) images show the coatings to be uniform, without cracks. The coatings present outstanding performance in a stain resistance test both on resin composite and bovine teeth. Being easy to handle and less time consuming than traditional methods, with a body-friendly temperature and material, this plasma brush provides a promising in-situ coating method on patient teeth in dental clinics.

Large-scale surface modification to improve hydrophilicity through using a plasma brush operated at one atmospheric pressure

A uniform plume with pulsed discharges is generated through using a plasma brush excited by a direct current power supply. The results indicate that the plume length increases with the increasing gas flow rate or dissipated power. The optical emission spectrum from the plasma brush reveals that active species are abundant in the plasma plume. Based on the spectrum, an electron density on the order of 1014 cm−3 is obtained, which increases with the increasing dissipated power and gas flow rate. After a single scan of the plasma brush on the polyethylene terephthalate surface, a uniform surface modification is achieved with an improved hydrophilic width of about 24 mm. The water contact angle of the surface decreases with the decreasing scanning velocity and nozzle-sample distance or the increasing dissipated power and gas flow rate. Moreover, the treated surface shows an aging behavior in 6 days. Raman spectra indicate that oxygen-containing polar groups are generated on the treated polyethylene terephthalate surface. The polar groups are contained in oxidized materials, which are observed by scanning electron microscopy.

Effect of Dentin Surface Treatment Using a Non-Thermal Argon Plasma Brush on the Bond Strength of a Self-Adhesive Resin Composite

Effect of Dentin Surface Treatment Using a Non-Thermal Argon Plasma Brush on the Bond Strength of a Self-Adhesive Resin Composite

Non-thermal air plasma jets at atmospheric pressure: The flow-dependent propagation in the afterglow

With a bare pin-to-nozzle electrode configuration, an ac-driven non-thermal air plasma jet with a length of several centimeters is generated. Depending on the gas flow rate, the propagation speed of these plasma columns is in the range of 100–350 m/s, which is close to the gas flow velocity. This indicates that the propagation of the plasma jet is determined by the transport of long lifetime species by gas flow instead of the electron-impact excitation and ionization of molecules under a high electric field. In comparison to the N2, O2, and Ar plasma jets, the length of the air plasma jet is much shorter than that of the N2 plasma jet but longer than that of the O2 and Ar plasma jets. A simple kinetic model reveals that the N2 (A3Σ) metastable plays a crucial role in sustaining the length of the N2 and air plasma jets, whose lifetime is strongly dependent on the quenching effect of O2, O, and NO as well as the compensation from the three-body recombination of nitrogen atoms. Based on the flow-dependent mechanism of the plasma jet, a visually uniform air plasma brush with a width of 2.8 cm and a length of 1.6 cm and a visually uniform N2 plasma brush with a width of 4 cm and a length of 4.4 cm have been demonstrated.

Evaluation of liquid from the Papanicolaou test and other liquid biopsies for the detection of endometrial and ovarian cancers.

We report the detection of endometrial and ovarian cancers based on genetic analyses of DNA recovered from the fluids obtained during a routine Papanicolaou (Pap) test. The new test, called PapSEEK, incorporates assays for mutations in 18 genes as well as an assay for aneuploidy. In Pap brush samples from 382 endometrial cancer patients, 81% [95% confidence interval (CI), 77 to 85%] were positive, including 78% of patients with early-stage disease. The sensitivity in 245 ovarian cancer patients was 33% (95% CI, 27 to 39%), including 34% of patients with early-stage disease. In contrast, only 1.4% of 714 women without cancer had positive Pap brush samples (specificity, ~99%). Next, we showed that intrauterine sampling with a Tao brush increased the detection of malignancy over endocervical sampling with a Pap brush: 93% of 123 (95% CI, 87 to 97%) patients with endometrial cancer and 45% of 51 (95% CI, 31 to 60%) patients with ovarian cancer were positive, whereas none of the samples from 125 women without cancer were positive (specificity, 100%). Finally, in 83 ovarian cancer patients in whom plasma was available, circulating tumor DNA was found in 43% of patients (95% CI, 33 to 55%). When plasma and Pap brush samples were both tested, the sensitivity for ovarian cancer increased to 63% (95% CI, 51 to 73%). These results demonstrate the potential of mutation-based diagnostics to detect gynecologic cancers at a stage when they are more likely to be curable.

Nanosecond Pulsed Plasma Brush for Bacterial Inactivation on Laminate

An array of nonthermal atmospheric-pressure helium plasma jets, in the shape of a brush, was generated in air when a rectangular, 0.1 mm thick anode was powered by 150 ns, 9.5 kV pulses at 2 kHz. With helium as the working gas at 1 slpm, each of the 11 jets of the plasma brush was 1 mm in width, and up to 1 cm long. The jets were spaced 4 mm apart, resulting in a lateral length of 51 mm. The bactericidal effect of the plasma brush was studied against Acinetobacter baumannii and Staphylococcus aureus inoculated on surfaces, including agar and laminate. The impact of humidity in the working gas, substrate type (agar versus laminate), and surface condition (wet versus dry) on the plasma-induced bactericidal effect was evaluated. In a humid discharge, bacterial inactivation was maximized at 0.6 log (75%), whereas adding water to the laminate surface before treatment yielded a 4 log (99.99%) reduction in bacterial viability. In addition, reactive plasma species, including excited O, NO, and OH were evaluated using optical emission spectroscopy for all plasma treatment conditions on laminate.

Disinfection of Streptococcus mutans biofilm by a non-thermal atmospheric plasma brush

This study investigated the argon plasma treatment effect on disinfecting dental biofilm by using an atmospheric pressure plasma brush. Streptococcus mutans biofilms were developed for 3 days on the surfaces of hydroxyapatite (HA) discs, which were used to simulate human tooth enamel. After plasma treatment, cell viability in the S. mutans biofilms was characterized by using 3-(4,5-dimethylazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay and confocal laser scanning microscopy (CLSM). Compared with the untreated control group, about 90% bacterial reduction in the biofilms was observed after 1 min plasma treatment. Scanning electron microscopy (SEM) examination indicated severe cell damages occurred on the top surface of the plasma treated biofilms. Confocal laser scanning microscopy (CLSM) showed that plasma treatment was effective as deep as 20 µm into the biofilms. When combined with antibiotic treatment using 0.2% chlorhexidine digluconate solution, the plasma treatment became more effective and over 96% bacterial reduction was observed with 1 min plasma treatment.

Improving bond strength of ground and intact enamel to mild self-etch adhesive by plasma treatment

Effects of non-thermal plasma treatment on ground and intact enamel surfaces to improve their bond strength to a mild self-etch adhesive were investigated in this study. Thirty-two bovine incisors were randomly divided into four groups (n=8). Their enamels were subjected to the following preparations: (1) ground and unetched (GU), (2) ground and etched (GE), (3) intact and unetched (IU), and (4) intact and etched (IE). After teeth preparation, each tooth was divided in two portions. One half was treated with a non-thermal plasma brush; the other half was shielded with a blade and used as untreated control. A mild, self-etch adhesive and a dental composite resin were subsequently applied on both surfaces following the manufacturers' instructions. The bond strength of the enamel with the adhesive was evaluated using the micro-tensile bond strength test (μTBS). μTBS results indicate that after plasma treatment, the bond strengths of GU, GE, IU, and IE enamel surfaces to the adhesive significantly increased by 33%, 15%, 35%, and 38% respectively, compared with untreated same tooth control. The mean bond strength of plasma-treated GU and IU enamel substrates to the adhesive were similar to that of untreated GE and IE enamel surfaces (p>0.05). A scanning electron microscope (SEM) was used to examine the fractured surfaces, which shows that more adhesive and composite left on plasma-treated enamel surfaces compared with untreated control. Water and adhesive contact angles measurements indicate that the plasma treatment increased surface energy, which enabled the adhesive to more effectively spread out and cover treated substrates. The Weibull analysis demonstrates that plasma treatment reduced defects in the interfaces and improved GU and IU enamel bond strengths with the adhesive to 41.7MPa and 26.0MPa respectively, which equals the GE and IE enamel bond strengths. This study provides the prospect of replacing the traditional selective etching step using a simple non-thermal plasma treatment technique.

Non-thermal atmospheric plasma brush induces HEMA grafting onto dentin collagen

ObjectiveNon-thermal atmospheric plasma (NTAP) brush has been regarded as a promising technique to enhance dental interfacial bonding. However, the principal enhancement mechanisms have not been well identified. In this study, the effect of non-thermal plasmas on grafting of HEMA, a typical dental monomer, onto dentin collagen thin films was investigated. MethodsHuman dentin was sectioned into 10-μm-thick films. After total demineralization in 0.5M EDTA solution for 30min, the dentin collagen films were water-rinsed, air-dried, treated with 35wt% HEMA aqueous solution. The films were then subject to plasma-exposure under a NTAP brush with different time (1–8min)/input power (5–15W). For comparison, the dentin collagen films were also treated with the above HEMA solution containing photo-initiators, then subject to light-curing. After plasma-exposure or light-curing, the HEMA-collagen films were rinsed in deionized water, and then examined by FTIR spectroscopy and TEM. ResultsThe FITR results indicated that plasma-exposure could induce significant HEMA grafting onto dentin collagen thin films. In contrast, light-curing led to no detectable interaction of HEMA with dentin collagen. Quantitative IR spectral analysis (i.e., 1720/3075 or 749/3075, HEMA/collagen ratios) further suggested that the grafting efficacy of HEMA onto the plasma-exposed collagen thin films strongly depended on the treatment time and input power of plasmas. TEM results indicated that plasma treatment did not alter collagen's banding structure. SignificanceThe current study provides deeper insight into the mechanism of dental adhesion enhancement induced by non-thermal plasmas treatment. The NTAP brush could be a promising method to create chemical bond between resin monomers and dentin collagen.