Atmospheric Pressure Plasma Jet Treatment Research Articles

Influence of Oxygen Impurity on Nitrogen Atmospheric-Pressure Plasma Jet

This study discussed the effect of oxygen impurity in the inlet gas of a nitrogen atmospheric pressure plasma jet (APPJ). A numerical model that takes into account the fluid dynamics, heat transfer, mass transfer, diffusion, and chemical reactions was developed to simulate the nitrogen APPJ. Further, a DC nitrogen APPJ experiment was performed to verify the plasma temperature characteristics on the treated surface. The plasma temperature decreased with an increase in the oxygen impurity. Moreover, the oxygen impurity influenced the related excited and neutral species. Specifically, with added oxygen impurity, N-related species decreased whereas O- and NOx-related species increased. Because the excited state species constitutes the most important reactant in APPJ treatment, this study could serve as a reference for the adjustment of a nitrogen APPJ.

Atmospheric-Pressure Plasma Jet-Induced Graft Polymerization of Composite Hydrogel on 3D-Printed Polymer Surfaces for Biomedical Application

Poly(lactic acid) (PLA) is currently the most widely used material in 3D printing. PLA has good mechanical properties, chemical stability, and biodegradability, but its surface is hydrophobic and cannot be effectively used. The growth metabolism of attachments, how to increase the strength of PLA with high brittleness, and 3D printing of PLA materials for the biomedical field have always been a topic of research by scientists. This experiment used fused filament fabrication (FFF) to prepare structures. First, the 3D-printed polymer surfaces were treated with an atmospheric-pressure plasma jet (APPJ) to make the surface hydrophilic and increase the number of polar functional groups on the surface. Then, UV photo-grafting polymerization of 2-hydroxyethyl methacrylate (HEMA), poly(ethylene glycol) methacrylate (PEGMA), and hydroxyapatite (HAp) was applied onto the 3D-printed polymer surfaces. The experimental results of the water contact angle for the wettability test show that APPJ-treated and UV-grafted composite hydrogels become hydrophilic to activate the 3D-printed polymer surface successfully. For the in vitro study, the effect of APPJ treatment and composite hydrogel on the viability of osteoblast-like MG63 cells was examined using the Alamar Blue cell viability assay, indicating that biocompatibility has been improved in this study. This method is expected to have potential in the application of bone scaffolds in the future.

Polylactic Acid/Polyaniline Nanofibers Subjected to Pre- and Post-Electrospinning Plasma Treatments for Refined Scaffold-Based Nerve Tissue Engineering Applications

Composite biopolymer/conducting polymer scaffolds, such as polylactic acid (PLA)/ polyaniline (PAni) nanofibers, have emerged as popular alternative scaffolds in the electrical-sensitive nerve tissue engineering (TE). Although mimicking the extracellular matrix geometry, such scaffolds are highly hydrophobic and usually present an inhomogeneous morphology with massive beads that impede nerve cell-material interactions. Therefore, the present study launches an exclusive combinatorial strategy merging successive pre- and post-electrospinning plasma treatments to cope with these issues. Firstly, an atmospheric pressure plasma jet (APPJ) treatment was applied on PLA and PLA/PAni solutions prior to electrospinning, enhancing their viscosity and conductivity. These liquid property changes largely eliminated the beaded structures on the nanofibers, leading to uniform and nicely elongated fibers having average diameters between 170 and 230 nm. After electrospinning, the conceived scaffolds were subjected to a N2 dielectric barrier discharge (DBD) treatment, which significantly increased their surface wettability as illustrated by large decreases in water contact angles for values above 125° to values below 25°. X-ray photoelectron spectroscopy (XPS) analyses revealed that 3.3% of nitrogen was implanted on the nanofibers surface in the form of C-N and N-C=O functionalities upon DBD treatment. Finally, after seeding pheochromocytoma (PC-12) cells on the scaffolds, a greatly enhanced cell adhesion and a more dispersive cell distribution were detected on the DBD-treated samples. Interestingly, when the APPJ treatment was additionally performed, the extension of a high number of long neurites was spotted leading to the formation of a neuronal network between PC-12 cell clusters. In addition, the presence of conducting PAni in the scaffolds further promoted the behavior of PC-12 cells as illustrated by more than a 40% increase in the neurite density without any external electrical stimulation. As such, this work presents a new strategy combining different plasma-assisted biofabrication techniques of conducting nanofibers to create promising scaffolds for electrical-sensitive TE applications.

LiMn2O4 Li-ion hybrid supercapacitors processed by nitrogen atmospheric-pressure plasma jet

LiCl–Mn(NO3)2·4H2O pastes were screen-printed on a carbon cloth substrate and furnace-calcined to convert them into LiMn2O4. The LiMn2O4 electrode was then post-processed using a nitrogen atmospheric-pressure plasma jet (APPJ). APPJ processing created oxygen vacancy defects on the electrode surface. Electrochemical tests of the Li-ion hybrid supercapacitors (Li–HSCs) were performed by cyclic voltammetry (CV) and galvanostatic charging/discharging (GCD) in 1-M Li2SO4 aqueous solution. The results indicate that proper APPJ treatment optimizes the Li–HSCs performance, whereas excessive APPJ treatment may cause material damage. After 3-min APPJ treatment at 620 °C, the Li–HSCs exhibited a maximum areal capacitance of 87.96 mF/cm2 with capacitance retention of 124.8% after a 1000-cycle CV test.

Improving electrochemical sensitivity of screen‐printed carbon electrodes by atmospheric pressure plasma jet treatment and electrochemical detection of dopamine

AbstractScreen‐printed carbon electrode (SPCE) has various crucial applications as biosensors. The binders used in the ink formulation of the SPCEs reduce the electron transfer from an electrolyte to it. In this study, we used an argon atmospheric pressure plasma jet (APPJ), a cost‐effective device, to modify the SPCE surface. Scanning electron microscopy and X‐ray photoelectron spectroscopy results show binder removal and oxidation of the APPJ‐treated SPCE surface. Due to binder removal and exposure of graphitic surface, the hydrophilicity of the APPJ‐treated SPCE surface enhances significantly. Moreover, oxidation makes the electrode more suitable for dopamine adsorption, resulting in enhanced sensitivity. The detection limit for the APPJ‐treated electrode is 1 μm, as observed in this study. Cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy have been performed on APPJ‐treated and untreated SPCEs.

Atmospheric pressure plasma jet treatment of PLA/PAni solutions: Enhanced morphology, improved yield of electrospun nanofibers and concomitant doping behaviour

To obtain uniform and bead-free nanofibers by means of electrospinning is sometimes very challenging, especially for polymers with low solubility, such as for example the intrinsically conducting polymers (ICPs). Recently, atmospheric pressure plasma jet (APPJ) treatment to pre-electrospinning polymer solutions has been found to effectively enhance the electrospinnability of a single polymer type. Here, such an APPJ treatment has been applied for the first time to a blended polymeric solution consisting of polylactic acid (PLA) and polyaniline emeraldine base (PAni EB) as well as its emeraldine salt (ES) form doped by camphorsulfonic acid (CSA). The plasma-induced physical changes of the solutions including pH, conductivity, viscosity and surface tension have been investigated and correlated with the ensuing physicochemical properties of the electrospun nanofibers. To do so, next to the liquid-based characterizations, the nanofibers have been examined by means of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), water contact angle (WCA) goniometry and uniaxial tensile testing. Results revealed that the pre-electrospinning plasma modification step resulted in a remarkably enhanced nanofiber morphology, deposition yield and mechanical performance of the electrospun nanofibers. Moreover, concomitant doping of PAni EB to PAni ES, as an unexpected side behaviour generated during the plasma treatment without the addition of any protonic acid, was found and further carefully investigated using ultraviolet/visible (UV–Vis) spectrometry. The findings obtained in this work thus enlarge the application range of pre-electrospinning APPJ treatment from single to blended polymeric solutions. Moreover, the recent pioneering discovery revealing the pre-electrospinning APPJ treatment role in enhancing electrospinning has surpassed the sole connotation of improved fiber morphology as new interesting effects are discerned in this study: boosted nanofiber deposition yield and doping capabilities.

The Therapeutic Effect of Atmospheric Pressure Plasma on Ultraviolet B-Induced Skin Photoaging and Damage in Mice

The active substances produced by atmospheric pressure plasma jet (APPJ) have biomedical effects such as disinfection, proliferation, anticancer, and wound healing. Plasma has been applied in dermatology; however, the mechanism of APPJ on ultraviolet B (UVB) induced skin photoaging and damage has not been widely investigated. In this study, we developed an APPJ device that is capable of generating plasma in open spaces and acting on biological surfaces. We then studied the effects of the APPJ application on UVB-induced skin photoaging and damage in mouse models. The results showed that APPJ prevented the degradation of collagen and elastin by decreasing the secretion of matrix metalloproteinases (MMPs). We also found that after the APPJ treatment, the density of the extracellular matrix (ECM) was maintained, the skin roughness caused by the UVB was decreased, and the epidermal and dermal thickness was improved. Molecular analysis of the skin tissue revealed that APPJ prevented UVB-induced apoptosis through p53, Caspase-8, caspase-9, and Bax in the pro-apoptotic pathway and Bcl-2 in the anti-apoptosis pathway and eventually reduced the expression of Caspase-3. In conclusion, APPJ application could protect skin against UVB-induced photoaging and damage, demonstrating its potential as a new therapeutic method for skin conditions.

Cleaning of nitrogen-containing carbon contamination by atmospheric pressure plasma jet

Atmospheric pressure plasma jet (APPJ) was used to clean nitrogen-containing carbon films (C–N) fabricated by plasma-assisted chemical vapor deposition method employing the plasma surface interaction linear device at Sichuan University (SCU-PSI). The properties of the contaminated films on the surface of pristine and He-plasma pre-irradiated tungsten matrix, such as morphology, crystalline structure, element composition and chemical structure were characterized by scanning electron microscopy, grazing incidence x-ray diffraction and x-ray photoelectron spectroscopy. The experimental results revealed that the removal of C–N film with a thickness of tens of microns can be realized through APPJ cleaning regardless of the morphology of the substrates. Similar removal rates of 16.82 and 13.78 μm min−1 were obtained for C–N films deposited on a smooth pristine W surface and rough fuzz-covered W surface, respectively. This is a remarkable improvement in comparison to the traditional cleaning method. However, slight surface oxidation was found after APPJ cleaning, but the degree of oxidation was acceptable with an oxidation depth increase of only 3.15 nm. Optical emission spectroscopy analysis and mass spectrometry analysis showed that C–N contamination was mainly removed through chemical reaction with reactive oxygen species during APPJ treatment using air as the working gas. These results make APPJ cleaning a potentially effective method for the rapid removal of C–N films from the wall surfaces of fusion devices.

Local oxynitriding of AZ31 magnesium alloy by atmospheric-pressure plasma treatment at room temperature

A surface-hardening treatment for AZ31 magnesium alloy using an atmospheric-pressure plasma jet (APPJ) at room temperature was developed. Magnesium is a potential engineering material because it is lightweight; however, magnesium alloys are difficult to heat-treat because of their low flaming temperature. Magnesium alloy specimens were irradiated with a localized atmospheric-pressure plasma jet generated by dielectric-barrier discharge for 180 s in air. The APPJ excited oxygen and nitrogen molecules in the ambient air, resulting in the formation of an oxynitrided layer; oxygen and nitrogen diffusion layer, on the surface of the magnesium alloy. The hardness and elemental distribution for the treated surface were examined. The top surface of the APPJ-treated magnesium alloy achieved a maximum hardness of 108 HV, which was ∼1.7 times greater than that of the untreated surface. Elemental analysis using an electron-probe microanalyzer revealed strong oxygen and nitrogen signals corresponding to the hardened region of the magnesium alloy, meaning that the hardness increased as a result of the formation of the oxynitrided layer. The proposed APPJ treatment is a promising approach for locally hardening magnesium alloys without using a heat treatment.

Atmospheric pressure plasma jet: formation of Wenzel’s model supportive surface modification on PMMA

ABSTRACT The generation of cold plasma at atmospheric pressure by using atmospheric-pressure plasma jet (APPJ) system and its use in the treatment of the poly-methyl-methacrylate (PMMA) have been reported in the manuscript. The cold plasma is generated at atmospheric pressure with 120 watt and 200 watt power and 3 litres/min and 5 litres/min argon flow using a 13.56 MHz radio frequency generator. PMMA samples are treated with aforesaid parameters for different time durations. After treatment, the formation of a carbon-rich surface has been observed, while a visible and significant amount of changes in surface morphology, roughness, adhesion strength and contact angle have been observed. Due to the APPJ treatment, the Wenzel’s model supportive microconical structures have been formed for hydrophobic surfaces. Optical emission spectroscopy has been used to identify the various species in the plasma and for electron temperature measurement. The discharge phenomenon at atmospheric pressure has been understood using the basic plasma model. The interaction of the plasma with the surface has been explained using the sub-plantation model.

Can we remove tattoos with non‐thermal atmospheric plasma?

AbstractCurrent methods for tattoo removal are long, costly and have drawbacks such as scarring among others. Looking for alternatives, here we assess the feasibility of non‐thermal plasma (NTP) as a standalone method for the removal of tattoos. We report the results of atmospheric pressure plasma jet treatment of real tattoo inks suspensions in water and in gelatin (liquid or as a solid film), selected as a model of skin. Analysis of the residual color and the temperature effect in all the samples after plasma treatment reveals significant differences between water and the skin model. Kinetic considerations and the extension of our results to more realistic scenarios allow us to conclude that NTP cannot compete with the current laser technology in a real application.

Improving the surface insulation of epoxy resin by plasma etching

Epoxy resin (EP) tends to accumulate a large amount of charge on its surface when exposed to a high-voltage DC electric field, which leads to a reduction in its insulative performance and an increase in potential safety risks in power systems. To suppress charge accumulation, improve the flashover voltage of the EP, and reduce the risk of gas insulated switchgear (GIS) / gas insulated transmission line (GIL) failure, we used two plasma-etching methods, i.e., atmospheric-pressure dielectric barrier discharge (DBD) and the atmospheric-pressure plasma jet (APPJ), to modify the surface of the EP. The surface morphology and electrical properties of the modified materials were explored as a function of time. The results show that after DBD treatment, the roughness of the sample increases by 103.9 nm, the conductivity increases by 3.9 × 10–18 S, and the flashover voltage increases by 14.4%; after APPJ treatment, the roughness of the sample increases by 223.5 nm, the conductivity increases by 3.4 × 10–17 S, and the flashover voltage increases by 18%. This shows that both plasma-etching methods can improve the insulation properties of materials by improving the surface-charge characteristics. The two methods are compared with each other: the APPJ treatment method is better at improving the surface roughness and electrical properties of materials, and this flexible treatment method has greater potential in industrial applications.

Atmospheric pressure plasma engineered superhydrophilic CuO surfaces with enhanced catalytic activities

Cupric oxide (CuO) thin film has found widespread application as a low-cost, earth-abundant material for electro and photo catalytic applications. High surface wettability is a key factor to achieve enhanced efficiency in these catalytic applications. Here, we report a fast and environment friendly route to fabricate super hydrophilic CuO thin films using a low power (5–10 W) atmospheric pressure plasma jet (APPJ). With APPJ treatment for 5 min, the CuO surface transforms from hydrophobic to super-hydrophilic with threefold increase in catalytic activity. The electrodes were extensively characterized using various bulk and surface-sensitive techniques. APPJ introduces anisotropy in the crystal structure and creates unique three-dimensional surface morphology with distinct surface chemical and electronic features. Interestingly, presence of oxygen in the plasma was found to be critical for the enhanced activities and the activity decreased when the functionalised with nitrogen plasma. Oxygen plasma functionalisation of CuO electrodes resulted in a 130 mV reduction in the onset potential for oxygen evolution reaction along with enhanced current density, 10 mA cm−2 against 3 mA cm−2 at 1 V vs Saturated Calomel Electrode in 0.1 M KOH without iR compensation. Importantly, without introducing any external dopants the work function could be decreased by 80 mV. Moreover, the treated films exhibited a higher rate of photo degradation (0.0283 min−1 compared to 0.0139 min−1) of Methylene Blue and phenol indicating efficient charge separation. This work presents the potential of APPJ functionalisation of CuO surface to boost the activity of other thin film catalyst materials and solutions processed systems.

Carbon Dioxide Tornado-Type Atmospheric-Pressure-Plasma-Jet-Processed rGO-SnO2 Nanocomposites for Symmetric Supercapacitors.

Pastes containing reduced graphene oxide (rGO) and SnCl2 solution were screen printed on carbon cloth and then calcined using a CO2 tornado-type atmospheric-pressure plasma jet (APPJ). The tornado circulation of the plasma gas enhances the mixing of the reactive plasma species and thus ensures better reaction uniformity. Scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) were performed to characterize the synthesized rGO-SnO2 nanocomposites on carbon cloth. After CO2 tornado-type APPJ treatment, the pastes were converted into rGO-SnO2 nanocomposites for use as the active electrode materials of polyvinyl alcohol (PVA)-H2SO4 gel-electrolyte flexible supercapacitors (SCs). Various APPJ scanning times were tested to obtain SCs with optimized performance. With seven APPJ scans, the SC achieved the best areal capacitance of 37.17 mF/cm2 in Galvanostatic charging/discharging (GCD) and a capacitance retention rate of 84.2% after 10,000-cycle cyclic voltammetry (CV) tests. The capacitance contribution ratio, calculated as pseudocapacitance/electrical double layer capacitance (PC/EDLC), is ~50/50 as analyzed by the Trasatti method. GCD data were also analyzed to obtain Ragone plots; these indicated an energy density comparable to those of SCs processed using a fixed-point nitrogen APPJ in our previous study.

Insight into the effect of He atmospheric pressure plasma jets on low-density polyethylene surfaces by fixed-point treatment

In order to further investigate the modification effect of atmospheric pressure plasma jets (APPJ) on the surface of low-density polyethylene (LDPE) film and related mechanisms, a series of experiments and simulations were carried out in this paper. A laminar helium flow with a flow rate of 6.0 standard liters per minute was used as a working gas and a homogeneous glow-like He APPJ was generated by an AC voltage with a peak-to-peak voltage of 10.1 kV and a frequency of 20 kHz. After 15 min He APPJ treatment at a fixed point on the film, the surface properties at different radial positions from this point were analyzed. This study was performed using water contact angle (WCA) measurement, x-ray photoelectron spectroscopy and atomic force microscopy. The results of WCA and surface free energy (SFE) indicate that the modification effect range is larger than APPJ’s spread range on the surface. Along the radial direction, the surface properties did not change monotonously but had extreme points: the change of the surface morphology was first etching and then deposition; APPJ incorporated oxygen containing functional groups including C–O, C=O/O–C–O and O–C=O into the LDPE surface, and their distributions on the surface were different. To explore what caused the difference, quantum chemical simulation analysis by ORCA software was used to explain the relationship between the change of surface energy and oxygen-containing functional groups. The simulation showed that C–O has more influence on the SFE of the LDPE surface.

Osseointegration of Plasma Jet Treated Titanium Implant Surface in an Animal Model.

Osseointegration of titanium implant is important for the success of both dental and medical implants. Previous studies have attempted to improve osseointegration by considering the use of plasma jet technology, where information with animal models and parameters related to osseointegration is still lacking. Therefore, this study investigated the effects of non-thermal atmospheric pressure plasma jet (NTAPPJ) treatment on titanium implants in terms of osseointegration in mongrel dogs. A total of 41 implants; 21 NTAPPJ treated and 20 control, were placed in the maxilla and mandible of six mongrel dogs for either 4 or 8 weeks. The bone volume (BV) and bone-to-implant contact (BIC) ratio were determined by region of interest (ROI). Statistical analysis was performed with the Wilcoxon rank-sum test. The NTAPPJ group at 4 weeks showed higher numbers in both BV and BIC (p < 0.05) compared to the control group. However, at 8 weeks there were less significant differences between the control or experimental group as the control group had caught up with the experimental group. Hence, NTAPPJ may be an effective treatment for the initial healing period which is critical to ensure reliable long-term predictability. The BV and BIC have been clinically proven to accelerate in the initial stages with the use of NTAPPJ to aid in the healing and initial stability of implants.

Assessment of Possible Application of an Atmospheric Pressure Plasma Jet for Shelf Life Extension of Fresh-Cut Salad.

Ready-to-eat salads are very perishable with quality losses within 6–7 days, and the extension of their shelf life is still a challenge. In this work, an atmospheric pressure plasma jet (APPJ) was applied for the surface decontamination of fresh-cut lettuce baby leaves. The APPJ antimicrobial efficiency on the natural microbiota and its impact on some physicochemical attributes of lettuce were evaluated as a function of the treatment duration (0–30 s). Then, the influence of plasma treatment on the salad shelf life was studied, following the growth of aerobic mesophilic bacteria in both untreated and plasma-treated samples during 9 days of storage at 4 °C, together with the plasma-induced changes in physicochemical parameters of lettuce leaves. The APPJ induced a fast (15 s) microbial decontamination (1.3 log10 CFU/g) of the salad surface. Exposure time and salad-plasma plume distance were the parameters that substantially affected the microbial inactivation. APPJ treatment retarded bacterial growth during the refrigerated storage, as plasma-treated samples were noticeably less contaminated than the non-treated ones in the first 3–4 days. No significant effect were observed on electrolyte leakage, pH, and dry matter content in both the set up phase and the shelf life study.

Enhanced photoelectrochemical response of 1D TiO2 by atmospheric pressure plasma surface modification

In this paper we demonstrate the use of atmospheric pressure plasma jet (APPJ) to functionalize the surface of hydrothermally synthesized vertically aligned TiO2 nanorods (TNRs) for photo electrochemical (PEC) application. The TNRs functionalized with the atmospheric pressure He-plasma showed relatively higher crystallinity, improved light absorption, and change in the morphology with additional surface area, leading to an enhanced photocurrent density than that of the untreated. Achieving the PEC performance on par with the best in the literature, this APPJ treatment is shown to be a promising technique to obtain better functionality with TNR kind of materials and many other nano-micro systems for various applications such as PEC hydrogen generation.

Carbon nanowalls functionalization for efficient O2 reduction catalyzed by laccase using design of experiment

An enzymatic biofuel cell cathode was elaborated by nano-structuration and functionalization of graphite using two consecutive plasma treatments before immobilization of laccase as a biocatalyst to perform oxygen reduction reaction (ORR) by direct electron transfer ((DET). Nano-structuration of graphite surfaces by synthesis of vertical graphen-like carbon nanowalls (CNWs) was performed by microwave excited plasma enhanced chemical vapor deposition (PECVD). Atmospheric pressure plasma jet (APPJ) system was then used to functionalize chemically the CNWs surface via a rapid and dry route. A partial fractional design evidenced two significant parameters of the APPJ treatment in terms of ORR current density: the treatment time and the inter-distance between the plasma jet and the surface of the carbon material. With the optimized APPJ treatment parameters, a four-fold enhancement of the ORR current density (-440 ± 70 μA/cm2) could be obtained on CNWs, compared to graphite electrodes. The best current density obtained was about −1 mA/cm2 with oxidized laccase covalently immobilized on the electrode without any agitation of the solution, confirming the main importance of enzyme orientation on the electrode surface for efficient DET transfer, the relevance of electrode nanostructuration and the advantage of covalent linking of the protein on the electrode surface.

Influence of Non-Thermal Atmospheric Pressure Plasma Jet on Extracellular Activity of α-Amylase in Aspergillus oryzae

In a previous study, we found that plasma can enhance spore germination and α-amylase secretion in A. oryzae, a beneficial fungus used in fermentation. To confirm this, in the current study, we investigated the effects of plasma on development and α-amylase secretion using an enlarged sample size and a different plasma source: a plasma jet. There was a ~10% (p &lt; 0.01) increase in spore germination upon non-thermal atmospheric pressure plasma jet (NTAPPJ) treatment for 5 min and 10 min, as compared with the control (no plasma treatment). The activity of α-amylase detected in potato dextrose broth (PDB) media during incubation was significantly elevated in plasma-treated samples, with a more obvious increase upon 10 min and 15 min treatments and 24–96 h incubation periods. The levels of the oxidation reduction potential (ORP) and NOX (nitrogen oxide species) were higher in the plasma-treated samples than in the control samples, suggesting that these two variables could serve as standard indicators for enhancing α-amylase activity after plasma treatment. Genome sequencing analysis showed approximately 0.0016–0.0017% variations (changes in 596–655 base pairs out of a total of 37,912,014 base pairs) in the genomic DNA sequence of A. oryzae after plasma treatment. Our results suggest that NATPPJ can enhance the spore germination and extracellular activity of α-amylase, probably by increasing the levels of ORP and NOX to an optimum level.