Plasma Post-treatment Research Articles

The Mechanical and Electrochemical Stability of Trimethysilane Plasma Nanocoatings Deposited onto Cobalt Chromium Cardiovascular Stents.

The objective of this study was to evaluate the coating integrity performance and corrosion protection property of trimethylsilane (TMS) plasma nanocoatings that were directly deposited onto cobalt chromium (CoCr) L605 cardiovascular stents. Hydrophilic surfaces were achieved for the TMS plasma nanocoatings that were deposited onto the coronary stents through NH3/O2 (2:1 molar ratio) plasma post-treatment. With a coating thickness of approximately 20-25 nm, the TMS plasma nanocoatings were highly durable and able to resist delamination and cracking from crimping and expansion by a Model CX with a J-Crimp Station. The stent surface that was evaluated by Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray Spectroscopy (EDS) showed no indications of pitting, corrosion, or adsorption products on either the luminal or abluminal surfaces of the stents, in contrast to the uncoated stent surface. The TMS plasma nanocoatings significantly enhanced the stent's corrosion resistance in immersion experiments that followed the ASTM F2129-15 corrosion protocol, evident in the increase of the open circuit potential (OCP) from 0.01 V for the uncoated L605 stent to 0.18 V for the plasma-nanocoated L605 stent, reducing potential cytotoxic metal ion release. Cyclic polarization (CP) curves show that the corrosion rate (density level) observed in plasma-nanocoated L605 stents was approximately half an order of magnitude lower than that of the uncoated stents, indicating improved corrosion protection of the stents. CP curves of the TMS plasma-nanocoated stents with different coating thicknesses show that, in the range of 20-65 nm, the coating thickness does not result in any difference in the corrosion resistance of the stents.

Effect of nanodiamonds surface deposition on hydrophilicity, bulk degradation and in-vitro cell adhesion of 3D-printed polycaprolactone scaffolds for bone tissue engineering

This study was designed to deposit nanodiamonds (NDs) on 3D-printed poly-ϵ-caprolactone (PCL) scaffolds and evaluate their effect on the surface topography, hydrophilicity, degradation, andin-vitrocell adhesion compared to untreated PCL scaffolds. The PCL scaffold specimens were 3D-printed by fused deposition modeling (FDM) technique with specific porosity parameters. The 3D-printed specimens' surfaces were modified by NDs deposition followed by oxygen plasma post-treatment using a plasma focus device and a non-thermal atmospheric plasma jet, respectively. Specimens were evaluated through morphological characterization by field emission scanning electron microscope (FESEM), microstructure characterization by Raman spectroscopy, chemical characterization by Fourier transform infrared (FTIR) spectroscopy, hydrophilicity degree by contact angle and water uptake measurements, andin-vitrodegradation measurements (n= 6). In addition,in-vitrobone marrow mesenchymal stem cells adhesion was evaluated quantitatively by confocal microscopy and qualitatively by FESEM at different time intervals after cell seeding (n= 6). The statistical significance level was set atp⩽ 0.05. The FESEM micrographs, the Raman, and FTIR spectra confirmed the successful surface deposition of NDs on scaffold specimens. The NDs treated specimens showed nano-scale features distributed homogeneously across the surface compared to the untreated ones. Also, the NDs treated specimens revealed a statistically significant smaller contact angle (17.45 ± 1.34 degrees), higher water uptake percentage after 24 h immersion in phosphate buffer saline (PBS) (21.56% ± 1.73), and higher degradation rate after six months of immersion in PBS (43.92 ± 0.77%). Moreover, enhanced cell adhesion at all different time intervals was observed in NDs treated specimens with higher nuclei area fraction percentage (69.87 ± 3.97%) compared to the untreated specimens (11.46 ± 1.34%). Surface deposition of NDs with oxygen-containing functional groups on 3D-printed PCL scaffolds increased their hydrophilicity and degradation rate with significant enhancement of thein-vitrocell adhesion compared to untreated PCL scaffolds.

Performance enhancement in spin transfer torque magnetic random access memory through in situ cap layer optimization

Magnetic tunnel junctions (MTJs), a key component of spin transfer torque magnetic random access memory, are typically fabricated using two main processes: plasma etching and in situ protective cap layer deposition. It has been found that while the etching process predominantly affects MTJ performance, the cap layer process can further enhance electrical and magnetic properties. In this study, we achieved performance improvements in MTJs by optimizing the cap layer deposition process through various experimental methods, such as modifying the gas mixtures used in the deposition process and incorporating a novel post-plasma treatment. During the deposition of the silicon nitride (SiNx) cap layer, N-rich dissociated compounds can induce passivation of the MTJ layer, leading to additional loss of tunneling magnetoresistance (TMR) and coercive field (Hc). To circumvent this challenge, we prioritized modifying the gas ratio in the SiNx deposition process. Additionally, hydrogen introduced during SiNx deposition can penetrate the MTJ pillars and degrade their properties. To mitigate this, we developed a novel post-nitrogen plasma treatment in a plasma-enhanced chemical vapor deposition chamber, which effectively desorbed the excess hydrogen from the MTJ film stack. As a result of these optimized processes, the TMR loss, compared to a blanket wafer, was reduced from 25% to 8%, and Hc increased by up to 33% for the same stack, achieving significant performance enhancements.

Impact of gliding arc cold plasma on deactivating of aflatoxin and post-treatment fungal growth on wheat grains

Wheat, a strategic global agricultural product, is prone to contamination by hazardous fungi and toxins, with aflatoxin being particularly prevalent and perilous. This study aimed to evaluate the efficacy of cold plasma in deactivating Aspergillus flavus (A.f.) and Aspergillus parasiticus (A.p.), as well as aflatoxins in wheat grains, offering an alternative to conventional chemical and thermal treatments. Wheat grains inoculated with fungi were subjected to humid air cold plasma at four power levels (5.39, 6.88, 8.98, and 10.88 W) and three plasma exposure periods (2, 6, and 12 min). Post-plasma treatment, Aflatoxin concentrations were analyzed using HPLC, while modified Gompertz and Baranyi and Roberts’ mathematical models were employed to study the growth kinetics of A.f. and A.p. species. Findings revealed that samples treated with 10.88 W power for 12 min exhibited a substantial reduction of 64%, 41%, 59%, 40%, and 61% in B1, B2, G1, G2 aflatoxins, and total aflatoxin, respectively. Additionally, plasma led to a 78.74% and 68.57% reduction in the growth of A.f. and A.p. fungi, respectively. Notably, plasma induced a fungal inhibitory effect by prolonging the lag time and decreasing the growth rate. These results underscore the significant potential of cold plasma as a capable technique for fungal inactivation and the emerging disinfection of contaminated wheat grains.

Long-Term Structural Changes in the Osteochondral Unit in Patients with Osteoarthritis Undergoing Corrective Osteotomy with Platelet-Rich Plasma or Stromal Vascular Fraction Post-Treatment.

This pilot study examined the long-term structural changes in the osteochondral unit of 20 patients with knee osteoarthritis (KOA) who underwent high tibial osteotomy (HTO) and received post-treatment with either platelet-rich plasma (PRP) or stromal vascular fraction (SVF). Ten patients were injected with autologous PRP (PRP subgroup), while another ten patients received autologous SVF (SVF subgroup) six weeks after surgery and were monitored for 18 months. Histological samples of bone and cartilage (2 mm in diameter and 2 cm long) were taken from tibial and femoral sites during surgery and 18-month post-HTO, and morphometric analyses were conducted using Mega-Morf12 software. Both post-treatment resulted in an increase in articular cartilage height at both sites (p < 0.001 in the tibia and femur), indicating positive outcomes. Significant improvements in subchondral and trabecular bone architecture were also observed, with SVF injection showing higher reparative capacity in terms of bone volume (p < 0.001 for the tibia and p = 0.004 for the femur), subchondral bone height (p < 0.001 for the tibia and p = 0.014 for the femur), trabecular bone volume (p < 0.001 for the femur), and intertrabecular space (p = 0.009 for the tibia and p = 0.007 for the femur). This pilot study, for the first time, demonstrates that HTO surgery combined with PRP and SVF post-treatments can lead to significant enhancements in knee articular cartilage and bone architecture in KOA patients, with SVF showing higher regenerative potential. These findings may contribute to improving treatment strategies for better clinical outcomes in HTO therapy for patients with KOA.

Oxide Reduction Treatment with a Thermal Plasma Torch: A Case Study

This article presents the findings of a study on oxide reduction utilizing a novel reducing plasma torch, employing greenhouse gases such as CO2 and CH4 as plasma gases. The primary aim of this investigation is to establish the viability of this approach. The innovative plasma torch was employed to reduce various oxides, including aluminum oxide, iron oxide, and titanium oxide, as well as a mixed oxide composition, employing a CO2/CH4 molar ratio of 1:1 within a spouted bed reactor. Following plasma treatment, X-ray diffraction (XRD) analysis was conducted to examine the metallic phases, notably titanium, iron, and aluminum. SEM–EDS observations were carried out to assess microstructural changes and identify elemental compositions pre- and post-plasma treatment. The results demonstrate that within the conical section of the reactor, titanium oxide experiences partial reduction, resulting in limited titanium production, while aluminum oxide and iron oxides (magnetite and hematite) undergo reduction to yield aluminum and iron, respectively. Thermodynamic calculations, performed using Factsage software version 8.3, were utilized to predict stable-phase formations following plasma treatment for each material.

Exploring Cold plasma technology: Enhancements in Carob seed germination, phytochemical Composition, and antioxidant activity

The cultivation of carob tree does not need many climatic and ecological requirements. The main limit to its large-scale cultivation is the defects for propagation with seeds. Addressing this, our study evaluated the effect of cold plasma pretreatment on carob seed germination.Impressively, cold plasma showcased beneficial effects by significantly increasing water uptake in seeds (CS: 1.71 ± 0.59; PS/3.99 ± 1.56) and decreasing the contact angle from 80.7° to 57.9°, enhancing the seed surface's hydrophilicity. While the germination rate enhancement was subtle, the treatment presented an innovative route to modifying the seed's physiochemical properties. Specifically, storage proteins like albumin, globulin, and prolamin were notably reduced (Albumin (from 7.67 to 4.95 mg/g DW), Globulin (from 8.52 to 5.80 mg/g DW) and Prolamin (from 3.53 to 1.66 mg/g DW)). Additionally, there was a decline in the overall content of polyphenols (from 846.88 to 760.94 mg GAE/100g DW) and flavonoids (from 790.93 to 502.95 mg GAE/100g DW) and a decrease in the ferric reducing power (from 34.48 to 26.39 mg AAE/g DW). However, radical scavenging activity remained consistent. Intriguingly, FTIR-ATR spectral analysis post plasma treatment indicated oxidative alterations in the seed coat, marked by a distinctive intensity at 1732 cm⁻1.This investigation suggests that the application of eco-friendly technology could provide improvements in seed surface's hydrophilicity, but appropriate conditions could be chosen to increase germination efficiency.

Characteristics of low-pressure-plasma-processed NiRu-MOFs/nickel foam for Hydrogen evolution reaction

NiRu bimetallic metal–organic frameworks (NiRu-MOFs) are grown by a simple hydrothermal method on nickel foam (NF) as an the electrocatalyst for the hydrogen evolution reaction. Low-pressure plasmas of pure Ar, 95%Ar + 5%H2, and 95% Ar + 5%O2 are used for the post-treatment of the NiRu-MOFs. NiRu-MOFs-AO with post-plasma treatment with 95%Ar + 5%O2 show the lowest overpotential of 123.3 mV at a current density of 10 mA cm−2 and a Tafel slope of 72.0 mV dec−1 in 1 M KOH electrolyte. Electrochemical impedance spectroscopy results indicate that post-plasma treatment can further reduce the charge transfer resistance. Moreover, the electric double-layer capacitance (Cdl) is calculated based on the cyclic voltammetry results, and the electrocatalyst subjected to 95%Ar + 5%O2 post-plasma treatment shows a 2Cdl value of 3.69 mF/cm2, suggesting a larger electrochemically active surface area after oxygen-containing-plasma treatment.

Correlation between seminal plasma biochemical markers and semen parameters in idiopathic oligoasthenoteratospermia: identification of biomarkers for L-carnitine therapy.

L-carnitine therapy for idiopathic sperm abnormalities exhibits variable effectiveness, and currently, there are no established criteria to predict patient response. This study investigated correlations between seminal plasma markers and semen parameters to identify biomarkers that can guide indications for L-carnitine therapy indications in patients with idiopathic sperm abnormalities. A retrospective review was conducted on 223 male patients with idiopathic oligoasthenoteratospermia, who sought medical attention at our clinic between January 2020 and October 2022. These patients underwent a pretreatment seminal plasma biochemical analysis, followed by a three-month continuous L-carnitine treatment. The correlation between seminal plasma biochemical parameters and pretreatment semen parameters was analyzed. Semen quality was compared between cases with normal and abnormal seminal plasma biochemical parameters, both pretreatment and posttreatment. The correlation between the changes in semen parameters after treatment and seminal plasma biochemical parameters were investigated. Correlation analyses revealed significant associations between all pretreatment semen parameters and seminal plasma biochemical markers, except for liquefying time and the ratio of normal morphology. Subgroup analysis, stratified by seminal fructose, zinc, citric acid, and neutral glycosidase levels, demonstrated that abnormal groups exhibited significantly different levels of semen parameters compared with the normal groups. The changing difference and changing ratio in the ratio of forward motile sperm showed a negative correlation with seminal fructose levels (r=-0.165 and -0.144). The changing difference in semen volume was negatively correlated with the level of seminal neutral glycosidase (r=-0.158). The changing ratio in semen volume, sperm concentration, total sperm count, and count of forward motile sperm all exhibited negative correlations with the levels of seminal neutral glycosidase (range from -0.178 to -0.224). Seminal plasma biochemical markers, particularly fructose and neutral glycosidase, may serve as valuable indicators for determining the eligibility of patients with idiopathic sperm abnormalities for L-carnitine therapy.

Abstract B030: Synergistic antitumor effects of cold atmospheric plasma and temozolomide in glioblastoma: multimodal approaches integrating in-vitro, in vivo, and in silico investigations for novel and enhanced therapeutic advancements

Abstract Glioblastoma multiforme (GBM) is a common and aggressive brain cancer with a median survival rate of 12 to 18 months after diagnosis. Despite standard treatments, including surgery, radiotherapy, and Temozolomide (TMZ), GBM remains highly resistant to therapy due to its infiltrative pattern of invasion, rapid growth, and propensity to relapse [1]. While overall mortality rates remain high, there is a crucial need for a better understanding of the molecular mechanisms and gene mutations involved in GBM and the development of more effective and adaptive therapeutic approaches. Modulating reactive oxygen species (ROS) levels has been suggested as a therapeutic strategy to selectively target the destruction of cancer cells. To address this, we propose a combination therapy utilizing multi-operational plasma devices, including using cold atmospheric plasma (CAP) jet and plasma discharge tube (PDT) in conjunction with TMZ for GBM treatment. CAP functions by elevating reactive oxygen and nitrogen species (RONS) levels and specifically targeting tumor spread. We investigated various plasma devices and their characteristics using optical emission spectroscopy (OES) and measured the electromagnetic potential and emissions of the PDT. The OES of PDT displayed a similar spectrum as the CAP jet, indicating the presence of ROS. In this study, we performed transcriptomic analysis of glioblastoma cells using high throughput deep RNA-Seq with next-generation sequencing (NGS) to quantify genome-wide gene expression changes. Additionally, we examined signaling pathways and predicted structural changes in consequential proteins caused by gene spectrum up or down-regulation. Our results demonstrate that the combination treatment of CAP and TMZ downregulated vital genes involved in MAPK, P53, DNA repair, and cell cycle pathways. The combination of CAP &amp; TMZ showed a significant antitumor effect, inducing apoptosis and damaging essential proteins in GBM cells. In vitro and microscopic studies verified these results, showing nuclear and cell membrane disruption in cancer cells post-plasma treatment. Our findings demonstrate that the combination of CAP/PDT and TMZ effectively sensitizes GBM cells to TMZ, leading to apoptosis. We have previously shown a non-invasive application of CAP jet on the skull of tumor-bearing mice causing ~78% tumor inhibition [2]. Our current study highlights the potential of PDT for non-invasive treatment in vitro, offering a modality for intracranial delivery in in-vivo models. In conclusion, we propose CAP/PDT and TMZ combination therapy as novel non-invasive treatments for GBM in murine models. This approach offers a promising avenue for addressing the dire need for more effective treatments with minimal impact on normal cells. Further investigations and validation in clinical settings are warranted to significantly improve GBM management and patient outcomes.

CH4/(Ar–H2) plasma post-treatments produce nano-diamond aggregation and improvement in field emission properties of ultrananocrystalline diamond films

CH4/(Ar–H2) plasma post-treatments produce nano-diamond aggregation and improvement in field emission properties of ultrananocrystalline diamond films

Post O2 Plasma-Induced Fabrication of 1T-WS2/a-WO3 Heterostructure for Superior Hydrogen Evolution Reaction Electrocatalysts Via Hydrogen Spillover

2D transition metal dichalcogenide (TMDC) group has been widely spotlighted as hydrogen evolution reaction (HER) electrocatalysts to replace the conventional Pt electrocatalyst due to their distinctive features of robustness, low cost, and accessibility to structural modification. However, the electrochemical activity of TMDC materials is mostly originated from its exposed edge sites, whereas its basal plane is relatively inert. There have been attempts to increase the relative fraction of active edge sites in the basal plane or employ the phase transition from semiconductive 2H phase to metallic 1T phase. The practical uses have been restricted compared to nobel metal Pt.Plasma engineering is a facile method to functionalize their basal plane and generate vacancies into the lattice as active sites to improve electrocatalytic activity. In our previous works, MoS2 and WS2 has been synthesized to have abundant defects with maximized active edge sites to impart superior HER performance by employing Ar+H2S plasma treatment on tungsten (W) thin metal film with a thickness of 1 nm. However, to surpass the intrinsic electrochemical properites, we introduce 1T-WS2/a-WO3 (WSO) heterostructure via post O2 plasma treatment by exploiting a plasma enhanced-chemical vapor deposition (PE-CVD). There has been a limitation in obtaining the best electrocatalytic performances from the plasma assisted 1T-WS2 films because of its much lower hydrogen affinity of 1T-WS2. On the contrary, tungsten trioxide (WO3) shows strong hydrophilic property in that W atomic site of WO3 can easily absorb H2O. In this regard, 1T-WS2 with hydrophilic amorphous WO3 (a-WO3) can have the outstanding HER activity by inducing hydrogen spillover effect that is a hydrogen transport phenomenon from a-WO3 to 1T-WS2. a-WO3, which has relatively stronger hydrogen affinity, plays an important role in transferring the absorbed hydrogen to 1T-WS2 as active sites. As a result, the HER performance of WSO thin film can be optimized by means of controlling the amount of a-WO3 depending on the post O2 plasma treatment time. It was also confirmed from density functional theory (DFT) calculation that the hydrogen movement on the WSO surface related to hydrogen absorption energy difference between 1T-WS2 and WO3.

Investigation of the Tensile Strength of Adhesive-Bonded Steels Using Surface Treatments.

This study explores the tensile strength of adhesive joints in steel, focusing on the influence of heat treatment and diverse surface modifications. Results indicate a notable relationship between annealing temperature and tensile strength, with the most favorable outcomes identified at 90 min and 165 °C. Particularly, surfaces treated through turning, sandblasting, and plasma treatment (type C) consistently outperformed other methods. A standout revelation emerged from the turned, sandblasted, and plasma-treated surface (C), showcasing an exceptional tensile strength of 69.06 MPa. Load-holding tests underscored its resilience under diverse load conditions. Surface analyses, including roughness measurements, wetting characteristics, and Scanning Electron Microscope imaging, provided valuable insights into structural transformations induced by different treatments. Chemical composition examinations unveiled significant alterations post-plasma treatment, impacting surface chemistry and contributing to an outstanding tensile strength of 67.63 MPa. In essence, this research offers a glimpse into the nuanced factors influencing adhesive joint strength in steel. The turned, sandblasted, and plasma-treated surface emerges as a promising avenue, sparking further curiosity into the underlying mechanisms propelling superior tensile strength in adhesive joints.

Modification of PA66 fibres with in-situ polymerisation of 2- hydroxyethylmethacrylate

Poly(hydroxyethylmethacrylate) (pHEMA) was successfully introduced as an adhesion promotion layer on polyamide 66 (PA66) fibre surface by graft polymerisation using hydrogenperoxide as initiator. The grafted pHEMA layer strongly changes the fibre surface chemistry by introducing oxygen containing groups that thereby improve the fabric's wettability and strengthen the interface to potential subsequent coating layers or matrix material in case of fibre reinforced composites. The grafting reaction and formation of grafted pHEMA could be monitored and verified using different microscopic and spectroscopic analytical techniques, e.g. SEM, FTIR and NMR. Furthermore, the influence of parameters such as time, temperature and post plasma treatment of the grafting process on the yield of pHEMA was investigated and optimised using a d-optimal experimental design. For the optimisation of the process, the design suggested short treatment times at lower process temperatures and plasma post treatment for the desired fabric properties as an improved wettability and minimised change on bulk properties.

Simple Non-Equilibrium Atmospheric Plasma Post-Treatment Strategy for Surface Coating of Digital Light Processed 3D-Printed Vanillin-Based Schiff-Base Thermosets.

A simple non-equilibrium atmospheric plasma post-treatment strategy was developed for the surface coating of three-dimensional (3D) structures produced by digital light processing 3D printing. The influence of non-equilibrium atmospheric plasma on the chemical and physical properties of vanillin-derived Schiff-base thermosets and the dip-coating process was investigated and compared to the influence of traditional post-treatment with UV-light. As a comparison, thermosets without post-treatment were also subjected to the coating procedure. The results document that UV post-treatment can induce the completion of the curing of the printed thermosets if complete curing is not reached during printing. Conversely, the plasma post-treatment does not contribute to the curing of the thermoset but causes some opening of the imine bonds and the regeneration of aldehyde functions. As a consequence, no great differences are observed between the not post-treated and plasma post-treated samples in terms of mechanical, thermal, and solvent-resistant properties. In contrast to the UV post-treatment, the plasma post-treatment of the thermosets induces a noticeable increase of the thermoset hydrophilicity ascribed to the reformation of amines on the thermoset surface. The successful coating process and the greatest uniformity of the lignosulfonate coating on the surface of plasma post-treated samples are considered to be due to the presence of these amines and aldehydes. The investigation of the UV shielding properties and antioxidant activities documents the increase of both properties with the increasing amount and uniformity of the formed coating. Interestingly, evident antioxidant properties are also shown by the noncoated thermosets, which are deduced to their chemical structures.

Limitation of the migration of plasticizers from medical devices through treatment with low-pressure cold plasma, polydopamine coating, and annealing

Poly(vinyl chloride) (PVC) is widely used in the manufacture of medical devices. The plasticizers added to PVC are potentially toxic for humans, likely to migrate, and thus unintentionally administered to patients. The objective of the present study was to reduce the migration of plasticizer (1,2-cyclohexanedicarboxylic acid, diisononylester (DINCH) or trioctyltrimellitate (TOTM)) from PVC by implementing a three-step surface treatment process: (i) pretreatment with low-pressure argon cold plasma, (ii) polydopamine coating, and (iii) post-treatment with cold plasma exposure or thermal treatment at 140 °C.Samples were then characterized in terms of the water contact angle (WCA) and the aspect in scanning electron microscopy. Plasticizer migration (n = 5) was measured using an HPLC technique with ultraviolet detection and found to depend on the treatment and the plasticizer.Plasticized PVC was hydrophobic, with a measured mean ± standard deviation WCA of 96.7 ± 3.6° for PVC-DINCH and 110.2 ± 5.8° for PVC-TOTM. Plasma post-treatment and thermal post-treatment were respectively associated with a mean decrease in migration of 38.3 ± 1.9% for DINCH and 61.5 ± 4.4% for TOTM.Our results are promising with regard to limiting the migration of plasticizers into the patient’s blood and thus enabling the development of safer medical devices.

Enhancement of in vitro cholesterol-lowering and anti-diabetic activities of gluten hydrolysate prepared using kiwifruit protease as affected by ultrasound and atmospheric cold plasma post-treatments

Enhancement of in vitro cholesterol-lowering and anti-diabetic activities of gluten hydrolysate prepared using kiwifruit protease as affected by ultrasound and atmospheric cold plasma post-treatments

In vitro biological responses of plasma nanocoatings for coronary stent applications.

In-stent restenosis and thrombosis remain to be long-term challenges in coronary stenting procedures. The objective of this study was to evaluate the in vitro biological responses of trimethylsilane (TMS) plasma nanocoatings modified with NH3 /O2 (2:1 molar ratio) plasma post-treatment (TMS + NH3 /O2 nanocoatings) on cobalt chromium (CoCr) alloy L605 coupons, L605 stents, and 316L stainless steel (SS) stents. Surface properties of the plasma nanocoatings with up to 2-year aging time were characterized by wettability assessment and x-ray photoelectron spectroscopy (XPS). It was found that TMS + NH3 /O2 nanocoatings had a surface composition of 41.21 ± 1.06 at% oxygen, 31.90 ± 1.08 at% silicon, and 24.12 ± 1.7 at% carbon, and very small but essential amount of 2.77 ± 0.18 at% nitrogen. Surface chemical stability of the plasma coatings was noted with persistent O/Si atomic ratio of 1.292-1.413 and N/Si atomic ratio of ~0.087 through 2 years. The in vitro biological responses of plasma nanocoatings were studied by evaluating the cell proliferation and migration of porcine coronary artery endothelial cells (PCAECs) and smooth muscle cells (PCASMCs). 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) assay results revealed that, after 7-day incubation, TMS + NH3 /O2 nanocoatings maintained a similar level of PCAEC proliferation while showing a decrease in the viability of PCASMCs by 73 ± 19% as compared with uncoated L605 surfaces. Cell co-culture of PCAECs and PCASMCs results showed that, the cell ratio of PCAEC/PCASMC on TMS + NH3 /O2 nanocoating surfaces was 1.5-fold higher than that on uncoated L605 surfaces, indicating enhanced selectivity for promoting PCAEC growth. Migration test showed comparable PCAEC migration distance for uncoated L605 and TMS + NH3 /O2 nanocoatings. In contrast, PCASMC migration distance was reduced nearly 8.5-fold on TMS + NH3 /O2 nanocoating surfaces as compared to the uncoated L605 surfaces. Platelet adhesion test using porcine whole blood showed lower adhered platelets distribution (by 70 ± 16%), reduced clotting attachment (by 54 ± 12%), and less platelet activation on TMS + NH3 /O2 nanocoating surfaces as compared with the uncoated L605 controls. It was further found that, under shear stress conditions of simulated blood flow, TMS + NH3 /O2 nanocoating significantly inhibited platelet adhesion compared to the uncoated 316L SS stents and TMS nanocoated 316L SS stents. These results indicate that TMS + NH3 /O2 nanocoatings are very promising in preventing both restenosis and thrombosis for coronary stent applications.

Low temperature Cu/SiO2 hybrid bonding via 〈1 1 1〉-oriented nanotwinned Cu with Ar plasma surface modification

Argon (Ar) plasma surface modification and highly (111)-oriented nanotwinned copper (nt-Cu) were combined to lower the bonding temperature of Cu/SiO2 hybrid joints. The contact angle of water on SiO2 could be reduced from 22.6° to 3.3° after the plasma treatment. Benefiting from the high surface diffusivity of nt-Cu and great hydrophilicity of the plasma-assisted SiO2, the bonding temperature could be reduced to 150 ℃. However, such a plasma treatment caused the serious oxidation of the activated Cu in the ambient. To balance the activation and oxidation of the Cu films, Ar plasma power was tuned. X-ray photoelectron spectroscopy (XPS) was used to analyze the SiO2 surfaces. We found an increase (13.6% to 28.3%) in Si-OH and decreases in Si-O and C-O intensities after the plasma activation. Such decreases in Si-O and C-O intensities could be attributed to the removal of organic compounds. Shear tests were also conducted to characterize the bonding strength of the joints. An excellent bonding strength > 35 MPa was achieved after the post annealing and plasma treatment.

Zero-water discharge and rapid natural dyeing of wool by plasma-assisted spray-dyeing

The application of plasma on textiles is a highly beneficial technique to improve dyeability and reduce the consumption of water, energy, and time. This is advantageous for the industries to demonstrate high productivity and quality of the product but at a lower cost. Plasma treatment usually is applied as a pre-treatment before the conventional dyeing process, where the generation of dye wastewater remains a challenge. Plasma post-treatment can make a huge difference in reducing the dye wastewater; however, this has received little attention and more specifically the effectiveness of plasma on natural dye fixation is unknown. Natural dyes from waste, such as onion skin (Allium cepa L.) are greatly abundant and a low-cost green option for sustainable dyeing of textiles. In this study, a clean method of dyeing wool fabric with onion skin is proposed using a plasma-assisted spray-dyeing technique with no wastewater discharge. Four different plasma parameters were used varying the plasma operating power (40 W and 64 W) and treatment duration (30 s and 60 s). Mordanting and dyeing were done by a successive spraying-drying method in multiple rounds to reach the identical shade of a parallelly conducted conventional dyeing process. The removal of the cuticle layer of wool by plasma treatment was perceived from the morphology of the treated fabric, possibly contributing to the wettability. A higher plasma operating power and longer treatment time were beneficial and affected the overall dyeability. The chemical structure of wool showed a higher hydroxyl peak intensity after dyeing and a lower peak intensity of C–H groups after plasma post-treatment. The colour fastness properties (washing and crocking) improved after plasma post-treatment and confirmed the possible attachment of unfixed dyes with fabric. Overall, the time and energy consumed by the plasma-assisted spray-dyeing technique was nearly one-third of conventional dyeing, with no wastewater generation and led to a better colour strength (20.4 compared to 15.8) and similar colour fastness. Results showed the great potential for this newly proposed method as a sustainable textile dyeing alternative.