Copper Release Research Articles

Cyclic Copper Uptake and Release from Natural Seawater-A Fully Sustainable Antifouling Technique to Prevent Marine Growth.

Unwanted growth of fouling organisms on underwater surfaces is an omnipresent challenge for the marine industry, costing billions of dollars every year in the transportation sector alone. Copper, the most widely used biocide in antifouling paints, is at the brink of a total ban in being used in antifouling coatings, as it has become an existential threat to nontargeted species due to anthropogenic copper inputs into protected waters. In the current study, using a porous and cross-linked poly(ethylene imine) structure under marine and fouling environments, available copper from natural seawater was absorbed and electrochemically released back as a potent biocide at 1.3 V vs Ag|AgCl, reducing marine growth by 94% compared to the control electrode (coupon) at 0 V. The coating can also function as an electrochemical copper sensor enabling real-time monitoring of the electrochemical uptake and release of copper ions from natural seawater. This allows tailoring of the electrochemical program to the changing marine environments, i.e., when the vessels move from high-copper-contaminated waters to coastal regions with low concentrations of copper.

Influence of Soil Characteristics on Wood Biodeterioration by Brown Rot Fungi

Soil conditions can directly influence the inoculum potential of wood decay fungi, which is likely to be a major factor in the premature failure of utility poles across Europe. The objective of our study was to assess the influence of soil pH, humic acid and iron on wood decay. For this purpose, we incubated Fe-impregnated wood specimens on artificial medium to evaluate the influence of the metal on the activity of brown rot fungi. Moreover, the impact of Cu-leaching from impregnated wood specimens that were exposed to humic acid solutions was measured. In addition, weight losses caused by brown rot fungi in impregnated wood pole segments and stiffness (Young’s modulus of Elasticity) of Cu-impregnated wood specimens were quantified. The pH measurements showed that the soil samples were slightly acid (pH = 6.7 ± 0.7). In comparison to non-impregnated controls, the Fe-impregnated samples significantly increased weight losses by brown rot fungi (>30–40%). In the presence of humic acid the release of copper from chromium-free wood preservatives (up to 143.34 mg L−1) was enhanced. Weight losses in impregnated wood segments by brown rot fungi ranged from 5.3 to 20.4%. The recorded reduction in stiffness by brown rot fungi ranged from approximately 3.96 to 55.52% for Cu-impregnated wood specimens after 12 weeks. Our study shows that the pH, humic acid, iron content and selected wood preservatives greatly influence susceptibility of impregnated wood to brown rot fungi during ground contact.

Copper release from nano‑copper/polypropylene composite films to food and the forms of copper in food simulants

The influences of temperature, exposure time, different types of polypropylene (PP), (3-Aminopropyl) triethoxysilane (KH550) used as coupling agent, sterilizing conditions on copper migration from nano‑copper/PP composite films into food/ food simulants were explored. Results showed that copper migrated more easily from polypropylene (PPH) films with a maximum rate of 34.51%, compared to those from copolymer polypropylene (PPR) and block copolymer polypropylene (PPB) to 3% acetic acid (w/v). Gamma (γ) irradiation could significantly increase the copper migration (P < 0.05). Different forms of copper were found in different simulants. Copper crystals were found in 10% ethyl alcohol and identified by scanning electron microscopy and energy dispersed analysis of X-rays (SEM-EDX). The hydroxylation (%) of nano‑copper/PP films was less than 100%. These films had certain antioxidant and antimicrobial properties which could extend the shelf life of packaged food. The migration amount of copper into rice vinegar was the largest, with a maximum of 0.65 mg/ kg. Industrial relevanceAlthough nanomaterials are potentially beneficial for food packaging, migration of nanoparticles to the packaged food can be harmful to the human body. Therefore, it is very important to determine the presence and characterize the morphology of nanoparticles in food. In this paper, we have developed a new and effective packaging material containing nanoparticles and have explored the migration form and morphology in food simulants. In conjunction with the results of current study, nano‑copper/PP packaging material can be suggested for maintaining the product quality and has commercial potential.

Ultrasound-induced and MRI-monitored CuO nanoparticles release from micelle encapsulation

Copper oxide nanoparticles (CuO NPs) have anticancer and antimicrobial activities. Moreover, they have a contrast enhancing effect in both MRI and ultrasound. Nonetheless, encapsulation is needed to control their toxic side effects and a mechanism for release on demand is required. A methodology is introduced herein for encapsulating and releasing CuO NPs from micelles by ultrasound induced hyperthermia and monitoring the process by MRI. For this aim, CuO NPs loaded poly(ethylene glycol)-block-poly(D,L-lactic acid) (PEG-b-PLA) micelles were prepared. Then, the profile of copper release with application of ultrasound was examined as a function of time and temperature using a colorimetric method. Finally, T1 weighted MRI images of suspensions and ex vivo poultry liver samples containing the CuO NPs loaded micelles were acquired before and after ultrasound application. The results confirmed that: (i) encapsulated NPs are detectible by MRI T1 mapping, depicting substantial T1 shortening from 1872 ± 62 ms to 683 ± 20 ms. (ii) Ultrasonic hyperthermia stimulated the NPs release with an about threefold increase compared to non-treated samples. (iii) Releasing effect was clearly visible by T1-weighted imaging (mean signal increase ratio of 2.29). These findings can potentially lead to the development of a new noninvasive methodology for CuO NPs based theranostic process.

Effect of contamination sources on the rate of zinc, copper and nickel release from various soil ecosystems

Background and objectiveSoil is a substantive component in biosphere habitually endangered to superfluity contaminants particularly potential toxic elements (PTEs). The source of soil contaminants is very critical in controlling both their release and expected hazards in the different soil ecosystems. This study aims to investigate the effect of low-quality irrigation water (LQW) on the extent of soil pollution through desorption of zinc (Zn), nickel (Ni) and copper (Cu) from different polluted soils, collected from LQW irrigated farms for more than 40–80 years at Giza and Kafr-Elsheikh Governorates, Egypt.ResultsModels incorporated modified Freundlich (MFE), Elovich, first order and parabolic diffusion (PDE) showed significant results in describing the kinetic data under Egyptian conditions. Results entailed that according to the coefficient of determination (R2) and standard error, all used models well described the desorption of Cu, Ni and Zn, the most prevalent contaminants in the trailed soil ecosystems; for example, the R2 values were higher than 0.96** for zinc desorption using MFE model. As far as the PTEs levels are considered, the highest contaminant desorption rates were recorded at Kafr-Elsheikh site, followed by Kombora, and the lowest ones were in Abo Rawash soil ecosystem. The succession of more than one model to describe the kinetic perspective confirmed that the different mechanisms take place in PTEs sorption, distribution and subsequently release from different soil ecosystems.ConclusionsThe numerical values indicated that the soil ecosystems contaminated with industrial effluents were higher than those irrigated with sewage effluents regardless of the type of land use. More attention should be paid to low-quality water application in agriculture irrigation and its environmental risks.

The efficiency of activated carbon/magnetite nanoparticles composites in copper removal: Industrial waste recovery, green synthesis, characterization, and adsorption-desorption studies

Due to population growth, industrial development, and increasing environmental pollution, the treatment of water, soil, and air is crucial. Convenient and low-cost methods, including adsorption, have attracted much attention in recent years. In the present study, powdered activated carbon (PAC) and granular activated carbon (GAC) composites with magnetite nanoparticles (Fe3O4) were synthesized via a green method, using green tea extract as reducing agent. The iron required for the synthesis of adsorbents was extracted from direct reduction iron (DRI) sludge resulting from the direct reduction process of the steel industry. The adsorbents were identified using XRD, FESEM, EDX, FTIR, VSM, and BET analyses. Copper removal was examined within the initial concentration range of 0–400 mg/L from an aqueous medium. Desorption tests were performed for 100 and 300 mg/L concentrations in a 10-day cycle. The results revealed that Langmuir and Freundlich models are well fitted with the copper adsorption data. The maximum copper adsorption capacity was obtained at 23.61 and 13.37 mg/g by powdered activated carbon-magnetite nanoparticles composite (MNP-PAC) and granular activated carbon-magnetite nanoparticles composite (MNP-GAC) respectively. MNP-PAC had a higher adsorption capacity compared to MNP-GAC. The desorption results showed that the release of copper from the surface of adsorbents was very low and it diminished over time. Owing to their high efficiency in removing copper from aqueous solutions and not releasing copper over time as well as the easy separation of adsorbents after the completion of adsorption, the use of these two adsorbents, especially the MNP-PAC is recommended for the removal of copper.

Smartphone-powered efficient water disinfection at the point of use

Clean water free of bacteria is a precious resource in areas where no centralized water facilities are available. Conventional chlorine disinfection is limited by chemical transportation, storage, and the production of carcinogenic by-products. Here, a smartphone-powered disinfection system is developed for point-of-use (POU) bacterial inactivation. The integrated system uses the smartphone battery as a power source, and a customized on-the-go (OTG) hardware connected to the phone to realize the desired electrical output. Through a downloadable mobile application, the electrical output, either constant current (20–1000 µA) or voltage (0.7–2.1 V), can be configured easily through a user-friendly graphical interface on the screen. The disinfection device, a coaxial-electrode copper ionization cell (CECIC), inactivates bacteria by low levels of electrochemically generated copper with low energy consumption. The strategy of constant current control is applied in this study to solve the problem of uncontrollable copper release by previous constant voltage control. With the current control, a high inactivation efficiency of E. coli (~6 logs) is achieved with a low level of effluent Cu (~200 µg L−1) in the water samples within a range of salt concentration (0.2–1 mmol L−1). The smartphone-based power workstation provides a versatile and accurate electrical output with a simple graphical user interface. The disinfection device is robust, highly efficient, and does not require complex equipment. As smartphones are pervasive in modern life, the smartphone-powered CECIC system could provide an alternative decentralized water disinfection approach like rural areas and outdoor activities.

Graphene Oxide/Copper Nanoderivatives-Modified Chitosan/Hyaluronic Acid Dressings for Facilitating Wound Healing in Infected Full-Thickness Skin Defects.

PurposeWound healing, especially of infected wounds, remains a clinical challenge in plastic surgery. This study aimed to manufacture a novel and multifunctional wound dressing by combining graphene oxide/copper nanocomposites (GO/Cu) with chitosan/hyaluronic acid, providing significant opportunities for the therapy of wound repair in wounds with a high risk of bacterial infection.MethodsIn this study, GO/Cu-decorated chitosan/hyaluronic acid dressings (C/H/GO/Cu) were prepared using sodium trimetaphosphate (STMP) crosslinking and the vacuum freeze-drying method, and chitosan/hyaluronic acid dressings (C/H) and GO-incorporated chitosan/hyaluronic acid dressings (C/H/GO) served as controls. The surface characterization, in vitro degradation under various pH values, antimicrobial potential, cytocompatibility and in vivo therapeutic efficacy in a bacteria-infected full-thickness skin defect model were systematically evaluated.ResultsOur experimental results indicated that the acidic environment facilitated the release of copper (CuNPs and Cu2+) from the dressings, and prepared C/H/GO/Cu dressings exhibited significant in vitro antimicrobial activities against the two tested bacterial strains (ATCC35984 and ATCC25923). All three dressings showed satisfactory cytocompatibility with mouse fibroblasts (NIH/3T3-L1). Moreover, remarkably accelerated wound healing was found in the C/H/GO/Cu group, with controlled inflammatory infiltration and improved angiogenesis in granulation tissues. In addition, no pathological damage was noted in the tissue structures of the tested organs (heart, lung, liver and kidney) in any of the four groups.ConclusionCollectively, GO/Cu-incorporated chitosan/hyaluronic acid dressings suggested a synergistic antimicrobial efficacy and acceptable biocompatibility both in vitro and in vivo, as well as a significantly accelerated healing process of bacteria-infected wounds. Thus, the multifunctional C/H/GO/Cu composite is expected to be a potential alternative for wound dressings, especially for the management of intractable wounds caused by bacterial infection.

In vitro evaluation of copper release from MRI-visible, PLGA-based nanospheres

Copper nanostructures offer remarkable therapeutic potential. In particular, copper oxide nanoparticles (CuO NPs) are increasingly studied for diagnostic and therapeutic purposes. Their anticancer potential, as well as contrast-enhancing capabilities for magnetic resonance imaging (MRI) and ultrasound (US), were previously demonstrated. To further exploit their unique multifunctional capabilities, here CuO NPs were successfully embedded in nanocarriers composed of poly(lactic-co-glycolic acid) (PLGA) and poly(ethylene–glycol)-block-poly(lactide-co-glycolide) (PEG-PLGA) and their release kinetics were studied. The CuO NPs-loaded nanospheres (NS) were obtained with a loading capacity of 3.6% ± 0.6 and 5.6% ± 0.8 respectively, and the copper in vitro release was analyzed over a period of 36 days. Copper release from PLGA-NS was found to follow a zero-order model, while that from PEG-PLGA-NS was best described by the tri-phasic release profile. The Higuchi model showed a higher correlation value (R2) for PLGA-NS and PEG-PLGA-NS (R2 = 0.994 and R2 = 0.959, respectively), suggesting that the release mechanism of CuO NPs is diffusion-controlled. In addition, CuO NPs, encapsulated within these polymeric nanospheres, retained their visibility, as demonstrated by T1-weighted MRI. Our results provide further insights into the benefit of using CuO NPs-loaded PLGA-based nanospheres as multifunctional nanomaterials, which may be considered as a future theranostic agent for multiple applications including drug delivery and imaging.

Polyetheretherketone with citrate potentiated influx of copper boosts osteogenesis, angiogenesis, and bacteria-triggered antibacterial abilities

A well designed coating for polyetheretherketone (PEEK) implants can provide enough support to overcome crucial medical challenges, which are insufficient osseointegration and high rate of infection. Herein, we utilize the co-deposition of polydopamine (PDA) and copper-citrate nanoclusters to construct a pH-responsive coating on porous PEEK for synergistic bone regeneration, vascular formation and anti-infection. Specifically, this PDA coating released high dose of copper and citrate at lower pH value, which increased intracellular copper content, boosted production of reactive oxygen species and severe damage of protein, leading to killing of 93 % planktonic bacterial and eradication of adherent bacteria. At pH of 7.4, the release of copper and citrate were in a slow and sustained behavior, synergistically enhanced vascular formation potential and osteodiffereration of Ad-MSC in vitro. After implanted in rabbit tibia for 6 and 12 weeks, the micro-CT evaluation and histological analysis consistently highlighted the ability of this PDA coating to increase new bone formation adjacent to coated PEEK implant and enhance bone-implant interfacial integration. These results were proven to be related to the synergistic effect that citrate facilitated a 2-fold influx of copper into cells, which not only enhanced the bacteria-killing ability but also encouraged bone regeneration of implants. This present work provides an effective method to control infections while promoting osseointegration simultaneously, which will show tremendous clinical application and can be a solution to current challenges facing orthopedics.

Antifouling paints leach copper in excess – study of metal release rates and efficacy along a salinity gradient

Antifouling paints are biocidal products applied to ship and boat hulls in order to prevent the growth and settlement of marine organisms, i.e. fouling. The release of biocides from the surface of the paint film act to repel or poison potential settling organisms. Currently, the most commonly used biocide in antifouling paints is cuprous oxide. In the EU, antifouling products are regulated under the Biocidal Products Regulation (BPR), which states that the recommended dose should be the minimum necessary to achieve the desired effect. For antifouling products, the dose is measured as the release rate of biocide(s) from coating. In this study, the release rates of copper and zinc from eight different coatings for leisure boats were determined through static exposure of coated panels in four different harbors located in Swedish waters along a salinity gradient ranging from 0 to 27 PSU. The results showed the release rate of copper to increase with increasing salinity. Paints with a higher content of cuprous oxide were also found to release larger amounts of copper. The coatings’ ability to prevent biofouling was also evaluated and no significant difference in efficacy between the eight tested products was observed at the brackish and marine sites. Hence, the products with high release rates of copper were equally efficient as those with 4 – 6 times lower releases. These findings suggest that current antifouling paints on the market are leaching copper in excess of the effective dose in brackish and marine waters. Additionally, the results from the freshwater site showed no benefit in applying a copper-containing paint for the purpose of fouling prevention. This indicates that the use of biocidal paints in freshwater bodies potentially results in an unnecessary release of copper. By reducing the release rates of copper from antifouling paints in marine waters and restricting the use of biocidal paints in freshwater, the load of copper to the environment could be substantially reduced.

THE EFFECT OF PEAT SWAMP WATER ON TOOTH DEMINERALIZATION OF COPPER AND SELENIUM ION

ABSTRACTBackground: The society of South Kalimantan has high rate of tooth decay. The high rate of tooth decay in South Kalimantan is caused by environmental factors, namely water sources originating from peat swamp. Swamp water has acidic pH can make tooth demineralization or releasing minerals in tooth. One of the minerals that can be demineralized by swamp water is copper ions (Cu2+) and selenium ions (Se4+). The released minerals in tooth makes tooth enamel slowly dissolve and make tooth more susceptible to caries. Objective: to analyze the effect of tooth immersion on peat swamp water on releasing copper and selenium ions. Methods: This research used a laboratory experimental study with eighteen specimens of extracted human maxillary premolar teeth. The specimens were divided into 2 treatment groups ie tap (PDAM) water and peat swamp water immersion, and 1 control group ie artificial saliva immersion. Tooth immersion is conducted for 7 days. The Measurement of copper and selenium ions release using a UV-Vis spectrophotometer. Data were statistically tested using One Way Anova. Result: The mean value of released copper ions in artificial saliva (3.8 ± 0.51 ppm), tap water (3.72 ± 1.02 ppm) and peat swamp water (3.37 ± 0.97 ppm) showed there were no significant differences among all immersion groups. Meanwhile, the mean value of released selenium ions in artificial saliva (7.61 ± 2.34 ppm), tap water (2.4 ± 0.62 ppm) and peat swamp water (0.85 ± 0,38 ppm) showed there were significant differences among all immersion groups on the release of selenium ions, subsequenty test using Post hoc Dunnett's T3 showed p=0.0001 (p&lt;0.05). Conclusion: There is no effect of tooth immersion in peat swamp water on the release of copper ions however there is an effect on the release of selenium ions.Keywords: Demineralization, Peat swamp water, Releasing copper ions (Cu2+), Releasing selenium ions (Se4+), tooth decay.

Sodium chloride assists copper release, enhances antibacterial efficiency, and introduces atmospheric corrosion on copper surface

Sodium chloride (NaCl) is commonly found in physiological buffers. This study found out its additional but important role in antibacterial efficiency test by better corroding metallic copper surface. Combined with multiple characterisation methods including scanning electron microscopy, grazing incidence X-ray diffractometry, and inductively coupled plasma mass spectrometry, 0.9% saline was observed to cause localised corrosion attacks on copper surface, enhancing release of copper content. The 1 h killing rate against Escherichia coli was thus promoted from 22% (when re-suspended in pure water) to 98%. By a long-term observation (3-week), residual NaCl crystals on 0.9% saline treated copper surface were found partially disappeared in atmospheric environment, contributing to an additional Cu2O layer forming above the treated surface. Besides, formation of oxygen-containing species was observed on fresh copper surface exposed by focused ion beam after saline treatment, suggesting a chloride-assisted atmospheric corrosion process.

Copper release from waste rocks in an abandoned mine (NE, Brazil) and its impacts on ecosystem environmental quality

This study aimed to estimate the impact of an abandoned copper (Cu) mine on ecosystem environmental quality, using integrated ecological and biogeochemical analyses. Through a controlled experiment, the amount of Cu released by waste rocks, Cu adsorbed in soils, Cu geochemical behaviour and its leached amount were measured. Furthermore, to investigate the impacts of mine drainage on the adjacent ecosystem, samples of sediments, water and aquatic macroinvertebrates were analysed. We found that waste rocks still have high Cu concentration even after 30 years under weathering, ranging from 7782 to 8717 mg kg−1, associated mainly with carbonates, amorphous oxides and sulphides. It was estimated that 7.2 tonnes of Cu were released by waste rocks into the environment over last 30 years. The concentration of Cu observed in Ubari stream water was (<dl to 90 μg L−1), in sediments (28.0–1185 mg kg−1) and in macroinvertebrates (1.3–28.9 mg kg−1 d/w). The ecological indexes showed that near mine discharge a significance decrease in the density of aquatic macroinvertebrates and a significance increase of Cu in biological tissues occurs, causing disturbances in biodiversity. The results showed that, even after long periods, the waste rocks from abandoned mines still contain high levels of metal, that are gradually released into the environment through weathering and erosion, representing a potential source of environmental pollution and a clear threat to the environmental quality of adjacent ecosystems.

Recyclable antimicrobial sulphonated poly (ether ether ketone) – copper films: Flat vs micro-pillared surfaces

The existence of bacteria and fungi on surfaces can be a serious threat to health causing numerous infections. With these microorganisms developing resistance over the years, there is an increasing need to develop surfaces that can kill or inhibit the growth of bacteria and fungi. In this work, we report the fabrication of sulphonated poly (ether ether ketone) (SPEEK) and its copper composite films as promising antimicrobial materials and investigated the effects of fabricating surface structures (micro-pillars) on the films. The fabricated films were systematically characterized and it was observed that both SPEEK and SPEEK – Cu films possessed antimicrobial properties which initially killed all of E. coli within 15 min of contact. Over longer times, as the films aged, the SPEEK – Cu film still achieved over 2 log (for flat film) and 4 log (for micro-pillared film) reduction of E. coli within 1 h of contact and it showed significant fungal growth reduction for Saccharomyces cerevisiae (yeast) and Aspergillus niger with 2 h of contact. Micro-pillared films had a larger water contact angle (131°) in comparison to flat films (64°) which thus rendered it hydrophobic. It was also observed that these micro-pillared films showed better antimicrobial properties and better copper release than flat as a result of better exposure of copper particles on the top surface of micro-pillars. The fabricated films were also thermally stable and exhibited tensile strengths ranging from 50 to 160 MPa depending on the surface morphology and copper content. Furthermore, the films were found to be recyclable by dissolution in sulphuric acid and re-casting to form new films with replenished sulphonic acid groups in the polymer matrix and restored antimicrobial properties.

Effect of soil particle size on the kinetics of Cu release from field-contaminated soils: Experiments and a quantitative model

Predicting the kinetics of heavy metal release from the field-contaminated soils requires the consideration of the chemical and physical heterogeneity of soil composition, such as multiple soil adsorbents, heterogeneous binding sites, and varying soil particle sizes. In this study, we conducted kinetic experiments to investigate kinetics of copper (Cu) release from different size fractions of two field-contaminated soils. The morphology and elemental distribution of different size fractions of soil particles were measured with scanning electron microscopy (SEM) and spherical aberration corrected scanning transmission electron microscopy (Cs-STEM). A kinetics model considering both variations of soil adsorbents and particle sizes was developed. Overall, different size fractions of soil particles showed highly heterogeneous physical and chemical properties. The reactive soil adsorbents (e.g., soil organic matter (SOM)) and Cu concentrations increased with the decrease of the particle size, and the rate of Cu release from soil particles also increased with the decrease of the particle size. The kinetics model described the experimental kinetics data from different size fractions of soil particles reasonably well. More significantly, the model was able to predict Cu release from the bulk soil samples based on Cu kinetic reactions with different size fractions of soil particles. SOM appeared to be the most dominant adsorbent for Cu under our experimental conditions, and, among different SOM binding sites, bidentate sites involving carboxylic and phenolic functional groups were the most significant. Our results suggested that a unified modeling framework, which specifically considers the chemical heterogeneity of soil binding sites and variations of particle sizes, is promising for predicting kinetic reactions of metals with heterogeneous soil particles in the field.

Changes in copper load in hepatocytes of Ohrid trout in relation to the ovarian maturation cycle

The main aim of this study was to histochemically estimate the relative copper content in the liver during the breeding cycle of female Ohrid trout, a wild population endemic to the Ohrid Lake. The histology of the oogenetic cycle in this species was documented for the first time. Histochemistry with semi-quantification revealed positive correlations between the gonadosomatic indices and copper load. Uptake of the metal increases in the liver as the ovaries increase in size, with the highest hepatic copper load occurring postspawning. The plasmatic levels of 17β-oestradiol were also quantified, but no correlations to copper load were found, so there is no direct estrogenic control on the uptake and release of copper from the bloodstream to either organ. Therefore, when interpreting field studies or assays on hepatic copper pollution and toxicity, breeding-related seasonal changes in Ohrid trout must be taken into account.

Antibacterial mechanisms of various copper species incorporated in polymeric nanofibers against bacteria

The fabrication of as-spun copper (II) sulfate polyacrylonitrile (PAN) composite nanofibers, copper hydroxide nanowires (Cu(OH)2 NWs), copper oxide nanowires (CuO NWs), and copper nanoparticles (Cu NPs) incorporated in/on PAN nanofibers were presented. SEM, TEM, FTIR, XRD, and XPS confirmed the success of the syntheses. The surface wettability was also investigated for all samples. All copper composite nanofibers exhibited considerable antibacterial properties against Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) and were compared to each other to investigate the mechanistic actions of different copper species. The results of the antibacterial assays suggested that the antibacterial effects of copper-containing samples were dependent on the release of soluble copper, including copper ions (Cu2+), the shape of the nano copper, and the copper content of the composite nanofibers.

Architectured Cu–TNTZ Bilayered Coatings Showing Bacterial Inactivation under Indoor Light and Controllable Copper Release: Effect of the Microstructure on Copper Diffusion

A Ti–23Nb–0.7Ta–2Zr–1.2O alloy (at %), called “gum metal”, was deposited by direct-current magnetron sputtering (DCMS) on an under layer of copper. By varying the working pressure during the deposition, columnar TNTZ (Ti–Nb–Ta–Zr) nanoarchitectures were obtained. At low working pressures, the upper layer was dense with a coarse surface (Ra = 12 nm) with a maximum height of 163 nm; however, the other samples prepared at high working pressures showed columnar architectures with voids and an average roughness of 4 nm. The prepared coatings were characterized using atomic force microscopy (AFM) for surface topography, energy dispersive X-ray spectroscopy (EDX) for atomic mapping, scanning electron microscopy (SEM) for cross-section imaging, contact angle measurements for hydrophilic/hydrophobic balance of the prepared surfaces, and X-ray diffraction (XRD) for the crystallographic structures of the prepared coatings. The morphology and the density of the prepared coatings were seen to influence the hydrophilic properties of the surface. The antibacterial activity of the prepared coatings was tested in the dark and under low-intensity indoor light. Bacterial inactivation was seen to happen in the dark from samples presenting columnar nanoarchitectures. This was attributed to the diffusion of copper ions from the under layer. To verify the copper release from the prepared samples, an inductively coupled plasma mass spectrometer (ICP-MS) was used. Additionally, the atomic depth profiling of the elements was carried out by X-ray photoelectron spectroscopy (XPS) for the as-prepared samples and for the samples used for bacterial inactivation. The low amount of copper in the bulk of the TNTZ upper layer justifies its diffusion to the surface. Recycling of the antibacterial activity was also investigated and revealed a stable activity over cycles.

Reactive magnetron co-sputtering of Ti-xCuO coatings: Multifunctional interfaces for blood-contacting devices.

Multifunctional interfaces that promote endothelialisation, suppress the viability of smooth muscle cells (SMCs), prevent the adhesion and activation of platelets, while demonstrating antibacterial activity are of great interest for surface engineering of blood-contacting devices. Here, we report for the first time the high-power pulsed magnetron sputtering (HPPMS)/DC magnetron sputtering (DCMS) co-sputtering of Ti-xCuO coatings that demonstrate this required multifunctionality. The Cu contents and surface chemistry of the coatings are optimized, and the critical role of copper release on the viability of endothelial cells (ECs) and SMCs, platelet adhesion, and antibacterial activities is elucidated. Rutile phase is formed for Ti-xCuO coatings with Cu atomic concentrations in the range of 1.9 to 13.7at.%. Rutile and nanocrystalline/amorphous structures were determined for the coatings with 16.8at.% Cu, while an amorphous phase was observed for the coating with 33.9at.% Cu. The Ti-xCuO coatings with higher Cu contents were more susceptible to corrosion, and the release rates of Cu ions increased with increasing the Cu contents, maintaining a stable releasing state for up to 28days. The Ti-xCuO coatings with optimum microstructure and Cu contents of 3.1 and 4.2at.% promoted the viability and proliferation of ECs, suppressed the viability of smooth muscle cells, inhibited the platelet adhesion and activation, and showed excellent antibacterial activities. Such multifunctionality was achieved in one-pot through controlled copper ions release in the presence of titanium oxides such as TiO2 and Ti2O3 on the surface. The Ti-xCuO coatings developed through HPPMS/DCMS co-sputtering are attractive for surface modification of blood-contacting materials such as implantable cardiovascular devices.