Electrophoretic deposition (EPD) of nanohydroxyapatite - nanosilver coatings on Ti13Zr13Nb alloy

Titanium and its alloys are the biomaterials most frequently used in medical engineering, especially as parts of orthopedic and dental implants. The surfaces of titanium and its alloys are usually modified to improve their biocompatibility and bioactivity, for example, in connection with the deposition of hydroxyapatite coatings.The objective of the present research was to elaborate the technology of electrophoretic deposition (EPD) of nanohydroxyapatite (nanoHAp) coatings decorated with silver nanoparticles (nanoAg) and to investigate the mechanical and chemical properties of these coatings as determined by EPD voltage and the presence of nanoAg. The deposition of nanoHAp was carried out at two voltage values, 15 and 30 V. The decoration of nanoHAp coatings with nanoAg was carried out using the EPD process at a voltage value of 60 V and a deposition time of 5 min. The thickness of the undecorated coatings was found to be 2.16 and 5.14 µm for applied EPD voltages of 15- and 30-V, respectively. The release rate of silver nanoparticles into an artificial saliva solution increased with exposure time and EPD voltage. The corrosion current, between 1 and 10 nA/cm², was significantly higher for undecorated nanoHAp coatings and close to that of the substrate for decorated nanoHAp coatings. The hardness of the undecorated nanoHAp coatings obtained at 15 and 30 V of EPD voltage attained 0.2245±0.036 and 0.0661±0.008 GPa, respectively. Resistance to nanoscratching was higher for thicker coatings. The wettability angle was lower for coatings decorated with nanoAg.     

Effects of electrophoretic deposition times and nanotubular oxide surfaces on properties of the nanohydroxyapatite/nanocopper coating on the Ti13Zr13Nb alloy

Load-bearing implants are developed with a particular emphasis placed on an application of ceramic hydroxyapatite coatings in order, to enhance the bioactivity of titanium implants and to shorten the healing time. Therefore, thin, fully crystalline coatings that are, highly adhesive, hydrophilic and demonstrating antibacterial properties are ly looked for. The aim of this research was to develop and characterize the properties of (nano)hydroxyapatite coatings implemented with nanocopper particles and obtained by the electrophoretic method. The deposition was carried out on the Ti13Zr13Nb alloy, either on a bare surface or a nanotubular oxide layer. The deposition was made for 1 or 2 min. The chemical composition, phase composition, coating structure, homogeneity, thickness, nanoindentation and nanomechanical properties, adhesion determined by a nanoscratch test, and wettability measured by a contact angle were investigated. The presence of nanotubular oxide layers caused no significant change in nanoindentation and nanomechanical propertie and an increase in adhesion strength and a decrease in the contact angle. The increase in deposition time resulted in an increased thickness, a decreased hardness, an increased adhesion strength and wettabilty. The observed effects in the composite (nano)HAp/Cu – (nano)TiO₂ coatings are attributed to the change in the structure of coatings following the increasing deposition time and coating thickness.     

Development of antibacterial silver treatments on HDPE nets for agriculture

The defense mechanism of crops associated with the use of polymeric nets and fabrics is only physical and, hence, ineffective against the bacterial contaminations. The presence of an antibacterial agent associated with the use of conventional agro‐textiles can represent a great advantage in the prevention of plant diseases and for food safety. The aim of this work was the development of antibacterial silver‐coated HDPE nets for an innovative application such as agriculture. Antibacterial coatings on high‐density polyethylene nets were obtained by a patented nanosilver deposition technique based on the in situ photo‐reduction of a silver solution. The concentration of silver deposited was defined by testing different silver solutions from a biological point of view. Moreover, in order to improve the adhesion of the silver coating to the substrate, the nets underwent low‐pressure plasma treatment before the silver deposition. The materials were characterized in terms of quality of the coating through scanning electron microscopy, and in terms of antibacterial capability on Gram positive and Gram negative bacteria through qualitative and quantitative microbiological tests. The most effective process parameters were defined and the importance of performing plasma pretreatment on this specific substrate was assessed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41623.     

The influence of nanosilver on thermal and antibacterial properties of a 2 K waterborne polyurethane coating

A two-component (2 K) waterborne polyurethane coating containing nanosilver (200 ppm) was prepared and compared to the blank coating with no nanosilver. The coatings were inoculated with Escherichia coli and Staphylococcus aureus by the agar-well diffusion method. According to the results, silver nanocomposite coating exhibited a growth reduction on both types of bacteria. The cross-section of samples was examined by scanning electron microscopy (SEM). The micrographs depicted uniform dispersion of Ag nanoparticles in the polyurethane matrix. Fourier transform infra-red (FTIR) spectra of the coatings revealed intensification of carbonyl group stretching band in the presence of nanosilver, which could be related to the partial protection of isocyanate groups from decomposition in the presence of water. Enhancement of thermal properties was observed by differential scanning calorimetry and thermogravimetry.     

Effects of solution composition and electrophoretic deposition voltage on various properties of nanohydroxyapatite coatings on the Ti13Zr13Nb alloy

The purpose of the research was to establish the influence of the solution composition and the electrophoretic deposition voltage on the coating homogeneity and thickness, nanohardness, adhesion, corrosion resistance and wettability. The Ti13Zr13Nb alloy was coated by the electrophoretic technique with hydroxyapatite in a solution containing 0.1, 0.2 or 0.5?g nanoHAp in 100?mL of suspension and at voltage 15, 30 or 50?V. The scanning electron and atomic force microscopies, polarization curves technique for corrosion assessment, nanoindentation and nanoscratch tests, and measurements of contact angle in simulated body fluid were performed. The obtained results revealed the complex and interrelated effects of both process determinants on the structure and properties of hydroxyapatite coatings, which were attributed to the role of the size, shape and content in suspension of hydroxyapatite particles.     

The use of liposomes in the modification of polycaprolactone fibers

Polycaprolactone is fully bioresorbable and biocompatible material. Liposomes containing nanocopper, nanosilver, and nanogold are known to have antifungal and antibacterial properties and to further aid in the synthesis of collagen and elastin in the skin. It is possible to combine the properties of polycaprolactone fibers and liposomes in new approaches to deliver active substances through cosmetics and medicines. The aim of the research was to examine the possibility of simple modification of PCL fibers with use of nanocopper, nanogold, and nanosilver incorporated liposomes. The size and the type of the liposomes were examined using optical microscopy and DLS techniques. The fibres modified with liposomes were investigated using SEM and FTIR techniques. Additionally the contact angle measurements were performed. The study shows an innovative method of modifying polycaprolactone nonwoven textiles. This combination of PCL fibers and liposomes allows easy and efficient preparation and delivery of active substances to a particular location. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43299.     

车身电泳缩孔产生原因分析与防治

针对涂装电泳车身出现批量小缩孔问题,经挂板试验分析、实车生产验证和槽液取样送检分析,确定电泳小缩孔是因电泳槽液老化和长菌导致.通过电泳倒槽、补充新电泳树脂和溶剂、添加药剂等手段,改善了槽液参数指标,提升了电泳漆膜的外观质量和防腐蚀性能,为延缓槽液老化的速度和改善生产工艺的现场管理提供参考.     

A study on melt spinning of polyethylene terephthalate filament yarns containing various concentrations of synthesized CuO nanoparticles

In this research the CuO nanoparticles were synthesized with four different methods then used to produce polyethylene terephthalate (PET) fibers with antibacterial, antifungal, and photocatalytic properties during the melt spinning process. Nanoparticles were synthesized in different ways using copper acetate salt (Cu(CH₃COO)₂) and sodium hydroxide (NaOH). The synthesis of copper oxide (CuO) nanoparticles was confirmed by field-emission scanning electron microscopy (FE-SEM images), EDX patterns, TGA, FTIR, X-ray diffraction pattern XRD, and UV-vis absorption spectrum. The results showed that synthesized nanoparticles exhibited strong antibacterial activity against gram-positive and gram-negative bacteria. Finally, after examining the fibers with different percentages of nanoparticles), fibers containing 1% of nanoparticles were produced using a 20% nanocopper oxide masterbatch as the optimal sample. The presence of nanoparticles in the fiber structure was confirmed by FE-SEM images, EDX, XRD, and FTIR analysis. Furthermore, the tensile properties, thermal behavior, and photocatalytic properties of the fibers were investigated. Evaluation of the antibacterial and antifungal activity of the produced fibers against gram-positive bacteria Staphylococcus aureus and Candida albicans fungus showed about 90% death of bacteria and fungi.     

基于电泳沉积工艺的低粘附抗菌涂层的制备

低表面能涂层因其优异的防污自清洁能力而受到广泛关注,但现有涂层存在易被细菌和真菌等微生物破坏而导致防污效果下降的问题,因此构建防污抗菌涂层具有深远的意义。本文基于电泳沉积工艺,将乙烯基硅油改性聚丙烯酸酯和固化剂沉积到导电基底,进一步负载纳米银杀菌剂,经过交联固化后获得了兼具抗细菌粘附与杀菌功能的涂层。采用傅里叶变换红外光谱仪(FT-IR)、核磁共振波谱仪(NMR)和扫描电子显微镜(SEM)等对涂层的结构和形貌进行了系统的表征,结果表明,成功合成了兼具低粘附与杀菌功能涂层。涂层表面具有优异的防油污、细菌及血液粘附的能力,涂层对大肠杆菌和金黄色葡萄球菌的抗细菌粘附效果达到99.9%以上。即使经过强酸、强碱等极端环境以及摩擦3000次后,涂层表面仍具有优异的防液体粘附效果。     

Determination of silver nanoparticle release from antibacterial fabrics into artificial sweat

Silver nanoparticles have been used in numerous commercial products, including textiles, to prevent bacterial growth. Meanwhile, there is increasing concern that exposure to these nanoparticles may cause potential adverse effects on humans as well as the environment. This study determined the quantity of silver released from commercially claimed nanosilver and laboratory-prepared silver coated fabrics into various formulations of artificial sweat, each made according to AATCC, ISO and EN standards. For each fabric sample, the initial amount of silver and the antibacterial properties against the model Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria on each fabric was investigated. The results showed that silver was not detected in some commercial fabrics. Furthermore, antibacterial properties of the fabrics varied, ranging from 0% to greater than 99%. After incubation of the fabrics in artificial sweat, silver was released from the different fabrics to varying extents, ranging from 0 mg/kg to about 322 mg/kg of fabric weight. The quantity of silver released from the different fabrics was likely to be dependent on the amount of silver coating, the fabric quality and the artificial sweat formulations including its pH. This study is the unprecedented report on the release of silver nanoparticles from antibacterial fabrics into artificial sweat. This information might be useful to evaluate the potential human risk associated with the use of textiles containing silver nanoparticles.     

Investigation of the Antibacterial Properties of Silver-Doped Amorphous Carbon Coatings Produced by Low Pressure Magnetron Assisted Acetylene Discharges

Hospital-acquired infections are responsible for a significant part of morbidity and mortality. Among the possible modes of transmission, this study focuses on environmental surfaces by developing innovative antibacterial coatings that can be applied on interior fittings in hospitals. This work aims to optimize a coating made of an amorphous carbon matrix doped with silver (a-C:H:Ag) produced by a hybrid PVD/PECVD process and to evaluate its antibacterial activity. We present a coating characterization (chemical composition and morphology) as well as its stability in an ageing process and after multiple exposures to bacteria. The antibacterial activity of the coatings is demonstrated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria through several bioassays. Moreover, the data suggest a crucial role of silver diffusion towards the surface and nanoparticle formation to explain the very promising anti-bacterial activities reported in this work.     

Electrochemical impedance spectroscopy study on silver coated metallic implants

This work presents the preparation of nano-structured silver coatings on TiAl₆V₄ and CoCrMo alloys by a pulse current technique and the study of time dependent electrochemical behaviour of silver coated metallic implants. EIS data as a function of immersion time in 0.9 wt% NaCl solution have been obtained to clarify the electrochemical processes occurring in the system. During early stage immersion (1–2 days), the impedance response shows near capacitive behaviour. As the time passes, the electrolyte gradually penetrates the silver coating and the sandblasted metallic implants. The silver comes into contact with the electrolyte and the conditions for galvanic corrosion are fulfilled. Due to the potential difference between silver coating and the metallic alloy, discrete anodic and cathodic areas are formed, which result in the release of silver, since the silver acts as an anode in galvanic cells. The cathode process is the reduction of the dissolved oxygen at the surface of the substrate. For antimicrobial applications of nanosilver coated TiAl₆V₄ and CoCrMo alloys, it is very important to maintain the continuous release silver ions. Degradation of silver coatings have been traced and confirmed by different methods such as SEM micrographs, EDX analysis, EIS measurements and solution analysis by ICP-MS methods.     

纳米银生物法绿色合成及其抗菌应用进展

纳米银是研究和应用最为广泛的纳米材料之一。近年来为避免纳米银合成过程中产生有毒副产物,人们在纳米银的绿色合成方向做了诸多研究。植物各组织和微生物细胞中富含的各类天然化合物均可完成纳米银的绿色合成,不同生物源合成纳米银的潜力有待进一步发掘。纳米银尺寸和形状的可控化,以及在使纳米银发挥抗菌作用的前提下减少迁移,减少副作用,是下一步的重点。综述了利用植物、细菌和真菌绿色合成纳米银的机制与方法,对各方法进行分析比较,介绍了纳米银的抗菌性能、抗菌机制和具体应用,对于未来发展提出建议。     

Morphology and antibacterial properties of natural rubber composites based on biosynthesized nanosilver

The objective of this work is to improve the properties of natural rubber composites (NRC) that were frequently used in medical and health supplies, using nanosilver additions. Silver nanocolloids were biosynthesized with an aqueous medium of aloe leaf extract (ALE) as capping agent, and then were filled in natural rubber matrix to prepare nanosilver‐based NRC. UV–vis spectrophotometer, X‐ray diffraction, and transmission electron microscopic analyses proved that the particle size of resultant silver was about 20 nm. The antibacterial activities against Staphylococcus aureus and Escherichia coli bacteria of NRC were dependable on the silver nanoparticles content and the treating methods on ALE, which was used in synthesizing silver nanocolloids. The morphology and thermal stability effect of nanosilver on NRC were determined with scanning electron microscopic and thermogravimetric analysis, respectively. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40746.     

Effect of ZrO2 nanoparticles addition to PEO coatings on Ti–6Al–4V substrate: Microstructural analysis,corrosion behavior and antibacterial effect of coatings in Hank's physiological solution

In this study, plasma electrolyte oxidation (PEO) method was employed to modify the surface of Ti–6Al–4V. Effects of different concentrations of ZrO₂ nanoparticles (0, 1, 3 and 5 g/l) into a phosphate-based electrolyte on the morphology, wettability, antibacterial and corrosion behaviors of coatings were investigated. Microstructural analyses of coatings were evaluated using scanning electron microscopy with an energy dispersive spectrometer. Also, X-ray diffraction, contact angle instrument and profilometry were respectively used to perform phase analysis, wettability, and surface roughness of the coatings. The antibacterial test was conducted with spot inoculation method on four pathogenic bacteria. Polarization and impedance spectroscopy measurements were performed in Hank's solution to investigate the corrosion behavior of coatings. The results revealed that PEO coatings without nanoparticles and by increasing the concentration of the ZrO₂ nanoparticles up to 3 g/l in the electrolyte led to a significant improvement in the antibacterial activities of gram-negative bacteria (P. aeruginosa and E. Coli). In the case of gram-positive bacteria, the PEO coated samples demonstrated improved antibacterial effects but addition of ZrO₂ nanoparticles in the PEO coatings resulted in deterioration of antibacterial effect. The sample coated with 3 g/l ZrO₂ nanoparticles showed the peak corrosion resistance compared to its counterparts.     

Studies on plasma sprayed bi-layered ceramic coating on bio-medical Ti-13Nb-13Zr alloy

Biomedical Ti alloys are prone to undergo degradation due to the combined effect of wear and corrosion. To overcome these problems, surface modification techniques are being used. In this paper, the biomedical Ti alloy Ti-13Nb-13Zr was plasma sprayed with nanostructured Al₂O₃-13 wt%TiO₂, yttria stabilized zirconia powders and bilayer containing alternate layers of the two coatings to improve the corrosion resistance and microhardness of the substrate. The plasma sprayed coatings were characterized by X-ray diffraction, scanning electron microscopy and Raman spectroscopy. The microstructure, microhardness and surface roughness of the coatings were investigated. The corrosion resistance of the coatings was studied in simulated body conditions. The results show improved corrosion resistance for the bilayered coating compared to the individual plasma sprayed coatings on biomedical Ti-13Nb-13Zr alloy substrate.     

Green Nanosilver as Reinforcing Eco-Friendly Additive to Epoxy Coating for Augmented Anticorrosive and Antimicrobial Behavior

Epoxy resin GY250 representing diglycidyl ethers of bisphenol-A (DGEBA) was reinforced with 1, 3 and 5wt % of surface functionalized silver nanoparticles (F-AgNPs) which were synthesized using Couroupita guianensis leaves extract with a view of augmenting the corrosion control property of the epoxy resin and also imparting antimicrobial activity to epoxy coatings on mild steel. Corrosion resistance of the coatings was evaluated by EIS, potentiodynamic polarization studies and cross scratch tests. AFM, SEM, HRTEM and EDX were utilized to investigate the surface topography, morphology and elemental composition of the coatings on MS specimens. Results showed that the corrosion resistance, hardness and T_g of the DGEBA/F-AgNPs coatings increased at 1wt % of F- AgNPs. The DGEBA/F-AgNPs coatings also offered manifold antimicrobial protection to the MS surfaces by inhibiting the growth of biofilm forming bacteria like P. aeruginosa, B. subtilis, the most common human pathogen E. coli and the most virulent human pathogenic yeast C. albicans.     

Nanotribology of silver and silicon doped carbon coatings

Amorphous hydrogenated carbon coatings a-C:H become very popular materials mainly because of their excellent properties such as low coefficient of friction, high hardness, good anti-wear and corrosion properties. More and more often are carried works aimed at improvement of biocompatibility and adhesion of bacterial cells by doping diamond-like carbon (DLC) coating with third element. Among them recently a great majority is devoted to carbon coatings doped with silver or silicon. The presence of silver in the coating ensures protection of the implant against the disadvantageous influence of bacteria and fungi causing biofilm associated infections, local inflammation and other implant-tissue reactions. Incorporation of silicon promotes osteointegration and leads to the enhancement of mechanical and tribological properties of the coating, which is beneficial for biomedical applications.Silver and silicon incorporated DLC coatings were prepared by a hybrid Radio Frequency Plasma Assisted Chemical Vapor Deposition/Magnetron Sputtering deposition technique on AISI316L substrates. Obtained coatings were characterized in terms of morphology, surface topography and mechanical properties. Tribological properties of the coatings were measured by lateral force microscopy and reciprocating sliding test using nanoindenter.     

A Novel Route for the Preparation of Silver Loaded Polyvinyl Alcohol Nanogels for Wound Care Systems

This study is aimed at the development of a composite wound dressing containing nanosilver loaded polyvinyl alcohol (PVA) nanogels. The PVA nanogels were prepared by fructose induced reduction of silver nitrate within PVA gel to develop nanosilver nanogel (nGel). The influence of various synthesis parameters on PVA nanogel formation was investigated. The particle size of the nanogels, as evaluated by transmission electron microscopy was observed to be in the range of 10–50 nm. Glycerol was added to the nGel system and this composition, nGel/Glc, was coated on cotton fabric to develop a composite wound dressing. The cumulative release of silver from the dressing was found to be ～36% of the total loading after 48 h. Even at such low concentrations, high antibacterial efficiency was achieved against both gram positive and gram negative bacteria. In vivo wound healing studies were carried out over a period of 21 days on full-thickness skin wounds created on Swiss albino mice. Fast healing was observed in nGel/Glc treated wounds with minimum scarring, as compared to other groups. These results suggest that nGel/Glc based dressing material could be promising candidates for wound dressing applications.     

Silver-coated wool yarns with durable antibacterial properties

The use of fabrics with antibacterial properties for commodity applications can provide numerous advantages such as a reduction in the release of odors due to bacterial proliferation in sweat and a reduction in the development of skin hypersensitivity reactions due to microorganisms trapped into the fabrics. Silver is one of the most effective antibacterial agents used for the high degree of biocompatibility and for its long-term antibacterial effectiveness against many different bacterial strains. In this study, an innovative technique for the deposition of nanosilver antibacterial coating on woolen fiber was analyzed. In particular, fabrics woven with different percentages of silver-treated fibers were compared to determine the best ratio preserving the antibacterial activity and optimizing the cost-effectiveness of the final product. Scanning electron microscopy revealed a uniform distribution of silver nanoclusters on the fibers. The impressive silver coating stability and durability were demonstrated after several washing cycles through thermogravimetric analysis. The antimicrobial activity of the silver-treated substrates was evaluated by antibacterial tests on Escherichia coli. A very strong antibacterial activity was found even in presence of the lower silver content; therefore, a blend of coated and uncoated fibers is proposed for practical applications. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012