“…This occurs because more Ag + species are generated which are responsible for inhibiting bacterial growth as explained in the following section and as reported by Liu et al [55]. The surface roughness value also provides information on the adhesion of the silver nanoparticles on the polymer, corroborating the TEM analysis, since as a nanometric-sized coating, electrostatic interactions between the metallic silver and the polymer result [56]. In addition, the surface contact of the nanometer probe with the silver deposited in a single layer does not drag but leaves a groove upon movement, showing the effective adhesion with the polymer as indicated by Wenfei Li et al [57].…”
Section: Atomic Force Microscopy (Afm) Analysissupporting
The coating of polymeric substrate polyetheretherketone (PEEK) with silver nanoparticles (AgNPs) was carried out by a wet chemical route at room temperature. The coating process was developed from the Tollens reagent and D-glucose as reducing agent. The resulting composite exhibited antimicrobial activity. The PEEK films were coated with a single layer and two layers of silver nanoparticles in various concentrations. The crystallographic properties of the polymer and the silver nanoparticles were analyzed by X-ray diffraction (XRD). Fourier transform infrared spectra (FTIR) show the interaction between the silver nanoparticles with the polymeric substrate. Transmission electron microscope (TEM) images confirmed the obtaining of metallic nanoparticles with average sizes of 25 nm. It was possible to estimate the amount of silver deposited on PEEK with the help of thermogravimetric analysis. The morphology and shape of the AgNPs uniformly deposited on the PEEK films was ascertained by the techniques of scanning electron microscopy (SEM) and atomic force microscopy (AFM), evidencing the increase in the amount of silver by increasing the concentration of the metal precursor. Finally, the antibacterial activity of the films coated with Ag in Escherichia coli, Serratia marcescens and Bacillus licheniformis was evaluated, evidencing that the concentration of silver is crucial in the cellular replication of the bacteria.
“…This occurs because more Ag + species are generated which are responsible for inhibiting bacterial growth as explained in the following section and as reported by Liu et al [55]. The surface roughness value also provides information on the adhesion of the silver nanoparticles on the polymer, corroborating the TEM analysis, since as a nanometric-sized coating, electrostatic interactions between the metallic silver and the polymer result [56]. In addition, the surface contact of the nanometer probe with the silver deposited in a single layer does not drag but leaves a groove upon movement, showing the effective adhesion with the polymer as indicated by Wenfei Li et al [57].…”
Section: Atomic Force Microscopy (Afm) Analysissupporting
The coating of polymeric substrate polyetheretherketone (PEEK) with silver nanoparticles (AgNPs) was carried out by a wet chemical route at room temperature. The coating process was developed from the Tollens reagent and D-glucose as reducing agent. The resulting composite exhibited antimicrobial activity. The PEEK films were coated with a single layer and two layers of silver nanoparticles in various concentrations. The crystallographic properties of the polymer and the silver nanoparticles were analyzed by X-ray diffraction (XRD). Fourier transform infrared spectra (FTIR) show the interaction between the silver nanoparticles with the polymeric substrate. Transmission electron microscope (TEM) images confirmed the obtaining of metallic nanoparticles with average sizes of 25 nm. It was possible to estimate the amount of silver deposited on PEEK with the help of thermogravimetric analysis. The morphology and shape of the AgNPs uniformly deposited on the PEEK films was ascertained by the techniques of scanning electron microscopy (SEM) and atomic force microscopy (AFM), evidencing the increase in the amount of silver by increasing the concentration of the metal precursor. Finally, the antibacterial activity of the films coated with Ag in Escherichia coli, Serratia marcescens and Bacillus licheniformis was evaluated, evidencing that the concentration of silver is crucial in the cellular replication of the bacteria.
“…In the last decades, there was an increase in the number of technologies to superficial modification of materials that sought to increase hardness, wear resistance, adhesion strength, hydrophilicity, biocompatibility, among other materials’ properties [ 9 , 10 , 11 , 12 ]. Among these technologies, the treatment of plasma in dielectric barrier discharge (DBD) has been used to increase the surface energy of polymeric materials by incorporating polar groups on the surface without changing its mass composition [ 13 , 14 , 15 , 16 , 17 ]. The process occurs between two electrodes, where at least one of which must be covered by a dielectric [ 18 , 19 , 20 ].…”
Section: Introductionmentioning
confidence: 99%
“…Several attempts have been reported in the literature using DBD plasma to improve the wettability of polymeric surfaces, since it does not deteriorate and can modify the treated surface [ 17 , 23 , 25 , 26 , 27 ]. The authors justify that the increase in wettability in polymeric materials is directly associated with the incorporation of functional groups such as C–O, C=O, and O–C–O [ 11 , 28 , 29 , 30 , 31 ].…”
In this work, the plasma was used in the dielectric barrier discharge (DBD) technique for modifying the high-density polyethylene (HDPE) surface. The treatments were performed via argon or oxygen, for 10 min, at a frequency of 820 Hz, voltage of 20 kV, 2 mm distance between electrodes, and atmospheric pressure. The efficiency of the plasma was determined through the triple Langmuir probe to check if it had enough energy to promote chemical changes on the material surface. Physicochemical changes were diagnosed through surface characterization techniques such as contact angle, attenuated total reflection to Fourier transform infrared spectroscopy (ATR-FTIR), X-ray excited photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Plasma electronics temperature showed that it has enough energy to break or form chemical bonds on the material surface, impacting its wettability directly. The wettability test was performed before and after treatment through the sessile drop, using distilled water, glycerin, and dimethylformamide, to the profile of surface tensions by the Fowkes method, analyzing the contact angle variation. ATR-FTIR and XPS analyses showed that groups and bonds were altered or generated on the surface when compared with the untreated sample. The AFM showed a change in roughness, and this directly affected the increase of wettability.
“…This technique consists in the application of a high potential difference between two electrodes, where at least one of them is coated by a dielectric material, which results in the emergence of plasma microfilaments on the surface of the insulator material used 1 . This technique is already widely used to the superficial modification of polymers, since it transforms hydrophobic polymeric materials into hydrophilic without deteriorating its internal structure [2][3][4] . It is also used for film deposition 5,6 , dental treatments and dermatological treatments 7 .…”
This work aimed to characterize a DBD plasma equipment through optical and electrical measurements, seeking to obtain a greater knowledge of the plasma production process and how it behaves through the adopted parameters, such as frequency and voltage applied between electrodes, at a fixed distance of 1.7 mm. In order to measure them, three different characterization techniques were applied. The first method was the Lissajous figures, a technique quite effective for a complete electrical characterization of DBD equipment. The second technique used was the Optical Emission Spectroscopy, a tool used for the diagnosis of plasma, being it possible to identify the excited species produced in filamentary and diffuse discharge in the plasma. And finally, the triple Langmuir probe technique was used to obtain the electron temperature and electron density. Based on this study, it was possible to identify the equipment efficiency in different regimes. The electron temperature measurement for both systems analyzed were 27.96 eV and 20.69 eV to the filamentary and diffuse regimes, respectively. The density of electrons number to these regimes were 1.09 × 1021 m−3 and 1.56 × 1021 m−3.
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