Ag Composites Research Articles

Surface-wrinkled SnO2 hollow microspheres decorated with AuAg bimetallic nanoparticles for triethylamine detection

Surface modification of metal oxides with bimetallic nanoparticles is regarded as an appealing way to improve the gas sensing properties. Herein, SnO2 hollow microspheres with wrinkle surface were synthesized, and were then decorated with Au, Ag, and bimetallic AuAg nanoparticles by immersing SnO2 into the solutions containing these as-prepared metal particles. Gas test results showed that the SnO2-AuAg displayed a higher response (61.3 to 100 ppm triethylamine at 240 °C), and shorter response/recovery time (4/24 s) than SnO2-Au (36.4, 5/26 s), SnO2-Ag (27.1, 5/32 s), and pure SnO2 (12.5, 6/37 s). Moreover, it showed excellent long-term stability. The surface chemical state of SnO2-AuAg were studied based on the experimental results. The mechanism of enhanced gas sensing performance was also proposed by the analysis of the morphological and structural composition, electronic and chemical sensitizations of Au and Ag, and the synergistic catalysis effect of AuAg bimetallic nanoparticles.

Prismatic Silver Nanoparticles Decorated on Graphene Oxide Sheets for Superior Antibacterial Activity.

Spherical silver nanoparticles (Ag NPs) and silver nanoprisms (Ag NPrsms) were synthesized and decorated on graphene oxide (GO) nanosheets. The Ag contents were 29% and 23% in the GO–Ag NPs and GO–Ag NPrsms, respectively. The Ag NPrsms exhibited stronger (111) crystal signal than Ag NPs. The GO–Ag NPrsms exhibited higher Ag (I) content (75.6%) than GO-Ag NPs (69.9%). Increasing the nanomaterial concentration from 25 to 100 µg mL−1 improved the bactericidal efficiency, and the antibacterial potency was in the order: GO–Ag NPrsms > GO–Ag NPs > Ag NPrsms > Ag NPs > GO. Gram-positive Staphylococcus aureus (S. aureus) was more vulnerable than Gram-negative Escherichia coli (E. coli) upon exposure to these nanomaterials. The GO–Ag NPrsms demonstrated a complete (100%) bactericidal effect against S. aureus at a concentration of 100 µg mL−1. The GO–Ag composites outperformed those of Ag or GO due to the synergistic effect of bacteriostatic Ag particles and GO affinity toward bacteria. The levels of reactive oxygen species produced in the bacteria–nanomaterial mixtures were highly correlated to the antibacterial efficacy values. The GO–Ag NPrsms are promising as bactericidal agents to suppress biofilm formation and inhibit bacterial infection.

Dental Implant Healing Screws as Temporary Oral Drug Delivery Systems for Decrease of Infections in the Area of the Head and Neck.

BackgroundPeriimplantitis is continuously one of major threats for the uneventful functioning of dental implants. Current approaches of drug delivery systems are being more commonly implemented into oral- and maxillofacial biomaterials in order to decrease the risk of implant failure due to bacterial infection. Silver nanoparticles and their compounds have been proven in eradicating oral bacteria responsible for peri-implant infections. Nevertheless, their evaluation as coating for implant abutments has not been extensively evaluated so far. This article describes a novel coating consisting of zinc oxide (ZnO) and silver (Ag) nanoparticles (NPs). This coating was used to modify healing abutments that could be used as drug delivery systems in oral implantology.Materials and MethodNanoparticles with a ZnO + 0.1% Ag composition were produced by microwave solvothermal synthesis and then incorporated into the surface of titanium healing abutments by high-power ultrasonic deposition. Surface morphology, roughness, wettability were evaluated. Ability of biofilm formation inhibition was tested against S. mutans, S. oralis, S. aureus and E. coli.ResultsZnO+0.1%Ag NPs were sufficiently deposed on the surface of the abutments creating nanostructured coating which increased surface roughness and decreased wettability. Modified abutments significantly decreased bacterial biofilm formation. Bacteria present in SEM studies were unlikely to settle and replicate on the experimental abutments as their cells were rounded, insufficiently spread on the surface and covered with released NPs.ConclusionExperimental nanostructured abutments were easily manufactured by high-power ultrasonic deposition and provided significant antibacterial properties. Such biomaterials could be used as temporary drug delivery abutments for prevention and treatment of intra- and extraoral peri-implant infections in the area of the head and neck.

Effect of Acupuncture Treatment on Post-stroke Depression by Using Diamond-Like Ultra-Thin Nano-Coating Technology.

This study aimed to explore the effect of acupuncture on account of composite diamond-like nano-membrane sensors (DLNF) sensors on post-stroke depression. Titanium/antigen-diamond-like carbon (Ti/Ag-DLC) composite DLNF sensors were prepared by coating Ti and Ag composites on the surface of DLC by radio frequency magnetron sputtering technology. The scanning electron microscope (SEM), X-ray photoelectron spectrometer (XPS), Raman spectrometer, nanoindenter, and sliding friction tester were adopted to analyze the characterization of Ti/Ag-DLC composite membrane, the chemical state of the main constituent elements on the surface, structural characteristics, membrane hardness, and tribological properties, respectively. 132 patients with post-stroke depression in our hospital were selected as the research objects, they were divided into the control group (receiving conventional treatment) and the acupuncture group (receiving acupuncture based on conventional treatment) according to different treatment methods, with 66 cases in each group. The depression of the two groups of patients before the treatment and 4 and 8 weeks after the treatment were compared. The psychological resilience scale and Herth scale were used to evaluate the mental toughness and hope level of patients. The results showed that when the Ag content was less than 0.55%, the Ti/Ag-DLC composite surface was smooth and showed no obvious particles, the membranes with different content had obvious absorption peaks at 1560 cm-1 and the friction life in a high vacuum environment was extended to around 900 revolutions. After 4 and 8 weeks of treatment, the scores of the hammer depression scale (HDS) in the two groups were significantly lower than before treatment (P<0.01) and the scores of the acupuncture group were much lower after 4 and 8 weeks of treatment in contrast to the control group (P<0.01). The optimism, self-strength, and tenacity in the psychological resilience scale of the acupuncture group patients rose higher than those in the control group (P<0.05) after 8 weeks of treatment. The Herth scale score of the acupuncture group was greatly higher compared with that of the control group after 8 weeks of treatment (P<0.01). It showed that the Ti/Ag-DLC composite DLNF sensor with good hardness and friction performance was prepared in this study. Acupuncture therapy could improve the negative emotions of patients with post-stroke depression, enhance mental resilience, and help raise the level of hope. Therefore, it was proved to be a potentially effective treatment.

SYNTHESIS OF SILVER (Ag) DOPED ZINC OXIDE (ZnO) NANOPARTICLES AS EFFICIENTPHOTOCATALYTIC ACTIVITY FOR DEGRADATION METHYLENE BLUE DYE

Zinc oxide (ZnO) and silver doped zinc oxide (Ag-ZnO) nanoparticles were prepared using zinc nitrates as oxidizers, glycine and citric acid as fuels as solution combustion synthesis (SCS) at 500°C. X-ray diffraction (XRD) pattern demonstrates the presence of Ag+ in the hexagonal zincite structure of ZnO. The average crystalline size of the particles of ZnO and Ag-ZnO were found to 47 nm and 74 nm respectively. From the Fourier transform infrared (FTIR) spectrum, the composition of Ag doped ZnO confirmed Ag-Zn-O stretching vibration at 510 cm-1. The UV-Visible absorption spectra results showed that synthesized ZnO and Ag-ZnO nanoparticles exhibited UV-visible absorption peaks at 370 nm, corresponds to a band gap of 3.24 eVand 3.08 eV respectively. Based on the above characterization techniques, the incorporation of silver affects the structural and optical behaviour of ZnO nanoparticles. The ZnO nanoparticles were observed that the particles are spherical morphologies. EDAX spectrum indicates no other elemental presence in the synthesized nanoparticle. The present work illustrate the Ag-ZnO nanoparticles as a photo-catalyst to decompose contaminants in the presence of UV light. The photo-catalytic activity of ZnO samples were investigated by UV- irradiation of methylene blue solution in a photocatalytic setup. The resulting mixtures were irradiated with UV light for a period of 45 mins. Based on results, the photocatalytic activity of Ag-ZnO nanoparticles were enhanced by the addition of Ag in pure ZnO nanoparticles. Ag doped ZnO nanoparticles showed higher photocatalytic activity efficiency than pure ZnO nanoparticles.

Properties of TiO2/PDMS-Ag Composites as Antibacterial Self Cleaning

TiO2 and TiO2-PDMS/Ag (PDMS = polydimethylsiloxane) composites have been prepared. The synthesis was carried out by preparing TiO2 using ball milling technique for 6, 8 and 10 hours, with the composition of TiO2: ball milling = 1:15; 1:20; and 1:25 (g/g). Furthermore, the TiO2-PDMS/Ag composite was synthesized through the solvent dispersion method with the aid of ultrasonication. The preparation of TiO2-PDMS/Ag composites was carried out with several compositions of TiO2, PDMS and Ag, as well as milling times, aiming to determine the effect of compositions and time of ball milling process on decreasing of TiO2 particle size. The addition of Ag to the TiO2-PDMS composites was carried out to investigate the effect of Ag on the antibacterial activity. TiO2-PDMS/Ag composite coating on glass was done by spray coating method. While the antibacterial activity was measured by determining the zone of inhibition by disc diffusion method against Staphylococcus aurous and Escherichia coli. The results exhibited that the ball milling treatment and milling time affected the change in the crystal size of TiO2. The highest composition of TiO2: ball milling at 1:25 for 10 hours was able to reduce the crystal size of TiO2 from 65.81 nm to 46.17 nm. The other hand, the observation of the physical properties of the contact angle of glass coated TiO2-PDMS/Ag composites before irradiation obtained 107° and after irradiation with visible light the contact angle decreased to 56°, which shows that the TiO2-PDMS/Ag composites exhibit photocatalytic activity in the presence of TiO2/Ag. Furthermore, the observation of antibacterial activity on the TiO2-PDMS/Ag as a self-cleaning photocatalytic materials resulted that the largest inhibition zone reached 11.37 mm, so that the TiO2/PDMS-Ag composites had great potential as an active antibacterial self-cleaning.

Bimetallic AgAualloy@ZnO core-shell nanoparticles for ultra-high detection of ethanol: Potential impact of alloy composition on sensing performance

The detection/sensing properties of chemiresistive gas sensors are greatly improved by catalytically triggered bimetallic alloyed nanoparticles, because of their synergistic effect. In this work, well-defined AgAualloy@ZnO core-shell nanoparticles are synthesized with the various compositions of Ag and Au. Alloying Au with Ag gave superior thermal stability to Ag, which favored gas sensing performance. As the amount of Ag within the AgAualloy core increased, the optimum working temperature was lowered to 300 ℃ with the dramatically enhanced ultra-high response of 1755 was obtained for Ag70Au30 @ZnO NPs sensor to 100 ppm ethanol. The outstanding sensing performance of AgAualloy@ZnO were endorsed to the improved the electronic and catalytic properties of AgAualloy core, aplenty chemisorbed oxygen on the surface of ZnO, unique core-shell structure that bring large active surface area and enhanced electron transfer process at the interface between core and shell. Ultraviolet photoelectron spectroscopy (UPS) analysis shows that with increasing Ag concentration, the work function (ϕ) decreases and the chemisorbed oxygen increases that brings wider depletion layer and Schottky barrier between the AgAualloy core and the ZnO shell, enhancing the gas sensing response. Our findings suggest that the incorporation of noble metal alloy-metal oxide semiconductor based core-shell nanostructures enhance the gas sensing performance with selectivity in the practical field of applications in environmental issues and human health monitoring.

Low concentration isopropanol gas sensing properties of Ag nanoparticles decorated In2O3 hollow spheres

In order to detect low concentrations of volatile organic compounds (VOCs) for the early diagnosis of lung cancer, sensors based on hollow spheres of In2O3 were prepared through the soft template method. Ag nanoparticle decorated In2O3 composites were synthesized via dipping and annealing. The microstructure, phase composition, element distribution, and state of Ag were analyzed by the scanning electron microscopy (SEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscopy (XPS). The gas sensing tests showed that Ag-In2O3 sensors had the highest response to isopropanol at 300 °C. The best response of Ag-In2O3 composite sensor was 5.2, which had a significant improvement compared with only In2O3. Moreover, the response and recovery time of Ag-In2O3 composite sensor was significantly shortened. The improved sensing properties of Ag-In2O3 composite sensor could be attributed to the Schottky barrier created at Ag-In2O3 interface and catalytical effect of Ag.

Controlled grain boundary interfaces of reduced graphene oxide in Ag2Se matrix for low lattice thermal conductivity and enhanced power factor for thermoelectric applications

Silver Selenide (Ag2Se), a promising thermoelectric (TE) material due to its high proficient performance in (300–400) K. In this report, Ag2Se and its composites with reduced graphene oxide (rGO) were synthesized by sonochemical assisted hydrothermal method followed by hotpress densification technique. The structural analysis confirmed the orthorhombic phase of Ag2Se and the composition of Ag–Se–Ag with rGO is confirmed from binding energy shift in X-ray photoelectron spectroscopy (XPS) analysis. The phase transition from orthorhombic to cubic phase is identified around (390–450) K from TG-DTA analysis. For 30 wt % of rGO in Ag2Se, the very low thermal conductivity (κ) of ∼0.492 Wm−1K−1 is obtained at 333 K. The maximum zT of ∼0.39 is achieved at 363 K for Ag2Se with 30 wt % rGO. The facile synthesis with modification by rGO shows the untapped potential of very low thermal conductivity in Ag2Se that is yet to be uncovered for TE generators.

Killing two birds with one stone: Silver nanoparticles loaded on ultrathin N-doped carbon-coated TiO2 porous spheres with narrow bandgap for efficient SERS sensing and photoinduced antibacterial applications

The bifunctional applications of noble metal-TiO2 heterojunctions are an interesting topic, such as antibacterial agents and chemical sensors via surface-enhanced Raman spectroscopy (SERS). The vital factor is to narrow the bandgap of TiO2 and shift the absorption wavelengths from ultraviolet to visible region. In this study, we reported the design and the fabrication of TiO2 spheres coated with an ultrathin nitrogen-doped carbon (NC) shell and subsequent loading Ag nanoparticles. This strategy endowed TiO2 spheres with a narrow bandgap (2.34 eV) and high fluorescence quenching ability. The TiO2@NC/Ag composites exhibited excellent charge transfer-induced SERS performance with high enhancement factor of 8.0 × 106 and good uniformity. The composites were further developed as a SERS sensor for rapid detection of phenformin hydrochloride in human urine with a low detection limit of 5 nM. In the antibacterial application, TiO2@NC/Ag showed a promising bactericidal feature against Escherichia coli under low-power LED (6 W) irradiation, which immensely emerged the synergistic antibacterial role of TiO2@NC and Ag. The inhibition rate under the LED irradiation for 8 h increased from 59.8% to 87.6% as compared to the rate in the dark.

Architecting an indirect Z-scheme NiCo2O4@CdS–Ag photocatalytic system with enhanced charge transfer for high-efficiency degradation of emerging pollutants

Bimetallic oxides with spinel structure show great prospects in the photocatalysis owing to many active sites. Herein, a novel 500NiCo2O4@CdS–5%Ag composite was fabricated via a feasible strategy. Interestingly, the combination with NiCo2O4 could significantly enhance the absorption ability of CdS for visible light. Benefiting from the formation of heterojunction structure between NiCo2O4 and CdS, the recombination of photogenerated electrons and holes was remarkably restrained. As an effective mediator, deposition of Ag could further promote the transfer of photogenerated charge carriers, thereby accelerating the reaction rate. Meanwhile, light absorption capacity of composite was also improved, owing to the surface plasmon resonance effect of metallic Ag. More importantly, 500NiCo2O4@CdS–5%Ag composite with great stability displayed an excellent performance in the photocatalytic degradation of OFX, and its highest removal efficiency was as high as 99.14%. Possible degradation pathways of OFX were given, and most of OFX could be degraded into CO2, H2O and other by-products with no toxicity. Significantly, the separation and transfer of photogenerated charge carriers followed indirect Z-scheme heterojunction mechanism. The O2−, OH and 1O2 were main active species in photocatalytic reaction system. All in all, current work inspired some new ideas for designing novel photocatalytic system in wastewater treatment.

Effect of Al atomic layer on the wetting behavior, interface structure and electrical contact properties of silver reinforced by Ti3AlC2 ceramic

Ti 3 AlC 2 ceramic exhibits potential in Ag-based composite electrical contact materials, but its interface characteristic with Ag matrix remains unexplored. In this work, sessile drop experiment is carried out to investigate the high-temperature wetting behavior of molten Ag with Ti 3 AlC 2 . Stable Ti 3 AlC 2 is hardly wetted by molten Ag below 1000 °C(contact angle of 148.5°), but the wettability of Ag/Ti 3 AlC 2 improves with the increasing temperature(final 14° at ∼1130 °C). In contrast, the Ti 3 C 2, a MXene with Al layer removed from its parent Ti 3 AlC 2 , exhibits inferior wettability with Ag(final 56.5° at ∼1130 °C). Wetting mechanism of Ag/Ti 3 AlC 2 is proposed on the basis of the interfacial structure and chemical composition. Increasing temperature accelerates dissociation of Ti 3 AlC 2 , and outward-escaping Al reacts with Ag to form interface layer with a composition of Ag 4.86 Ti 8.66 AlC 7.59 , Ag also diffuses along Ti 3 AlC 2 grain boundaries and forms gradient reactive products(Ag–Ti–Al–C), which promotes their wettability. Finally comprehensive properties of Ag/Ti 3 AlC 2 and Ag/Ti 3 C 2 are compared. Al–Ag interdiffusion slightly decreases the electrical conductivity of Ag/Ti 3 AlC 2 bulk material, but strengthen the interface bonding of composite and promote the viscosity of the molten pool, leading to the superior mechanical and anti-arc erosion properties. Absence of Al–Ag interdiffusion does remarkably improve the electrical conductivity of Ag/Ti 3 C 2 bulk materials, but lack of Al layer damages the mechanical core and wettability with Ag, resulting in a drastic decrease of anti-arco erosion property.

Highly stretchable transparent bar coated Ag NW/PEDOT:PSS hybrid electrode for wearable and stretchable devices.

In this study, we demonstrated poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) as a composite with Ag nanowire (Ag NW) to enhance the stretchability of the Ag NW network electrode. The composite Ag NW/PEDOT:PSS hybrid ink (AP ink) was prepared at a ratio of 1 : 10, 1 : 20, and 1 : 30, respectively and bar coated on polyurethane substrate. The different ink ratios were studied and optimized with a sheet resistance of 14.93 Ω sq−1. and a transmittance of 88.6% showing a high performance in mechanical stress tests such as bending, folding, rolling, twisting, and stretching. It also showed a conductive bridge effect where the PEDOT:PSS acted as an anchor or support to Ag NW during mechanical strain and PEDOT:PSS also enhanced the electrical conductivity of the Ag NW. Therefore, to prove the real time performance of the electrode as a wearable device, we fabricated transparent electroluminescence devices and thin film heater devices which are highly flexible and demonstrated excellent performance proving that the AP electrode is more suitable candidate for future wearable transparent devices.

Improved performance of the pyrimidine-modified porous In-MOF and an in situ prepared composite Ag@In-MOF material.

A stable porous In-MOF 1 was prepared for the first time via an asymmetric N,O-containing (2-pyrimidin-5-yl)terephthalic acid (H2L). It was found that the 1,4-benzenedicarboxylate anions (bdc2-) were formed in the synthesis process of 1. Thus, another new isomorphic In-MOF 2 was formed by employing the H2bdc ligand in the synthesis process of 1. More importantly, when adding AgNO3 in the synthesis process of 1 and 2, only composite Ag@1 was obtained via the in situ reduction of Ag(I) to Ag NPs without additional reducing agent. MOF 1 and Ag@1 had great sorption capacity; in particular, 1 had remarkable dynamic selectivity for C2H2/CH4 and CO2/CH4, and they were also efficient catalysts for fixing CO2 and epoxides. It is hoped that this work may supply an effective strategy to build stable MOFs and composite Ag@MOF materials with excellent multifunctional applications.

Bunch of Grape-Like Shape PANI/Ag2O/Ag Nanocomposite Photocatalyst for Hydrogen Generation from Wastewater

Polyaniline (PANI) and PANI/Ag2O/Ag composites I and II were prepared under different AgNO3 oxidant concentrations using the oxidative photopolymerization method. The chemical structure and optical, electrical, and morphological properties were determined for the prepared nanocomposite. The PANI/Ag2O/Ag composite II has the optimum optical properties, in which the bandgaps of PANI, composite I, and composite II are 3.02, 1.71, and 1.68 eV, respectively, with the morphology of a bunch of grape-like shapes with average particles sizes of 25 nm. Under the optimum optical properties, glass/PANI/Ag2O/Ag composite II electrode is used for hydrogen generation from sewage water. The measurements are carried out from a three-electrode cell under a xenon lamp. The effects of light wavelengths and temperature on the produced current density ([Formula: see text]) are mentioned. Under the applied voltage (at 30°C), the current density values ([Formula: see text]) increase from 0.003 to 0.012 mA.cm-2 in dark and light, respectively. While increasing the temperature, [Formula: see text] values increase to 0.032 mAcm-2 at 60°C. The thermodynamic parameters are calculated, in which the activation energy ([Formula: see text]), enthalpy ([Formula: see text]), and entropy ([Formula: see text]) values are 27.1 kJ·mol-1, 24.5 J mol-1, and 140.5 J K-1 mol-1, respectively. Finally, a simple mechanism for the produced hydrogen generation rate is mentioned. The prepared electrode is a very cheap (1$ for [Formula: see text]) electrode.

Phase transitions in thermoelectric Mg-Ag-Sb thin films

α-MgAgSb thin films are expected to be compatible with the complementary metal oxide semiconductor (CMOS) technology, and could be used to develop thermoelectric modules integrated to microelectronic devices for energy harvesting. However, bulk studies showed that the presence of secondary phases in addition to α-MgAgSb, such as the metallic phase Ag3Sb, deteriorates the thermoelectric properties. Consequently, understanding phase transformations in Mg-Ag-Sb thin films produced by CMOS-compatible magnetron sputtering is capital for the production of homogeneous α-MgAgSb thin films to be used in energy harvesting thermoelectric modules integrated into microelectronic devices. In this work, different Mg-Ag-Sb films were deposited by magnetron sputtering using either a single alloyed target with the average composition Mg1/3Ag1/3Sb1/3 or using Mg, Ag, Sb co-deposition from three elementary targets. In situ X-ray diffraction measurements were used to investigate the phase transitions in the films, aiming to determine the thermal stability of α-MgAgSb and to investigate the possibility of producing α-MgAgSb films without secondary phases. The results show that the use of the single alloyed target does not allow the production of homogenous α-MgAgSb films. The phase formation sequence observed in the films is different from bulk samples in this case. Co-sputtering of the three elements Mg, Ag, and Sb, allowing the composition of the as-deposited film to be better controlled, confirmed that the Mg1/3Ag1/3Sb1/3 stoichiometry does not allow the production of homogenous α-MgAgSb films. Contrasting with usual belief, the results show that the Ag and Sb compositions of the phases α-MgAgSb and γ-MgAgSb vary during annealing, and the phase transitions α-to-β, β-to-γ, and α-to-γ are not allotropic. These finding are of major importance for the production of the thermoelectric compound α-MgAgSb, and explain the large variations of the α-MgAgSb Seebeck coefficient reported in the literature.

Enhancement of Physical and Mechanical Characteristics of NiTi Composite Containing Ag and TiC

Enhancement of Physical and Mechanical Characteristics of NiTi Composite Containing Ag and TiC

Comparative studies of the biological efficacies of Ag and Ag-MgO nanocomposite formed by the green synthesis route

The present study investigates the changes occurring to the physicochemical and biological properties of silver (Ag) nanoparticles (NPs) before and after conjugating with that of magnesium oxide (MgO). In that view, to form Ag NPs and Ag-MgO nanocomposite, we adopted a green synthesis route that makes use of Citrus paradisi(grapefruit red) extract as a reducing agent and the formed particles are thoroughly characterized for the crystallinity, surface bonding and functionality, morphology, composition, surface charges, etc. From the physicochemical analysis, the successful formation of Ag and Ag-MgO composites are confirmed from the UV–Vis and FTIR spectroscopy, while the TEM indicated the spherical morphology and DLS for the average particle size of 260 nm in solution. Further, on testing the biological efficacy, the Ag-MgO nanocomposite (up to 320 µg/mL) was found to have efficient antibacterial and antifungal activities against Staphylococcus aureus and Candida albicans (respectively). Also, the studies of β-galactosidase enzyme activity resulted that Ag’s composite formation with MgO (Ag-MgO with IC50 of 27.6 µg/mL) is not significantly enhancing the effectiveness as compared to pure Ag NPs (IC50 of 28.6 µg/mL). Also, the in vitro cell viability studies indicated the anticancer activity of Ag-MgO nanocomposite in a dose-dependent manner when tested against the Hela cancer cells was in the concentration range of 1–100 µg/mL (24 h period). Based on the overall analysis, the easy making process by the green synthesis route and inexpensive Ag-MgO nanocomposite can serve as a superior antimicrobial and anticancer ingredient for the development of therapeutic products in the biomedical sector.

Preparation of PVA/PAM/Ag strain sensor via compound gelation

AbstractPolyvinyl alcohol (PVA) and polyacrylamide (PAM) hydrogels as well as silver particles (Ag) composites are prepared by compound gelation. The structure and properties of the composites, which are controlled by the reaction of acrylamide in the hydrogel, are analyzed and the feasibility of their application in strain sensors are explored. The effects of different PVA concentration, content, and particle size of Ag on the mechanical properties, rheological properties of the composites are studied. PVA/PAM/Ag composites are selected as the substrate of the strain sensor, when the concentration of PVA is 0.08 g/ml, the particle size of Ag is 60 nm and the addition amount is 0.15 wt%. The strain sensing performance of the composites under low strain (5%, 20%, and 50%) and high strain (100% and 200%) are tested respectively. The hydrogel composite sensor shows sensitive and stable response to human motion, and it has the ability of distinguish the movement of different human body joints.

Antibiofilm activity of nanosilver coatings against Staphylococcus aureus

Implant infections due to bacterial biofilms constitute a major healthcare challenge today. One way to address this clinical need is to modify the implant surface with an antimicrobial nanomaterial. Among such nanomaterials, nanosilver is arguably the most powerful one, due to its strong and broad antimicrobial activity. However, there is still a lack of understanding on how physicochemical characteristics of nanosilver coatings affect their antibiofilm activity. More specifically, the contributions of silver (Ag)+ ion-mediated vs. contact-based mechanisms to the observed antimicrobial activity are yet to be elucidated. To address this knowledge gap, we produce here nanosilver coatings on substrates by flame aerosol direct deposition that allows for facile control of the coating composition and Ag particle size. We systematically study the effect of (i) nanosilver content in composite Ag silica (SiO2) coatings from 0 (pure SiO2) up to 50 wt%, (ii) the Ag particle size and (iii) the coating thickness on the antibiofilm activity against Staphylococcus aureus (S. aureus), a clinically-relevant pathogen often present on the surface of surgically-installed implants. We show that the Ag+ ion concentration in solution largely drives the observed antibiofilm effect independently of Ag size and coating thickness. Furthermore, co-incubation of both pure SiO2 and nanosilver coatings in the same well also reveals that the antibiofilm effect stems predominantly from the released Ag+ ions, which is especially pronounced for coatings featuring the smallest Ag particle sizes, rather than direct bacterial contact inhibition. We also examine the biocompatibility of the developed nanosilver coatings in terms of pre-osteoblastic cell viability and proliferation, comparing it to that of pure SiO2. This study lays the foundation for the rational design of nanosilver-based antibiofilm implant coatings.