Field Emission Scanning Electron Microscopy/energy Dispersive X-ray Spectroscopy Research Articles

Nanoarchitecturing of Mo2C nanospheres on carbon cloth as an electrochemical sensing platform for determination of caffeic acid tea samples

In the present paper, carbon cloth (CC) as a flexible substrate was modified by molybdenum carbide nanospheres (Mo2C NSs @CC) by the drop-coating method to develop a sensitive electrochemical platform for detecting caffeic acid. The uniform Mo2C NSs were prepared via an easy route followed by pyrolyzing the precursor of the Mo-polydopamine (Mo-PDA) NSs. The Mo2C NSs were characterized and analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDS), Raman spectroscopy (RS), and electrochemical methods. CC not only gave a flexible feature to the sensor but also provided a larger surface area for Mo2C NSs. Meanwhile, the excellent conductivity and large electroactive specific surface area of Mo2C NSs exhibited excellent electrocatalytic performance for caffeic acid determination. The developed sensor showed high sensitivity and selectivity, good reproducibility, and long-term stability with a limit of detection (LOD) and a wide linear range of 0.001 μM (S/N = 3) and 0.01–50 μM, respectively. In addition, the Mo2C NSs @CC sensor showed a promising application prospect for the detection of caffeic acid in green and black tea samples, indicating its importance in food safety and the food industry.

Synthesis, Characterization, and Antibacterial Activity of Plant-Derived Zinc Oxide Nanostructure Using <i>Lavandula angustifolia</i> and <i>Phyllanthus niruri</i> Extracts

In recent years, green synthesized nanomaterials have garnered wide interest due to its inherent features like rapidity, cost-effectiveness, and environmentally friendly technique. The green synthesis of Zinc oxide nanostructures (n-ZnO) using two kinds of plant extract, lavender (Lavandula angustifolia) and meniran (Phyllanthus niruri), were discussed and their antibacterial activities were compared. Characterization by means of X-ray diffraction (XRD), Fourier transform infrared (FTIR), and field emission-scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDS) were used to confirm the successful formation of n-ZnO using both plant extracts. The antibacterial activity of the n-ZnO synthesized from two different plant extracts was tested against Klebsiella pneumoniae and methicillin-resistant Staphylococcus aureus (MRSA). The results show that both n-ZnO has antibacterial activity against MRSA. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values for n-ZnO synthesized from meniran extract were 78 and 156 mg/mL, respectively, while MIC and MBC values for n-ZnO synthesized from lavender extract were 156 and 312 mg/mL, respectively. These results confirm that the n-ZnO prepared from meniran extract is more effective in inhibiting MRSA than the n-ZnO prepared from lavender extract. This study proves that plant-based n-ZnO has anti-microbial activities and may serve as antimicrobial therapeutics.

Synthesis and characterization of aluminum doped zinc oxide nanoparticles via a novel and low cost aqueous chemical process

Pure and Aluminum doped Zinc Oxide Nanoparticles (AZO NPs) with various doping concentrations were synthesized using an original aqueous chemical process under atmospheric pressure and moderate temperature, using only deionized water as a solvent with a filtration step followed by heat treatment.The X-Ray Diffraction (XRD), Raman and Field Emission Scanning Electron Microscopy- Energy-Dispersive X-ray Spectroscopy (FESEM-EDS) analysis of nanoparticles reveals a hexagonal wurtzite structure, with a size around 60 nm and the presence of aluminum in our samples. Optical investigations demonstrate that the material is of high quality, with few deep structural defects, since Photoluminescence (PL) is largely dominated by excitonic emission at low temperatures.

Revealing the rock heterogeneity in Sebau, Lombok Island by applying morphological and elemental composition analyses

Lombok Island is situated in east Indonesia. Its heterogeneity is very complex. It is one of the seismically and volcanically active regions in Indonesia. Several earthquakes occurred on Lombok Island in July-August 2018. Lombok Island is also known as the place of an active volcano (Mt. Rinjani) and geothermal resources in Indonesia. We applied the morphological and elemental composition analyses to know in more detail the rock heterogeneity in Lombok Island by using X-ray fluorescence (XRF), field emission-scanning electron microscopy/energy-dispersive X-ray spectroscopy (FESEM-EDS), and X-ray Powder Diffraction (XRD). In this study, we chose the Sebau hot springs as the study area and collected the rock sample in the study area in August 2022. The FESEM-EDS result shows that the crystalline structures of the rock sample have a compact, unconsolidated, and fine structure with some layers. The significant elements of the rock samples by applying XRF analysis are Si (36.91%) and Fe (30.787%). It is also supported by the XRD analysis that revealed the dominant compounds in the rock samples are pyrite (FeS2) and cristobalite (SiO2). Therefore, there is an indication of the study area is the surface manifestation of the past Mount Rinjani volcanic activity.

Efficacy of a Novel Bioactive Glass-Polymer Composite for Enamel Remineralization following Erosive Challenge.

Introduction Dental caries is the most common cause of tooth loss. However, it can be stopped by enhancing remineralization. Fluoride and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) are among the most important remineralizing agents. Recent studies have used bioactive glass as a remineralizing agent in different forms. This study aimed to assess the efficacy of a composite paste (prepared by mixing urethane polypropylene glycol oligomer with bioactive glass powder for easier application). Materials and Methods Enamel disks were cut out of the buccal surface of extracted sound third molars. The samples were randomly divided into 3 groups of 15 and underwent Vickers microhardness test. X-ray diffraction (XRD) and field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FESEM/EDS) were performed. All samples were immersed in a demineralizing solution for 14 days. The tests were then repeated. Next, bioactive glass paste, fluoride, and CPP-ACP were applied on the surface of the samples and they were then stored in an artificial saliva for 14 days. The tests were repeated again. The microhardness values were analyzed using repeated measures ANOVA followed by one-way ANOVA and Tukey's post hoc test (P < 0.05). Results The microhardness of the bioactive glass group was significantly higher than that of other groups (P < 0.05). XRD revealed an enamel structure more similar to sound enamel in the bioactive glass and CPP-ACP groups compared with the fluoride group. FESEM/EDS revealed higher hydroxyapatite deposition in the bioactive glass group than in the other two groups. Conclusions All three remineralizing agents caused remineralization, but bioactive glass paste had a greater efficacy.

Stachys byzantina extract: A green biocompatible molecules source for graphene skeletons generation on the carbon steel for superior corrosion mitigation

The presence of bio-active compounds in Stachys byzantina (SB) extract has made it a powerful source of green inhibitors in controlling steel corrosion. In this study, it has been attempted to create a highly durable corrosion protective film on the surface of the metal with SB and divalent zinc (II) cations and investigated them by Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic polarization (PP) tests, and surface analysis methods. EIS results show that after 24 h of placing the steel samples in 3.5% NaCl solution containing 700 SB − 300 ZN, the synergistic corrosion inhibition behavior was about 92%. Besides, the results of the PP demonstrated a significant reduction of the icorr. Furthermore, surface analyses such as Field Emission Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (FE-SEM/EDS) and Atomic Force Microscopy (AFM) images illustrated the low metal surface degradation, which indicates that the mix of SB and Zn caused a protective layer creation on the surface, especially for SB 700 - Zn 300. Also, new compounds of graphitic materials’ structure were made using SB extract which is a natural-based chemical, and investigated by Fourier-Transform Infrared Spectroscopy (FTIR) test, Grazing Incidence X-ray Diffraction (GIXRD) technique, Ultraviolet–visible spectroscopy (UV–Vis) analysis, and Raman spectroscopy.

Residual, Corrosion &amp; Tribological Behavior of HVOF Sprayed Sustainable Temperature-Dependent Carbon-Based Hybrid Composite Coating

At present, cost-effective coatings that cause less pollution are in great demand; to decrease frictional losses, carbon-based hybrid composite coatings have been developed using a high-velocity oxy-fuel (HVOF) spray process. The microstructural, tribological, corrosion, and mechanical properties of these coatings have been evaluated using high-resolution X-ray diffraction (HRXRD), field emission scanning electron microscopy-Energy dispersive X-ray Spectroscopy (FESEM-EDS), Raman spectrum, Vickers micro-hardness tester, µ-360 cos(α) residual stress analyser, corrosion tester, and high temperature tribometer. The residual stress, corrosion and tribological behaviour at high temperatures were investigated using a pin-on-disc high-temperature tribometer. The tribological performance was evaluated using a high-temperature tribometer, and the experimental result shows that a coefficient of friction (COF) varies from 0.12 to 0.52, while wear results were in the range of 45 µm to 120 µm, as the test condition of temperature ranging from 50 °C to 350 °C, load from 60 N to 90 N and sliding velocity from 0.1 m/s to 0.4 m/s respectively. The experimental results of corrosion testing show that the mass loss decreases from 0.10 g to 0.04 g, when samples were dipped for 1 h; when the samples were dipped for 8 h, the mass loss of hybrid composite coating varied from 0.12 g to 0.045 g. The tribological test showed a 78.9 % increase in micro-hardness, a 78 % decrease in residual stress, and 60 % and 62.5 % decreases in mass loss due to corrosion at 1 h and 8 h, respectively, a 76.9 % decrease in COF and 62.5 % reduction in the wear at test condition of 350 ºC temperature, a sliding velocity of 0.4 m/s and 90 N load.

Characterization of Powder Obtained from Surface of Waste-Plastic Bricks

The basic aim of this work is to perform characterization of the powder obtained from surface of waste plastic brick which in turn provides a base to study the physical and chemical composition of bricks made from waste plastic bags and sand (Plastic bricks). The powder used for characterization was obtained from the surface of waste plastic bricks by scratching the surface of bricks with knife-like stainless-steel instruments. Before characterization, this powder was strained through a double layer strainer (mesh number 325, pore size 44 microns) to obtain fine powder particles. This fine powder was further characterised for determining the particle size, crystallinity percentage, elemental composition and to find functional groups present. The techniques used in characterization of powder includes X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) and Field Emission Scanning Electron Microscopy / Energy Dispersive X-ray Spectroscopy (FESEM/EDS). The results obtained from XRD data analysis showed the particle size to be 9.595 nanometres with a crystallinity percentage of 2.113275 percent. EDS and FTIR results when studied simultaneously showed presence of clay minerals like MgO, SiO2, Al2O3, etc.

The effects of anode additives towards suppressing dendrite growth and hydrogen gas evolution reaction in Zn-air secondary batteries

In our continual effort to develop a cost effective rechargeable Zn-air batteries, herewith, we demonstrated Zn anodes comprising of (i) 30 wt.% Zn: 3 wt.% bismuth oxide: 10 wt.% potassium sulfide (ZBK), (ii) 30 wt.% Zn: 3 wt.% bismuth oxide: 5 wt.% lead (II) oxide (ZBP), and (iii) 30 wt.% Zn: 3 wt.% bismuth oxide: 10 wt.% potassium sulfide: 5 wt.% lead (II) oxide additives (ZBKP) in 6 M KOH aqueous solutions and 1.88 wt.% polyacrylic acid as the gelling agent. KOH gel constituted the remaining mass of the anode wt.%. Results were confirmed via cycle voltammetry (CV), Tafel, electrochemical impedance spectroscopy (EIS), etc., measurements. Among the various Zn anodes analyzed, ZBKP showed a superior cathodic peak of − 1.805 and 1.950 V vs. Hg/HgCl at 5th and 40th cycles during electrochemical cycle voltammetry. Tafel fitting on linear polarization test shows that ZBK exhibits the highest corrosion behavior followed by ZBP while ZBKP has the lowest corrosion behavior with an estimated corrosion inhibition efficiency of 36.06%. Furthermore, ZBKP displays the lowest dendrite growth, least corrosion rate, and superior capacity even at 60th cycles compared to ZBK and ZBP. In view of our finding, ZBKP has a higher positive electrode potential compare to ZBK and ZBP electrodes. Thus, ZBKP is the most suitable for aqueous battery due to its low minimal side effect. Field emission-scanning electron microscopy/energy dispersive x-ray spectroscopy (FE-SEM/EDS) images confirm that the various elemental additives were evenly deposited on the Zn anode surface. Ex situ spectroscopy and electrochemical performance studies also verified that the dendrite-free nature of improved Zn anode and the modified interfaces between electrolyte and Zn play vital roles towards advancing the energy storage performance. With all this indices and yard stick, the level of improvement we demonstrated in this current study is attractive for the design of an advanced secondary zinc-air batteries.

Magnetic arginine-functionalized polypyrrole with improved and selective chromium(VI) ions removal from water

Magnetic arginine-functionalized polypyrrole (Fe3O4@Arg-PPy) nanocomposite was fabricated by in-situ polymerisation of pyrrole (Py) monomer in the presence of arginine and Fe3O4 nanoparticles for toxic chromium(VI) ions removal from simulated and chromium ores leaching effluent. The nanocomposite adsorbent was characterised using a variety of techniques, including, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDS), high resolution-transmission electron microscopy (HR-TEM), vibration sample magnetometer (VSM), Braunauer-Emmett-Teller (BET) method and X-ray photoelectron spectroscopy (XPS). The adsorption kinetics study for the removal of Cr(VI) ions using Fe3O4@Arg-PPy demonstrated that the process followed a pseudo-second-order model. Isothermal investigation, on the other hand, revealed a monolayer adsorption behaviour following the Langmuir model with a maximum absorption capacity of 322.58 mg/g at 25 °C and pH 2. The plausible Cr(VI) adsorption mechanisms were inferred taking into consideration the presence of amino functional groups within Fe3O4@Arg-PPy moiety, the fates of chromium valence state, and the solution pH variation. Reduction of Cr(VI) to Cr(III) by active electron rich nanocomposite was established using ion chromatography-inductively coupled plasma-mass spectrometry (IC-ICP-MS) and XPS analyses. Cr(VI) removal took place via electrostatic attractions, reduction and chelation. Even in high salinity conditions, Fe3O4@Arg-PPy also retained its impressive adsorption efficiency towards Cr(VI) ions. Further, assessment for Cr(VI) ions removal in chromium ores leaching water samples demonstrated its potential practicability. The described adsorbent could equally be regenerated for four adsorption-desorption cycles, retaining up to 64% of its adsorption efficiency.

Hydrous CeO2-Fe3O4 decorated polyaniline fibers nanocomposite for effective defluoridation of drinking water

Hydrous CeO2-Fe3O4 (HCeFe) decorated polyaniline nanofibers (HCeFe NFs) were obtained through a simple co-precipitation deposition approach on pre-synthesized polyaniline nano-fibers (PANI NFs), and evaluated as adsorbents for fluoride removal from synthetic and real water samples. Field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDS), high resolution-transmission electron microscopy (HR-TEM), Braunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric-differential thermal analysis (TGA-DTA), X-ray photoelectron spectroscopy (XPS) and dynamic mechanical analysis (DMA) techniques were used to characterize the hybrid nanomaterials. The optimised HCeFe NFs adsorbent with specific surface area 66 m2/g, exhibited excellent adsorption efficiency towards fluoride ions (F−) via both electrostatic interactions and ion exchange mechanisms. F− adsorption followed the pseudo-second-order rate model and best fitted the Langmuir isotherm, with the maximum capacities within 93.46–117.64 mg/g over a broad pH range 3–10, respectively. The determined thermodynamic parameters, including enthalpy (ΔH° − 15.1 kJ/mol) and Gibbs free energies change (ΔG° < 0) indicated to the exothermic and a spontaneous nature of the sorption process. The regeneration of HCeFe NFs showed a considerable adsorption-desorption efficiency over three consecutive cycles. Ultimately, the adsorbent was tested on spiked F− containing groundwater and the obtained results demonstrated its potential utility for defluoridation of natural water.

Zerovalent Selenium Adsorption Mechanisms on CaO Surface: DFT Calculation and Experimental Study.

Zerovalent Se (Se atom and small Se2 molecule) adsorption mechanisms on a CaO surface were studied by both density functional theory (DFT) calculations and adsorption experiments. Nonvalent Se adsorption on the CaO(001) surface was simulated using a slab model. The adsorption energy, adsorption structure, electron density clouds, and electron properties were calculated. Different Se surface coverages were investigated to elucidate the adsorption process. In the experiments, the Se adsorption products were prepared in a U-shaped quartz reactor at 300 °C. The properties were investigated by X-ray photoelectron spectroscopy (XPS), inductively coupled plasma atomic emission spectroscopy (ICP-AES), field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDS), and X-ray diffraction (XRD), respectively. The experimental results match up with the DFT results, which reveal fundamentalmonochemisorption mechanisms of zerovalent Se on the CaO surface.

Optimization, kinetics, equilibrium isotherms, and thermodynamics studies for Congo red dye adsorption using calcium alginate beads immobilized with dual adsorbent (Neurospora crassa dead fungal biomass and wheat bran)

The present study is concerned with the batch adsorption of Congo red (CR) from aqueous solutions using calcium alginate beads (CAB) immobilized with dead biomass of Neurospora crassa along with wheat bran (DB–WB) as a dual adsorbent. The optimum conditions for CR adsorption were determined by studying various operational parameters such as initial pH, dye concentration, dual adsorbent loading in CAB, adsorbent dosage, agitation speed, and temperature. The process parameters were optimized using factorial experimental design to attain the maximum percentage adsorption. The CAB immobilized with DB–WB was characterized by attenuated transmission reflector and field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FESEM/EDS) analysis. The experimental equilibrium data were analyzed with various isotherm models. The results show that the best fit was achieved with the Langmuir isotherm model. Kinetic rate constants were found using different kinetic models. The adsorption kinetics for CR dye removal by CAB immobilized with DB–WB dual adsorbent follows pseudo-second-order kinetic model. Thermodynamic studies were evaluated by maximum adsorption capacities (qmax) at different temperatures. From the results, the adsorption was found to be spontaneous, endothermic in nature of the adsorption process and favored at high temperature. Desorption experiments were carried out using various desorbing agents to explore the possibility of regenerating the CAB immobilized with dual adsorbent. The maximum percentage of CR dye was desorbed using the solvent methanol. The reusability studies of CAB immobilized with dual adsorbent for the adsorption of CR was carried out in three runs.

Genetic analysis of arsenic metabolism in Micrococcus luteus BPB1, isolated from the Bengal basin

A highly arsenic-metabolizing bacterial strain was isolated from an agricultural field known for arsenic contamination near Munshiganj (Bangladesh). Based on 16S rRNA gene analysis, the strain was identified as Micrococcus luteus and designated as strain BPB1. Arsenate and arsenite minimal inhibitory concentrations of 650 mM and 7.5 mM, respectively, were observed for strain BPB1, slightly higher than the figures observed in its close relative M. luteus DSM 20030T. Such observations were consistent with the presence of arsenic-metabolizing genes in the genome of M. luteus. We describe this strain as having an MSH/Mrx-dependent class of arsenate reductase, and an arsenite transporter family in the ACR3(1) group. Besides an intracellular arsenic resistance mechanism, experiments carried out using field emission scanning electron microscopy-energy dispersive X-ray spectroscopy (FESEM-EDS) and Fourier transform infrared spectroscopy (FTIR) demonstrated the ability of BPB1 to sequester arsenate in extracellular polymeric substances on its cell surface.

Acidic Microenvironments in Waste Rock Characterized by Neutral Drainage: Bacteria–Mineral Interactions at Sulfide Surfaces

Microbial populations and microbe-mineral interactions were examined in waste rock characterized by neutral rock drainage (NRD). Samples of three primary sulfide-bearing waste rock types (i.e., marble-hornfels, intrusive, exoskarn) were collected from field-scale experiments at the Antamina Cu–Zn–Mo mine, Peru. Microbial communities within all samples were dominated by neutrophilic thiosulfate oxidizing bacteria. However, acidophilic iron and sulfur oxidizers were present within intrusive waste rock characterized by bulk circumneutral pH drainage. The extensive development of microbially colonized porous Fe(III) (oxy)hydroxide and Fe(III) (oxy)hydroxysulfate precipitates was observed at sulfide-mineral surfaces during examination by field emission-scanning electron microscopy-energy dispersive X-ray spectroscopy (FE-SEM-EDS). Linear combination fitting of bulk extended X-ray absorption fine structure (EXAFS) spectra for these precipitates indicated they were composed of schwertmannite [Fe8O8(OH)6–4.5(SO4)1–1.75], lepidocrocite [γ-FeO(OH)] and K-jarosite [KFe3(OH)6(SO4)2]. The presence of schwertmannite and K-jarosite is indicative of the development of localized acidic microenvironments at sulfide-mineral surfaces. Extensive bacterial colonization of this porous layer and pitting of underlying sulfide-mineral surfaces suggests that acidic microenvironments can play an important role in sulfide-mineral oxidation under bulk circumneutral pH conditions. These findings have important implications for water quality management in NRD settings.

Risk of metal mobility in soils from a Pb/Zn depleted mine (Lugo, Spain)

The risk of Pb, Zn and Cd mobility is evaluated in soils from a depleted mine at Rubiais (Lugo, Spain). This area is under special protection because of its outstanding natural value. Soils from nine different areas were selected: at the mining zone (R1, R2, R3), at minespoils (R4, R5, R6) and soils developed on the settling pond (R7, R8, R9). A control soil (RC) was sampled outside the mine. The objectives are (i) to study the characteristics of soils with high influence on metal retention, (ii) to determine the content of Pb, Zn and Cd comparing it with the generic reference levels, and (iii) to evaluate the distribution and the interactions between the metals and the soil geochemical phases by means of sequential chemical extraction, X-ray diffraction, field emission scanning electron microscopy/energy-dispersive X-ray spectroscopy (FE-SEM/EDS) and time of flight secondary ion mass spectrometry (TOF–SIMS). The concentration of Pb, Zn and Cd ranges 850–6,761, 1,754–32,287 and 1.8–43.7 mg kg−1, respectively, and the highest proportion is in the residual fraction. The Mn oxides highly influence the retention of Cd while Pb retention is mainly influenced by Fe oxides. Zn is uniformly distributed amongst the residual fraction and the Fe and Mn oxides. TOF–SIMS and SEM/EDS techniques confirm the fractionation results, showing how Pb and Zn are as sulphide and associated with Fe and Mn oxides. Nevertheless, care should be taken since oxides and sulphides could suffer sulphide oxidation processes or alteration of the oxides causing leaching and the contamination of the protected ecosystem.

Synthesis and Characterization of Porous Zero-Valent Iron Nanoparticles for Remediation of Chromium-Contaminated Wastewater

The physical and chemical properties of porous zero-valent iron nanoparticles (ZVINs) have highly been acknowledged in the decontamination of heavy metal containing wastes and groundwater. In the present work, the treatment of Cr-contaminant through adsorption onto the ZVINs has been studied. The morphology, crystal structure, and surface composition of Fe(O) nanoparticles were investigated by field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDS), transmission electron microscope (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS), respectively. X-ray absorption near edge structure (XANES) revealed that the Cr(VI) species reduce to Cr(III) while oxidizing the ZVINs to Fe2O3, Fe3O4 or FeO electrochemically. Furthermore, the nitrogen adsorption-desorption isotherm of the porous nanoparticles was similar to a type IV curve with an obvious mesopore-characteristic H3 hysteresis loop, whereas the sizes of mesopores were in the range of 30-50 nm. Experimentally, the efficiency for Cr(VI) removal in the range of 150-300 ppm was found to be > 99.9%. Remarkably, the reduction reaction was completed within 10 min in the absence of additional pH controls. This work also highlights the utility of X-ray absorption spectroscopy (XAS) coupled with conventional characterization methods to comprehensively study the speciation and possible reaction pathway in adsorption process.

Antimicrobial Action Effect and Stability of Nanosized Silica Hybrid Ag Complex

Nanosized silica hybrid silver complex (NSS) showing strong antifungal activity, in which nanosilver (nano-Ag) was bound to silica (SiO2) molecules, was synthesized via gamma-irradiation at room temperature. NSS was characterized via field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDXS), ultraviolet-visible (UV-Vis) spectrophotometer, and thermogravimetric analysis (TGA). The FESEM images and EDXS data showed that well-dispersed 3-to-10-nm Ag nanoparticles (core part) were loaded onto the outer parts of 5-to-20 nm SiO2 nanoparticles. The antifungal efficiency of NSS was evaluated against Rhizoctonia solani, Botrytis cinerea, and Colletotrichum gloeosporioides. In the case of Rhizoctonia solani, the growth rate was decreased typically by more than 90% at a 6 microg/ml concentration of NSS as a medium additive. The antifungal-action mechanism was investigated via transmission electron microscopy (TEM) analysis of the NSS treatment against Botrytis cinerea. The stability and antimicrobial activity of NSS were determined, using the plate culture method, from several water samples containing NSS after 7-day NSS treatment. Moreover, the NSS solution maintained stable antifungal activity for at least 24 mos. These results suggest that NSS, an environment-friendly nanomaterial, can be used as strongly effective growth inhibitor of various microorganisms, making it applicable to diverse antimicrobial-control systems.