Concentration Of AgNO3 Solution Research Articles

Improvement photothermal property of MoS2/Fe3O4/GNR nanocomposite in cancer treatment

The objective of the present study was to develop a novel molybdenum disulfide/iron oxide/gold nanorods (MoS2/Fe3O4/GNR) nanocomposite (MFG) with different concentrations of AgNO3 solution (MFG1, MFG2, and MFG3) for topical doxorubicin (DOX) drug delivery. Then, these nanocomposites were synthesized and characterized by Fourier transform infrared (FTIR), Transmission electron microscopy (TEM), Dynamic light scattering (DLS), and Ultraviolet-visible (UV–Vis) spectroscopies to confirm their structural and optical properties. Cytotoxicity of samples on Hela cell was determined using MTT assay. Results indicated that nanocomposites possess little cytotoxicity without NIR laser irradiation. Also, the relative viabilities of Hela cells decreased when the concentration of AgNO3 solution increased in this nanocomposite. Using NIR irradiation, the relative viabilities of Hela cells decreased when the concentration of samples increased. Acridine orange/propidium iodide (PI) staining, flow cytometry were recruited to evaluate the effect of these nanocomposites on apoptosis of Hela cells. Finally, results revealed when DOX loading increased in nanocomposite, then cell viability was decreased in it. Therefore, these properties make MFG3 nanocomposite a good candidate for photothermal therapy and drug loading.Graphical

Synthesis of silver (Ag) nano/micro-particles via green process using Andrographis paniculata leaf extract as a bio-reducing agent

In this work silver nano/micro-particles have been synthesized using sambiloto (Andrographis paniculata) plant extract as a bio-reducing agent. The effects of different plant extract concentrations, AgNO3 precursor concentrations, and reaction time on the synthesized silver nano/micro-particles were investigated. The silver nano/micro-particles samples were then analyzed using UV-Vis spectrophotometer (UV-Vis), X-Ray Diffractometer (XRD), Field Emission Scanning Electron Microscopy (FESEM), Particle Size Analyzer (PSA), and Fourier Transform Infra-Red (FTIR) spectroscopy. The UV-Vis absorbance spectrum of the colloid silver nano/micro-particles exhibited that all samples had absorbance peaks at a wavelength around 450 nm, confirming the formation of silver nano/micro-particles. It was also found that the UV-Vis absorbance peak of the silver nano/micro-particles inversely increased with decreasing AgNO3 solution concentration. Whereas, the higher the sambiloto extract concentration the higher the UV-Vis absorbance peaks. The UV-Vis absorbance peak increased with increasing synthesis time, suggesting that silver nano/micro-particles became more prominent. The UV-Vis absorbance peaks of the silver nano/micro-particles were about 0.0462, 0.0637, 0.0729, and 0.0936 at reaction time of 5, 10, 20, and 40 min, respectively. The XRD analysis result confirmed that the synthesized silver nano/micro-particles were in the form of nanocrystals with a face-centered cubic centered without any impurities. Additionally, the FESEM images showed that the silver nano/micro-particles had the primary particle size of 150-300 nm. There was the formation of some secondary particles with the size of about 0.7-1.5?m due to the agglomeration of primary particles. The particle size distribution analysis further confirmed the presence of primary and secondary particles. Meanwhile, the FTIR analysis confirmed the presence of four main peaks, linked to functional groups in the sambiloto extract and involved in the creation of silver nano/micro-particles.

Fabrication of magnetically separable Ag–ZnFe2O4 hollow nanospheres with efficient photocatalytic activity

Abstract Environmental pollution seriously affects the survival of human beings. Semiconductor photocatalysis technology is considered to be one of the most effective ways to solve environmental pollution and energy shortage. The high degradation efficiency of nanometric photocatalysts has attracted extensive attention, but the photocatalysts are difficult to recycle and reuse, which limits their application. ZnFe2O4 hollow nano-photocatalysts loaded with different contents of Ag were successfully prepared by template-assisted calcination and photoreduction, and can be conveniently separated from water in a magnetic environment. The results indicate that Ag–ZnFe2O4 possess a hollow nano-shell structure with a particle size distribution of about 280 nm and a shell thickness of about 24 nm. Ag–ZnFe2O4 shows the strongest photocurrent intensity and photocatalytic performance compared to bulk ZnFe2O4 and nano ZnFe2O4. When the concentration of AgNO3 solution is 0.2 mmol, Ag–ZnFe2O4 has the strongest photodegradation efficiency to degrade RhB under visible light irradiation. After several photodegradation experiments, the photodegradation efficiency is only decreased by 2.8 %, further proving that Ag–ZnFe2O4 possess good application value in wastewater treatment.

Antimicrobial activity of Chitosan-silver nanoparticles made from jewelry industry silver waste

Local management of bacterial infections is challenging. The antimicrobial effect of silver has long been recognized, but its use is limited due to its expensive nature and reduced applicability in liquids. This study aimed to synthesize chitosan-silver nanoparticles (CS-AgNPs) from reusable silver waste of the jewelry industry and investigate their antimicrobial properties against pathogenic microorganisms. X-Ray diffraction (XRD) analysis was used to confirm the crystalline structure of the recycled silver, with a strong diffraction peak observed at 2?=38.60?. Agar disk diffusion showed inhibitory effects for CS-AgNPs on the growth of Escherichia coli, Staphylococcus aureus, and Candida albicans that depended on the concentration of AgNO3 solution used for preparation. In these tests, S. aureus was more susceptible to the treatment than E. coli and C. albicans. The CS-AgNP inhibited the growth of tested microorganisms with minimum inhibitory concentration (MIC50) values between 1.7 and 4.25 mg/mL. These findings highlight the potential of CS-AgNPs as effective antimicrobial agents. The use of waste materials in nanoparticle synthesis in this research offers a promising approach for sustainable and eco-friendly nanotechnology.

Photocatalytic and Biological Activities of Spherical Shape Cellulose/Silver Nanocomposites Using Xenostegia tridentata (L.) Leaf Extract

A novel green synthesis of cellulose/Ag nanocomposites (Cell/XTLL Ag NCs) with in situ generated silver nanoparticles using Xenostegia tridentata (L.) leaf extracts (XTLL). The synthesized nanocomposites have been appreciably characterized by SEM, TEM, FT-IR, XRD, UV-Vis spectrometer, AFM, DRS, XPS, TGA, and ICP-OES. The Ag nanoparticles found for the Cell/XTLL 60 mM AgNO3 have an average particle size of 33.78 nm. Moreover, Cell/XTLL Ag NC film, prepared with 60 mM AgNO3, suggests greater antioxidant activity. The most potent cell/XTLL 60 mM AgNO3 against Escherichia coli, Staphylococcus aureus, Trichoderma viride, and Fusarium oxysporum has strong antimicrobial activity and the best antimicrobial properties due to the fact that because the concentration of AgNO3 solution increased, the zone of inhibition additionally accelerated. The Cell/XTLL 60 mM becomes examined in vitro for its ability of human tumor cell growth inhibitory impact on human breast cancer cell line MCF-7 using MTT assay. The catalytic activity of Cell/XTLL 60 mM AgNO3 was assessed by the photocatalytic degradation of methylene blue and compared with bare cellulose. The Ag NPs are homogeneously unfolded out in Cell/XTLL 60 mM AgNO3 which leads to low electron-hole recombination and accelerated dye adsorption. In particular, 100 mg of Cell/XTLL 60 mM AgNO3, as catalyst, showed excellent photocatalytic activity with the efficiency of 91% degradation of methylene blue (MB).

In situ synthesis of silver nanoparticles on bamboo viscose fibers

In this study, a facile method for preparation of bamboo viscose fibers composite silver nanoparticles by in-situ synthesis was investigated. The bamboo viscose fiber was used as both reducing and protecting agents, and it was reacted with different concentrations of AgNO3 solutions under high temperature and high pressure. The structure and properties of the composites were analyzed by ultraviolet visible spectroscopy analysis, X-ray diffraction analysis, and scanning electron microscopy. The results show that the reaction products are spherical or near-spherical silver nanoparticles with the face-centered cubic geometry. The silver nanoparticles are dispersed uniformly on the surface of the bamboo viscose fibers with the size range of 10–60 nm. A mechanism was proposed where the silver nanoparticles are uniformly loaded onto the bamboo viscose fibers by bonding with the hydroxyl groups containing in the cellulose macromolecules. The antibacterial properties of the bamboo viscose fiber/silver nanoparticles against Escherichia coli and Staphylococcus aureus were tested by inhibition zone and dynamic shake flask methods. The results show that when the concentration of AgNO3 solution participating in the reaction was 0.001 M, the antibacterial rate of the composite material on the two kinds of bacteria could reach more than 99%. According to these results, the bamboo viscose fiber/silver nanoparticles nanocomposites with the excellent antibacterial properties offer a potential opportunity to be used as functional antimicrobial fabrics and medical devices.

Single-step laser ablation synthesis of ZnO–Ag nanocomposites for broad-spectrum dye photodegradation and bacterial photoinactivation

We present the single-step production of zinc oxide (ZnO)–silver (Ag) nanocomposites using a second harmonic nanosecond laser. The Ag concentration was controlled using various concentration of AgNO3 solution as the medium. The evaluation of the structural and optical characteristics indicated the formation of ZnO–Ag nanocomposites. The resulting nanocomposites exhibited photocatalytic activity in broad-spectrum light, both UV and visible light, for the degradation of rhodamine 6G. Furthermore, the nanocomposites were assessed as antibacterial agents, and the addition of Ag improved the antibacterial activity of pure ZnO against Escherichia coli and Staphylococcus aureus. Under light exposure, Ag greatly increased S. aureus degradation through a simultaneous antibacterial process. Eventually, the nanocomposites could be anticipated as photoactivation antibacterial agent and water purification nanocatalyst applications.

Biosynthesis of Silver Nano/Micro-Particles Using <i>Sambiloto</i> (<i>Andrographis paniculata</i>) Leaves Extract: Effect of AgNO<sub>3</sub> Solution Concentrations

Silver nano/micro particles have been successfully produced via biosynthesis using sambiloto (Andrographis paniculata) leaves extract as the reductor agent. The obejctive of current was to study the effect of four different AgNO3 solution concentrations (i.e. 0.0125, 0.025, 0.05, 0.075 M) on the production of silver nano/micro particles via biosynthtesis. The sambiloto extract concentration used in this study was 0.5% w/v. The silver nano/micro particles produced via biosynthesis was characterized using UV-Vis spectrophotometer and Scanning Electron Microscopy (SEM). The UV-Vis analysis results showed that absorbance peaks for all four samples were observed at wavelength around 450 nm, which can be attributed to the presence silver nano/microparticles. The absorbance peak values for all samples were 0.1115; 0.0876; 0.052; 0.0424 for AgNO3 solution concentration of 0.0125; 0.025; 0.05; 0.075 M, respectively. The UV-Vis analysis results could also qualitatively conclude that the size of silver nano/micro particles produced at lower AgNO3 solution concentration were smaller than the size of silver nano/micro particles produced at higher AgNO3 solution concentration. In the other hand, SEM image showed that the size of silver particles prepared using AgNO3 solution concentration of 0.075 M was in the range of 5 – 10 μm, hence it can be called silver micro-particles. It was assumed that the size of silver nano/micro particles produced at higher AgNO3 solution concentration were bigger than the size of silver nano/micro particles produced at lower AgNO3 solution concentration.

Raman enhancement properties of TiO2/Ag carbon fiber cloth using the ultraviolet-induced method: high sensitivity, flexible and reusable

We report a low-cost fabrication strategy to prepare a large-area carbon fiber cloth (CFC) coated by Ag nanoparticles (AgNPs) as a flexible surface-enhanced Raman scattering substrate. AgNPs were deposited on a hydrophilized CFC by ultraviolet (UV) irradiation of AgNO3 solution, named UV-AgNPs@CFC. The UV irradiation duration and AgNO3 solution concentration can affect the AgNPs structure. SERS property is investigated using rhodamine 6 G (R6G) and crystal violet (CV) as standard analytes and the detection concentration level is down to 10−10 mol/L. The analytical enhancement factor can reach 1.22 × 109. Also, the substrate has remarkable stability and uniformity; the relative standard deviation (RSD) of the characteristic peak calculated at 611cm−1 is 14.4%. Additionally, the UV-AgNPs@CFC substrate can detect two different molecules simultaneously. Our flexible SERS substrate enables efficient molecular extraction and Raman measurements on the curved surface of apples. The detection concentration level for CV is down to 10−5 mol/L. Moreover, the electric field distribution of the hybrid structure is simulated by the finite difference time domain and COMSOL Multiphysics software, and the maximal electric field intensity is 25.7 V/m. Meanwhile, we deposited AgNPs on the TiO2 nanorods-modified CFC (TiO2-CFC) by UV irradiation. A reusable self-cleaning UV-AgNPs@TiO2-CFC substrate was fabricated.

Photo-reduced Synthesis of Ag Fe/NC Nanoparticles and their Visible-Light-Enhanced Electrocatalytic Performances

Rational design of surface plasmon-enhanced electrocatalysts can effectively integrate solar energy into fuel cells. Herein, iron and nitrogen codoped carbon (Fe/NC) nanoparticles synthesized with microemulsion are used to absorb and photo-reduce Ag ions in solutions to form Ag nanoparticles on Fe/NC (Ag-Fe/NC). Different Ag-Fe/NC materials are prepared by adjusting the concentration of AgNO3 solution. Among them, Ag-Fe/NC obtained with 0.5 mg ml−1 AgNO3 solution shows the highest oxygen reduction reaction (ORR) catalytic performance and light-enhanced ORR characteristics, even better than commercial Pt/C. Besides, Ag-Fe/NC displays excellent long-term stability and high methanol resistance for ORR performances in alkaline medium. Therefore, this study will provide a new method for integrating light to recover Ag ions in solutions and improve electrocatalytic properties.

Effect of hydrothermal treatment of titanium in high concentration of AgNO 3 solution on surface morphology and roughness.

Development of silver (Ag) modified titanium (Ti) as an antibacterial dental implant has recently been growing. Ag demonstrated an excellent antibacterial property without the risk of bacterial resistance. Hydrothermal treatment using AgNO 3 solution is one of the facile and promising methods to modify Ti surface with Ag. However, the effect of high AgNO 3 concentration and the absent of a toxic reduction agent has not been clearly studied. In this study, Ti surface was hydrothermally treated in 0.01 mol/L and 0.1 mol/L AgNO 3 solutions at 150 oC for 24 hours. Analysis of surface morphology using scanning electron microscopy with energy dispersive X-ray analysis suggested the formation of non-homogenous Ag coating with a tendency to be aggregated and thicken with the increase of AgNO 3 concentration. The Ag coating deposited on Ti surface were composed of mainly metallic and some oxide forms. Surface roughness of all AgNO 3 treated Ti surface was comparable based on the analysis of surface roughness parameter. In conclusion, hydrothermal treatment of Ti surface in solely AgNO 3 solution at high concentration produced non-homogenous Ag coating on its surface without significantly changed surface roughness. Keywords: Silver nitrate, titanium, hydrothermal, surface morphology, roughness.

POTENSI EKSTRAK KULIT JERUK KUNCI (Citrus microcarpa Bunge) SEBAGAI BIOREDUKTOR DALAM SINTESIS NANOPARTIKEL PERAK

Nowadays silver nanoparticles (AgNPs) synthesized so often by plant extracts as a reductor. The synthesis of AgNPs was carried out by Citrus microcarpa Bunge fruit peel extract a reductor in various extract concentrations (10, 15, and 20%), concentration of AgNO3 solution of 0.15M and temperature of 700C. The presence of AgNPs was determined by color test and the formation of Surface Plasmon Resonance (SPR) using UV-Vis Spectrophotometer while to determine the morphology and size of the nanoparticles using Scanning Electron Microscope (SEM). The results of the analysis showed that AgNPs was formed at colloidal phase with dark brown color with wavelengths of 457.30 nm, 478.90 nm, and 422.80 nm for variation concentration of 10, 15 and 20% with slightly spherical, slightly elongated and jagged morphology with average size of 253.8 nm (10%), 254.2 nm (15%) and 253.9 nm (20%).

Silver‐coated conductive composite fabric with flexible, anti‐flaming for electromagnetic interference shielding

AbstractWith the development of modern electronic technology, there is an urgent need to prepare multifunctional polymer composite materials with flame retardant and electromagnetic shielding functions. Herein, use the chemical activity of polydopamine (PDA) to modify polyphenylene (PP) fabric to enhance its interface compatibility. Then, the dipping method was used to achieve the successful deposition of Ag nanoparticles on the surface of the PP non‐woven fabric, and by adjusting the concentration of the Ag precursor and the immersion time of the flame retardant constructed a conductive composite material with lightweight, flexible and has good flame retardant properties. The results showed that when the concentration of AgNO3 solution was 2% and the thickness was 0.166 mm, the average shielding effectiveness shielding effectiveness (SE) and SSE/t of the composite fabric reached 25.01 dB and 6097.56 dB cm2g−1, respectively. In particular, the composite fabric still maintained stable electrical conductivity after flame retardant treatment, and the average shielding effectiveness SE and SSE/t of the composite fabric reached 20.20 dB and 1518.80 dB cm2 g−1. The multifunctional conductive composite fabric prepared in this study has broad development prospects in the fields of electromagnetic shielding and smart wear.

Green Synthesis of Silver Nanoparticles Using Pomegranate and Orange Peel Extracts and Their Antifungal Activity against Alternaria solani, the Causal Agent of Early Blight Disease of Tomato.

This study aimed to synthesize silver nanoparticles (AgNPs) by pomegranate and orange peel extracts using a low concentration of AgNO3 solution to controlearly blight of tomato caused by Alternaria solani. The pathogen was isolated from infected tomato plants growing in different areas of Saudi Arabia. The isolates of this pathogen were morphologically and molecularly identified. Extracts from peels of pomegranate and orange fruits effectively developed a simple, quick, eco-friendly and economical method through a synthesis of AgNPs as antifungal agents against A. solani. Phenolic content in the pomegranate peel extract was greater than orange peel extract. Phenolic compounds showed a variation of both peel extracts as identified and quantified by High-Performance Liquid Chromatography. The phenolic composition displayed variability as the pomegranate peel extract exhibited an exorbitant amount of Quercitrin (23.62 mg/g DW), while orange peel extract recorded a high amount of Chlorogenic acid (5.92 mg/g DW). Biosynthesized AgNPs were characterized using UV- visible spectroscopy which recorded an average wavelength of 437 nm and 450 nm for pomegranate and orange peels, respectively. Fourier-transform infrared spectroscopy exhibited 32x73.24, 2223.71, 2047.29 and 1972.46 cm−1, and 3260.70, 1634.62, 1376.62 and 1243.76 cm−1 for pomegranate and orange peels, respectively. Transmission electron microscopy showed spherical shape of nanoparticles. Zetasizer analysis presented negative charge values; −16.9 and −19.5 mV with average particle sizes 8 and 14 nm fin case of pomegranate and orange peels, respectively. In vitro, antifungal assay was done to estimate the possibility of biosynthesized AgNPs and crude extracts of fruit peels to reduce the mycelial growth of A. solani. AgNPs displayed more fungal mycelial inhibition than crude extracts of two peels and AgNO3. We recommend the use of AgNPs synthesized from fruit peels for controlling fungal plant pathogens and may be applied broadly and safely in place by using the chemical fungicides, which display high toxicity for humans.

A facile chemical process to form an ultrathin hydroxyapatite layer with a customizable silver-releasing function on a titanium implant.

Silver-containing hydroxyapatite (Ag/HAp) layer on a bioinert material provides both bioactive and antibacterial properties; however, the Ag release duration needs to be customized to a patient's age and metabolism for minimizing the toxic effects. Herein, we present a facile chemical process to produce an ultrathin Ag/HAp layer on a Ti implant with a customized Ag-releasing profile. The process involves the following steps: preparation of a slurry-type reagent by mixing calcium phosphate powder with an aqueous AgNO3 solution, burying a Ti substrate in the slurry, and heating the slurry in air. An HAp layer, approximately 50 nm thick, with Ag particle deposits was obtained using this process. The Ag-particle content can be varied by adjusting the concentration of AgNO3 solution used for slurry preparation, resulting in different Ag-release profiles in a physiological solution. For instance, Ag release was retained for up to 30 days when 100 mM AgNO3 was used, whereas the release lasted 15 days when 10 mM AgNO3 was used. The duration of the antibacterial activity varied accordingly, but Ag-release-derived cytotoxicity was not observed irrespective of the AgNO3 concentration. In addition, differentiation of osteoblast-like cells was facilitated owing to the formation of the HAp layer. Thus, the chemical process presented in this study allows the production-at a clinical site-of an Ag/HAp layer customized to the patient's needs.

Silver nanoparticle embedded polymethacrylic acid/ polyvinylpyrrolidone nanofibers for catalytic application

A facile way to fabricate the highly uniform and mono-disperse silver nanoparticles (AgNPs) immobilized in polymer nanofibers has been successfully developed by combining electrospinning technique and photo-reduction method, applicable as efficient catalysts. Herein, poly-vinyl pyrrolidone (PVP) forbids the silver grain growth due to its steric effect and polymethacrylic acid (PMAA) contributes abundant carboxylic groups, which enhances the absorption of silver ions in nanofibers ensuring the growth of high density of AgNPs. UV exposure of nanofibers for 24 h leads to the maximum density of growth of AgNPs in PMAA/PVP nanofibers. The present investigation indicates that the size and spatial distribution of AgNPs can be tailored by changing the concentration of AgNO3 solution consequently, controlling the catalytic activity of AgNPs-immobilized nanofibrous mats. Interestingly, the prepared nanofibers exhibit good catalytic activity towards the reduction of methylene blue an environmental organic pollutant, due to the high density of AgNPs formation in nanofibers.

Production of silver nanoparticles via green method using banana raja peel extract as a reducing agent

In this study, biosynthesis of silver nanoparticles using the extract of a local banana peel (variant name: Raja) as bio-reductor was carried out. This study aimed to determine the effect of two different ratios of Banana Peel Extract (BPE)/distilled water on the synthesis of silver nanoparticles. The two of BPE/water ratios were 1% (v/v) and 5%(v/v), named as Sample A and Sample B, respectively. Whereas, the concentrations of AgNO3 solution as the precursor were varied as follows: 0.125; 0.1; 0.075; and 0.05 M. The synthesized colloidal silver nanoparticles were characterized using a UV-Vis spectrometer, while the BPE solution was analyzed using Fourier Transform Infra-Red (FT-IR) to study its functional groups. While, the solid silver nanoparticles was characterized using a Scanning Electron Microscopy (SEM) with an Energy-dispersive X-ray spectroscopy (EDX) analysis. The UV-Vis spectrometer results qualitatively showed that sample A produced better silver nanoparticles than that of sample B. All samples showed absorbance peaks at wavelength of 450 nm. It was found that the highest absorbance value (i.e. 1.59) occurred at sample A with a concentration of AgNO3 solution 0.1 M. Additionally, FT-IR analysis result showed the presence of a hydroxyl group specifically for alcohols as phenols, which indicated the possibility of polyphenol compounds. The SEM micrograph showed that some of the silver nanoparticles were in the shape of tetrahedron or triangular like particle and spherical The SEM image analysis results using ImageJ software showed that most of the silver nanoparticles produced had the size of 100-300 nm. Furthermore, the EDX analysis result showed a peak count at 3 keV, which confirmed the formation of silver nanoparticles.

Construction of silver nanoparticles anchored in carbonized bacterial cellulose with enhanced antibacterial properties

Carbon materials have been widely used in the field of water treatment. However, a drawback of this kind of materials is that bacteria breeding on their surface may deteriorate water quality. Herein, antibacterial carbonized bacterial cellulose (CBC) composites with well-dispersed silver nanoparticle were synthesized, using bacterial cellulose (BC) as inexpensive and abundant source of carbon. The formed composites (Ag@CBC) were characterized by various physicochemical characterization. The results showed that the Ag nanoparticle amount, surface and porous structure of the Ag@CBC were dependent on initial concentration of AgNO3 solution. As an antibacterial material, Ag@CBC samples exhibited excellent antibacterial activity. The minimal inhibitory concentrations of Ag@CBC with 1.9 % Ag such as 12 μg/mL (against S. aureus) and 8 μg/mL (against E. coli), which have very promising application in water purification.

Using MgO nanoparticles as a potential platform to precisely load and steadily release Ag ions for enhanced osteogenesis and bacterial killing

Bio-functional fillers including bio-ceramic, degradable metallic and composite particles are commonly introduced into bone tissue engineering (BTE) scaffolds to endow the materials with specific biological functions for enhanced bone defect therapy. In this work, MgO nanoparticles (NPs) were employed as a potential platform for precise loading and sustained release of Ag+. The results showed that MgO NPs possessed strong adsorption capacity (almost 100%) towards Ag+ in AgNO3 solutions with different concentrations (0.1, 1 and 10 mM). After the adsorption of Ag+ in AgNO3 solutions, cube-shaped MgO NPs transformed to lamella-structured nano-composites (NCs) composed of Mg(OH)2 and Ag2O, which were referred as MgO-xAg (x = 0.1, 1 or 10) NCs depending on the employed concentration of AgNO3 solution. After being suspended in distilled water, as-prepared positively charged NCs underwent a fast degradation process during the initial 4 days. From day 4 and 14, steady release behaviors of Mg2+ and/or Ag+ from the NCs were noticed. With the lowest loading amount of Ag+, MgO-0.1Ag NCs did not exhibit significant modulatory effect on SaOS-2 cell response. On the contrary, MgO-10Ag NCs loaded with the highest amount of Ag+ showed significant cyto-toxicity towards SaOS-2 cells. With appropriate amount of Ag+ loading, MgO-1Ag NCs showed significantly stimulatory effects on SaOS-2 cell proliferation and differentiation. This is evidenced by the enhanced cell viability, alkaline phosphatase (ALP) activity and collagen (COL) production as well as the gene expressions of ALP, COL and osteoprotegerin (OPG) in MgO-1Ag group. Moreover, MgO-1Ag exhibited strong bactericidal capacity against both Escherichia coli and Staphylococcus aureus. Together, the results indicate that MgO could be employed as a potential platform for precise loading and sustained release of Ag+. MgO-1Ag NCs are promising to be used as bio-functional fillers in BTE scaffolds for simultaneously promoted osteogenesis and bacterial killing.

Preparation of Silver Nanoparticles-Loaded Gel Fibers Based on Microfluidic Method and its Application as SERS Substrates

Surface-enhanced Raman scattering (SERS) spectroscopy technology has broad application prospects in food safety, environmental monitoring, surface science and material analysis because of the characteristics of ultra-high sensitivity and non-destructive testing. However, there are still some challenges in the preparation of SERS substrates. As SERS substrates, the common colloidal noble metal nanoparticles usually show low storage stability and poor repeatability of analytical results. In order to overcome these limitations, a coaxial microfluidic spinning device was designed to prepare flexible SERS substrates in this paper. Based on the microfluidic spinning and subsequent in-situ reduction reaction of AgNO3, novel gel fibers uniformly loaded with AgNPs were successfully prepared. The effects of the concentration of AgNO3 solution and UV irradiation duration on the formation of AgNPs were investigated. Transmission electron microscopy (TEM) showed that the average particle size was about 2.7 nm. The gel fibers loaded with AgNPs were used as SERS substrates to detect 4-mercaptobenzoic acid (4-MBA), which showed obvious Raman enhancement effect and good repeatability. The relative standard deviation of 10 test results was 4.75%, and the detection line range was 10-14-10-5 mol·L-1.