Papers by Keyword: Silver Nanoparticle

Abstract: This study aimed to investigate the effect of pH value raging from pH 4 - 8 on color development of silver colloids. Silver colloids with different colors were synthesized by chemical reduction method using NaBH₄ as a reducing agent and then adjusted pH value by adding dropwise of acetic acid. These silver colloids were characterized by Transmission Electron Microscopy and UV-Vis spectrophotometer. The results showed that the colors of silver colloids ranging from blue to yellow depended on amount of NaBH₄ added. Due to Localized Surface Plasmon Resonance (LSPR) properties, different shapes and sizes of silver nanoparticles resulting in different colors. It was found that the pH value also affected color development of silver colloids. By adjusting the pH value, the colors of silver colloids changed to different colors or shades, which were clarified by the changes in the center as well as intensity of the absorption spectra. Moreover, the silver colloid in an acidic condition led to aggregation of nanoparticles.

Abstract: Silver nanoparticle (AgNP) synthesized using aqueous extract of Fingerroot (Boesenbergia rotunda) as reducing and stabilizing agent was incorporated in heat cured acrylic resin PMMA with different concentrations (i.e. 0, 0.025, 0.05, 0.075 and 0.1 wt.%). Flexural strength of AgNP/PMMA denture base was investigated with three-point bending method using Universal tensile tester. Viscoelastic behavior of filled PMMA was studied using the dynamic mechanical analyzer (DMA) over a wide range of frequencies. The flexural strength of AgNP filled acrylic denture base materials were not statistically significantly different with the increase in concentrations of AgNP. The dynamic mechanical analysis showed the frequency dependence of storage modulus (G'), loss modulus (G"), and damping factor (tanδ).

Abstract: Silver nanoparticles (AgNPs) were synthesized by bioreduction method using aqueous extracts of Boesenbergia rotunda as reducing and stabilizing agents. Ultraviolet-Visible (UV-Vis) spectrophotometer was utilized to monitor the qualitative formation of AgNPs. The UV-Vis spectrum showed that the spherical AgNPs with diameter of 20-40 nm were formed. The antifugal activity of synthesized AgNPs was investigated using Candida albicans, which was found that the synthesized AgNPs could be used as effective growth inhibitors. The influence of the incorporation of prepared AgNPs on thermal properties of the acrylic denture base material was investigated. Glass transition temperature of filled acrylic resins was studied using the dynamic mechanical analyzer (DMA). The temperature sweeps were performed with tension mode. Thermogravimetry analysis (TGA) was used to examine effect of AgNP concentration and thermocycling (1250, 2500, 5000, and 10000 cycles) on thermal stability of AgNP filled acrylic resin denture base materials. Glass transition temperature (T_g) of the acrylic resins slightly increase with increasing AgNP contents. TGA results indicated that AgNP retarded thermal degradation of acrylic resin denture material, and thermocycling did not affect thermal stability of AgNP filled acrylic resin denture material.

Abstract: Synthesis of silver nanoparticles (AgNPs) by reduction of AgNO₃ with o-hydroxybenzoic, p-hydroxybenzoic and o,p-dihydroxybenzoic acids as reducing agents was investigated. This research was conducted to determine the effect of the position and number of hydroxyl groups towards the size, shape and stability of the resulted AgNPs. Surface Plasmon Resonance (SPR) of AgNPs was characterized by UV/Vis spectrophotometer, the shape and size of AgNPs was determined by Transmission Electron Microscope (TEM). The results showed that the reducing agent that has substituents in the para position (p-hydroxybenzoic acid) has the higher reduction ability than the others. AgNPs were yielded by all types of reducing agents in alkaline system. Reducing agents which have greater number of substituents (o,p-dihydroxybenzoic acid) could produce AgNPs with smaller concentration of AgNO₃ than the others. AgNPs that was produced by reducing agent having substituents on the para position (p-hydroxybenzoic acid) was more stable and smaller particle size, i.e. 34 ± 1.78 nm than reducing agent that has substituent on the ortho para positions (with particle size 45 + 3.67 nm) and ortho positions (with particle size 70 ± 4.96 nm).

Abstract: Nowadays, green and efficient synthetic strategies have been gaining great interest for the synthesis of nanoparticles. In this study, the biosynthesis of silver nanoparticles and its photocatalytic activity for photodegradation of organic dye and antimicrobial property was studied. The initial syntheses of Ag nanoparticles were characterized by UV–Vis spectrophotometer and showed the surface plasmon resonance band at 430-450 nm. Attenuated Total Reflection Fourier Transform Infrared Spectroscopy (ATR-FTIR) study showed evidence that proteins are possible reducing agents. The structure of AgNPs was determined by Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). SEM and TEM studies revealed the synthesized AgNPs to be spherical. The AgNPs exhibited photocatalytic activity for photodegradation of organic dye such as Methylene Blue. Approximately 18% degradations of methylene blue within 4 h was observed with biosynthesized Ag nanoparticles in the photocatalytic degradation process.

Abstract: Silver nanoparticle (AgNP) is extensively used in the consumer products and in the medical applications due to its antibacterial property. In this study, AgNPs were synthesized by a simple green chemistry procedure using three difference pH values of pomegranate peel extract as reducing and stabilizing agent and silver nitrate (AgNO₃) as a precursor. The formation of AgNPs was elucidated using various instrumentation techniques including UV-Vis, FTIR, XRD, EDX and TEM. UV-Vis spectra showed the surface plasmon resonance (SPR) peak in the range of 400-500 nm. Crytalline nature and fcc phase of AgNPs were revealed by XRD pattern. FTIR analysis provided the presence of phytochemicals responsible for the reduction and stabilization of AgNPs. TEM analysis demonstrated that size and morphology of the prepared AgNPs were in the nanoscale range of 5-45 nm with irregular spherical in shape. The existence of the elemental silver was observed from EDX analysis. Furthermore, AgNPs showed an effective antibacterial activity to Staphylococcus aureus and Escherichia coli.

Abstract: To increase the durability of bamboo it is important to find an easy method to fill the micro and meso structure of the biological matrix using a nanostructural material with an anti-fungical activity. A colloidal solution of silver nanoparticle (Ag-NPs) is a dispersion of metal nanoparticle in water with a diameter between 5-100 nm. Even if the biological mechanism is not completly understood yet, Ag-NPs show a satisfactory bactericidal and antifungical activity. We present a simple and rapid production of Ag-NPs made by a sol-gel synthesis in flow mode by means of microreactor tecnology through a chemical reduction of AgNO₃ with NaBH₄ in presence of two different organic ligands: sodium/potassium tartrate and trisodium citrate. The synthesis of Ag-NPs in continuous flow compared to the batch technique allowed to reduce the time of synthesis, facilitating the reproducibility of the process and consequently obtaining NPs with more uniform physical and chemical characteristics. The microorganisms of the genus Aspergillus were used for the microbiological tests. The effect of different Ag-NPs on microbial growth was observed daily. In particular, it was shown that the response of the fungus is inversely proportional to the size of the nanoparticles, cell growth is disrupt depending on the proportion between silver and organic ligand and microbialstatic effect, especially in relation to sporulation stage was also observed.

Abstract: This paper reported on the properties of sago starch (SS) films impregnated with different concentration of sliver nanoparticles (SNP) of 100, 2000, 5000 rpm with weight ratio of 1% and 10% to be used as wound healing material. The SS films were prepared through film moulding technique by mixing aqueous SNP with SS, glycerol and water at weight percentage of 6.5:3.5:90. The performance of SS-SNP films produced is studied. The morphology study shows the existence of SNP embedded in the SS particles. SNP with 2000ppm has the biggest particle width but small in particle sizes, which make the SS-SNP film of 2000ppm is superior in thickness, denser and has lower moisture content compared to other SS-SNP film with different composition. The highest water absorption occurred in the SS-SNP of 100ppm, due to the high existence of pores in the network of amylose content in starch. SNP act as particulate reinforcement in the SS film meaning higher number of ppm made the film more brittle and easy to rupture. Thus, the SS-SNP film of 5000ppm has the lowest tensile strength and modulus for tensile strength and modulus. It can be concluded that the SS-SNP film of 2000ppm is suitable to be used as wound healing material, as the addition of 2000ppm SNP inside the SS films help in improving the properties of SS-SNP film produced.

Abstract: In this research, green synthesis of silver nanoparticles using elaeis guineensis leaves extract was investigated and the influence of pH and reaction time in the reaction kinetic were studied. UV-visible spectrophotometer was used to monitor the reduction reaction of silver ions to silver nanoparticles and formation of silver nanoparticles shown at sharp peak at pH 10 with λ_max of 391 nm. Transmission electron microscopy (TEM) shows silver nanoparticles are polydispersed and irregular shape with size ranging from 55-85 nm. Formation of silver nanoparticles was confirmed by energy dispersive x-ray analysis (EDAX) and crystalline structure using XRD. From this research, it was found that pH 10 influenced the reaction kinetic therefore reduce the reaction time.

Abstract: The synthesis of nanoparticles is in the spotlight in modern nanotechnology. In recent years, the development of competent green chemistry methods for synthesis of metal nanoparticles (NPs) has become a main limelight of researchers. Biological synthesis of nanoparticles using plant extract is currently under exploitation. The first time in this paper we have reported the green synthesis of silver nanoparticles (AgNPs) by reduction of silver nitrate, using fruit extracts of Momordica charantia (bitter melon); commonly found plant in south East Asia. The reaction process for the synthesis of silver nanoparticles is simple, cost-effective, novel, rapid and eco-friendly route using fruit extract of M. charantia plant, which acted as a reducing and stabilizing agent simultaneously at room temperature. Formation of the nanosilver was confirmed by surface Plasmon spectra using UV-Vis spectrophotometer and absorbance peak at 440 nm. Different silver ion concentration and contact times were experimenting in the synthesis of silver nanoparticles. The prepared nanoparticles properties were characterized by UV-Vis.