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Biosynthesis of Silver Nanoparticles Using <i>Selaginella bryopteris</i> Plant Extracts and Studies of Their Antimicrobial and Photocatalytic Activities
摘要： The present study focuses on the green synthesis of silver nanoparticles (AgNPs) using aqueous extract of S. bryopteris which is a lithophyte with remarkable resurrection capabilities. These biosynthesized NPs were characterized with the help of UV-vis spectrophotometer, X-ray diffraction (XRD), FT-IR and Transmission electron microscopy (TEM). Formation of AgNPs was confirmed by UV-Visible spectrophotometer analysis which showed surface plasmon resonance (SPR) at around 420 nm. The TEM images showed the nanoparticles to be polydispersed, nearly spherical in shape and have sizes in range 4–30 nm. The synthesized AgNPs possessed high antibacterial activity as well as photocatalytic dye degradation properties under solar light irradiation in the absence of chemical reducing reagents. Stability of bio-reduced silver nanoparticles was analyzed using UV-vis absorption spectra, and their antimicrobial activity was screened against various gram-positive bacteria.
关键词： Characterization,Photodegradation,Antimicrobial Activity,Biosynthesis,S. bryopteris Extract,Silver Nanoparticles
更新于2025-09-04 15:30:14
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Synthesis of silver nanoparticles from bottom up approach on borophosphate glass and their applications as SERS, antibacterial and glass-based catalyst
摘要： In this paper, we report a facile, low cost synthesis and characterization of silver nanoparticles (AgNPs) on borophosphate glass by a two-step process involving a melting quenching technique and a post-annealing method. The structural, optical properties and several applications of silver-doped borophosphate glasses as a function of Al2O3 concentration are reported here. Micro Raman and infrared spectroscopies revealed that the addition of aluminium ions leads to depolymerization and the formation of phosphate-aluminium structures. Moreover, the addition of Al2O3 increases the glass transition temperature, improve the chemical stability, and the AgNPs remain ?rmly grafted (i.e., not released) when the glass surface is exposed to water. The presence of silver ions and metallic silver on glass surface was con?rmed by the X-ray photoelectron spectroscopy (XPS) and X-ray powder di?raction (XRD), respectively. The fabricated AgNPs have many advantages, such as low growth temperature and good uniform nanoparticle clusters over large areas, size-controlled, and easy to fabricate. Finally, the silver-doped glasses have proved to be an ideal substrate for highly e?cient SERS applications, antibacterial materials and great potential in catalysts.
关键词： Antimicrobial glass,Glass catalyst,Borophosphate glasses,SERS substrates,Silver nanoparticles
更新于2025-09-04 15:30:14
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Structural basis for a naphthyl end-capped oligothiophene with embedded metallic nanoparticles for organic field-effect transistors
摘要： We report on the apparent structure of 5,500-bis(naphth-2-yl)-2,20:50,200-terthiophene (NaT3) in organic field-effect transistors (OFETs) with and without embedded silver nanoparticles. Using regular- and microbeam grazing incidence wide- and small-angle X-ray scattering, the device structure is characterized locally in the area with the embedded particles. The NaT3 thin film order is reduced and the found unit cell (a ? 25.7 A? , b ? 5.87 A? , c ? 8.03 A? , and b ? 98.9(cid:2)) differs significantly from the one reported in the bulk, but shows no significant change, when the particles corresponding to the crystal size are incorporated into the device structure. At the same time, the apparent thin film crystal sizes in OFETs are found to be similar with and without the embedded particles. In both cases, the carrier mobilities are of the order of 10(cid:3)4 cm2/(V s).
关键词： X-ray scattering,oligothiophene,organic field-effect transistors,silver nanoparticles,crystal structure
更新于2025-09-04 15:30:14
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OPTIMIZATION OF GREEN SYNTHESIZED SILVER NANOPARTICLES FROM CARALLUMA UMBELLATA
摘要： Objective: The current study focuses on optimization and ecologically innocuous green synthesis of silver nanoparticles (AgNPs) using tribal plant Caralluma umbellata and to study its potential as an antibacterial and antifungal agent. Methods: The synthesis of AgNPs were confirmed by the colour change of the stem extract from yellow to dark brown and by UV-Visible spectroscopy. The optimum conditions for synthesis of AgNPs were analysed using Response surface methodology (RSM) based Box-Behnken design (BBD) using Design Expert software (7.0.0 trial version). The AgNPs synthesized were characterized by Scanning electron microscope (SEM), Energy dispersive X-ray (EDX), Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analysis. Further, antibacterial and antifungal activity were performed using well diffusion method for both plant extract and AgNPs. Results: The UV-Visible spectrum of AgNPs revealed characteristic peak at 425.5 nm. The crystalline nature of synthesized AgNPs was confirmed by XRD with average size 26 nm. SEM confirms the spherical shape of AgNPs and by EDX the presence of elemental silver was observed. The ability of the plant to produce both reducing and capping agents were confirmed by FTIR. The optimum conditions for synthesis of AgNPs were found to be 0.55 mmol AgNO3 concentration, 45 °C temperature and 24h reaction time. Both plant sample and synthesized AgNPs exhibited good antimicrobial activity where AgNPs showed superior efficacy as an antimicrobial agent over the other. Conclusion: From the results obtained, it can be deduced that both C. umbellata stem extract and synthesized AgNPs can act as potent antimicrobial agent. But the synthesized AgNPs is more potent against bacteria and fungus.
关键词： Nanomedicine,BBD,Antimicrobial agent,Tribal plant,Silver nanoparticles
更新于2025-09-04 15:30:14