PDF Publication Title:
Text from PDF Page: 003
B. Adebayo-Tayo et al. Heliyon 5 (2019) e02502 The inoculum was added to 200 μL of already prepared Tryptic Soy Broth (TSB) in a 96 well microtiter plate and incubation was done at 37 ̊C for 48 h. The non-adherent bacterial cells were removed by discarding the mixture carefully and rinsing the microtiter plate with sterile water three times. The adherent cells were fixed with 95% ethanol for 5 min before rinsing with sterile water. Aliquot of 200 μL crystal violet was added to the fixed cells for 15 min, rinsed with sterile water and air-dried. For biofilm inhibition, 150 μL of TSB was added to microtiter wells and 50 μL of OsSNPs were added. Same procedure was used for biofilm inhibition process. Quantification of the biofilm formation and inhibition were done at the absorbance of 560 nm (OD560) using ELISA reader (BIOTEX model: ELx800, Biotex Instruments, USA). Percentage of biofilm inhibi- tion was calculated as: % biofilm inhibition 1⁄4 ODcontrol – ODtreatment / ODcontrol 100 (1) 2.6. In vitro cytotoxicity assay of OsSNPs against brine shrimp Brine shrimp lethality test for larvae nauplii was used to determine the toxicity of OsSNPs [32]. The Brine shrimp eggs hatching were done in a dish using the sea water. The active free floating phototropic nauplii were collected from bright illumination with pipette after 48 h and were used for the assay. The nauplii were dispensed into a sterile well plate contain 2 mL of sea water and suspension of yeast under illuminated condition. Different concentrations (100, 500, 1000, 2000, 3000 and 4000 μg/mL) of silver nanoparticles was added into the each wells that contains 10 nauplii and incubated at room temperature in the dark for 24 h. Sea water without silver nanoparticles was used as control. Macro- scopic count of the survivors’ nauplii every 3 h for 24 h was done and percentage of mortality, LD50 for the tested concentration of OsSNPs were determined using probit analysis [33]. 3. Results and discussion The methanol extract of Oscillatoria sp. was able to bio-reduced the AgNO3 to biosynthesized OsSNPs. The greenly biosynthesized nano- particles was characterized. 3.1. Visual Observation of the nanoparticles biosynthesis Formation of silver nanoparticles through reduction of silver nitrate into silver ion by the reducing agent is known to be associated with colour change (Fig. 1). The reaction mixture of AgNO3 and the methanol extract of Oscillatoria sp. turned brown indicating formation of silver nanoparticles. The intensity of the colour increases after 24 h of incubation. Fig. 1. Visual Observation of SNPs formation: (a) Oscillatoria sp. extract; (b) Silver nitrate solution and (c) SNPs. Silver nanoparticles formation was identified visually by colour change. The immediate colour change as observed in formation of silver nanoparticles biosynthesized using Oscillatoria sp. extract was due to the excitation of Surface Plasmon Resonance (SPR) of nanoparticles in the reaction mixture. This was also reported by Rajeshkumar et al. [23] who observed colour change in the reaction mixture during silver nano- particles formation biosynthesized from Padina tetrastromatica. 3.2. UV-vis spectrophotometry analysis The biosynthesized OsSNPs were characterized at different incuba- tion hours using UV-Vis Spectrophotometer. At different hours of incu- bation Surface Plasma Resonance (SPR) peak was observed at 500 nm and broad spectrum range was at 400–600 nm (Fig. 2). The results ob- tained from the UV-Vis spectra suggested the formation of silver nanoparticles. 3.3. Fourier transform infrared (FTIR) The FTIR spectra of the biosynthesized OsSNPs showed 16 major bands each of which suggested the presence of different functional groups of compounds present (Fig. 2). The UV-vis spectroscopy is a technique used to confirm the formation and stability of nanoparticles based on the optical properties of the nanoparticles and it also serves as an indirect method used to determine the reduction of silver nitrate to silver nanoparticles in the aqueous so- lution. The optical property of silver nanoparticles is dependent on size and shape [34]. The result obtained as shown by the UV-vis spectra of the biosynthesized silver nanoparticles was formed after 24 h of incubation, a drop in the surface Plasmon peak was observed at 48 h and maximum increase in the resonance was observed after 72 h of incubation. This shows that complete nanoparticles formation occurred after 72 h of in- cubation and it implies that nanoparticles formation is associated with incubation time. This is not in agreement with the work of Singh et al. [21] who reported consistent increase in the peak after 24, 48, 72, till 168 h of incubation while working on silver nanoparticles biosynthesized from Acinetobacter calcoaceticus. Mie's theory states that only a single surface plasmon resonance band is expected in the absorption spectra of spherical metal nanoparticles whereas anisotropic particles can give rise to two or more surface plasmon resonance bands, depending on the shape of the particles [35, 36]. From the UV-vis spectra of silver nanoparticles synthesized from Oscillatoria sp. methanol extract, a single SPR peak was observed which suggests that the biosynthesized silver nanoparticles are spherical in shape and this was confirmed by the scanning electron micrograph. Broadening of the surface plasmon resonance can be attributed to the electron surface scattering which can be enhanced for small aggregates [37]. Silver nanoparticles formed in such enhanced process are usually stable and their absorption spectra can be unaltered even after six months at room temperature [21]. The FTIR spectrum of the nanoparticles is shown in Fig. 3. The peak at Fig. 2. UV-Vis spectra of silver nanoparticle biosynthesized at different hours of incubation. 3PDF Image | Green synthesis of silver nanoparticle Oscillatoria extract
PDF Search Title:
Green synthesis of silver nanoparticle Oscillatoria extractOriginal File Name Searched:
PIIS2405844019361626.pdfDIY PDF Search: Google It | Yahoo | Bing
Turbine and System Plans CAD CAM: Special for this month, any plans are $10,000 for complete Cad/Cam blueprints. License is for one build. Try before you buy a production license. More Info
Waste Heat Power Technology: Organic Rankine Cycle uses waste heat to make electricity, shaft horsepower and cooling. More Info
All Turbine and System Products: Infinity Turbine ORD systems, turbine generator sets, build plans and more to use your waste heat from 30C to 100C. More Info
CO2 Phase Change Demonstrator: CO2 goes supercritical at 30 C. This is a experimental platform which you can use to demonstrate phase change with low heat. Includes integration area for small CO2 turbine, static generator, and more. This can also be used for a GTL Gas to Liquids experimental platform. More Info
Introducing the Infinity Turbine Products Infinity Turbine develops and builds systems for making power from waste heat. It also is working on innovative strategies for storing, making, and deploying energy. More Info
Need Strategy? Use our Consulting and analyst services Infinity Turbine LLC is pleased to announce its consulting and analyst services. We have worked in the renewable energy industry as a researcher, developing sales and markets, along with may inventions and innovations. More Info
Made in USA with Global Energy Millennial Web Engine These pages were made with the Global Energy Web PDF Engine using Filemaker (Claris) software.
Infinity Turbine Developing Spinning Disc Reactor SDR or Spinning Disc Reactors reduce processing time for liquid production of Silver Nanoparticles.
| CONTACT TEL: 608-238-6001 Email: greg@infinityturbine.com | RSS | AMP |