Tangential Flow Ultrafiltration: A “Green” Method for the Size Selection and Concentration of Colloidal Silver Nanoparticles

The overall goal of this procedure is to demonstrate the feasibility of the tangential flow ultra filtration method for larger volumes of colloidal nanoparticles and smaller volumes of Tate. First synthesize four liters of cretin colloidal silver nanoparticles. Verify the quality of the colloid by determining the surface plasma resonance using UV vis absorption, spectro pho telemetry.

Next, use tangential flow, ultra filtration to size, select and concentrate this colloid into four milliliters of water. Then with inductively coupled plasma optical emission spectroscopy quantify the amount of silver in the original colloid and the representative samples of the ultra filtration process. Ultimately transmission electron microscopy in conjunction with image processing.

In Image J software is used to show the size distribution of the silver nanoparticles in the original colloid and the final ultra filtration. Tate Individuals new to Nanomaterial quantification using I-C-P-O-E-S will need to learn the glassware cleaning procedures critical to ensure that the glassware is free from any trace metal contamination. Also important is the time that is required to properly digest the colloidal samples and to prepare the I-C-P-O-E-S calibration standards.

Unlike other methods such as fication size, dependent solubility, size, exclusion chromatography, fractional crystallization, and gel electrophoresis, this method avoids issues such as aggregation, toxicity of synthesis, reagents, undesired coatings, high cost and or reduced inefficiency, Demonstrating the synthesis of the Colorado Suen nanoparticles and their characterization by vis sub social spectral Optometry and I-C-P-O-E-S will be Austin Williams, Joshua Baker, and Catherine Anders, research students from my laboratory. Hi, I am Dr.Woolley and I'll be performing the tangential flow filtration and Jackie Cisco will be performing the electron microscopy Meticulously clean. All glassware is described in the accompanying text.

Using autoclave water cooled at 10 degrees Celsius, prepare 300 milliliters of a two millimolar sodium bur hydride solution and 100 milliliters of a one millimolar silver nitrate solution. Now add 300 milliliters of the sodium hydrate solution to a 500 milliliter Erlin Meyer reaction flask containing a stir bar. Wrap the flask with aluminum foil to prevent silver oxidation and stir on ice.

To prime a 25 milliliter burette rinse with a full column of ultrapure water, followed by a full column rinse using silver nitrate. Then wrap the burette with aluminum foil and fill it with silver nitrate solution. In a dark room, add 50 milliliters of silver nitrate solution to the sodium or hydride solution.

Cover the middle section of the apparatus with a foil tent to minimize light exposure. Replenish the ice bath periodically over this time. Continue to stir the colloidal solution over ice for an additional 45 to 50 minutes.

The formation of silver nanoparticles is signaled by a changing color from colorless to a golden yellow, which is characteristic of the surface plasma in resonance maximum of silver nanoparticles Refrigerate the resulting colloid. Fill a one milliliter disposable Q vet with Creighton colloid and ultrapure water in a one to 10 volume ratio. For a blank baseline correction, fill another Q Vet with ultrapure water.

Wipe the outside of both Q vets with a Kim wipe. Set the spectrophotometer to absorbance mode from a Y minimum of negative 0.5 to a Y maximum of 1.0. Also, set the X scanning window at 200 to 800 nanometers and select a fast scan rate with baseline correction.

Insert the Q vet filled with water into the instrument and run a baseline scan. Repeat if necessary until a non-zero baseline control is achieved. Replace the blank Q.Vet with the sample Q vet and initiate an absorbent scan for the collection of the UV vis absorption spectrum of the colloidal sample.

Connect 17 master flex feeding tubing to the peristaltic pump as described in the accompanying text, select counterclockwise pump direction using the DIR button and verify the mode button is on INT. Set the pump rate to less than 300 milliliters per minute. Next, prime the system by creating a vacuum in the filtration loop.

Once the liquid is flowing freely through the system, turn off the pump and close the port in the tubing junction and remove the clamp. Turn on the pump again and monitor the tubing circuit for leaks. Now increase the pump flow rate according to the tubing size.

Continue filtration until the liquid in the reservoir bottle is almost depleted and turn off the pump, lower the pump rate and collect the tate from the filtration loop. The tate consists of nanoparticles larger than 50 nanometers. Next, collect the filtrate, which consists of nanoparticles smaller than 50 nanometers.

The Tate may be safe for further analysis and the filtrate is used in the next step. Next to select nanoparticles of less than 20 nanometers in diameter. Rinse the tubing with 2%nitric acid in ultrapure water.

Repeat the filtration process with a 100 kilodalton CROs filter. Collect the reten from the filtration loop. The sample can be further concentrated by using the smaller a hundred KD micross filter and the smaller size 14 tubing with the lower pump rates of 30 mil and 90 mil for the priming and filtration steps.

This method is designed to quantify the silver through the purification steps of the silver nanoparticle preparation. Use low density polypropylene containers to prevent silver leaching from the samples. First chemically digest the samples with concentrated nitric acid.

Also prepare a silver calibration curve using eight standards. Now proceed to the I-C-P-O-E-S instrument set parameters of the wavelength for silver, the radio frequency power, the plasma flow, the auxiliary flow, and the nebulizer pressure. Also set the instrument to measure samples in triplicate with a replicate time of 10 seconds.

Use it between measurement stabilization time of 15 seconds and a sample uptake delay of 30 seconds. Also, be sure to introduce a method blank in between each sample to reduce potential cross-contamination. Now, load the samples and measure dilute the 100 kilodalton tate sample with ultrapure water.

Now deposit 20 microliters of the original colloid and the diluted 100 kilodalton tate on 300 mesh form bar coated gold grids. Place the grids to air dry. Set the accelerating potential of the TEM instrument Add to 70 kilovolts to visualize the silver nanoparticles capture electron micrographs using the high resolution camera and save as tagged image files format.

In this preparation of four liters of cret and colloidal silver nanoparticles, the final colloid had a characteristic golden yellow color. The UV vis absorption spectrum of this colloid had a typical sharp symmetrical surface plasmin peak at 394 nanometers. The Raman spectrum of the original cretin colloid and the final 100 kilodalton Tate presented only three vibrational modes.

The bending mode at 1, 640 and the symmetric and asymmetric stretching modes of water. The three step tangential flow, ultra filtration process for size, selection, and concentration of the silver nanoparticles yielded a final 100 kilodalton reten, eight of four milliliters. Most of the synthesis byproducts and excess reagents were eliminated through the water solvent.

The amount of silver was then determined using the I-C-P-O-E-S calibration curve. Here, the actual yield is very close to the typical theoretical yield of 15.4 parts per million. For the cretin reaction, the extreme concentration of silver nanoparticles was reflected by a dramatic change in color from gold and yellow for the original colloid to dark brown for the final 100 kilodalton ate the I-C-P-O-E-S measurements, confirmed the visual observations, and revealed a silver concentration for the final 100 kilodalton tate.

These TEM micrographs of the original cretin colloid and the final 100 kilodalton tate indicate that in their un aggregated state silver nanoparticles appear as black round areas on a lighter gray background. These TEM size histograms were constructed by analyzing approximately 800 silver nanoparticles for original creon silver nanoparticles and the final 100 kilodalton ate. After watching this video, you should have a good understanding of how to perform tangential flow filtration for the concentration and size selection of silver nanoparticles.

Various volumes can be concentrated with minimal aggregation. You should also have a good understanding of how to characterize the nanoparticles. Once mastered, this technique can be performed in six hours or less.

While attempting this procedure, it is important to remember that highly concentrated colloidal suspensions will have a limited lifetime even upon refrigeration. This limitation may be managed through careful research, planning and preparation. Remember, when working with hot nitric acid reagent during the chemical digestion for I-C-P-U-S, analysis can be hazardous and proper precautions should be taken as in working at chemical femme hood or wearing your proper protective equipment while doing this procedure.