Team:Concordia/Demonstrate/Synthesis Results
NANOPARTICLE SYNTHESIS RESULTS:
Plant Synthesis: Aloe Vera
Triangular Gold Nanoparticles(10-100 nm) Synthesized using Aloe Vera Extract.
Optimal variables:
1 mM HAuCl4 solution with 40%(v/v) Aloe Vera Extract.
The colour change to purple of the solution 12-14 hrs after mixing aloe vera extract and chloroauric solution suggests the successful formation of gold nanoparticles. The colour change only suggests nanoparticle formation and further steps have to taken to actually characterize the nanoparticles synthesized.
We had initially expected the nanoparticles to be triangular in shape and to be around 100 nm in size. Upon inspection, we found that the nanoparticles were a variety of sizes from 10 to 100 nm and were not exclusively triangular. We also found that there was a film around the nanoparticles, which we learned was potentially organics from our extracts.
An Energy-dispersive X-ray spectrogram (EDS) was obtained for our samples to confirm that they were indeed gold. High peaks for copper and carbon are a result of the grid used in the microscope. The peaks containing gold (Au) are a confirmation that the nanoparticles are made of gold.
A maximum absorbance at approximately 530 nm confirms the presence of gold nanoparticles, which was most strongly displayed by nanoparticles that were synthesized using an aloe vera extract that was 40%(v/v) in solution. This result further confirms the presence of gold nanoparticles.
Conclusion:
Based on the images presented above, we can conclude that we have successfully synthesized gold nanoparticles utilizing chloroauric acid and aloe vera extract. The expected triangular shapes were observed in some of the synthesized nanoparticles but not all of them and the size ranges was far from the 100 nm that were expected. The drop-rate of the chloroauric acid into the aloe vera extract can be controled more efficiently and perhaps this would yield better results. After testing different concentrations of chloroauric acid and different aloe vera to chloroauric acid ratios we found that the optimal parameters for the synthesis of these gold nanoparticles is 1 mM chloroauric acid with 40% (v/v) Aloe Vera extract.
Plant Synthesis: Garlic
Spherical Gold Nanoparticles(2-10 nm) Synthesized using Garlic Extract
Optimal variables:
0.25 mM HAuCl4 solution with 1%(v/v) garlic extract (filtered using 0.45 and 0.75 micron filter paper)
After several minutes, a color change from clear to pinkish-red is expected to occur, according to our reference. This indicates the formation of nanoparticles. The color transformation successfully happened.
We expected a maximum absorbance to occur at an approximate wavelength of 530 nm, according to our reference. This would confirm the presence of gold nanoparticles. This was successfully obtained as demonstrated by our results.
We tested Garlic synthesized gold nanoparticles with different percentage amounts of garlic extract, We found that the smallest nanoparticles can be synthesized utilizing 1% Garlic extract with 0.25 mM HAuCl4.
The TEM images of the gold nanoparticles indicate that the nanoparticles are in fact spherical and that their average size is 4.5 nm (ranging between 2-8 nm) as expected. The nanoparticles also have a good crystal lattice and a uniform shape. The TEM images also indicate that no agglomeration or aggregation has occurred between the nanoparticles as well.
Conclusion:
After having tested multiple variables, those that yielded the relatively best results were samples that contained 0.25mM HAuCl4 mixed with a basic 1%(v/v) garlic extract. They were the quickest to undergo a colour transformation (i.e to synthesize). Furthermore, according to our TEM photos, they were also the most stable to produce as there was no aggregation or agglomeration that formed and the majority of the nanoparticles formed were nearly uniformly shaped and sized. Thus, the concentration of chloroauric acid versus plant extract concentration has been optimized.
Plant Synthesis: Cabbage
Spherical Silver Nanoparticles (5-30 nm) Synthesized using Cabbage Extract
Conclusion:
Based on the results presented, we can conclude that we have successfully synthesized silver nanoparticles using cabbage extract. The nanoparticles synthesized were slightly smaller than the 30-50nm range that was expected but they were spherical as expected. The EDS and UV-vis analysis confirm the presence of silver.
Chemical Synthesis: Martin Method
Spherical Gold Nanoparticles (1-10 nm) Synthesized using the Martin method
The Martin method of synthesis was used to create gold nanoparticles ranging in size from 1-10nm. The colour change from clear to dark red indicates the formation of our nanoparticles.
Individual nanoparticles cannot be observed through a typical light microscope because of their small size. Once synthesis of our nanoparticles was complete, we brought samples to a Transmission Electron Microscope (TEM) to observe our nanoparticles. Above is one of the images from the TEM. The nanoparticles were all spherical in size and fell into our expected range of 1 - 10nm. Most of the nanoparticles were around 5 nm in size, which is optimal for our nanoshell attachment method.
One method for confirming the presence of our nanoparticles involved measuring the absorbance of our samples using uv-vis spectroscopy. Gold nanoparticle synthesis appears to be successful from this UV-vis data. We were expecting a peak at 513±3nm and obtained a peak at 511 nm.
One method for determining the size of nanoparticles involves the use of dynamic light scattering (DLS). This method measures the size of nanoparticles based on the water molecules surrounding the nanoparticles. This hydrodynamic size confirms the diameter of our nanoparticles. According to our DLS data, most of the nanoparticles synthesized through the Martin Method were 3nm or 5nm. This falls into our expected range of 1-10nm.
Conclusion:
The Martin method was very simple to perform and gave very consistent results. The colour change to red in the solution indicated the presence of gold nanoparticles which were later confirmed and characterized with TEM imaging and DLS. UV-vis analysis detected a peak at around 511 nm which is within the range indicated in the literature confirming the presence of gold nanoparticles.
Chemical Synthesis: Turkevich Method
Spherical Silver Nanoparticles (10-70nm) synthesized using the Turkevich Method.
Optimal variables:
883 µM silver nitrate mixed with 1%(m/v) sodium citrate.
A color transformation from clear to dark yellow, within 4-5 minutes of mixing silver nitrate and sodium citrate in solution, indicates the formation of silver colloids, potentially silver nanoparticles. This successfully occurred.
An absorbance peak at a wavelength of approximately 420 nm indicates the presence of silver nanoparticles. This was successfully obtained, according to our results.
The size range of the nanoparticles synthesized is between 10-70 nm. The majority of the nanoparticles synthesized were approximately 30 nm in diameter and a bit over 10 nm in diameter.
According to our TEM results, the nanoparticles range in size between 10 and 22 nm. However, that is only with respect to the sample that was used for imaging purposes. It does not reflect the range of the whole stock. The DLS confirms that the size range is bigger, being between 10-70 nm. The TEM also indicates that the nanoparticles are consistently spherically shaped and that they are in a relatively stable state, as there are minor aggregates and agglomerates present in the images.
Conclusion:
In conclusion, our best results were generated when mixing 883 microM of silver nitrate and 1% (m/v) sodium citrate together. The majority of the nanoparticles generated under these conditions were consistent in shape and size. They were also the most relatively stable samples to be produced, as only minor aggregates and agglomerates were detected. Overall, they are in good condition to be used for attachment to cells.
