Nanoparticle Synthesis Laboratory Notebook: Turkevich Method

DAY 1

Purpose: To synthesize nanoparticles I the 50 nm range using the Turkevich method.

Source:

DOI: 10.1039/c4ra15857a

DOI:10.1021/j100214a025

                                                                                                          DOI: 10.1021/bp0501423

Protocol:

1. Fill a 50 mL falcon tube with ddH2O

2. Weigh out 36 mg (0.036g) of AgNO3 powder.

• Light sensitive - limit light exposure by covering with tin foil

1. Measure 20 mL of ddH2O in a 25 mL graduated cylinder. Pour the water into a 100mL beaker.

1. Add the AgNO3 to the ddH2O in the beaker and place the stir bar into the solution to mix it in - place a watch glass on the opening of the beaker to prevent vapours from escaping

1. On the hot plate, stir the solution and boil it to fully dissolve the AgNO3

• Light sensitive - limit light exposure by covering with tin foil

• At this step, nanoparticle synthesis should occur

1. Measure 4 mL of 1% sodium citrate in the 10 mL graduated cylinder

1. Add the sodium citrate to the solution drop by drop into the beaker with continuous stirring  

• Keep stirring till a YELLOW-BROWN color change is observed, about 10 min - indicator of citrate attachment to the Ag nanoparticles

1. Remove the solution of citrate-coated nanoparticles from the hot plate and let it cool down at room temperature

Modifications:

No modifications were made to this protocol.

Results:

Color formation: The expected colour change was a yellow brown color within 10 minutes. But within 2 min a grayish black color was observed and the particles/colloids formed were visible as grain like particles by the naked eye. This was a clear that there wasn’t any nanoparticle formation.

UV-vis results: An absorbance peak of 420 nm was expected for silver nanoparticle formation. No absorbance peak was observed indicating inadequate nanoparticle formation Figure 1.

Figure 1: UV-vis of silver nanoparticles synthesized through Turkevich method batch #1

DAY 2

Purpose: To synthesize silver nanoparticles that are 50 nm by trouble shooting the previously mentioned protocol.

After looking through the references cited by our source paper we found out that our paper has mad a mistake when it came to the quantity of AgNO3 used. Thus, we used 3.6 mg instead of 36 mg,

Protocol:

1. Fill a 50 mL falcon tube with ddH2O

2. Weigh out 36 mg (0.036g) of AgNO3 powder.

• Light sensitive - limit light exposure by covering with tin foil

3. Measure 20 mL of ddH2O in a 25 mL graduated cylinder. Pour the water into a 100mL beaker.

4. Add the AgNO3 to the ddH2O in the beaker and place the stir bar into the solution to mix it in - place a watch glass on the opening of the beaker to prevent vapours from escaping

5. On the hot plate, stir the solution and boil it to fully dissolve the AgNO3

• Light sensitive - limit light exposure by covering with tin foil

• At this step, nanoparticle synthesis should occur

6. Measure 4 mL of 1% sodium citrate in the 10 mL graduated cylinder

7. Add the sodium citrate to the solution drop by drop into the beaker with continuous stirring  

• Keep stirring till a YELLOW-BROWN color change is observed, about 10 min - indicator of citrate attachment to the Ag nanoparticles

8. Remove the solution of citrate-coated nanoparticles from the hot plate and let it cool down at room temperature

Modifications:

The trisodium citrate solution was added drop wise at a rate of 1 mL per minute

Results:

Color formation: The solution turned Yellow brown within 4-5 min. This color change indicates the formation of silver colloids, possible silver nanoparticles.

UV-vis results: An absorption peak of 420 was expected. As it can be observed by Figure 2, an absorbance peak around 420nm was obtained.

DLS results: According to the DLS results the average size was between 15-20 nm, which is definitely no where close to the expected 50 nm size. Figure 3, it could be that the reaction time of 4-5 min may not be adequate reaction time.

Figure 2: UV-vis of silver nanoparticles synthesized through Turkevich method batch #2

Figure 3: Hydrodynamic size determination of silver nanoparticles synthesized through the Turkevich method batch 2

DAY 3

Purpose: To synthesize silver nanoparticles that are 50 nm and to test out various reaction times to observe which time of reaction gives the best sizes/results. This will tell us if the reaction needs more time in order to form bigger nanoparticles.

Protocol:

1. Fill a 50 mL falcon tube with ddH2O

2. Weigh out 3.6 mg (0.036g) of AgNO3 powder.

• Light sensitive - limit light exposure by covering with tin foil

1. Measure 20 mL of ddH2O in a 25 mL graduated cylinder. Pour the water into a 100mL beaker.

2. Add the AgNO3 to the ddH2O in the beaker and place the stir bar into the solution to mix it in - place a watch glass on the opening of the beaker to prevent vapours from escaping

3. On the hot plate, stir the solution and boil it to fully dissolve the AgNO3

• Light sensitive - limit light exposure by covering with tin foil

• At this step, nanoparticle synthesis should occur

1. Measure 4 mL of 1% sodium citrate in the 10 mL graduated cylinder

2. Add the sodium citrate to the solution drop by drop 1 mL per minute into the beaker with continuous stirring  

• Keep stirring till a YELLOW-BROWN color change is observed, about 10 min - indicator of citrate attachment to the Ag nanoparticles

1. Remove the solution of citrate-coated nanoparticles from the hot plate and let it cool down at room temperature

Modifications:

Samples were taken at different time points from the reaction in order to check through DLS to determine the optimum time to stop the reaction. To DLS the 2nd batch made using the Turkevich method.

Results:

Color formation: All the samples had different tones of the Yellow-brown color, while getting darker as the time of reaction increased. This indicates some form of reduction is happening which can possibly indicate the formation of silver nanoparticles.

DLS results:  

DLS results indicated that the further the time of reaction increased the smaller were the nanoparticles. Thus it was considered that

it was optimum to remove the nanoparticles colloid solution from the heat source as soon as a dark yellow solution formed; which is around 4 min of reaction time. This can be seen in Figure 4. This means that our initial reaction time didn’t contribute to the formation of such small nanoparticles.

Figure 4: Hydrodynamic size determination of silver nanoparticles synthesized through the Turkevich method at various reaction times.

DAY 4

Purpose: To synthesize silver nanoparticles that are 50 nm by trouble shooting the previously mentioned protocol. It was decided that the sodium citrate will be added to the slver nitrate solution in a slow steady stream instead of drop by drop.

Protocol:

1. Fill a 50 mL falcon tube with ddH2O

2. Weigh out 36 mg (0.036g) of AgNO3 powder.

• Light sensitive - limit light exposure by covering with tin foil

3. Measure 20 mL of ddH2O in a 25 mL graduated cylinder. Pour the water into a 100mL beaker.

4. Add the AgNO3 to the ddH2O in the beaker and place the stir bar into the solution to mix it in - place a watch glass on the opening of the beaker to prevent vapours from escaping

5. On the hot plate, stir the solution and boil it to fully dissolve the AgNO3

• Light sensitive - limit light exposure by covering with tin foil

• At this step, nanoparticle synthesis should occur

6. Measure 4 mL of 1% sodium citrate in the 10 mL graduated cylinder

7. Add the sodium citrate to the solution slowly into the beaker with continuous stirring  

• Keep stirring till a YELLOW-BROWN color change is observed, about 10 min - indicator of citrate attachment to the Ag nanoparticles

8. Remove the solution of citrate-coated nanoparticles from the hot plate and let it cool down at room temperature

Modifications:

No modifications were made on this modified protocol.

Results:

Color formation: The solution turned Yellow brown within 4-5 min. This color change indicates the formation of silver colloids, possible silver nanoparticles.

UV-vis results: An absorption peak of 420 was expected. As it can be observed by Figure 2, an absorbance peak of 420nm was obtained.

DLS results: According to figure 6, the average nanoparticle size was mostly concentrated in the 20-60 nm range. Although this range is big it clear that bigger nanoparticles have been finally formed. This batch will be sent for TEM analysis.

Figure 5: UV-vis of silver nanoparticles synthesized through Turkevich method batch #4

DAY 4

Purpose: To synthesize silver nanoparticles that are 50 nm by trouble shooting the previously mentioned protocol. It was decided that the sodium citrate will be added to the slver nitrate solution in a slow steady stream instead of drop by drop.

Protocol:

1. Fill a 50 mL falcon tube with ddH2O

2. Weigh out 36 mg (0.036g) of AgNO3 powder.

• Light sensitive - limit light exposure by covering with tin foil

3. Measure 20 mL of ddH2O in a 25 mL graduated cylinder. Pour the water into a 100mL beaker.

4. Add the AgNO3 to the ddH2O in the beaker and place the stir bar into the solution to mix it in - place a watch glass on the opening of the beaker to prevent vapours from escaping

5. On the hot plate, stir the solution and boil it to fully dissolve the AgNO3

• Light sensitive - limit light exposure by covering with tin foil

• At this step, nanoparticle synthesis should occur

6. Measure 4 mL of 1% sodium citrate in the 10 mL graduated cylinder

7. Add the sodium citrate to the solution slowly into the beaker with continuous stirring  

• Keep stirring till a YELLOW-BROWN color change is observed, about 10 min - indicator of citrate attachment to the Ag nanoparticles

8. Remove the solution of citrate-coated nanoparticles from the hot plate and let it cool down at room temperature

Modifications:

No modifications were made on this modified protocol.

Results:

Color formation: The solution turned Yellow brown within 4-5 min. This color change indicates the formation of silver colloids, possible silver nanoparticles.

UV-vis results: An absorption peak of 420 was expected. As it can be observed by Figure 2, an absorbance peak of 420nm was obtained.

DLS results: According to figure 6, the average nanoparticle size was mostly concentrated in the 20-60 nm range. Although this range is big it clear that bigger nanoparticles have been finally formed. This batch will be sent for TEM analysis.

Figure 5: UV-vis of silver nanoparticles synthesized through Turkevich method batch #4

DAY 5

Purpose: To TEM the 4th batch of presumed silver nanoparticles synthesized by the Turkevich method in order to determine the actual nanoparticle size.

Results:

Figure 7: TEM of Turkvich synthesized silver nanoparticles batch 4.

By analyzing the TEM results, figure 7, we have successfully synthesized silver nanoparticles. Although a size range of 50 nm was expected, 20-40 nm is still a proper size range for attachment.