Nanoparticle Synthesis Laboratory Notebook: Using Cabbage Extract (Green Synthesis)

JUNE 14

Experiment: Silver Nanoparticle Synthesis using Cabbage Extract Optimization Trial #1

A) Make Cabbage Plant Extract

1. Cut cabbage and weigh out 25g on a scale.

2. Wash the cut cabbage thoroughly with dH2O.

3. Dry the washed cabbage with paper towels.

4. Using scissors, cut the cabbage into fine pieces.

5. Using a 200mL graduated cylinder, measure out 150mL of sterile distilled water.

6. Pour the 150mL of water into a clean 250mL beaker and place on a hot plate, then allow the water to reach a boil.

7. Place the pieces of cabbage into the boiled water in the beaker.

8. Boil the cabbage and water mixture for 5-10 mins (at an interval of 30secs).

9. While the cabbage is boiling, take a new clean 250mL Duran bottle and cover its surface in aluminum foil so its contents can be protected from light exposure.

9. Place a funnel with a Whatman paper 1 filter coating its opening, at the mouth of the aluminum foil-covered Duran bottle.

10. Pour the boiled cabbage solution into the Duran bottle through the filter-funnel to remove the chunks of remaining cabbage from the cabbage extract solution. Cap the bottle once the transfer is complete.

11. Store at 4oC in the covered Duran bottle. Do NOT place the cabbage extract solution in a freezer (at -20oC or -80oC). Keep the cabbage extract solution away from light exposure to prevent breakdown of reactive species in solution.

 

B) Make Nanoparticles using the Cabbage Extract

1. Gather the cabbage extract solution from storage in the 4oC fridge.

2. Then prepare 90mL of 1mM silver nitrate (AgNO3) solution in a 150mL beaker/Erlenmeyer flask.

3. On a scale, weigh out 0.01529g (15.29mg) of AgNO3 solid.

4. Using a 100mL graduated cylinder measure out 90mL of sterile distilled water.

5. In the fume hood, pour the distilled water into a 150mL Erlenmeyer flask coated in aluminum foil, then add the AgNO3 solid and mix by using Parafilm to seal the top of the flask for inversion.

6. Use aluminum foil to cover the exterior of the flask to prevent the solution from being exposed to light, as it is light sensitive.

7. Using the same graduated cylinder used to measure water, measure 10mL of cabbage extract solution.

8. Pour the measured cabbage extract solution into the Erlenmeyer flask containing the 1mM AgNO3 solution.

9. Given the flask is sealed with Parafilm, invert the solution to allow mixing.

9. Let the flask sit at room temperature for to allow nanoparticle synthesis.

10. After 15mins, the solution should appear change from colorless to dark brown or honey brown in color indicating nanoparticle formation.

11. The nanoparticle solution can be stored at room temperature.

 

JUNE 15

Observation: Silver Nanoparticle Synthesis using Cabbage Extract Optimization Trial #1

A) Prepare samples for UV-vis readings:

1. To isolate the silver nanoparticles from solution, aliquots of the nanoparticle solution are placed in 1.5mL microfuge tubes using micropipets.

2. The aliquots can be centrifuged twice to pellet the nanoparticles. Centrifugation can be performed at 14,000rpm

3. After centrifugation, the supernatant can be discarded by careful micropipet removal from the desired nanoparticle pellet.

4. The supernatant must be discarded in the designated nanoparticle waste container. When removing the supernatant, ensure to be careful not to disturb the pellet at the bottom of the microfuge tube.

5. Place the microfuge tubes containing nanoparticle pellets (kept open) in a hot air oven for ~30mins at 100oC. This is done to fully dry the nanoparticle pellet and evaporate excess reaction solution.

6. Keep the nanoparticle dried powder/pellet at room temperature.

7. UV-vis spectrophotometry can be used to detect the presence of silver nanoparticles, which have an expected maximum absorbance peak at ~420nm.

 

B) Results:

Observed colour changes in cabbage sample: from clear to light brown, indicating successful synthesis of nanoparticles.

UV-vis-IR results:

Absorbance profiles of different synthesis methods (including cabbage agnp synthesis and aunp synthesis made the day prior) (trial#1)

 

Cabbage AgNPs had a weak peak at around 420nm, this indicates a presence of AgNPs

The signal is way too weak, and we should repeat and alter the procedure for better results.

 

Experiment: Silver Nanoparticle Synthesis using Cabbage Extract Optimization Trial #2

C) Make Nanoparticles using Cabbage Extract:

-Cabbage Plant Extract

Weighed 24.97g Cabbage leaves, cut into small chunks with scissors

Boiled 150 mL of water and then added the cabbage chunks (let boil for about 10 min)

Strained into labelled container covered with aluminum foil using a funnel with filter Whatman 2

Stored in fridge

 

-1mM AgNO3 (aq) solution

15.3 mg of solid AgNO3 were weighed (in dim light)

Dissolved in 90mL of distilled water

Mixed

Silver NP rxn started when 20 mL of Cabbage extract were mixed with the 90 mL of HAgCl4 solution

Incubate away from light (covered with aluminum foil) in the biosafety cabinet overnight (~30hrs)

 

JUNE 16

Observation: Silver Nanoparticle Synthesis using Cabbage Extract Optimization Trial #2

A) Results:

Observed colour changes in cabbage sample: from clear to light brown, indicating successful synthesis of nanoparticles.

Read UV-vis-IR of the cabbage nanoparticle sample made the day prior. This attempt of Ag NP synthesis is slightly more successful since the peak at around 420nm is stronger than the last attempt.

Absorbance profile of of Cabbage AgNPs (trial #2)

JUNE 20

Experiment: Silver Nanoparticle Synthesis using Cabbage Extract Optimization Trial #3

 

A)Make AgNPs using Cabbage Extract introducing the variables indicated on Table 1

A 400 mL stock 1 mM AgNO3 solution was prepared by weighing 68.9mg of solid AgNO3 and dissolved in 400 mL of ddH2O

An extra batch of Cabbage extract was made by boiling 150 mL of ddH2O and then adding 24.99 g of chopped cabbage, let boil for 10 min, then filtered into a light proof container with a filter Whatman 2. Solution was left overnight in the biosafety cabinet.

Table 1

JUNE 21

Observation: Silver Nanoparticle Synthesis using Cabbage Extract Optimization Trial #3

A) Results:

Observed colour changes in cabbage sample: from clear to light brown, indicating successful synthesis of nanoparticles.

UV-vis-IR readings: The graph shows that the optimal cabbage percentage is between 30 and 50% (more testing needed) as the highest peak at around 440-460 nm was observed at 30% cabbage extract (400 nm range indicates formation of AgNPs)

JULY 17

Experiment: Silver Nanoparticle Synthesis using Cabbage Extract Optimization Trial #4

 

A) Make Cabbage Extract:

Weighed 25g cabbage cut into small pieces and left to boil for in 150 mL distilled water in fume hood.

Strained into labelled bottle covered with aluminum foil using a funnel with whatman 2 filter paper

Left to cool in fridge

Filtered using 0.45 um syringe then 0.22 um syringe

Use old cabbage extract and filtered using same syringes

 

Extracts obtained:

1. Old extract unfiltered

2. New extract unfiltered

3. Old extract 0.45 um filter

4. Old extract 0.22 um filter

5. New extract 0.45 um filter

6. New extract 0.33 um filter

 

B) Make AgNPs usings all 6 extracts

Left the 6 vials in biosafety cabinet overnight

JULY 18

Observation: Silver Nanoparticle Synthesis using Cabbage Extract Optimization Trial #4

 

A) Results:

Observed colour changes in cabbage sample: from clear to light brown, indicating successful synthesis of nanoparticles.

UV-vis-IR readings of samples prepared the day before:

Graph 1 shows that the old cabbage extract, no matter how filtered, was too old to be used for synthesis since no silver nanoparticles were formed (hence cabbage extract should be prepared right before being used for synthesis to ensure that it is fresh).

Graph 2 shows that the more the extract is filtered prior to synthesis, the lower the peak of absorbance.

JULY 20

Observation: Silver Nanoparticle Synthesis using Cabbage Extract Optimization Trial #5

A) Results of silver nanoparticles synthesized using new cabbage extract(made using .22 + .45 micron filter paper) from the day before:

TEM images of silver nanoparticles synthesized using cabbage extract.According to the protocol we followed from published literature, we expected our silver nanoparticles from cabbage extract to be within 30-50nm in size and spherical. Upon visualization using a TEM, we found that our nanoparticles were indeed spherical, but smaller than expected (within 5-30nm)

EDS analysis: confirmed that the particles were made of silver, though the signals were low likely due to the small particle sizes. Copper and carbon peaks are due to the grid used in the TEM analysis.