Gold Nanorod Synthesis
7/5/2011
A) Seed preparation:
In 20 mL vial:
1) 9 mL 0.1M CTAB (in 35 C water bath)
2) 250 uL 4mM HAuCl4
3) Add stir bar and stir on hot plate (29 C water bath, plate set at 50 C)
4) Add 600 uL ICE COLD 0.01M NaBH4
5) Stir for 2 hours (29 C water bath) (actual: 3 hours)
Seeds good for one week after preparation.
7/5/11: Visualized seed solution 3x (100 uL, 200 uL, and 500 uL). Takes ~1 hour for reaction to complete.
Very slight absorbance detected at 500 nm
B) GNR Synthesis:
In 50 mL Falcon tube:
1) 35 mL 0.1 M CTAB (pour)
2) 5 mL 4mM HAuCl4
3) 400 uL mM AgNO3
4) Invert tube gently to mix (~3x)
5) Add 280 uL 0.08 M ascorbic acid. Color changes from orange to clear
6) Add stir bar in 50 mL tube, place in water bath (28 C)
7) Add 100 uL seed solution
8) Stir for 12 hours at 28 C (actual: 19 hours)
9) Centrifuge 2X at 8500 rpm for 30 min and discard supernatant (check with UV-VIS to ensure you are not
discarding rods)
7/6/11: Centrifuged 50 mL tube at 6000 rpm for 28 min. Gold rods detected by UV-VIS in supernatant.
Peaks at 5xx nm and 7xx nm. We resuspended the pellet in the 50 mL tube and distributed 1.5 mL seed
solution into eight 1.5 mL-tubes and centrifuged at 8500 rpm for 5 min. There was a small pellet, but
supernatant still pink-ish hue so we spun again at 8500 rpm for 10 min. Gold rods still detected by UV-VIS
in supernatant. Centrifuged at 10,000 rpm for 10 min.
10) Re-disperse in solution for functionalization (thiols, etc.)
Reagent prep:
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Gold Nanorod Synthesis
4 mM HAuCl4
31.48 mg salt in 20 mL H2O
(actual: 31.8 mg)
0.1M CTAB
9.1 g CTAB in 250 mL H2O
(actual: 9.1 g)
0.01 M NaBH4 (n.b. toss after use)
18.9 mg NaBH4 in 50 mL H2O
(actual: 18.9 mg)
8 mM AgNO3
13.5 mg AgNO3 in 10 mL H2O
(actual: 13.5 mg)
0.08 M ascorbic acid (n.b. good for one week, be aware of color change)
141 mg acscorbic acid in 10 mL H2O
(actual: 140.9 mg)
SEM images of gold nanorods synthesized on 7/6/11:
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Gold Nanorod Synthesis
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Gold Nanorod Synthesis
7/13/11: Old seed solution, ascorbic acid, and NaBH4 remade.
8 mM NaBH4
3.78 mg NaBH4 in 10 mL H2O
(actual: 3.7 mg)
0.08 M ascorbic acid
141 mg ascorbic acid in 10 mL H2O
(actual: 141.0 mg)
Heated CTAB in 29 C water bath with stir bar and kept NaBH4 on ice until ready for use. Seed solution
stirred for 2 h 5 min in 37 C water bath (temp lower in sample).
In 50 mL Falcon tube, prepared GNR solution and stirred at 37 C. Start time: 2:23 pm. Next step: spin down
in 1.5 mL tubes and wash with water 2x to isolate GNR.
UV-VIS: supernatant absorbance showed two peaks at 510 nm and 800 nm (800 nm higher intensity)
indicating presence of gold nanorods; resuspended pellet absorbance showed two peaks around same
location as supernatant but 800 nm intensity was less than that of 510 nm peak (abnormal).
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Gold Nanorod Synthesis
SEM images of gold nanorods synthesized on 7/13/11:
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Gold Nanorod Synthesis
SEM images of supernatant:
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Gold Nanorod Synthesis
Next steps: Try new mesophase concentrations
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