96
S. E. H. Murph and A. Goriounova
optical properties. The Zetasizer and Zeta potential of the nanoparticles were obtained
using a Brookhaven Instruments DLS NanoBrook Omni (110–240 V) manufactured
in 2014. A Hitachi SU8200 Scanning Electron Microscope coupled with energydispersive X-Ray spectroscopy was used for evaluating nanomaterials morphologies
and compositions.
Experimental
Gold Nanoparticles Prepared in Solution
All glassware used in the following protocols was cleaned with Aqua Regia and
then rinsed with deionized water. A sodium citrate solution (1%, 1 mL) was quickly
added to a boiling solution of HAuCl 4 (2.5 × 10
–7 M) under vigorous stirring. The
solution was boiled for 10 min and then allowed to cool off. The appearance of a
red color indicated the formation of the nanoparticles. The nanoparticles solution
(1 mL aliquots) was then purified by centrifugation for 7 min at 10,000 rpm and
redispersion in DI water. The gold nanoparticles were then redispersed in 1 mL of
deionized water.
Gold Nanoparticles Prepared on Stainless-Steel Wool Filters
A sodium citrate solution (1%, 1 mL) was quickly added to a boiling solution of
HAuCl 4 (2.5 × 10
–7 M) under vigorous stirring that contained a 1.5 cm
2 stainlesssteel wool filter in the flask. The solution was boiled for 10 min and allowed to
cool off at room temperature (RT). The appearance of a purple-red color indicated
the formation of the nanoparticles. The nanoparticle-treated filter was removed from
the solution and rinsed with deionized water through three-step washing. It was
subsequently transferred to a petri dish to dry for further use.
Gold Nanoparticles Surface Functionalization
The gold nanoparticles, both in solution and on the stainless-steel wool filters, were
functionalized with L-cysteine. 100 µL aliquots of L-cysteine (10 mM) was added
to the 1 mL gold nanoparticle solution and incubated with stirring for 2 h at room
temperature. The functionalization of the gold nanoparticles on stainless-steel wool
filters was done in the same manner in a 50-mL falcon tube. The solution was
incubated for set time intervals (2, 6, and 24 h) without stirring at room temperature.
S. E. H. Murph and A. Goriounova
optical properties. The Zetasizer and Zeta potential of the nanoparticles were obtained
using a Brookhaven Instruments DLS NanoBrook Omni (110–240 V) manufactured
in 2014. A Hitachi SU8200 Scanning Electron Microscope coupled with energydispersive X-Ray spectroscopy was used for evaluating nanomaterials morphologies
and compositions.
Experimental
Gold Nanoparticles Prepared in Solution
All glassware used in the following protocols was cleaned with Aqua Regia and
then rinsed with deionized water. A sodium citrate solution (1%, 1 mL) was quickly
added to a boiling solution of HAuCl 4 (2.5 × 10
–7 M) under vigorous stirring. The
solution was boiled for 10 min and then allowed to cool off. The appearance of a
red color indicated the formation of the nanoparticles. The nanoparticles solution
(1 mL aliquots) was then purified by centrifugation for 7 min at 10,000 rpm and
redispersion in DI water. The gold nanoparticles were then redispersed in 1 mL of
deionized water.
Gold Nanoparticles Prepared on Stainless-Steel Wool Filters
A sodium citrate solution (1%, 1 mL) was quickly added to a boiling solution of
HAuCl 4 (2.5 × 10
–7 M) under vigorous stirring that contained a 1.5 cm
2 stainlesssteel wool filter in the flask. The solution was boiled for 10 min and allowed to
cool off at room temperature (RT). The appearance of a purple-red color indicated
the formation of the nanoparticles. The nanoparticle-treated filter was removed from
the solution and rinsed with deionized water through three-step washing. It was
subsequently transferred to a petri dish to dry for further use.
Gold Nanoparticles Surface Functionalization
The gold nanoparticles, both in solution and on the stainless-steel wool filters, were
functionalized with L-cysteine. 100 µL aliquots of L-cysteine (10 mM) was added
to the 1 mL gold nanoparticle solution and incubated with stirring for 2 h at room
temperature. The functionalization of the gold nanoparticles on stainless-steel wool
filters was done in the same manner in a 50-mL falcon tube. The solution was
incubated for set time intervals (2, 6, and 24 h) without stirring at room temperature.