Biomedical Engineering Reference
In-Depth Information
(2)
Mix this with 5.0 mL of 0.5 mM HAuCl
4
.
(3)
Add 0.60 mL ice-cold 10 mM NaBH
4
solution and stir vigorously at 25 °C.
(4)
Prepare the growth solution using CTAB (5 mL, 0.20 M) with 0.15 mL of
4 mM AgNO
3
solution at 25 °C, followed by 5.0 mL of 1 mM HAuCl
4
and
70 µL of 78.8 mM ascorbic acid.
(5)
Add 12 µL of the seed solution to the growth solution at 27-30 °C.
(6)
Keep the temperature of the growth medium constant at 27-30 °C in all
preparations.
(7)
Continue reaction to last for about 10 h.
(8)
Centrifuge and re-disperse in pure water and store in glass bottles at RT
before use.
The protocol for the synthesis of nanostars is summarized as follows:
(1)
Dilute 1 mL, 1 wt% HAuCl
4
·3H
2
O aqueous solution with 90 mL water.
(2)
Inject 2 mL of 38.8 mM trisodium citrate and add freshly prepared NaBH
4
solution (1 mL, 0.075 wt% in 38.8 mM trisodium citrate solution).
(3)
Allow the reaction to proceed with constant stirring at RT overnight to form
the seed solution.
(4)
Mix 50-mL gold seed solution with 10 mM polyvinylpyrrolidone (PVP) at
RT for 24 h to prepare the PVP-coated gold seed solution.
(5)
Add 82 µL of 50 mM HAuCl
4
aqueous solution to 15 mL of 10 mM PVP in
dimethylformamide (DMF), followed by the rapid addition of 43 µL of the
PVP-coated gold seed solution ([Au] ≈ 4 mM) with constant stirring at RT
for about 13 h.
(6)
Centrifuge and re-disperse in pure water and store in glass bottles at RT
before use.
Silver (Ag) has been known to have a disinfecting effect and has found applica-
tions in traditional medicines. Just like the salts of silver and their derivatives,
silver nanoparticles (AgNPs) have been found to exhibit antimicrobial proper-
ties.
84
AgNPs have been reported to eliminate microorganisms on textile
85
or
are used for water purification.
86
One of the easiest ways to synthesize AgNPs is by reduction. Reduction
synthesis uses silver nitrate as the raw material source of silver.
2.2.5 Protocol for Synthesis of AgNPs
87
The AgNPs were produced by reducing silver nitrate with hydrazine in the pres-
ence of PVP.
87,88
The synthesis is carried out as follows:
(1)
Dissolve 300 mg of PVP powder in 8 mL of aqueous 25-mM silver nitrate
solution (AgNO
3
).
(2)
Dilute the solution with 14-mL deionized water.
(3)
After 5 min at RT add 4 mL of 70-mM hydrazine (N
2
H
4
·H
2
O) dropwise in
stoichiometric excess to achieve complete reduction of the silver salt with
continuous stirring.
