Biomedical Engineering Reference
In-Depth Information
References
Frens G (1973) Nature (Phys Sci) 241:20
Gold colloid with smaller diameter is made by reduction of the
tetrachloroauric acid with a citrate/tannic acid reaction mixture
given in Table 4.4.
Mix 79 ml Reagent A with 1 ml Soln. B and heat to 60
◦
C while
stirring. Prepare the reduction mixture according to Table 4.4 and
heat to 60
◦
C, too. Add quickly the hot reaction mixture to the gold
solution and continue heating and stirring for 15 min.Whenthe
color has changed to red, reflux for 10 min.
Table4.4.
Reductionmixtures forpreparationof colloidal gold (5-10 nm)
Diameter (nm)
Solution A
Solution C
Solution E
Solution F
(ml)
≈
10
16
4
0.09
0
≈
6
16
4
0.4
0
≈
4
16
4
2
2
References
Leunissen JLM, De Mey JR (1989) Preparation of gold probes. In: Verkleij
AJ, Leunissen JLM (eds.) Immuno-gold labeling in cell biology. CRC
Press, Boca Ratan, p 3
4.1.11.2 Adsorption of Protein to Colloidal Gold
A5mM buffer solution with a pH near to the pI of the respective
Solutions/Reagents
protein
B2M KCl in pure water
C5% w x 0M (polyethyleneglycol with M
r
20.000)
7
D
0.05% Carbowax 20 M (w/v), 0.05% Tween 20 (w/v) in PBS
PBS
The adsorption of protein on colloidal gold occurs in a relative
small pH range. Immunoglobulins are bound at pH 7.4, Protein A
has an optimum at pH 6.5. For adjusting the pH, the gold colloid
as well as the protein solution are dialyzed twice at RT against
a 100-fold volume of Soln. A for 1 h each.
Determine the amount of protein necessary for saturation of the
gold sol: Pipet 0.5 ml of the dialyzed colloidal gold into Eppendorf
tubes and add 0.1 ml of a dilution series of the dialyzed protein to
7
There are differences in polyethylene glycols of different manufacturers.
If Carbowax 20 M is not available, check different lots of PEG 200 000.
