Biology Reference
In-Depth Information
potential at the pH used for encapsulation. Thus they adsorb most
strongly to the positivePAHsurface.
Nanoparticle Quantification:
Tooptimizethenanoparticleloadingof
a particular electrochemical label it is necessary to have a means
of determining that loading. This can be done in a systematic way
based on UV absorbance, voltammetry, and TEM measurements, as
outlined below.
Nanoparticle recovery.
Thenanoparticlerecoveryistheproportion
of the initial metal ions that are converted into metal nanoparticles.
This can be calculated by first determining the mean nanoparticle
radius from TEM. Most methods of synthesis will produce a
distribution of radii, as shown for the silver particles in Fig. 8.12;
this distribution represents the main error in the determination.
Basedonthemeanradiusandthebulkdensityvaluefromliterature,
we can calculate the mean mass of 1 nanoparticle. Since we know
Figure 8.12.
TEM image of silver nanoparticles at pH 6, synthesized
by NaBH
4
reduction of AgNO
3
Inset: particle size histogram from
>
100
particles. Taken with permission from [105], P. Rijiravanich, M. Somasun-
drum,andW.Surareungchai,
Anal. Chem
.
80
,3904-3909(2008).Supporting
Information. c
American Chemical Society.
