Biomedical Engineering Reference
In-Depth Information
(9)
Add 10 µL of buffer C and react for another 15 min.
(10)
Purify by dialysis, ultracentrifugation, or spin filtration to remove excess
reagents.
(11)
Wash three times with buffer D.
(12)
Reconstitute with buffer D to 4-µM NM or as desired.
(13)
Run the original NM and the NM-biomolecule in 1-1.5% agarose gel at
100 V for 30-40 min to verify conjugation efficiency.
(14)
Store the purified NM-biomolecule conjugates at 4 °C until use.
Although these protocols may be applied to various types of NMs with carboxyl
groups on the surface, the conditions for each type of NM may vary. Thus, for
each type of NM and for each type of biomolecule, the conditions for conjuga-
tion must be optimized.
Figure 4.5
shows a typical agarose gel electrophoresis of QDs with carboxyl
groups on the surface, thereby allowing them to migrate toward the positive elec-
trode. The left lane contains the unconjugated QDs and the right lane contains
the QD-protein-conjugated QD. The results indicate the retardation of migration
toward the positive pole after conjugation which is expected as the surface of the
QD gets covered with the proteins. The QD-protein also shows tailing on the gel
which is indicative of the different number of proteins that attached to the surface
of each QD NP. Similarly,
Figure 4.6
shows a typical agarose gel electrophoresis
of 10-nm IOMNP with carboxy groups on the surface. The left lane contains the
unconjugated IOMNP and the right lane contains the IOMNP-antibody. The gel
electrophoresis results are similar to those of the QDs.
4.5 SELF-ASSEMBLED MONOLAYERS
Self-assembled monolayers (SAMs) refer to a single layer of molecules that
assemble themselves in an orderly manner on a solid surface. Traditional
formation of SAMs may be modified to manipulate NP surfaces for various
applications.
FIGURE 4.5
Agarose gel electrophoresis of QD with and without conjugated BSA.
Courtesy of Ocean
NanoTech.
(For color version of this figure, the reader is referred to the online version of this topic)
