Liposomes for DNA Nanotechnology: Preparation, Properties, and Applications - DNA Nanotechnology: From Structure to Function - page 69

Fig. 4.7 Assemble liposomes via streptavidin-biotin system for mass amplification

were employed [ 58 ]. One aptamer was functionalized on liposome, and the other
via streptavidin-biotin system adhered to a microtiter plate. A detection limit of
64 pM was measured, which is ten times better than the limit reported previously.
This assay can also be performed in human blood serum, where a detection limit of
5 nM was determined.
In addition to using encapsulated dye, liposomes can amplify signals based on
its mass. For example, Willner et al. used liposome-attached DNA as amplification
probes and studied them using quartz crystal microbalance. At first thiol-modified
13-mer DNA1 was functionalized to the Au surface, then a 27-mer DNA2 was
added forming a duplex. Afterwards, a 14-mer biotinylated DNA3 was added. The
duplex formed with the three DNA contained a biotin end. Addition of streptavidin
and liposome functionalized with biotin formed an aggregated liposome structure
as shown in Fig. 4.7 , thus producing a much larger mass change compared to the
binding of a single DNA. This method has produced a detection limit of the target
DNA2 of 0.1 pM.

4.8.2 Liposomes for Aptamer Display

The fluidity of the cell membrane is more and more appreciated by the scientific
community since it allows membrane proteins to reorganize and assemble in
response to external/internal stimuli for complex functions including signaling and