Biology Reference
In-Depth Information
ferrocenylsidechainsforuseinasandwichtypeassay.Interestingly,
the DNA-diblock copolymer dendrimers used for detection showed
higher binding a
nity and sharper melting profiles than the
ssDNA used to form the dendrimer. Two ferrecenyl derivatives,
ferrocenylanddibromoferrocenyl,wereusedtoformthedendrimer
allowing one to tailor the redox characteristics of each DNA-
diblock copolymer dendrimer probe. Using this strategy detection
of multiple targets simultaneously and detection of point mutations
was possible. Target DNA could be detected at 100 pM and higher
concentrations.
Nanoscale dendrimers of DNA have also been utilized for
electrochemical DNA detection. Wei and coworkers [64] employed
a polymer-DNA dendrimer surface for DNA and RNA detection.
StreptavidinfunctionalizedDNAdendrimerswereincorporatedinto
polypyrrole on an Au electrode via electropolymerization. This
was followed by immobilization of biotin-terminated capture probe
DNA. The capture probe was designed to form a hairpin loop in
the absence of target DNA, and contained a FITC label on the
end opposite of the biotin group. In the presence of target DNA
or RNA, the hairpin loop opened exposing the FITC group. An
anti-FITC antibody-horseradish peroxidase conjugate bound to the
exposed FITC group. In the presence of substrate and mediator,
the horseradish peroxidase produced an electroactive signal. The
authorsreportadetectionlimitof10aMwhichtheyattributetothe
conducting polymer-DNA dendrimer interface providing enhanced
electron-transfer kineticsand highprobe density.
14.3.6
Apoferritin Nanovehicles
Apoferritin is a spherical protein shell composed of 24 protein sub-
units,forminganouterdiameterof12.5nmandanaqueousinterior
about 8 nm in diameter [65]. This protein cage is capable of holding
about 4500 iron atoms and can be reversibly dissociated into its 24
subunitsatlow pH(2.0), andreassembled athighpH (8.5).Modula-
tion of pH can thus serve as a method to load and release electroac-
tivemarkersallowingapoferritintobeemployedasanelectroactive
label. Such an approach avoids the use of harsher acid dissolution
of quantum dot NP labels and complicated semiconductor NP
