Biomedical Engineering Reference
In-Depth Information
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
675
675
775
Wavelength (nm)
875
775
Wavelength (nm)
875
0.6
0.6
0.4
0.4
0.2
0.2
0
0
−
0.2
−
0.2
−
0.4
−
0.4
−
0.6
−
0.6
675
775
Wavelength (nm)
875
675
775
Wavelength (nm)
875
Fig. 7.16.
Photoluminescence spectra of a mesoporous silicon biosensor similar to
the one shown in Fig. 7.15 before and after exposure to bacterial cell lysates (
top row
)
and differential spectra (
bottom row
). The spectra on the
left
have been obtained
for bacteria that are Gram(+) and the spectra on the
right
for bacteria that are
Gram(-)
mesopores but easy into macropores. Furthermore, each streptavidin tetramer
has four equivalent sites for biotin (two on each side of the complex), which
makes it a useful molecular linker.
To create a biotin-functionalized sensor for the capture of streptavidin,
microcavities were first thermally oxidized, then silanized with aminopropy-
ltriethoxysilane to create amino groups on the internal surface. The probe
molecules, Sulfo-NHS-LC-LC-biotin, were then immobilized inside the pores.
As shown in Fig. 7.17a, the red shift of the resonance increased with increas-
ing biotin concentration. A 10 nm red shift corresponds to a nearly complete
(95%) biotin surface coverage.
