Biomedical Engineering Reference
In-Depth Information
Fig. 6 Schematic representation of the QCM sensor based on artificial antibody replicas
(reproduced with permission from [ 64 ])
nanoparticles directly as sensing elements, Schirhagl and coauthors exploited them
as a “secondary template” to transfer their imprints onto a modified QCM wafer
[ 64 ]. The authors first prepared MIP nanoparticles for IgG raised against human
rhino virus 14 by precipitation polymerization (Fig. 6a ), and following removal of
the template (Fig. 6b ) used them as stencils to imprint a secondary polymeric layer
deposited on a QCM wafer (Fig. 6c , d).
The fabricated chemosensor responded to the virus generating signal 6 times
higher than that of the sensor coated with natural antibodies. The mechanism of this
phenomenon is not clear and typically antibodies-based sensor show higher
response than MIP-based devices [ 91 ]. QCM sensor based on MIP NPs exhibited
a faster and stronger response and higher selectivity than sensors made of bulk
polymer [ 91 ]. Bompart and coauthors investigated the possibility of using micro-
Raman spectroscopy to quantify the target molecule adsorbed by MIP NPs [ 92 ].
The authors obtained 200 nm NPs imprinted with R -or S -propranolol by precipita-
tion polymerization. Micro-Raman spectroscopy of nanoparticles pre-equilibrated
with the template allowed detection of propranolol with good selectivity at 1
M
concentration. However it was very difficult to achieve standardization of all
measurement parameters and the detection level was not impressive. To increase
the sensitivity of the system the authors used surface-enhanced Raman spectros-
copy (SERS) performed on 400 nm composite gold core-shell MIP nanoparticles
produced by seeded emulsion polymerization [ 93 ]. This allowed performing target
molecule measurements on single MIP nanoparticles, reaching a detection limit of
0.1 m M. This detection capacity was retained even in the presence of a 100-fold
excess of interfering compounds such as caffeine or acetylsalicylic acid. In addi-
tion, measurements could also be performed in spiked biological samples (diluted
equine serum) down to a detection limit of 1
m
M. The possibility of performing
multiplexed measurements by using different MIP nanoparticles is indeed quite
attractive and deserves further investigation. Sener and coauthors have developed a
m
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