MIP Sensors on the Way to Real-World Applications - Designing Receptors for the Next Generation of Biosensors - page 172

Fig. 6 Mass-sensitive transducer-quartz crystal microbalance (QCM)
improved by increasing the fundamental frequency of the respective transducer
[ 26 ].
Especially when keeping real-world applications in mind, chemical and bio-
chemical sensors require high sensitivity, selectivity, adsorption capacity, and
reversibility. For instance, the selectivity of chemical sensor materials has to be
substantially higher than in other applications, such as separation materials: a
sensor can only make use of one plate of separation, whereas a chromatographic
column can have tens to hundreds of thousands of them. Furthermore, high adsorp-
tion capacity of the layer is also of seminal importance, because the volume in
which recognition takes place is usually limited. Therefore, the recognition layer
also has substantial influence on the overall sensitivity of a sensor. As artificial
layers are usually developed for long-term application of the respective system, the
layer should show reversible interaction behavior with the analyte combined with
low tendency for drift. The main challenge is that these parameters often contradict
one another: high selectivity may mean reduced sensitivity and high sensitivity
often means partly irreversible binding and therefore limited reusability.
4 Real-Life Applications of MIP
In real-life and online monitoring, the main challenge for an analytical chemist is to
deal with very low concentrations of analytes in complex environments, especially
under the strong influence of humidity and interfering compounds. MIPs have
already received substantial interest by laboratory chemists. However, only a
limited number of papers can be found where such materials have indeed been
taken from the lab bench into real-life environments. These include virus detection
in plant saps [ 27 ], monitoring oxidative degradation phenomena in oil matrices
[ 28 - 30 ], sensing bacteria [ 31 , 32 ], yeast cells [ 33 ], or volatile organic compounds
[ 11 , 34 - 40 ]. MIPs have also already been applied in the field of environmental
monitoring, especially for sensing pesticides [ 41 - 44 ], endocrine-disrupting
compounds, and heavy and toxic metals in soil and water. In the latter case, such