MIP-based Sensor Platforms for detection of Analytes in Nano- and Micromolar Range

The development of accurate and low-cost sensor systems is of considerable interest. The receptor layer in such a sensor should exhibit excellent binding behavior and selectivity toward the desired target molecules. Although numerous examples of such receptors can be found in nature, unfortunately they have several drawbacks when applied outside their natural environment, such as instability in changing chemical and physical environments and resulting limited shelf life. In contrast, molecularly imprinted polymers (MIPs) are robust and inert over, for example, a wide temperature and pH range, while exhibiting similar specific binding characteristics and selectivity as antibodies. Different readout techniques, such as spectroscopic methods, piezoelectric measurements, and electrochemical detection, are possible in combination with MIP-based sensing. In this chapter, a straightforward and versatile MIP-based sensor platform is presented, which is compatible with both impedimetric and microgravimetric detection. Impedance spectroscopy allows for the accurate detection of target molecules in the nanomolar range. Microgravimetry permits detection in the micromolar range. In this way, the binding events occurring in the MIPs can be monitored over a large concentration range. Optimization of the MIP synthesis for sensor purposes has been demonstrated for a variety of target molecules. It is demonstrated that well-functioning MIPs can be obtained with different synthetic MIP protocols, depending on the target and measuring environment of interest. Furthermore, it becomes evident that the synthesis of a MIP for sensor applications requires special adjustments to the commonly utilized preparation procedures. Typical issues, which have been resolved, are the achievement of better binding behavior in aqueous environments of varying pH, a more homogeneous morphology with associated binding characteristics, and a satisfactory timing of the sensor response. After these optimizations, it can be concluded that the unique combination of specificity, binding capacity, and binding kinetics makes MIPs a valuable class of recognition elements for sensing applications.