## 3 MIPs' Applications
### MIPs as Chemical Sensors and Biosensors  
In the last years, chemical sensors and biosensors are of increasing interest in the field of modern analytical chemistry, as can be seen from the growing number of published papers. This is due to new demands that are appearing particularly in clinical diagnostics, environmental analysis and also in food analysis. Recently, a big effort to synthesize artificial receptors capable of binding a target analyte with comparable affinity and selectivity to natural antibodies or enzymes has been done. MIP technology can also be used as antibody-like materials with high selectivity and sensitivity, owing to their long-therm stability, chemical inertness and insolubility in water and most organic solvents [133]. To date, MIPs have been successfully used with different types of transducers and several methods have been used to achieve a close integration of the transduction platform with the polymer [24]. In particular, the integration of MIPs with sensors can be realized by _in situ_ polymerization, using a photochemical or thermal initiator [134], or by surface grafting with chemical or UV initiation [135, 136]. The advantage of this latter approach lies in the possibility of controlled modification of inert electrode surfaces with thin films of specific polymers. Moreover, polymers can also be electropolymerized on the surface of transduction platform. In this case, there are some adhesion problems, especially during the washing process of the polymerized MIP-coated QCM (Quartz Cristal Microbalance) with organic solvents that, sometimes lead to a partly peeling off of the MIP layers produced. For this reason, specific pretreatment to enhance the adhesion of MIPs on transducer platforms, must be done. The first generation of MIP sensors was prepared using imprinted polymers synthesized in the form of monoliths. The obtained MIP particles were deposited in close proximity to the electrode by incorporation of the particles into the carbon paste of screen-printed electrode [137] or into a supporting agarose gel [138]. It was observed that the response of the sensor was strongly dependent on how intimately the MIP and transduction element were integrated and how efficient the electrical communication was between them. Competitive amperometric morphine sensor using MIP particulates immobilised with agar gel on the electrode surface, has been reported by [PERSON]'s group [139]. The device employed a competitive two-stage displacement strategy in which initially the electro-active template bound to a morphine imprinted polymer which had been immobilized in a thin layer of agarose. Subsequently an electro-inactive competitor, codeine, was added which resulted in the displacement of the morphine from the MIP. The displaced template was then determined amperometrically. The result obtained in this study reported a working concentration range of 0.1-1.0 \(\upmu\)g/mL and also a stability of the sensor in a range of different conditions. In particular these results suggest a high degree of ruggedness. MIP-based recognition elements were also prepared as layers or thin films by deposition or grafting onto the transducer platform [140, 141]. The thickness of the film deposited on the transducer is important to obtain a good time response of the sensor. This approach was firstly used with acoustic [142] and optical [143] transducers and then with electrochemical sensors [144]. Today, a simple approach to obtain sensor device, is the combination of MIPs with a piezoelectric transducer (e.g., quartz) to create an acoustic sensor called QCM-MIP sensor. The coating of the crystal with the MIP can be obtained by _in situ_ polymerization directly onto the surface of the device [145, 146] or via pre-prepared MIP particles that are immobilized on the sensor surface using a PVC matrix [147]. A QCM-MIP sensor has been employed by [PERSON] and co-workers to obtain a sensor device for atropine detection.