## 3 Overview of Molecularly Imprinted Polymers as Catalysts and Support for Catalysts
### MIPs as Efficient Catalysts  
One area where MIPs have gained significant attention is catalysis, owing to their unique and specific properties. MIPs can indeed be viewed as efficient catalytic materials, although they differ in some key aspects from traditional catalysts. They have a series of advantages, as MIPs can be designed to have high specificity for certain target molecules due to their molecular recognition capabilities [8], which can be advantageous in catalysis for allowing selective reactions. Furthermore, MIPs are very stable under a wide range of conditions, including extreme pH and temperature values, making them robust catalysts for various applications. In addition, MIPs are often reusable, which is a significant advantage compared to some traditional catalysts, which can degrade over time or lose activity [50; 62; 84]. Many studies use MIPs as catalysts. Thus, MIPs can be synthesized to imitate enzymes and other biological molecules, expanding their catalytic potential beyond traditional catalytic materials. Enzymes are natural biocatalysts responsible for catalyzing various biochemical reactions in living organisms. As in other proteins, natural enzymes are macromolecules composed of long chains of amino acid residues with added cofactors and other post-translational modifications. Enzymatic catalysis usually occurs in a small part of the enzyme molecule (known as the active site) with high selectivity and rate. The tight binding of a substrate to the functional groups in an enzyme facilitates catalysis through proximity effects. Although natural enzymes can catalyze reactions with high regioselectivity and stereoselectivity under mild biological conditions, they are often costly to obtain and unstable in practical applications. Consequently, replacing biomolecular enzymes with more durable synthetic compounds or materials has become an appealing endeavor to meet the diverse requirements of catalytic reactions [62; 85; 86]. For instance, carboxypeptidase A (CPA) has been one of the most studied enzyme compounds in the analytical field of MIPs. In the reaction illustrated in Figure 3[87; 88], molecularly imprinted nanogels containing a proline derivative were prepared for the first time. These nanogels exhibit high catalytic activity, turnover, and enantioselectivity in the cross-aldol reaction between cetone and 4-nitrobenzaldehyde, following the enamine-based mechanism typical of aldolase type I enzymes. Furthermore, a novel approach for active-site titration was developed, utilizing the reaction between a catalyst and a substrate to produce a readily detectable product. This method enabled the precise calculation of catalytic parameters, providing valuable insights into the composition of the polymer [89]. Pioneering work on MIPs [88] focused on printing acrylamide-based nanogels using a covalent method that involves the formation of a reversible enaminone, resulting in nanogel preparations with exceptional catalytic activity, turnover, and enantioselectivity. Additionally, recent studies by [PERSON] et al. [90] demonstrated that nanogels can be effectively utilized as drug delivery systems, highlighting their versatility and potential in biomedical applications, which complements and expands upon the initial MIP studies. Additionally, the strategic design of the model molecule enables the creation of catalysts tailored to produce a variety of molecules that are otherwise challenging to synthesize. Furthermore, recent research has focused on various applications of MIPs in catalysis. One area of interest is the development of MIP-based enzyme mimics, often called \"artificial enzymes\" or \"nanozymes\", designed to catalyze specific biochemical reactions with high efficiency. Studies have demonstrated MIPs mimicking peroxidase activity for use in biosensing and environmental applications [91; 92].