## 6 Important Applications
### Continuous Porous Polymers as Bioreactors  
The immobilization of enzymes on solid supports is of particular interest in biocatalytic processes. Some of the advantages offered by these materials include the ease of separation of the catalyst support upon completion of the reaction and the possibility of reuse in several reaction cycles. In one of his works, [PERSON] _et al._ reported comparative studies using trypsin immobilized on poly(GMA-co-EGDMA) in particle-form and monolithic rods [137]. The sequence of reactions for immobilizing the enzyme is shown in Figure 11(a). The results indicated that the enzyme immobilized in the rod-shaped support presented higher activity than that in the particulate-shaped support at a linear rate of 25 cm/min. These differences were due to the increase in the mass transfer rate as a result of convective transport reached with the rod-shaped support. In addition, the monolithic bioreactor showed activity at flow rates of even 40 cm/min, whereas the particulate support considerably increased the pressure of the system at these flows rates. In another paper [138] it was reported the immobilization of trypsin on substrates of poly(VAZ-co-AAm-co-EGDMA). The immobilization reaction is shown in Figure 11(b). The polymer proved to be more hydrophilic and more suitable for processes involving biological molecules. The coupling of the enzyme was facilitated by a single step. Figure 10: PolyHIPE-supported synthesis of biphenyl-4-carboxylic acid methyl esters [136]. Reprinted with permission from the American Chemical Society. In another research reported by [PERSON], [PERSON] and coworkers, the azlactone functionalities were used for the preparation of enzymatic microreactors synthesized into capillaries and microfluidic chips [139]. The porous monoliths consisted of VAZ, EGDMA, and AAm or HEMA were prepared by UV-initiated polymerization reaction at room temperature. Once the macroporous polymer was obtained, the trypsin immobilization was carried out using a simple mechanical pump demonstrating the open-pore structure of the supports. The proteolytic activity of the enzymatic microreactor on chip was demonstrated using a fluorescently labeled casein and myoglobin as substrates at a very fast flow rate which afforded very short digestion time. The digest was then characterized using MALDI-TOF MS and sequence coverage of 67% was reached. Sometimes when hydrophobic proteins are analyzed, a proper hydrophylyzation of the polymer surface is required to avoid hydrophobic nonspecific interactions. Therefore, a novel approach was recently developed for the modification of the surface chemistry of macroporous poly(GMA-co-EGDMA) via multistep/multilayer photo-grafting reactions to obtain capillary enzymatic microreactors containing trypsin and endoproteinase LysC for the characterization and identification of proteins [140]. First, the monolith was hydrophylyzed via photo-grafting of poly(ethylene glycol methacrylate) followed by photo-grafting of a VAZ to provide a polymeric surface with the functionalities required for immobilization. This new approach minimized the undesired nonspecific  
Figure 11: Sequence of reactions in immobilizing trypsin on rods of (a) poly(GMA-co-EGDMA) and (b) poly(VAZ-co-AAm-co-EGDMA). Adapted from references [137,138]. adsorption of proteins and peptides and facilitated the control of enzyme immobilization and protein digestion processes. Figure 12 shows the different reaction steps followed in the synthesis of these enzymatic reactors.