Detection integrated with reaction

Sensors based on integrated dialysis, reaction and detection differ from those described in Section 4.3.1 in the fact that a (bio)chemical reaction takes place after separation (simultaneously with detection). They thus fit the generic configuration depicted in Fig. 5.1. A. Some of the ingredients of such a reaction may be immobilized at the sensing microzone, even though the reaction may also take place in the solution passed through it. 

As with sensors based on a triply integrated process involving gas diffusion, there are few reported examples of sensors integrating dialysis, reaction and detection. There follows a description of die most salient examples based on the ingredient of the (bio)chemical reaction that is dialysed at the sensing micro2one. 

An early example by Reetz and co-workers [79] demonstrated the evaluation of a series of biocatalysts for the hydrolytic kinetic resolution of chiral glycidyl phenyl ethers. Employing a fused-silica reactor, the authors developed an integrated reaction system capable of performing biocatalytic hydrolysis, along with separation and detection of the reaction products. Using the enantioselective hydrolysis of 2-phenoxymethyloxirane (136) to 3-phenoxypropane-l,2-diol (137) as a model reaction (Table 6.14), the authors evaluated the biocatalytic activity of a series of epoxide... 

Gottschlich et al. [134] developed a microfluidic system that integrated enzymatic reactions, electrophoretic separation of the reactants from the products, and postseparation labeling of the proteins and peptides prior to fluorescence detection (see Fig. 12). Tryptic digestion of oxidized insulin p-chain was performed in 15 min under stopped flow conditions in a heated channel serving as the reactor, and the separation was completed in 60 s. Localized thermal control of the reaction channel was achieved using a resistive heating element. The separated reaction products were then labeled with naphthalene-2,3-dicarboxaldehyde (NDA) and detected by fluorescence detection. 

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