Microreactors chip-based reactor

Microreactors belong to the family of sfructured reactors as well (Figure 6). Current microfabrication techniques allow fabrication of small structured catalytic reactors (8). The versatile fabrication possibilities for chip-based reactors have led to the simultaneous development of sfructured and unstructured reactors (9,10), but in the final analysis, the structured version was usually favored. 

To fulfill such requirements, attempts have been made in the past decade by researchers working on peptide mapping and proteomics through development of immobilized microfluidic enzymatic reactors. Microfluidic enzymatic microreactors are an alternative to in-solution method employing immobilization of proteases on microchaimels of chip-based reactors or surfaces of capillaries. The microreactors that enable proteolytic digestion by enzymes immobilized on solid supports are also referred to as immobilized enzyme reactors, IMERs. The great potential of IMERS for proteomic applications comprise rapid and enhance... 

Biocatalytic reactions performed using immobilized enzyme microreactors under continuous flow mode have been found effective for hydrolysis reactions [121,158-161], with the enzyme either trapped in the matrix [159], covalently linked to modified surface wall [160,121], enzymes entrapped in hydrogels [162], or enzymes immobilized on monolith [179]. The experimental setup consists of either chip-type microreactors with activated chaimel walls where enzymes bind, enzymes that bind to beads, enzymes entrapped in the matrix, enzymes adsorbed in nanoporous materials, and most recently, nanosprings as supports for immobilized enzymes in chip-based reactors, or enzyme immobilized monolith reactors, where support is packed inside a capillary tube (Table 10.4). 

A chip-based integrated precolumn microreactor with 1 nl reaction volume has been explored by Jacobson et al. [67]. The reactor is operated in a continuous manner by electrokinetically mixing of sample (amino acids) and reagent (o-phthaldialdehyde) streams. The reaction time is adjusted via the respective flow velocities. By switching of potentials, small plugs of the reaction product were injected into a 15.4 mm separation channel in a gated injection scheme (< 1.8% RSD in peak area). The separation efficiency achieved was relatively poor, however, electrokinetic control of reaction time (and yield) permitted to monitor the kinetics of the derivatization under pseudo first-order conditions. A similar integrated precolumn reactor operated in a stopped flow mode has been described by Harrison et al. [68]. 

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