Micro enzyme reactor

Micro Enzyme Reactors (yilMERS) and Total Analysis Systems (/[Pg.531]

Micro enzyme reactor for continuous glucose monitoring pSi is fabricated on high aspect ratio Si microstmctures of the reactor by electrochemical etch Surface enlarging effect, 100-fold increase in enzyme activity Drott et al. 1998... 

Jiang, Y. and Lee, C.S. (2001) On-line coupling of micro-enzyme reactor with micro-membrane chromatography for protein digestion, peptide separation, and protein identification using electrospray ionization mass spectrometry. 

In fermentation reactors, cell growth is promoted or maintained to produce metabolite, biomass, transformed substrate, or purified solvent. Systems based on macro-organism cultures are usually referred as tissue cultures. Those based on dispersed non-tissue forming cultures of micro-organisms are loosely referred as microbial reactors. In enzyme reactors, substrate transformation is promoted without the life-support system of whole cells. Frequently, these reactors employ immobilized enzymes, where an enzyme is supported on inert solids so that it can be reused in the process. Virtually all bioreactors of technological importance deal with a heterogeneous system involving more than two phases. 

Microbial bioreactors differ from enzyme reactors with regard to the fact that the biocatalyst (micro-organism) grows with the progress of the reaction (i.e., it is an autocatalytic process). 

Components incorporated in chemical analysis systems are rapidly being developed in micro scale. Today microstructured pumps, valves and flow channels are already available, [1]. Micro scaled flow transducers and temperature sensors as well as chemical sensors i.e. PO2, PCO2, pH, [2], have also been developed. Flow injection analysis systems commonly use enzyme reactors for the analysis of more complex components, and until recently little work has been done on the wafer integration of enzyme reactors [3,4]. 

Bartolini, M., Cavrini, V., and Andrisano, V. (2004) Monolithic micro-immobilised-enzyme reactor with human recombinant acetylcholinesterase for online inhibition studies./. Chromatogr. A, 1031,27-34. 

Celebi B, Bayraktar A, Tuncel A (2012) Synthesis of a monolithic, micro-immobilized enzyme reactor via click-chemistry. Anal Bioanal Chem 403(9) 2655-2663... 

The values of the Michaelis-Menten kinetic parameters, Vj3 and C,PP characterise the kinetic expression for the micro-environment within the porous structure. Kinetic analyses of the immobilised lipase in the membrane reactor were performed because the kinetic parameters cannot be assumed to be the same values as for die native enzymes. 

The experimental results in Fig. 27 show the influence of the reactor system (see Fig. 28) on the disintegration of enzyme activity. It was found that the low-stress bladed impeller results in less activity loss than the propeller stirrer which causes much higher maximum energy dissipation ,. The gentle motion the blade impeller produces means that stress is so low that its disadvantage of worse micro mixing in NaOH (in comparison with the propeller) is more than compensated. 

Concerning function integration, for example, micro-flow membrane reactors can exhibit similar process intensification, as shown already for their large-scale counterparts [75]. Separation columns for proteomics, immobilizing enzymes, utilize the large surface-to-volume ratios. Surface tension differences can guide and transport liquids selectively. 

Membrane reactors can be considered passive or active according to whether the membrane plays the role of a simple physical barrier that retains the free enzyme molecules solubilized in the aqueous phase, or it acts as an immobilization matrix binding physically or chemically the enzyme molecules. Polymer- and ceramic-based micro- and ultrafiltration membranes are used, and particular attention has to be paid to the chemical compatibility between the solvent and the polymeric membranes. Careful, fine control of the transmembrane pressure during operation is also required in order to avoid phase breakthrough, a task that may sometimes prove difficult to perform, particularly when surface active materials are present or formed during biotransformahon. Sihcone-based dense-phase membranes have also been evaluated in whole-cell processes [55, 56], but... 

There is an increasing number of areas where bioreactors are serious alternatives to conventional chemical reactors, particularly when their mild conditions and high selectivity can be exploited. In the pharmaceutical industry micro-organisms and enzymes can be used to produce specific stereo-isomers selectively, a very desirable ability since it can be that only the one isomer (possibly an optical isomer) may possess the required properties. In such applications the limitations of bioreactors are clearly outweighed by the advantages in their use. The fact that the products are formed in rather dilute aqueous solution and at relatively low rates may be of secondary importance and it may then be economically feasible to employ multiple separation stages in their purification. 

Chapter 5, on Biochemical Engineering, has been completely rewritten in two sections by Dr R. L. Lovitt and Dr M. G. Jones with guidance from the previous author, Professor B. Atkinson. The earlier part deals with the nature of reaction processes controlled by micro-organisms and enzymes and is prefaced by background material on the relevant microbiology and biochemistry. In the latter part, the process engineering principles of biochemical reactors are discussed, and emphasis is given to those features which differentiate them from the chemical reactors described previously. 

Membrane bioreactors have been reviewed previously in every detail [3,4,7,8,18], There are two main types of membrane bioreactors (i) the system consists of a traditional stirred-tank reactor combined with a membrane separation unit (Figure 14.1) (ii) the membrane contains the immobilized biocatalysts such as enzymes, micro-organisms and antibodies and thus, acts as a support and a separation unit (Figure 14.2). The biocatalyst can be immobilized in or on the membrane by entrapment, gelification, physical adsorption, ionic binding, covalent binding or crosslinking [3, 7, 18]. Our attention will be primarily focused on the second case where the membrane acts as a support for biocatalyst and as a separation unit, in this study. The momentum and mass-transport process, in principle, are the same in both cases, namely when there is... 

For periodic reuse of the enzymes a new project was developed including a microreactor incorporated into the FIA system. The micro-reactor shown in Fig. 2, made of acrylic acid and with a 0.91-mL void volume, and length-to-diameter ratio of 3 1, was packed with AOD immobilized on glass beads. The beads were retained in the microreactor with a 110-mesh nylon screen and two rubber O-rings with an 11.4-mm external diameter. The lids were attached to the microreactor with four stainless steel screws. 

Another important research direction is the mimieking of enzymes and the construction of selective catalysts. For these purposes, the polymer is imprinted with the desired reaetion-product or better, a molecule which resembles the transition state of the reaction adducts. If the educts bind specifically to the recognition site, they become confined into these micro-reactors and are supposed to react faster and more defined than outside the cavities [445]. Examples for reactions in the presence of such synthetic enzymes can be found in [452,453,454,455,456,457] (cf Figure 40c). First positive results have been reported, e.g. an synthetic esterase , increasing the rate of alkaline hydrolysis of substituted phenyl-(2-(4-carboxy-phenyl)-acetic esters for 80 times [488] and Diels-Alder catalysis fiuic-tional holes containing titanium lewis-acids [489]... 

---