Membrane enzymatic

In this case study, an enzymatic hydrolysis reaction, the racemic ibuprofen ester, i.e. (R)-and (S)-ibuprofen esters in equimolar mixture, undergoes a kinetic resolution in a biphasic enzymatic membrane reactor (EMR). In kinetic resolution, the two enantiomers react at different rates lipase originated from Candida rugosa shows a greater stereopreference towards the (S)-enantiomer. The membrane module consisted of multiple bundles of polymeric hydrophilic hollow fibre. The membrane separated the two immiscible phases, i.e. organic in the shell side and aqueous in the lumen. Racemic substrate in the organic phase reacted with immobilised enzyme on the membrane where the hydrolysis reaction took place, and the product (S)-ibuprofen acid was extracted into the aqueous phase. 

Long, W.S., Kamaruddin, A.H. and Bhatia, S. (2005) Enzyme kinetics of kinetic resolution of racemic ibuprofen ester using enzymatic membrane reactor. Chemical Engineering Science, 60 (18), 4957—1970. 

MWNTs favored the detection of insecticide from 1.5 to 80 nM with a detection limit of InM at an inhibition of 10% (Fig. 2.7). Bucur et al. [58] employed two kinds of AChE, wild type Drosophila melanogaster and a mutant E69W, for the pesticide detection using flow injection analysis. Mutant AChE showed lower detection limit (1 X 10-7 M) than the wild type (1 X 10 6 M) for omethoate. An amperometric FIA biosensor was reported by immobilizing OPH on aminopropyl control pore glass beads [27], The amperometric response of the biosensor was linear up to 120 and 140 pM for paraoxon and methyl-parathion, respectively, with a detection limit of 20 nM (for both the pesticides). Neufeld et al. [59] reported a sensitive, rapid, small, and inexpensive amperometric microflow injection electrochemical biosensor for the identification and quantification of dimethyl 2,2 -dichlorovinyl phosphate (DDVP) on the spot. The electrochemical cell was made up of a screen-printed electrode covered with an enzymatic membrane and combined with a flow cell and computer-controlled potentiostat. Potassium hexacyanoferrate (III) was used as mediator to generate very sharp, rapid, and reproducible electric signals. Other reports on pesticide biosensors could be found in review [17],... 

Long, W.S. Kamaruddin, A.H. andBhatia, S., Chiral Resolution of Racemic Ibuprofen Ester in an Enzymatic Membrane Reactor. Journal of Membrane Science., 2005, 247, 185-200. 

Zumft, W. G., and Frunzke, K. (1982). Discrimination of ascorbate-dependent nonenzy-matic and enzymatic, membrane-bound reduction of nitric oxide in denitrifying Pseudomonas perfectomarinus. Biochim. Biophys. Acta 681, 459-468. 

It should also be pointed out that in the case of an in vivo measurement, the microdialysis probe will be able to recover not only glucose but also many other biological compounds with low molecular weight from the subcutaneous tissue. The electrochemical interferents are greatly reduced by the use of PB at a low applied potential. However, other biological compounds could negatively affect the stability of the enzymatic membrane. Also, it is possible to have a sort of passivation or fouling of the electrode surface due to the absorption of... 

Recent studies in the pharmaceutical field using MBR technology are related to optical resolution of racemic mixtures or esters synthesis. The kinetic resolution of (R,S)-naproxen methyl esters to produce (S)-naproxen in emulsion enzyme membrane reactors (E-EMRs) where emulsion is produced by crossflow membrane emulsification [38, 39], and of racemic ibuprofen ester [40] were developed. The esters synthesis, like for example butyl laurate, by a covalent attachment of Candida antarctica lipase B (CALB) onto a ceramic support previously coated by polymers was recently described [41]. An enzymatic membrane reactor based on the immobilization of lipase on a ceramic support was used to perform interesterification between castor oil triglycerides and methyl oleate, reducing the viscosity of the substrate by injecting supercritical CO2 [42],... 

The hydrolysis of caroteno-proteins for the production of astaxanthin using protease was developed in an enzymatic membrane bioreactor [19], in which the concentration of the protein fraction by ultrafiltration and the separation of the pigments in the permeate were simultaneously carried out. 

A very interesting field in membrane bioreactors is the production of cyclodextrins or oligosaccharides. In general, they have applications in food pharmaceutical, cosmetic agricultural, and plastics industries as emulsifiers, antioxidant, and stabilizing agents. In the food industry cyclodextrins are employed for the preparation of cholesterol-free products. The use of enzymatic membrane reactors to produce... 

The selection ofthe membrane to be used in enzymatic membrane reactors should take into account the size of the (bio)catalyst, substrates, and products as well as the chemical species ofthe species in solution and ofthe membrane itself. An important parameter to be used in this selection is the solute-rejection coefficient, which should... 

The first published information on the industrial application of a hybrid system with a HF contactor for production of the drug dilthiazem intermediate was reported by Lopez and Matson [23]. An enzymatic resolution of dilthiazem chiral intermediate is realized in an extractive enzymatic membrane reactor. The enzyme is entrapped in the macroporous sponge part of the hydrophilic hollow-fiber membrane made of a... 

On-wafer membrane deposition and patterning is an important aspect of the fabrication of planar, silicon based (bio)chemical sensors. Three examples are presented in this paper amperometric glucose and free chlorine sensors and a potentiometric ISRET based calcium sensitive device. For the membrane modified ISFET, photolithographic definition of both inner hydrogel-type membrane (polyHEMA) and outer siloxane-based ion sensitive membrane, of total thickness of 80 pm, has been performed. An identical approach has been used for the polyHEMA deposition on the free chlorine sensor. On the other hand, the enzymatic membrane deposition for a glucose electrode has been performed by either a lift-off technique or by an on-chip casting. 

In order to maintain the advantage of the microfabrication approach which is intended for a reproducible production of multiple devices, parallel development of membrane deposition technology is of importance. Using modified on-wafer membrane deposition techniques and commercially available compounds an improvement of the membrane thickness control as well as the membrane adhesion can be achieved. This has been presented here for three electrochemical sensors - an enzymatic glucose electrode, an amperometric free chlorine sensor and a potentiometric Ca + sensitive device based on a membrane modified ISFET. Unfortunately, the on-wafer membrane deposition technique could not yet be applied in the preparation of the glucose sensors for in vivo applications, since this particular application requires relatively thick enzymatic membranes, whilst the lift-off technique is usable only for the patterning of relatively thin membranes. 

Immobilized HRP onto a polyacrylonitrile membrane A membrane with a specific HRP activity of 1.15 U/g of support dry wt was obtained. After an operation period of 35 h, the enzymatic membrane had a specific productivity of 59.5 pmol of H202 reduced/Qi-Uimmob hrp) [42]... 

Other Applications of One-Stage Enzymatic Membrane Reactors.273... 

When looking for an economically feasible enzymatic system, retention and reuse of the biocatalyst should be taken into account as potential alternatives [98, 99]. Enzymatic membrane reactors (EMR) result from the coupling of a membrane separation process with an enzymatic reactor. They can be considered as reactors where separation of the enzyme from the reactants and products is performed by means of a semipermeable membrane that acts as a selective barrier [98]. A difference in chemical potential, pressure, or electric field is usually responsible from the movement of solutes across the membrane, by diffusion, convection, or electrophoretic migration. The selective membrane should ensure the complete retention of the enzyme in order to maintain the full activity inside the system. Furthermore, the technique may include the integration of a purification step in the process, as products can be easily separated from the reaction mixture by means of the selective membrane. 

Enzymatic membrane reactors are classified in three main categories ... 

Fig. 10.3 Scheme of an enzymatic membrane reactor for the decolorization of the azo dye Orange II by manganese peroxidase... 

Table 10.3 Effect of MnP addition mode in dye decolorization (A) and efficiency (B) in the enzymatic membrane reactor with an Orange II concentration in the influent of 100 mg/L and HRT of 1 h...

Fig. 10.6 Experimental (open circle) and simulated data (Line) in the enzymatic membrane reactor with HRT of 72 min. Initial Orange II concentration 91.1 mg/L H202 addition rate 15 pmol/(L min)...

Lopez C, Moreira MT, Feijoo G et al (2004) Dye decolorization by manganese peroxidase in an enzymatic membrane bioreactor. Biotechnol Prog 20 74-81... 

Lopez C, Mielgo I, Moreira MT et al (2002) Enzymatic membrane reactors for biodegradation of recalcitrant compounds. Application to dye decolourisation. J Biotechnol 99 249-257... 

Prazeres DMF, Cabral JMS (1994) Enzymatic membrane bioreactors and their applications. Enzyme Microb Technol 16 738-750... 

Rios GM, Belleville MP, Paolucci D et al (2004) Progress in enzymatic membrane reactors -a review. J Membr Sci 242 189-196... 

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