Creatinine Sensors

The bacteria consume oxygen during ammonia oxidation, so oxygen depletion can be detected by using an oxygen electrode. A combined creatinine sensor thus consists of a cellulose dialysis membrane, immobilized creatinine deaminase, immobilized nitrifying bacteria and an oxygen electrode [130]. 

Scheller s group [87] generated creatinine-specific antibodies for sensitive and specific immunochemical creatinine determinations in a reusable sensor. The creatinine sensor was constructed by fixing a creatinine-modified membrane on top of a platinum working electrode, which was then incorporated into a stirred electrochemical measuring cell. For creatinine... 

Meyerhoff and Rechnitz (1976) developed a potentiometric creatinine sensor by inclusion of creatinine iminohydrolase between the gas-permeable membrane of an ammonia electrode and a dialysis membrane. Since the specific activity of the enzyme used was very low, 0.1 U/mg, only 43 mU could be entrapped at the electrode. Therefore the sensor was kinetically controlled and reacted to addition of the enzyme activator tripolyphosphate by an increase in sensitivity from 44 mV to 49 mV per concentration decade and a corresponding decrease of the detection limit. These effects agree with theoretical considerations of reaction-transport coupling. The samples were treated with a cation exchanger to remove endogenous serum ammonia. 

Panasyuk-Delaney, T. Mirsky, V.M. Wolfbeis, O.S. Capacitive creatinine sensor based on a photografted molecularly imprinted polymer. Electroanalysis 2002,14 (3), 221-224. 

To create a potentiometric creatinine sensor, creatinine iminohydrolase, which catalyzes the production of ammonia from creatinine, can be immobilized on the surface of an ammonium ion selective electrode. There is no interference from creatine but some from the ammonium ions in blood and urine. 

Patel, A.K. Sharma, P.S. Prasad, B.B. Development of a creatinine sensor based on a molecularly imprinted polymer-modified sol-gel film on graphite electrode. Electroanalysis 2008, 20 (19), 2102 2112. 

Del Moral, P. Diez, M.T. Resines, J.A. Bravo, I.G. An n, M.J. Simultaneous measurements of creatinine and purine derivatives in ruminant s urine using ion-pair HPLC. J. Liq. Chromatogr. Rel. Technol. 2003, 26 (17), 2961 2968. Patel, A.K. Sharma, P.S. Prasad, B.B. Development of a creatinine sensor based on a molecularly imprinted polymer-modified sol-gel film on graphite electrode. Electroanalysis 2008, 20 (19), 2102-2112. 

Creatinine Creatine deaminase N-Methylhydantoin, NH4 Tris/NaH2P04 pH 8.5 NH3-Gas-Sensor 1-100 mg %... 

One of the pitfalls of microbial sensors, viz. their low selectivity, can be overcome by combining cells with an immobilized enzyme. Thus, creatinine deaminase (CDA, EC 3.5.4.21) hydrolyses creatinine to N-methylhydantoin and ammonium ion, the ammonia produced being successively oxidized to nitrite and nitrate ion by nitrifying bacteria. These bacteria have not yet been characterized but are known to be a mixed culture of Nitrosomonas sp. and Nitrobacter sp. The reaction sequence involved is as follows ... 

Electrochemical transducers work based on either an amperometric, potentio-metric, or conductometric principle. Further, chemically sensitive semiconductors are under development. Commercially available today are sensors for carbohydrates, such as glucose, sucrose, lactose, maltose, galactose, the artificial sweetener NutraSweet, for urea, creatinine, uric acid, lactate, ascorbate, aspirin, alcohol, amino acids and aspartate. The determinations are mainly based on the detection of simple co-substrates and products such as 02, H202, NH3, or C02 [142]. 

Substitution of other oxoreductase enzymes for glucose oxidase allows amperometric biosensors for other substrates of clinical interest to be constructed. Practical sensors with commercial application in critical care analyzers for blood lactate have been realized. Other amperometric biosensors reported include cholesterol, pyruvate, alanine, glutamate, and glutamine. By using the multiple enzyme cascade shown in the reactions below, an amperometric biosensor for creatinine is also possible. Electrochemical oxidation of H2O2 is the detection mechanism. 

Ho, W. O. Krause, S. McNeil, C. J. Pritchard, J. A. Armstrong, R. D. Athey, D. Rawson, K., Electrochemical sensor for measurement of urea and creatinine in serum based on ac impedance measurement of enzyme-catalyzed polymer, Anal. Chem. 1999, 71, 1940-1946... 

The combination of the creatinine-converting enzymes with sensors indicating primary reaction products, such as ion sensitive electrodes, NH3 gas sensors, or thermistors, is an effective alternative to enzyme sequence sensors (see Section 3.2.1). Enzyme reactors as well as true biosensors for creatinine have been described. 

For creatine determination the appropriate bienzyme electrode was used. Creatinine and creatine could be assayed in parallel by combining a trienzyme electrode and a bienzyme electrode. Both electrodes reached a steady signal 2 min after sample addition. With a 25 pi sample volume the linear range was 1-100 mg/1. The sensors were stable for more than 500 measurements. The CV of creatine determination in serum was 1.3% with 21.7 mg/1 and 11.7% with 8.2 mg/1, and a day-to-day CV of 8.4% was achieved. Comparison with the Jaffe method for 55 serum... 

Fiber-optic sensors may also be combined to form a bundle of fiber applicable to the simultaneous sensing of, eg, physiological pH, oxygen, electrolytes, anesthetics, glucose, creatinine, temperature, and flow rate. This is possible because of the minute size of the fibers. There is considerable industrial activity in this direction. 

Creatinine Crealininase Creatinine— N-melhylhydanioin + NH3 NHj-gas sensor NH -glass or polymer... 

This membrane is designed for a sensor which has a layered structure. The sensor can measure glucose, lactate, urea, and creatinine. The membrane is composed of polymer, surfactant, and hydrophyllic compound. Upon conditioning, the membrane structure includes a system of pores which give the membrane excellent permeability. 

Other simulation experiments performed in our laboratory include design of MIP adsorbents for solid-phase extraction of atrazine [77], DDT, lindane, aflatoxin Bl, ochratoxin A, and tylosin (unpublished data) and the development of assay/ sensor recognition elements for biotin (unpublished data) and creatinine [78]. In all these cases, molecular modeling proved to be a useful tool for MIP design. It would... 

In an early approach towards MIP-based sensors using capacitance measurement, thin MIP membranes were prepared by in situ polymerization of MAA/ EDMA and then sandwiched as a sensing layer in afield effect device a capacitance decrease was observed due to specific binding of the template L-phenylalanine anilide [103]. Recently, two promising alternative approaches towards ultrathin MIP films for capacitive sensors had been reported electropolymerization of phenol for imprinting of phenylalanine [74], and photo-initiated graft copolymerization of AMPS/MBAA for imprinting of desmetryn [82] and creatinine [83] (cf Sections III.C.2, III.C.3). 

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