Buffers, Electrodes, and Biosensors

C Mathews, K vanHolde, and K Ahem, Biochemistry (2000), Benjamin/Cummings (San Francisco), pp 33-50 Review of pH, buffers, and water chemistry J Risley,/ Chem. Educ. 68,1054 (1991) Prepanng Solutions in the Biochemistry Lab. J Wang and C Macca,/. Chem. Educ. 73, 797 (1996) Use of Blood-Glucose Strips for Introducing Enzyme Electrodes and Modern Biosensors ... 

The three electrodes biosensor as working electrode, the Ag/AgCl as reference electrode and the platinum as auxiliary electrode are immersed in a 10-mL electrochemical cell containing 5.0 mL of 0.05 M phosphate buffer solution (pH 6.0). Under continuous magnetic stirring, apply a potential of +150 mV. 

Carbo q lic groups of CNTs/SPE disposable electrodes were activated by reaction with EDAC/NHS in a buffer solution allowing incubation for a certain time. In a parallel way the target to be determined, ceruloplasmin, was dissolved in the same buffer solution and then dropped on the CNTs modified surface, as described by the whole detailed procedure in Fig. 7. This strategy provided a rapid, sensitive and low cost electrochemical biosensor for portable screening for the determination ceruloplasmin in human serum. 

The pH electrode is another suitable transducer for the construction of a urea biosensor. The classical glass electrode is sensitive to H ions and urease is attached in a gel of either polyacrylamide [107] or methacrylamide-aoylamide cqxdymer [108]. me metallic electrodes are also sensitive to H ions (for example, the antimony electrode) and can also be used in conjunction with a urease membrane [109]. The enzyme pH electrode detects a very weak variation in proton concentration arising from an enzymatic reaction, and the signal amplitude is determined by the buffering capacity of the solution. Both the nature of the buffer solution and the working pH value of the biosensor can reduce its practical use. A differential measurement at different pH values can be used to correct for any variation. 

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