Development of a micro-planar amperometric bile acid biosensor for urinalysis

Development of new disposable NADH biosensors based on NADH oxidase

“…Several reports described the use of the electrochemical oxidation of H 2 O 2 (Reaction (2)) as an indicator reaction for the quantification of NADH in solution or when produced by a dehydrogenase based reaction [13][14][15][16][17][18][19][31][32][33][34][35]. Two drawbacks are associated with such a detection system.…”

“…The first is the high oxidation potential needed to achieve Reaction (2) which favours the oxidation of many interfering products [36,37]. The second is the need to add significant amounts of FAD or FMN to activate NADox so that Reaction (1) is completed at a reasonable speed [13][14][15][16][17][18][19][31][32][33][34][35]. This represents two significant inconveniences for developing NADox based biosensors which can be used in real industrial conditions.…”

“…Previous reports on the use of NADox for the oxidation of NADH with O 2 as natural electron acceptor mentioned, whatever the origin of the enzyme [12,13,[15][16][17][18][19], the necessity to add a flavin cofactor (FAD or FMN) to activate the enzyme since the cofactor is not bound to the active site of the enzyme [13][14][15][16]. In an earlier work [29] we showed that the NADox from Thermus thermophilus could oxidize NADH using O 2 or ferricinium derivatives as electron acceptors without adding any extra FMN or FAD.…”

“…The oxidation of NADH with the regeneration of active NAD + can be achieved by enzymatic means and the biosensor behaviour is as favourably influenced as this oxidation is rapid and complete. The enzymes commonly used for this oxidation are lipoamide dehydrogenase [10], diaphorase [11,12] and NADH oxidase (NADox) [13][14][15][16][17][18]. Comparatively the latter enzyme has the advantage of being more stable and less sensitive to pH variations [19].…”

Immobilized enzymatic fluorescence capillary biosensor for determination of sulfated bile acid in urine

“…So they cannot be adapted to actual clinic assay. Besides, other methods were also reported for the determination of SBAs, such as monoclonal antibody-based enzyme-linked immunosorbent assay (Kobayashi et al, 2000), amperometric method (Koide et al, 2007) and electrospray ionization mass spectrometry (Shinka et al, 2007), etc. These methods possess some good characteristics, but they still need further perfection and simplification.…”