Lactate Sensors

Albareda-Sirvent and Hart [65] L-Malate, l-lactate Wines Lactate oxidase or malate dehydrogenase/in sol-gel matrix Sol-gel thick-film printed graphite electrode (contained NAD+ for malate sensors)/+ 350 mV vs. Ag/AgCl for lactate sensor and -125 mV vs. Ag/ AgCl for malate Meldola s Blue (mediator for the dehydrogenase)... 

I. Rohm, M. Genrich, W. Collier and U. Bilitewski, Development of ultraviolet-polymerizable enzyme pastes bioprocess applications of screen-printed L-lactate sensors, Analyst, 121 (1996) 877-881. 

Kenausis G, Chen Q, Heller A. Electrochemical glucose and lactate sensors based on wired thermostable soybean peroxidase operating continuously and stably at 37°C. 

Ex vivo blood monitoring experiments with human volunteers were performed by placing a device comprising two glucose and two lactate sensors into the sampling line of a double lumen catheter. Venous blood was continuously withdrawn and in line heparinized with a dilution of less then 5 %. 

Fig. 10. L-Lactate sensor reading (solid line) and reference values (boxes) of an IVGTT/OGTT...

Kurita, R., Hayashi, K., Fan, X., Yamamoto, K., Kato, T., Niwa, O., Microfluidic device integrated with pre-reactor and dual enzyme-modified microelectrodes for monitoring in vivo glucose and lactate. Sensors Actuators B 2002, 87, 296-303. 

Recently, Kenausis et al. reported novel glucose and lactate sensors by constructing four polymer coated layers on vitreous carbon, based on wired thermostable soybean peroxidase and redox hydrogels (A) [54]. The first layer... 

Implantable glucose (and lactate) sensors have been based, almost exclusively, on electrochemical transducers. 

Kulys, J.J. and Svirmickas, G.J.S. (1980) Reagentless lactate sensor based on cytochrome-b2. Analytica Chimica Acta, 117,115-120. 

Besides sensors using isolated enzymes, cell-based lactate sensors using cytochrome b2-containing yeast (Hansenula anomala, Saccharo-myces cerevisiae) (Kulys and Kadziauskiene, 1978 Vincke et al., 1985a Hauptmann, 1985 Racek and Musil, 1987) and erythrocytes (Racek, 1987) have also been proposed. 

Blaedel and Jenkins (1976) evaluated two LDH—NAD combinations for a reagentless lactate sensor (Fig. 55). NAD was either coimmobilized with LDH to cellulose or an NAD+-agarose complex was constrained together with LDH to a region near the electrode surface. By bringing the bound NAD into intimate physical contact with the electrode, the immobilized cofactor was recycled electrochemically and reused by the enzyme. This eliminated the need to supply NAD as a reagent. 

Attempts to construct lactate sensors by biochemical modification of electrode surfaces have been made using LDH as well as cytochrome b2. 

With a constant of K = 2.7640-5 mol/1 (pH 7.0, 25°C) the equilibrium of the LDH-catalyzed reaction lies far to the lactate side. This means that whereas for lactate sensors based on LDH the forward reaction has to be forced by alkaline buffer and pyruvate- or NADH-trapping agents, the reduction of pyruvate proceeds spontaneously under normal conditions. This direction of the reaction has been used in a sequence electrode for pyruvate assay (Weigelt et al., 1987b). In the presence of lactate monooxygenase (LMO) lactate formed from pyruvate by LDH is oxidized by molecular oxygen, the consumption of which was indicated at a Clark-type electrode. The enzymes were immobilized in a gelatin membrane. Of course such a sensor measures the concentration of lactate in the sample, too. Therefore it is suited to the determination of the lactate/pyruvate ratio, which is a clinically important parameter. Pro-... 

The normal lactate concentration in blood is between 1.2 and 2.7 mmol/1. For accurate lactate determination hemolysis of the sample is required to account for the (low) lactate content of erythrocytes. On the other hand, the glycolytic reactions in the sample have to be efficiently and rapidly inhibited in order to avoid lactate formation. Therefore the best-suited sample material is deproteinized blood however, the time period inevitably required for its preparation prevents rapid lactate assay. That is why the study of blood lactate sensors focuses not only on the sensor itself but also on the rapid pretreatment of blood samples. 

Kulys, J. J., Svirmickas, G.-J. S., Reagentless Lactate Sensor Based on Cytochrom Bj , Anal. Chim. Acta U7 (1980) 115-120. 

Figure 18-20. Typical response curve, res >onse time, and analytical range of an intrinsic lactate sensor. From [79],...

Examples of enzymes used for biosensors include glucose oxidase for glucose sensors, alcohol oxidase for ethanol sensors, lactate oxidase for lactate sensors and urease for urea sensors. A typical enzyme reaction, as described by equation 5.2 might involve the transfer of an electron, a pH change, hydrolysis, esterification or bond cleavage. The type of enzymatic reaction that occurs determines the type of transducer that is used. 

Electrochemical sensors are used extensively in many biomedical apphcations including blood chemistry sensors, POj, PCOj, and pH electrodes. Many practical enzymatic sensors, including glucose and lactate sensors, also employ electrochemical sensors as sensing elements. Electrochemically based biomedical sensors are found to have in vivo and in vitro apphcations. We believe that electrochemical sensors will continue to be an important aspect of biomedical sensor development. 

Anzai. J. Takeshita. H. Kobayashi. Y. Osa. T. Hoshi. T. Layer-by-layer constmetion of enzyme multilayers on an electrode for the preparation of glucose and lactate sensors Elimination of ascorbate interference by means of an ascorbate oxidase multilayer. Anal. Chem. 1998. 70. 811. 

The reaction is followed by a platinum electrode vs the saturated calomel electrode. The system is relatively insensitive to oxygen concentration. Another example of a reagentless electrode is the lactate sensor demonstrated by Blaedel and Engstrom[154]. The further improvement of reagentless electrodes was achieved by chemical modification of... 

A similar system has been used in construction of a lactate sensor where lactate oxidase (LOD) and lactate dehydrogenase (LDH) were coupled. Using a very thin layer of coimmobilized LOD and LDH a very high amplification effect was reached, about 4100 times [159]. 

Yan, Q., Major, T.C., Bartlett, R.H., Meyerhoff, M.E., 2011. Intravascular glucose/lactate sensors prepared with nitric oxide releasing poly(lactide-cn-glycolide)-based coatings for enhanced biocompatibUity. Biosensors and Bioelectronics 26,4276-4282. 

The sensors for lactate and penicilline in Table 8.5 make use of fluorescence itself rather than fluorescence quenching. The lactate sensors stand for a group of optodes where the inherent fluorescence of NAD (nicotinamide-adenine-dinucleotide, see Chap. 7, Sect. 7.4.2) is evaluated. Reaction (8.8) can be influenced by establishing a specific pH so that it runs either from left to right or right to left. In this way, lactate as well pyruvate sensors can be manufactured. 

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