Hypoxanthine sensor

J.H. Pei and X.Y. Li, Xanthine and hypoxanthine sensors based on xanthine oxidase immobilized on a CuPtCl6 chemically modified electrode and liquid chromatography electrochemical detection. Anal. Chim. Acta 414, 205-213 (2000). 

The micro-hypoxanthine sensor was made by immobilizing xanthine oxidase with bovine serum albumin and glutaraldehyde on the micro-oxygen electrode (Fig. 3.18.D). The detection limit achieved was 6.7 pM and the sensitivity was ca. 10 times higher than that afforded by conventional hypo-xanthine sensors. 

Tamiya E., Seki A., Karube I., Gotoh M. and Shimizu I. (1988) Hypoxanthine sensor based on an amorphous silicon FET. Anal. Chim. Acta, 215, 301-305. 

The principle of antioxidant detection is shown in Fig. 17.3. Superoxide was enzymatically produced and dismutated spontaneously to oxygen and H202. Under controlled conditions of superoxide generation such as air saturation of the buffer, optimal hypoxanthine concentration (100 pM) and XOD activity (50mU ml-1) a steady-state superoxide level could be obtained for several min (580-680 s). Since these steady-state superoxide concentrations can be detected by the cyt c-modified gold electrode, the antioxidate activity can be quantified from the response of the sensor electrode by the percentage of the current decrease. 

A fiberoptic biosensor has been used for the determination of xanthine and hypoxanthine by immobilization of xanthine oxidase and peroxidase on different preactivated membranes, which were mounted onto the tip of the fiberoptic bundle [47], The hydrogen peroxide generated was measured using the luminol reaction. A linear calibration curve of the sensors occurred in the range of 1-316 nM hypoxanthine and of 3.1-316 nM xanthine, respectively, with a detection limit of 0.55 nM. 

In addition to analyzing compounds, enzyme sensor has been used to determine the freshness of meats. Xanthine oxidase has been used to determine the levels of xanthine and hypoxanthine that are accumulated from purine degradation during muscle aging so as to monitor fish freshness for a long time. Traditional methods including the automated colorimetric method (54) were time consuming. Jahn et al (55) developed a dipstick test by... 

P. Kotzian, P. Brazdilova, K. Kalcher and K. Vytras, Determination of hydrogen peroxide, glucose and hypoxanthine using (bio)sensors based on ruthenium dioxide-modified screen-printed electrode, Anal. Lett., 38 (2005) 1099-1113. 

C.A. Marquette, M.F. Lawrence and L.J. Blum, DNA covalent immobilization onto screen-printed electrode networks for direct label-free hybridization detection of p53 sequences, Anal. Chem., 78 (2006) 959-964. J.-M. Zen, Y.-Y. Lai, H.-H. Yang and A.S. Kumar, Multianalyte sensor for the simultaneous determination of hypoxanthine, xanthine and uric acid based on a preanodized nontronite-coated screen-printed electrode, Sens. Actuators B Chem., 84 (2002) 237-244. 

Enz5une sensors or assays exist for the determination of adenosine triphosphate (ATP) and its degradation products inosine 5 -monophosphate (IMP), inosine (HxR), hypoxanthine (Hx) and xanthine (X) as ATP is used as an indicator of the presence of microorganisms and the concentrations of its degradation products are used as indicators for fish and meat freshness in food industry [118]. 

A vast amount of literature exists on enzyme-modified metal nanopartides. Crumbliss and co-workers pioneered the use of metal nanopartides for enzymatic sensors for various analytes such as H2O2, glucose, xanthine and hypoxanthine [156-158]. GCE or Pt electrodes are modified with enzyme-capped Au colloids, either by simple evaporation or electrodeposition. The nanopartides act as mediators, transferring electrons between the redox-active site on the immobilized biomolecule and the electrode and thus eliminating the need for external mediators. These sensors are classified as third generation biosensors . 

Watanabe et al. (1986) developed a sequence sensor for the successive assay of hypoxanthine (HX) and inosine (HXR) by arranging nucleoside phosphorylase (EC 2.4.2.1) and xanthine oxidase (EC 1.2.3.2) in spatially separated layers in front of an oxygen probe. Nucleoside phosphorylase was... 

Gotoh et al. (1988) constructed a sensor for hypoxanthine by immobilizing xanthine oxidase on the gate of an amorphous silicon ISFET. The enzyme-FET responded to HX in the range 0.02-0.1 mmol/1. By coimmobilization of nucleoside phosphorylase, inosine could be measured in the same concentration range. 

For a given substrate, e.g. hypoxanthine, the sensitivity decrased with increasing number of enzymes, i.e. from the monoenzyme electrode to the four-enzyme electrode. The sensitivity of each enzyme sensor decreased likewise in the order HX, HXR, IMP, AMP. This indicates kinetic control by several enzyme reactions. In order to measure the concentrations of all four of the analytes in a sample, the sensitivity of each sensor for each substrate must be known because the current changes are coupled with each other according to ... 

E. Watanabe, S. Tokimatsu, and K. Toyama, Simultaneous Determination of Hypoxanthine, Inosine, Inosine-5 -Phosphate and Adenosine-5 -Phosphate with a Multielectrode Enzyme Sensor. Anal. Chim. Acta, 164 (1984) 139. 

Other metabolites that have been measured with calorimetric sensors include ascorbic acid, ATP/ADP (adenosine 5 -diphosphate), cephalosporins, galactose, hydrogen peroxide, lactose, malate, phospholipids, uric acid, xanthine, and hypoxanthine. 

Hernandez-Cazares, A.S., Aristoy, M.C. and Toldra, F. (2010) Hypoxanthine-based enzymatic sensor for determination of pork meat freshness. Food Chem., 123, 949-954. 

In a series of papers, heated indium tin oxide (ITO) electrodes were proposed as carriers for electrochemiluminescent sensors of diverse analytes [70-74]. The system couples the advantages of a heated electrode with the optical transparency property of ITO glass. In [70], H2O2/MCLA and TPrA/Ru(bpy)3 have been used to test the arrangement which was constructed very similar to the scheme given in Fig. 6.15. In [71], TPrA and colchicine were detected in human serum by means of the ruthenium bipyridyle ECL system. Immobilised xanthine oxidase as a sensor system for hypoxanthine has been mentioned already. It has been used also with a heated ITO electrode [72]. Further examples for electrochemiluminescence detection with heated ITO electrodes were the analysis of Ns-methyladenosine in urine... 

The sensitivity of biosensors towards biological products means that they are particularly suitable for monitoiing ingredients, food additives, contaminants, and toxins. A glucose electrode can determine the freshness of meat by the glucose consumption of the microbes on its surface [283]. Similarly, the fteshness of fish is indicated by a sensor that is sensitive to hypoxanthine, inosine and inosine-5 -mono-phosphate [284, 285]. There are multiple uses for biosensors in the food produce industry, such as the determination of lactate for the... 

Watanabe E., Endo H. and Toyama K. (1988) Detomination of inosine-5 -monophosphate in the presence of inosine and hypoxanthine with an enzyme sensor. Appl. Microb. BiotechnoL, 29, 341-345. 

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