Glucose oxidase--an overview.

Glucose oxidase (GOX) from Aspergillus niger is a well-characterised glycoprotein consisting of two identical 80-kDa subunits with two FAD co-enzymes bound. Both the DNA sequence and protein structure at 1.9 A have been determined and reported previously. GOX catalyses the oxidation of D: -glucose (C(6)H(12)O(6)) to D: -gluconolactone (C(6)H(10)O(6)) and hydrogen peroxide. GOX is produced naturally in some fungi and insects where its catalytic product, hydrogen peroxide, acts as an anti-bacterial and anti-fungal agent. GOX is Generally Regarded As Safe, and GOX from A. niger is the basis of many industrial applications. GOX-catalysed reaction removes oxygen and generates hydrogen peroxide, a trait utilised in food preservation. GOX has also been used in baking, dry egg powder production, wine production, gluconic acid production, etc. Its electrochemical activity makes it an important component in glucose sensors and potentially in fuel cell applications. This paper will give a brief background on the natural occurrence, functions as well as the properties of glucose oxidase. A good coverage on the diverse uses of glucose oxidase in the industry is presented with a brief outline on the working principles in the various settings. Furthermore, food grade GOX preparations are relatively affordable and widely available; the readers may be encouraged to explore other potential uses of GOX. One example is that GOX-catalysed reaction generates significant amount of heat (~200 kJ/mol), and this property has been mostly neglected in the various applications described so far.

Glucose oxidase: natural occurrence, function, properties and industrial applications

There is an urgent need in the medical diagnostics laboratories for accurate, fast and inexpensive devices, which can be routinely used. The reliable and accurate information on the desired biochemical parameters is an essential prerequisite for effective healthcare. In this context, biosensors are considered to provide viable solutions to the problems posed by the contemporary healthcare industry. This is because these biosensing devices offer considerable advantages, such as specificity, small size faster response and cost. It is anticipated that these bioanalytical tools can be used for frequent measurements of metabolites, blood cations and gases, etc. In this paper, an attempt has been made to highlight some of the trends that rule the research and developments of some of the important biosensors that are likely to accelerate the growth of clinical diagnostics industry.

Biosensors for clinical diagnostics industry

http://rua.ua.es/dspace/bitstream/10045/65156/2/2017_Abellan-Llobregat_etal_BIOS_preprint.pdf

A stretchable and screen-printed electrochemical sensor for glucose determination in human perspiration.

Principles and applications of thermal biosensors.

Evaluation of a miniaturized thermal biosensor for the determination of glucose in whole blood

A miniaturized flow-injected thermal biosensor was developed for the determination of urea and L-lactate in undiluted blood in 1-microL samples. The sensor employed a small enzyme column constructed of stainless steel tubing and microbead thermistors. Urease and lactate oxidase/catalase were separately immobilized onto controlled-pore glass beads, which, in turn, were charged into the enzyme column. With a flow rate of 70 microL/min, linear analytical ranges from 0.2 to at least 50 mmol/L and 0.2 to 14 mmol/L were obtained for urea and lactate, respectively. The relative standard deviations (CVs) for measurements of analyte in buffer were 0.91% for urea and 1.84% for lactate. For urea in whole blood, the CV for 50 determinations was 4.1%. Contrived samples containing various concentrations of urea and L-lactate in whole blood were determined with this sensor and with a spectrophotometric method. Comparisons of the results gave correlation coefficients of 0.989 and 0.984 for 30 blood urea and 30 blood lactate assays in concentrations ranging from 4 to 20.9 mmol/L and from 1.7 to 12.7 mmol/L, respectively.

Urea and lactate determined in 1-microL whole-blood samples with a miniaturized thermal biosensor.

The glucose concentration in diluted whole blood has been measured, using a miniaturized thermal biosensor based on the enzyme thermistor principle. The biosensor is a small flow injection system. A sample volume of 20μl is injected into a flow of 50μl/min. The heat produced when the sample passes the enzyme column is measured with a thermistor connected to a Wheatstone bridge. The enzyme column contains glucose oxidase and catalase co-immobilized on a solid support material. Samples of whole blood usually cause problems in flow-systems. The blood cells tend to block the enzyme column and the back pressure increases. We have tested a superporous agarose material as enzyme support material using tenfold diluted samples of whole human blood. The blood was collected from the finger-tip and diluted with buffer containing an anticoagulant and sodium fluoride. The number of samples possible to inject and the accuracy compared to the Boehringer Mannheim Reflolux have been determined. At least 100 ten-fo...

Ulrika Harborn

Papers

Evaluation of a miniaturized thermal biosensor for the determination of glucose in whole blood

Urea and lactate determined in 1-microL whole-blood samples with a miniaturized thermal biosensor.

Determination of Glucose in Diluted Blood with a Thermal Flow Injection Analysis Biosensor