Review of designing an information processing ware for a diabetic chip.

Miniaturization of clinical chemistry analyzers can empower research conducted to better understand, diagnose, manage, and cure diseases such as diabetes. For the last decade, we have been working on the design and development of miniaturized clinical chemistry devices, including a Diabetic Chip (diabetiChip). These devices measure a small array of analytes, are small, portable, fast, easy-to-operate, and inexpensive. The chosen analytical method for the diabetiChip uses bioluminescence, which is highly sensitive and specific, and is based on photon counting and specific enzymatic reactions. Bioluminescent reactions were intentionally chosen for analyzing metabolic reactions because they use some of the central nodes of metabolism, such as adenosine triphosphate. Operations of the diabetiChip's information processing ware are the focus of this paper; we show the feasibility of using a set of kinase-containing enzymatic reactions of a firefly bioluminescence-coupled glucose assay in designing the diabetiChip. We have developed and tested the feasibility of the glucose assay; the assay's analytical detection limits (before sample dilution) were 5-185 microM. Uncertainty associated with reporting a 100 microM concentration was about +/- 5 microM. The results show that an FFL bioluminescent-coupled glucose assay is promising in terms of reducing sample volume and cost. The concept of GlucoFaces in visualizing measurements of the diabetiChip is also discussed.

An ImmunoChip prototype for simultaneous detection of antiepileptic drugs using an enhanced one-step homogeneous immunoassay.

The development and characterization of a one-step homogeneous immunoassay-based multiwell ImmunoChip is reported for the simultaneous detection and quantitation of antiepileptic drugs (AEDs). The assay platform uses a cloned enzyme donor immunoassay (CEDIA) and a Beta-Glo assay system for generation of bioluminescent signal. Results of the one-step CEDIA for three AEDs (carbamazepine, phenytoin, and valproic acid), in the presence of serum, correlate well with the values determined by fluorescence polarization immunoassay. CEDIA intra- and interassay coefficients of variation are less than 10%. A microfabrication process, xurography, was used to produce the multiwell ImmunoChip. Assay reagents were dispensed and lyophilized in a three-layer pattern. The multiwell ImmunoChip prototype was used to detect and quantify AEDs in serum samples containing all three drugs. Luminescent signals generated from each well were recorded with a charge-coupled device (CCD) camera. The assays performed on an ImmunoChip were fast (5 min), requiring only small volumes of both the reagents (<1 microl/well) and the serum sample. The ImmunoChip assay platform described in this article may be well suited for therapeutic monitoring of drugs and metabolites at the point-of-care setting.

Homogeneous enzyme immunoassay modified for application to luminescence-based biosensors.

Application of immunoassay to biosensors for use in the point-of-care setting ideally requires immunoassay without separation steps and with small volumes of both sample and reagents. The suitability of cloned enzyme donor immunoassay (CEDIA), one of a few homogeneous immunoassays available, was investigated for application to biosensors. This method is based on the bacterial enzyme beta-galactosidase, which has been genetically engineered by others into two inactive fragments, enzyme donor (ED) and enzyme acceptor (EA). Association of the ED and EA fragments in the assay results in formation of active enzyme, which acts on substrate to generate a detectable signal. Sensitivity of commercially available CEDIA kits were compared, with respect to the sample and reagent volumes, using three different signal generation processes. The CEDIA kit for valproic acid and three substrates, a colorimetric (chlorophenol red-beta-D-galactopyranoside), a chemiluminescent (Lumi-Gal 530), and a bioluminescent (Beta-Glo Assay System), were employed in the study. Our results indicate that the high sensitivity of the bioluminogenic substrate, D-luciferin-O-beta-galactopyranoside, with short assay time and small volumes of sample and reagents required for the assay, simple handling, and relatively low expense, make this substrate, together with CEDIA, suitable for application to biosensors intended for drug and metabolite monitoring in the point-of-care setting.

Modeling of homogeneous cloned enzyme donor immunoassay.

One of the most widely used analytical techniques for sensitive detection of biologically and clinically significant analytes is the immunoassay. In recent years direct immunoprobes allowing label-free detection of the interaction between the antibody and the target analyte have proved their capabilities as fast, simple, and nevertheless highly sensitive methods. Cloned enzyme donor immunoassay (CEDIA) homogeneous assay is based on the bacterial enzyme beta-galactosidase, which has been genetically engineered into two inactive fragments, enzyme donor and enzyme acceptor. Reassociation of the fragments in the assay forms active enzyme, which acts on substrate to generate a colored product. A comprehensive kinetic model of CEDIA is developed to aid in understanding this method and to facilitate development of a truly homogeneous version, potentially applicable to a dipstick-type multianalyte point of care analytical device (ChemChip). Although the standard assay involves a two-step process, we also chose to model a single-combined process, which would be simpler to apply in a ChemChip device. From the modeling simulation, we obtain the time courses of the amounts of product and active enzyme, from which the dynamic ranges can be obtained as 10(-6)-10(-7) and 10(-5)-10(-7)M analyte concentration for two-step and single-combined processes under the conditions of the assumed parameters, respectively. A simple one-step immunoassay has the merit of reducing time and cost and has an improved dynamic range.

Public adventures in diabetes: personal interactivity in a modern science center.

About 100 million Americans visit science centers each year to participate in experiential science and technology activities. There is great potential for diabetes awareness and education via the several hundreds of science centers in the United States. Most science centers tend to avoid medically related topics in part because of the difficulty in meeting the interactive goals of science center activities. The Utah Science Center (USC) is addressing these difficulties by creating environments for personal interactive activities in a range of medically related topics, including diabetes. The USC will open in early 2005 in Salt Lake City. The design of diabetes activities for the USC is reviewed: (1) activities (aims, description, stages of development, and partnerships); (2) specific stage I activities (body mass index, "feeling" hypoglycemia, and urine chemistry); and (3) conclusion.