A miniaturized self-contained single-use disposable quantitatitve test for hemoglobin A1c in blood at the point of care.

DRx HbA1c is a finger-stick (< or =10 microL) test for hemoglobin A1c (HbA1c) developed by Metrika, Inc., for rapid quantitative testing at the point of care. It incorporates microelectronics, optics, and dry reagent chemistry inside a self-contained, integrated, single-use device. Test results (%HbA1c) are displayed in numeric form on the device's liquid crystal display within 8 min after sample application. Having no switches or buttons, DRx HbA1c self-activates upon addition of sample. It contains two dry reagent lateral flow strips, each having an HbA1c immunoassay test zone and a total hemoglobin (Hb) test zone. An on-board microprocessor calculates %HbA1c from the reflectances of the test zones. The microprocessor also corrects for lot-specific reagent characteristics and optical variation, in addition to checking electrical functioning and proper sample volume. For testing accuracy, subjects both with and without diabetes were recruited in order to obtain samples with a wide range of HbA1c values. Whole blood samples were analyzed using both DRx HbA1c units and a laboratory method (Bio-Rad DiaSTATT). DRx HbA1c testing was performed by laboratory personnel and by subjects who received brief training. Repeatability, linearity, sample volume tolerance, diluted sample stability and hematocrit tolerance of the DRx HbA1c test were assessed by trained laboratory personnel as described in the text. The linear %HbA1c range of the assay extended from approximately 3% to 15%. Hb was measurable from 6.8 to 20.0 g/dL, encompassing over 99.8% of the normal population. DRx HbA1c clinical sample test results (n = 50) correlated linearly to the Bio-Rad DiaSTAT method (r = 0.935) with slope and intercept values of 0.994 and 0.003, respectively. The repeatability for %HbA1c was within 5-9% CV. We conclude that DRx HbA1c performance is closely equivalent to that of existing tests.

Luminescent oxygen channeling assay (LOCI): sensitive, broadly applicable homogeneous immunoassay method.

Luminescent oxygen channeling assay (LOCI) is a homogeneous immunoassay method capable of rapid, quantitative determination of a wide range of analytes--including high and very low concentrations of large and small molecules, free (unbound) drugs, DNA, and specific IgM. Assays have been carried out in serum and in lysed blood. Reliable detection of 1.25 microU/L thyrotropin (TSH) and 5 ng/L hepatitis B surface antigen (HBsAg) corresponds to detection limits approximately 3- and approximately 20-fold lower, respectively, than those of the best commercially available assays. An assay of chorionic gonadotropin is capable of quantification over a 10(6)-fold range of concentrations without a biphasic response. Latex particle pairs are formed in the assay through specific binding interactions by sequentially combining the sample and two reagents. One particle contains a photosensitizer, the other a chemiluminescer. Irradiation causes photosensitized formation of singlet oxygen, which migrates to a bound particle and activates the chemiluminescer, thereby initiating a delayed luminescence emission. Assay times range from 1 to 25 min.

Luminescent oxygen channeling immunoassay: measurement of particle binding kinetics by chemiluminescence.

A method for monitoring formation of latex particle pairs by chemiluminescence is described. Molecular oxygen is excited by a photosensitizer and an antenna dye that are dissolved in one of the particles. 1 delta gO2 diffuses to the second particle and initiates a high quantum yield chemiluminescent reaction of an olefin that is dissolved in it. The efficiency of 1 delta gO2 transfer between particles is approximately 3.5%. The technique permits real-time measurement of particle binding kinetics. Second-order rate constants increase with the number of receptor binding sites on the particles and approach diffusion control. By using antibody-coated particles, a homogeneous immunoassay capable of detecting approximately 4 amol of thyroid-stimulating hormone in 12 min was demonstrated. Single molecules of analyte produce particle heterodimers that are detected even when no larger aggregates are formed.