Hemoglobin Assay Based on Fluorescent Quenching Technology

A new assay for glycated hemoglobin (A1C) is based on fluorescent quenching technology. The amount of glucose that combines with the hemoglobin is directly proportional to the total amount of glucose that is currently in an individual's system. The assay will aid in the diagnosis of diabetes and subsequent follow-up of patients.

The A1C level provides an overall record of glucose levels for as long as the individual red blood cells live, which is about two or three months. Whereas the fasting glucose test gives an indication of current glucose levels, the A1C gives a picture of average levels over the whole two-to-three-month period.

The fluorescence of a conjugate of boronic acid and a fluorophore is reduced (or "quenched”) upon binding to cis-diol groups that are present on carbohydrates attached to hemoglobin molecules. Utilizing solid state opto-electronic technology, a desktop reader quantifies the concentration of A1C in the sample. The total amount of hemoglobin is then quantified by absorption measurement. The combination of these two values produces an A1C % result.

Called Quo-Test, the fully automated homogenous assay system was developed by Quotient Diagnostics (Surrey, UK). There are no separation steps, and the system controls all the critical steps that may influence or affect the quality of the result. Results are delivered in about three minutes from a blood sample of less than 5 µl. The starter kit contains a reader, barcode scanner, mini-printer, and a pack of 10 disposable cartridges.

Diabetes is one of the most challenging health problems in the 21st century, with close to 200 million people worldwide already diagnosed as having the disease. In addition, there is strong reason to believe that more than half of the diabetics in the world remain undiagnosed. According to Quotient's CEO David Chatterton, the trend is for both diagnosis and follow-up to be performed in special clinics, hence the development of Quo-Test. "We have drawn on our broad experience in both assay and instrument development to create an instrument that we are confident will have a major impact on diabetes care,” he explained.




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