15 July 2014

Microchip for differential diagnosis of diabetes

Researchers at Stanford University, working under the guidance of Dr. Brian Feldman, have developed a cheap portable test based on a microchip for the diagnosis of type 1 diabetes. Its use will speed up the diagnosis of the disease, as well as study the processes underlying its development.

Currently, there is a pronounced need to improve the differential diagnosis of type 1 and type 2 diabetes mellitus. This is due to changes in the structure of morbidity observed in recent years, which reduce the effectiveness of diagnostics, traditionally based on the assessment of factors such as age, ethnicity and body weight.

Several decades ago, type 1 diabetes was diagnosed only in children (with rare exceptions), and type 2 diabetes is almost always in middle–aged people who are overweight. This difference was so pronounced that laboratory confirmation of the diagnosis was considered unnecessary and was often not carried out due to its complexity and high cost. Today, against the background of the epidemic of childhood obesity, approximately one in four children at the time of diagnosis has concomitant type 2 diabetes. At the same time, for some unknown reason, type 1 diabetes is increasingly being diagnosed in adults.

Type 1 diabetes mellitus is an autoimmune disease caused by the destruction of insulin–producing beta cells of the pancreas by its own immune system. This leads to the cessation of the synthesis of insulin, a hormone necessary for the utilization of carbohydrates. To differentiate this disease from type 2 diabetes mellitus, an analysis of the content of auto-antibodies specific to beta cells in the blood allows. The results of recent studies indicate that early diagnosis and aggressive treatment of type 1 diabetes significantly improve the long-term prognosis for the patient, apparently due to the preservation of some insulin-producing cells.

Currently, radioimmune and enzyme immunoassay methods are used to detect auto-antibodies, the implementation of which requires quite a lot of time and financial costs, as well as special training and equipment. The microchip proposed by the authors, on the contrary, does not use radioactive isotopes, provides a result within a few minutes and requires only minimal preparation. The estimated cost of one chip, which allows for up to 15 tests, is only about $20. For one test, a drop of capillary blood from the patient's finger is enough.

Schematic image of a microchip (from an article in Nature Medicine).

The operation of the chip is based on a fluorescent antibody identification method. The innovation proposed by the researchers is that gold nanoparticles are applied to the glass plates forming the basis of the microchip, which enhance fluorescence and thus ensure high sensitivity of antibody detection. To validate the microchip, blood samples of patients with newly diagnosed diabetes and people without this disease were used.

In addition to differential diagnosis of the disease, the new microchip can be used to identify predisposition to type 1 diabetes in people at risk, including close relatives of patients. Theoretically, it can even be used for screening large populations.

The developers have already submitted a package of documents for patenting the microchip and plan to create a company that will improve the method and promote it.

Article by Bo Zhang et al. A plasmonic chip for biomarker discovery and diagnosis of type 1 diabetes is published in the journal Nature Medicine.

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of Stanford University Medical Center:
Researchers invent nanotech microchip to diagnose type-1 diabetes.


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