Chipping Away at Diabetes
Sensitive and specific point-of-care testing with plasmonic gold chips
Michael Schubert |
Historically, the two major types of diabetes were easy to distinguish: type 1 (T1D, the autoimmune form) appeared in childhood and type 2 (T2D, the metabolic form) was considered the adult-onset form of the disease. The distinction has faded in recent years – significantly more adults are developing T1D, while the rapid rise in childhood obesity is accompanied by a corresponding increase in childhood T2D (1). But though the diseases present with similar symptoms, they need very different treatment approaches – so how can we quickly distinguish between the two types?
A group led by Brian Feldman at Stanford University in Califiornia, USA, have devised a potential solution: a plasmonic gold chip that allows near-infrared fluorescence-enhanced (NIR-FE) detection of antibodies that attack the islet cells of the pancreas. The chip features multiplexed islet cell antigen microarrays with nanostructured gold islands; the combination of the gold substrate and nanogaps supports techniques like electric field enhancement and surface plasmon resonance that yield 100-fold improvements in NIR-FE detection.
The chip increases the efficiency of diagnosis as well as the sensitivity. While current tests for diabetes require several milliliters of blood drawn in a laboratory, a test using lower sample volumes would allow diagnosis at the point of care, saving time and reducing patient stress and inconvenience. The plasmonic chip can reliably detect islet antigen-specific autoantibodies even in ultralow blood volumes like those obtained from a finger prick. Using only two microliters of blood with no processing required, the chip was able to diagnose T1D with the same sensitivity (100 percent) and specificity (85 percent) as standard radioassays (2).
With such results, it may come as a surprise that this is the first time protein microarrays on plasmonic gold chips have been used for human disease diagnosis. And the future looks bright; the microarrays can perform isotype-specific analysis of the autoantibodies and may one day even be used to anticipate the onset of diabetes. One thing is certain: as the incidence of both types of diabetes continues to rise, the need for rapid and efficient diagnostic technologies will only become greater.
- RB Kumar et al., “The development of next-generation screening and diagnostic platforms will change diabetes care”, Expert Rev Mol Diagn, Jan 13, 1–4 (2015). PMID: 25583407.
- B Zhang et al., “A plasmonic chip for biomarker discovey and diagnosis of type 1 diabetes”, Nat Med, 20, 948–953 (2015). PMID: 25038825.