Automating Quantum Dot Barcode Assays Using Microfluidics and Magnetism for the Development of a Point-of-Care Device

The
impact of detecting multiple infectious diseases simultaneously at
point-of-care with good sensitivity, specificity, and reproducibility
would be enormous for containing the spread of diseases in both resource-limited
and rich countries. Many barcoding technologies have been introduced
for addressing this need as barcodes can be applied to detecting thousands
of genetic and protein biomarkers simultaneously. However, the assay
process is not automated and is tedious and requires skilled technicians.
Barcoding technology is currently limited to use in resource-rich
settings. Here we used magnetism and microfluidics technology to automate
the multiple steps in a quantum dot barcode assay. The quantum dot-barcoded
microbeads are sequentially (a) introduced into the chip, (b) magnetically
moved to a stream containing target molecules, (c) moved back to the
original stream containing secondary probes, (d) washed, and (e) finally
aligned for detection. The assay requires 20 min, has a limit of detection
of 1.2 nM, and can detect genetic targets for HIV, hepatitis B, and
syphilis. This study provides a simple strategy to automate the entire
barcode assay process and moves barcoding technologies one step closer
to point-of-care applications.