Background Undiagnosed and untreated STIs cause large morbidity and mortality, including birth defects and stillborn babies. Since most STI's have known treatments, the largest barriers for treating patients include high cost of transporting specimens to central labs and lack of access to diagnostic testing. We present data on a portable and low-cost microfluidics device for point-of-care diagnosis of multiple STDs (such as HIV and syphilis) in combination. In order to reduce the cost and size of the assay while maintaining high performance, we incorporated microfluidic designs such as single-use plastic microfluidic cassettes, a passive method for delivering reagents, and an amplification chemistry using gold nanoparticles.
Methods Our overall device is named mChip (mobile microfluidic chip for immunoassay on protein markers). We demonstrated an ability of mChip to simultaneously detect antibodies against HIV and syphilis in needle-pricked sample volumes. Both commercial specimens and archived specimens from Sub-Saharan Africa were used.
Results The test sensitivities and specificities for detection of HIV-specific antibodies and treponemal-specific antibodies matched the performances from lab-based ELISA. Compared to ELISA, our test can be performed anywhere, uses a very small volume of blood, and is about 10 times faster. Some of these results are in press in Nature Medicine, 2010.
Conclusion The mChip provided excellent performance in the diagnosis of HIV using only 1 μl of unprocessed whole-blood and <15 min assay-time, and an ability to simultaneously diagnose HIV and syphilis with sensitivities and specificities equal to lab-based assays. Overall, we demonstrate an integrated strategy for miniaturising complex laboratory assays using microfluidics and nanoparticles to enable POC diagnostics and early detection of infectious diseases in remote settings.