A portable flow-through fluorescent immunoassay lab-on-a-chip device using ZnO nanorod-decorated glass capillaries

We report a portable flow-through fluorescent immunoassay lab-on-a-chip device using inexpensive disposable glass capillaries for medical diagnostics. The device is made up of a number of serially connected glass capillaries, of which each interior surface is grown using zinc oxide (ZnO) nanorods, which different probe antibodies are attached to. The ZnO nanorods not only provide a large surface area for high density probe attachment, but also enhance the fluorescent signals to significantly improve the detection signal responses. The glass capillary also allows for convenient flow-through detection. Coupled with a homemade handheld analyzer integrated with an automatic pump system and a fluorescence readout module, a portable immunoassay capillary device enables quantitative detection of multiple biomarkers in 30 min with detection limits of 1-5 ng mL(-1) and wide dynamic ranges for prostate specific antigen (PSA), α-Fetoprotein (AFP) and carcinoembryonic antigen (CEA) in serum. This new conceptual lab-on-a-chip device eliminates the need for expensive micro-fabrication processes, while offering inexpensive and disposable, but replaceable tube-type "microchannels" for multiplexed detection in portable clinical diagnostics.