Chemiluminescence detection for microfluidic cloth-based analytical devices (μCADs)

In this work, we report the first demonstration of chemiluminescence (CL) detection for microfluidic cloth-based analytical devices (mu CADs). Wax screen-printing is used to make cloth channels or chambers, and enzyme-catalyzed CL reactions are imaged using an inexpensive charge coupled device (CCD). We first evaluate the relationship between the wicking rate and the length/width of cloth channel. For our device, the channel length and width between the loading and detection chambers are optimized to be 10 mm and 3 mm. Thus, the detection procedure can be accomplished in about 15 s on a cloth-based device (15 x 30 mm(2)) by using 25-mu L sample spotted on it. Next, several parameters affecting cloth-based CL intensity are studied, including exposure time, pH, and concentrations of luminol and enzyme. Under optimal conditions, a linear relationship is obtained between CL intensity and hydrogen peroxide (H2O2) concentrations in the range of 0.5-5 mM with a detection limit of 0.46 mM. Finally, the utility of cloth-based CL is demonstrated for determination of H2O2 residues in meat samples. On our device, the chicken meat soaked for 6 h with 3% H2O2 can be detected. Moreover, the supernatant of grinded meat sample can be directly applied, without need for other treatments. We believe that mu CADs with CL detection could provide a new platform of rapid and low-cost assays for use in areas such as food detection and environmental monitoring. (C) 2015 Elsevier B.V. All rights reserved.