A colorimetric assay system for dopamine using microfluidic paper-based analytical devices.

Abstract We report the colorimetric detection of dopamine (DA) on microfluidic paper-based analytical devices (μPADs) using an oxidation-reduction method. Here, dopamine reacts with ferric chloride forming reduced Fe2+ that subsequently reacts with phenanthroline to form the red tris(1,10-phenanthroline)iron(II) complex. The devices were fabricated by wax printing and changes in color intensity were recorded using a common cell phone. Subsequent analysis using Photoshop software, yielded a limit of detection (LOD) for DA of 0.37 μmol/L with a linear range of 0.527–4.75 μmol/L and relative standard deviation of 0.11% (inter-day) and 0.15% (intra-day) for n = 15 paper chips. The effects of detection conditions have been investigated and are discussed. Cow serum samples and human blood serum and plasma samples were detected. The work, herein, demonstrates the potential of this method as a low cost and rapid colorimetric technique to detect DA in real samples. Graphical abstract fx1 Highlights • A colorimetric detection of dopamine (DA) on microfluidic paper-based analytical devices (μPADs) was developed. • The changes in color intensity were recorded using a common cell phone and analysis using Photoshop software. • The method provide an inexpensive and selective determination of DA with low LOD. It does not need other assistances. • The relative standard deviation (RSD) of inter-day (n =15) and intra-day (n =15) is no more than 0.2%. • Cow serum samples and human serum and plasma samples were detected. [ABSTRACT FROM AUTHOR]