Label-Free Sensing of Cysteine through Cadmium Ion Coordination: Smartphone-Based Electrochemical Detection.

ABSTRACT

The detection of biologically important compounds such as cysteine remains a challenge for monitoring body metabolism. This work proposes a transition metal ion coordination-based label-free cysteine sensor with smartphone-based square wave voltammetry sensing system for the point-of-care testing (POCT). In the sensing system, potential excitation and current measurements were accomplished by a miniaturized and integrated circuit board with a smartphone to wirelessly control the system via Bluetooth. The electrochemical currents changed with the cysteine concentrations ranging from 0 µM to 200 µM with a linearity correlation coefficient of 0.9915. The limit of detection was as low as 0.0149 µM for cysteine. The smartphone-based system provides an effective strategy for cysteine detection, and it can also serve as a promising portable sensing platform for the analysis of other small molecules.