Sustainable monitoring of Zn(II) in biological fluids using office paper

Herein, we describe a sustainable and inexpensive approach to monitor Zn(II) in biological fluids by fabricating an office paper-based electrochemical sensor. By following two easy steps, consisting of wax patterning and electrode screen-printing, the office paper provides an effective electroanalytical tool that is easily extensible to a broad range of analytes. This approach would be able to develop affordable user-friendly sensing devices, tackling the lack of resources in regions with poor-settings/facilities. In order to provide more details regarding the screen-printed electrodes fabrication, office paper, Whatman #1 chromatrographic paper, and polyester have been characterized with electrochemical, morphological, and mechanical tests and compared. Using office paper, Zn(II) has been detected linearly up to 2 μg/mL with a detection limit equal to 25 ng/mL and a relative standard deviation of 8%. To highlight the feasibility, reliability, and easiness of the proposed electrochemical sensor, Zn(II) has been detected in serum and sweat at physiological level (μg/mL), and the accuracy of the method has been verified by satisfactory recoveries close to 100%.