Inkjet printed electrochemical aptasensor for detection of Hg2+ in organic solvents

Abstract

Real-time detection of heavy metal traces from industrial waste is key to control any potential environmental pollution by early critical point intervention. This opens a market niche for real-time, portable, and cost-efficient devices for environmental and biosafety monitoring. Despite the rapid growth of heavy metal monitoring as a research field, and the promising performance of an increasing number of novel platforms reported, the chances to transfer the lab-scale platforms developed to successful commercialization stages are dramatically low.This work proposes for the first time the use of ink-jet printed gold electrodes as a reliable, stable and fully-scalable approach for aptamer-based detection of mercury (Hg2+) traces in water and organic solvents. A controlled fabrication process was demonstrated by keeping the 90% of the charge transfer (RCT) values obtained from the as-fabricated electrodes (n = 11) within ± 1 SD (RSD = 2.92%) from the mean value and following a mesokurtic normal-like distribution (p = 0.905). The as-fabricated platform achieved a LOD of 0.01 ppm in water and enhanced sensitivity of 2-fold when tested in organic solvents, with a LOD of 0.005 ppm which is far below the minimal sensitive required for practical implementation, according to the EPA stipulations. Finally, the aptamer-based gold ink-jet printed platform provided with enough evidence to state that the signal collected from Hg2+ was significantly different (p < 0.001) from the signal provided by interferent ions tested (arsenic, lead and cadmium) at the same concentration (50 ppm), evidencing a high specificity. From the best of our knowledge, this work reports for the first time a gold inkjet-printed impedimetric platform for aptamer-based detection of Hg2+ in organic solvents, showing promising viability for future prototyping and scaling-up.