Harnessing the Potential of Dip-Pen Nanolithography to Pattern Meta-Chemical Surfaces with Glutathione Inks: An Electrochemical Sensor for Pb(II) and Hg(II)

Traditional methods are complex and unsuitable for on-site detection of heavy metals, which become ubiquitous in groundwater contamination. This research introduces a novel approach for creating meta-chemical surfaces using dip-pen nanolithography with glutathione-based ink, which can be used as an affordable and portable electrochemical sensor. The sensitivity, which is quantified by LoD value (0.84 ppb and 0.99 ppb for Pb(II) and Hg(II), respectively), is influenced by the exposed gold surface, the pattern pitch, and the binding strength between the ligand and the cations. The results indicate that the LoD values are almost unaffected by the presence of the two cations in solution, which can be explained by DFT calculations. In addition to the efficient sensor developed in this study, the finding that the pattern pitch affects the fill factor, which in turn affects the sensor's sensitivity, is significant and novel. Thus, the sensor's sensitivity can be regulated by altering the pattern pitch, which has far-reaching implications in the field of sensing.