Visual colorimetric detection of tin(II) and nitrite using a molybdenum oxide nanomaterial-based three-input logic gate

We report a molybdenum oxide (MoO 3 ) nanomaterial-based three-input logic gate that uses Sn 2+ , NO 2 − , and H + ions as inputs. Under acidic conditions, Sn 2+ is able to reduce MoO 3 nanosheets, generating oxygen-vacancy-rich MoO 3− x nanomaterials along with strong localized surface plasmon resonance (LSPR) and an intense blue solution as the output signal. When NO 2 − is introduced, the redox reaction between the MoO 3 nanosheets and Sn 2+ is strongly inhibited because the NO 2 − consumes both H + and Sn 2+ . The three-input logic gate was employed for the visual colorimetric detection of Sn 2+ and NO 2 − under different input states. The colorimetric assay’s limit of detection for Sn 2+ and the lowest concentration of NO 2 − detectable by the assay were found to be 27.5 nM and 0.1 μM, respectively. The assay permits the visual detection of Sn 2+ and NO 2 − down to concentrations as low as 2 μM and 25 μM, respectively. The applicability of the logic-gate-based colorimetric assay was demonstrated by using it to detect Sn 2+ and NO 2 − in several water sources.