Lac-extract doped polyaniline nano-ribbons as fluorescence sensor and molecular switch for detection of aqueous AsO43- and Fe3+ contaminants

Detection of contaminants dissolved in water is an essential step for water quality monitoring and can guide us from consuming unhealthy water. Herein, we demonstrate the development of a novel low-cost polymer by doping polyaniline nanoribbons with lac-extract (LAC-PANI) and report its excellent fluorescence sensing properties against aqueous AsO43- and Fe3+ ions, both of which AsO43- and Fe3+ can pose health hazard for humans with the former being extremely toxic. When excited with radiation of 320 nm, the sensor showed contrasting fluorescence response against AsO43- and Fe3+ ions as the luminescence intensity showed sharp quenching upon exposure to Fe3+ but against AsO43- it showed a sharp rise in intensity. When other cations and oxoanions were concurrently tested with Fe3+ and AsO43- respectively, the sensor showed high specificity only to these two ions. Furthermore, a reversible and distinct fluorescence turn on-off-on switching response was observed upon sequential addition of AsO43-, Fe3+ and AsO43- ions which points to the utility of the sensor as a NOT-AND compound molecular logic gate for simultaneous detection of two electronically divergent analyte classes. Thus, the LAC-PANI sensor developed in this work shows enormous potential for next generation fluorescence sensor useful for water quality monitoring.

Automated summary

This study demonstrates the development of a low-cost polymer by doping polyaniline nanoribbons with lac-extract, which shows excellent fluorescence sensing properties against aqueous AsO43- and Fe3+ ions. The sensor exhibits high specificity and reversibility, making it a potential candidate for next-generation fluorescence sensors for water quality monitoring.