Hemicyanine dye sensor for aqueous ammonia detection: A breakthrough in monitoring microbial growth

In this study, we present a novel hemicyanine dye which has 4-hydroxybenzene moiety as a donor. The dye has been explored for its ability to sense ammonia in both liquid and gaseous states. The sensing mechanism and kinetic interactions between the dye and ammonia were investigated using UV-Visible spectroscopy. Additionally, ¹H NMR, FT-IR, and HRMS analyses were performed to elucidate the mechanistic aspects. Theoretical calculations from DFT measurements (Gaussian 16) further supported these findings. The sensor demonstrated an exceptional limit of detection at 0.263 ppm, marking the lowest value reported to date. Its practical utility was validated through microbial studies, where the dye successfully monitored ammonia evolution as a marker for bacterial growth. Notably, this is the first sensor documented in the literature for detecting liquid ammonia. Its real-world applicability was confirmed through microbial studies, where the dye effectively tracked ammonia evolution as an indicator of bacterial growth.