Integrated microfluidic channel and stretchable organogels embedded probe for cyanide capture

A novel dual-mode sensor, denoted as PBO, has been synthesized and thoroughly characterized for the selective and efficient detection of cyanide ions through both colorimetric and fluorimetric responses. The molecular framework of PBO is designed with a donor-π-acceptor configuration, where phenothiazine acts as the electron-donating moiety and benzo-oxazole functions as the electron-accepting unit, thereby facilitating an intramolecular charge transfer (ICT) transition with cyanide ion. The sensing mechanism was elucidated using ¹H NMR titration and high-resolution mass spectrometry (HRMS), confirming the formation of a stable adduct between PBO and cyanide. Additionally, Job's plot analysis verified a 1:1 stoichiometric ratio between the probe and the analyte. The probe exhibits remarkable sensitivity, achieving detection limits of 1.29 μM for (absorption) and 2.8 × 10^-10 M (fluorescence), both of which fall well below the World Health Organization (WHO) guideline for safe cyanide levels in water. The versatility of the PBO sensor was demonstrated in sophisticated solid-state and flow-based systems in addition to conventional solution-phase sensing. It was successfully integrated into specialized microfluidic devices and flexible PVP-HA organogels, providing quick and reliable cyanide ion detection in liquid streams and gel matrices. These small, affordable instruments provide quick field-based analysis without the need for complex laboratory setups, offering a robust, incredibly sensitive, and user-friendly approach to protecting environmental quality and worker safety.