An Al3+ ions-responsive blue emitting ionic liquid-based nano-optode and its implications for the detection of 2, 4, 6-trinitrophenol

Abstract

This report introduces a novel IL-mediated fluorescence turn-on photoluminescence nano-optode designed for the highly sensitive and selective monitoring of aluminium ions (Al³⁺). The fabricated nano-optode exhibited pronounced optical responsiveness to Al³⁺ ions, with an exceptionally low detection threshold in the picomolar range, attributed to chelation-enhanced fluorescence (CHEF) within the IL, demonstrating significant progress beyond the current state of the art. To enable on-site analysis, a portable paper-strip solid sensor was fabricated using the nano-optode formulation, allowing for instantaneous visual detection of Al³⁺ ions contamination in aqueous samples. Furthermore, the IL-based Al³⁺-complex served as an intermediate bridge in a cascade sensing system for the subsequent detection of picric acid, demonstrating dual recognition. A smartphone-based fluorometric platform was also developed for quantitative analysis, enabling real-time, user-friendly monitoring without reliance on high-end laboratory instruments. This investigation unveils a novel approach for fabricating photonic IL-based nano-optodes as a cost-effective, highly responsive, and portable sensing platform for environmental and security applications.