Three in one: coordination-induced emission for inherent fluorescent Al-MOF synthesis combined with inner filter effect@aggregation-induced emission mechanisms for designing color tonality and ratiometric sensing platforms.

Abstract

Three phenomena, namely coordination-induced emission (CIE), aggregation-induced emission (AIE), and inner filter effect (IFE), were incorporated into the design of a ratiometric and color tonality-based biosensor. Blue fluorescent Al-based metal-organic frameworks (FMIL-96) were prepared from non-emissive ligand and aluminum ions via CIE. Interestingly, the addition of tetracycline (TC) led to ratiometric detection and color tonality, as the blue emission at 380nm was quenched (when excited at 350nm) due to IFE, while the green-yellowish emission at 525nm was enhanced due to AIE. Based on that, an ultra-sensitive visual-based color tonality mode with smartphone assistance was developed for detection of TC. The sensor exhibited a linear relationship within a broad range of 2.0 to 85.0μMTC with a detection limit of68.0nM. TC in milk samples was quantified with high accuracy and precision. This integration of smartphone and visual fluorescence in solution isaccurate, reliable, cost-effective, and time-saving, providing an alternative strategy for the semi-quantitative determination of TC on-site.