Lanthanide doped metal-organic frameworks as a ratiometric fluorescence biosensor for visual and ultrasensitive detection of serotonin

It is of considerable importance to develop a fluorescence sensor with high efficiency and good sensitivity in biosensing. In this work, a ratiometric fluorescence sensor was constructed by incorporating Tb3+ in situ into a bismuth-based metal-organic framework (Tb3+-NOTT-220) and subsequently utilized for rapid and sensitive detection of serotonin (5-hydroxytryptamine) in serum media. When serotonin was exposed to the sensor, the energy transfer from the ligand to Tb3+ was inhibited upon addition of serotonin, which is accompanied by the increase in the fluorescence intensity of the ligand and reduce the emission of Tb3+. Thus, a ratiometric fluorescence assay can be established by virtue of Tb3+ and ligand as the recognition site for serotonin detection. The developed sensor exhibited good selectivity and sensitivity to serotonin with the limit of detection of 0.57 ​μM and 1.21 ​μM in water and serum, respectively. Furthermore, the application of fluorescent hydrogel provides an effective scheme for rapid and portable determination of serotonin. The ratiometric fluorescence sensing system presents a new strategy for simple, reliable and on-site determination of serotonin.