Boron difluoride modified zinc metal-organic framework-based "off-on" fluorescence sensor for tetracycline and Al detection.

A novel fluorescence "off-on" probe was developed using a boron difluoride-modified zinc metal-organic framework (Zn-MOF3) for sensitive determination of tetracycline (TC) and Al. The Zn-MOF3 has excellent optical property and good applicability in aqueous phase. The fluorescence recorded at 436 nm was quenched at the excitation wavelength of 336 nm. Signal-off detection of tetracycline via fluorescence quenching of Zn-MOF3 is based on the inner filter effect. Fluorescence on-off-on detection of Al occurs via the specific binding between tetracycline and Al. The limits of detection for TC and Al were 28.4 nM and 106.7 nM, respectively. This probe exhibited high selectivity which was used for the determination of TC and Al with satisfied recoveries (89.8 to 105.6% for TC, 90.0 to 110.4% for Al) and good precision (< 5%) in milk. The developed sensor represents the first "off-on" system for fluorescence detection of TC and Al based on Zn-MOF3 with a better aspect of the innovation.