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A novel ratiometric fluorescence probe was designed for the determination of Al3+ by self-assembling of NH2-MIL-101(Fe) and [Ru(bpy)3]2+. Under the excitation wavelength of 360 nm, the NH2-MIL-101(Fe)@[Ru(bpy)3]2+ presented a dual-emitting luminescent property at 440 and 605 nm, respectively. In the presence of Al3+, the blue fluorescence of NH2-MIL-101(Fe)@[Ru(bpy)3]2+ at 440 nm was enhanced remarkably, while the red emission at 605 nm was almost not influenced. Therefore, taking the fluorescence at 440 nm as the report signal and 605 nm as the reference signal, quantitative determination was achieved for Al3+ concentration in the ranges 0.2–25 μM and 25–250 μM. The limit of detection (LOD) and limit of quantification (LOQ) were calculated to be 73 nM and 244 nM, respectively. The sensing mechanisms were studied by theoretical calculation and optical spectra. The analysis of real food samples confirmed the suitability of the proposed method. More importantly, portable fluorescent test papers were successfully manufactured to provide a strategy for visual, rapid, and on-site detection of Al3+. [ABSTRACT FROM AUTHOR]

• A novel and sensitive fluorescent sensor was developed for tetracycline detection. • The prepared tungsten oxide quantum dots exhibited low toxicity and superior optical property. • The sensing mechanism was studied by theoretical calculation and optical spectra. • This prominent technique could be applied in milk and milk powder samples. Tetracyclines (TCs) residues in animal products have attracted extensive concern due to their potential toxic to human health. Accordingly, it is urgent to develop an efficient method to determine TCs for providing consumers with risk pre-warning. Herein, a novel tungsten oxide quantum dots (W x O y QDs) fluorescence probe for tetracycline (TET) detection was constructed through ethanol-thermal method, which exhibited intense blue fluorescence under 365 nm UV light. Interestingly, blue-emitting W x O y QDs could be quenched obviously after the addition of TET, which may be attributed to the synergism of inner filter effect (IFE), fluorescence resonance energy transfer (FRET) and photo-induced electron transfer (PET). Thereby, the fluorescence method was established for TET detection based on W x O y QDs. Additionally, the presented method was demonstrated by monitoring TET in milk and milk powder with satisfactory recoveries. More importantly, this work offered good demonstration for the detection of food hazard factors. [ABSTRACT FROM AUTHOR]

A new type of "turn-on" fluorescence probe coumarin-based DTC was developed for specifically detecting hypochlorite ion (ClO−) with high sensitivity. DTC can display a significant enhancement of fluorescence and emit blue fluorescence at 452 nm after reaction with ClO−. Moreover, probe DTC can detect ClO− without interference from other reactive oxygen species (ROS), and has a low detection limit for ClO− of 96 nM. Meanwhile, DTC can also detect ClO− in the physiological environment, and DTC can be further used as a test paper-strip for portable and rapid detection of ClO−. [Display omitted] • A novel "turn-on" fluorescence probe DTC was developed for detecting hypochlorite ion. • DTC can detect ClO− with a low detection limit as 96 nM. • DTC has high selectivity towards ClO− and can be applied in the physiological environment. • DTC is successfully integrated on a paper-strip to detect ClO−. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel europium-based MOF (1) was designed and synthesized. • 1 was applied in simultaneous detection and removal of tetracycline (TC). • 1 possesses ultrasensitive recognition and high adsorption capacity toward TC. • Mechanisms of recognition and adsorption were systematically explored. • 1 was used for TC detection in real samples with satisfactory recoveries. The misuse of tetracycline (TC) will cause adverse effects on environment and has become a serious problem threatening human health. In this work, a novel bifunctional europium-based metal organic framework (1) containing characteristic metal chains was successfully synthesized via a facile one-pot hydrothermal method for the first time and used in simultaneous detection and removal of TC. Detailed characterizations including scanning electron microscope, energy dispersive X-ray spectroscope, Fourier-transform infrared, X-ray diffraction and X-ray single crystal diffraction were conducted to confirm the successful synthesis of 1. Subsequently, the prepared 1 showed significant fluorescence enhancement at 615 nm with a wide sensitive range (0.05–60 μM) and low detection limit (3 nM) for detection of TC under pH 9. The excellent adsorption behaviours (387.14 mg g−1) of 1 toward TC were demonstrated by kinetic and equilibrium experiments. Possible mechanisms of recognition and adsorption including host-guest capability of Eu nodes, hydrogen bonding, π-π interactions and electrostatic attraction were further explored. In addition, the practical feasibilities of 1 for TC sensing were further investigated in real samples with satisfactory recoveries (94.89 %−112.86 %, RSD ≤ 6.03 %). This work provides a facile strategy for design of MOF-based bifunctional turn-on fluorescence sensor for efficient TC monitoring. [ABSTRACT FROM AUTHOR]

P -nitrophenol (PNP) has been widely applied to industry processing for many purposes, but the persistence and toxicity of residuum may pose risks to human health. To analyze PNP in industrial and agricultural wastewater, a versatile fluorescent probe sensing platform was proposed. In this work, we devised a fluorescence approach that utilized nitrogen, silicon co-doped carbon dots (N,Si-CDs) to monitor PNP originating from the inner filter effect (IFE). The N,Si-CDs were generated in a one-step hydrothermal synthesis, and which possessed outstanding fluorescence signal and water-dispersity. Emission at 441 nm was monitored with excitation at 360 nm using a common spectrofluorometer. The method achieved an exceptionally low limit of detection (LOD) of 0.011 μM. Furthermore, this method not only eliminates the interference from metal ions and acid ions, but also provides a potential application prospect for N,Si-CDs in the field of water monitoring. Analysis of tap and lake water led to 93.30–106.30% recoveries and <1% relative standard deviation at 2.5–25 μM PNP concentrations. Unlabelled Image • A novel fluorescence nanoprobe based on N,Si-CDs was designed for PNP detection. • The N,Si-CDs possessed outstanding fluorescence signal and water-dispersity. • This fluorometric assay has lower detection limit than other detection methods. • This fluorescence nanoprobe had been used to detect PNP in actual water samples with great recoveries. [ABSTRACT FROM AUTHOR]

• The rhombic-like Al nanosupporter (RAlNS) based fluorescence immunochromatographic assay was constructed. • The synthesized RAlNS can label antibodies in one-step stirring, avoiding the use of the complex cross-linkers. • The sensor possessed high sensitivity and specificity for tetracycline (TET). • Significant recovery rates of TET detection in real samples demonstrates the sensor's applicability. Fluorescence-based lateral flow immunoassay (FLFIA) is a prospective technology in detecting tetracycline (TET). However, the existing fluorescent materials (FMs) often require cross-linkers to bind with antibodies (Abs) to form FLFIA FM-Ab probe, which complicates the modification process and may affect the fluorescence intensity of FMs. Herein, the rhombic-like Al nanosupporter (RAlNS) was prepared via a one-step hydrothermal method and used for designing fluorescence nanosupporter for FLFIA to detect TET in real samples. The RAlNS not only possessed excellent water stability, strong fluorescence intensity and favorable thermal stability, but also could adsorb Abs to obtain FMs-Ab probe by simple centrifugation. Under optimal conditions, the limit of detection (LOD) of RAlNS-FLFIA was 0.0516 ng/mL (n = 3), which was 18 times lower than traditional colloidal gold-based LFIA. Meanwhile, the proposed sensor also exhibited high specificity for TET against other antibiotics. Furthermore, the RAlNS-FLFIA was successfully applied to the detection of TET in beef, chicken, milk and honey samples, separately, which demonstrated a significant recovery of 80.40–112.05%. The novel RAlNS-FLFIA provided great potential for the detection of various analytes in food analysis. [ABSTRACT FROM AUTHOR]