No abstract

The toxic agrochemical contamination of food and the environment is one of the most pressing concerns for human health and environmental sustainability. In this work, a water-stable 3D lanthanidebased MOF, [Tb 2 (H 2 btec)(btec)(H 2 O)]•4H 2 O (Tb-MOF) has been demonstrated as a turn-off luminescent sensor for the detection of poisonous paraquat. The ligand 1,2,4,5-benzenetetracarboxylic acid (H 4 btec) was incorporated into Tb-MOF to act as a detection recognition site for a selective interaction with paraquat, resulting in a dramatic luminescence quenching. The obtained Tb-MOF not only is water stable but also tolerates acidic and basic conditions. On top of that, the rapid detection of paraquat in aqueous solution with high sensitivity and selectivity can be obtained even in the presence of common contaminants in the environment. The linear range for paraquat detection was observed in the concentration range from 0 to 50 μM with a low limit of detection of 2.84 μM and a high quenching constant of 3.95 × 10 4 M −1 . Tb-MOF can be applied to detect paraquat in water and agricultural samples with satisfactory recoveries from 85.59 to 105.20%. To gain insights into the molecular recognition, time-dependent density functional theory (TD-DFT) calculations were conducted to reveal the specific interactions between paraquat and the ligand in the backbone structure of the MOF. The quenching mechanism is attributed to a photoinduced electron transfer (PET) from the MOF to paraquat and the competitive absorption of excitation energy by paraquat. To demonstrate a practical implementation of the MOFbased sensor, a PVA/Tb-MOF@paper strip was fabricated, which can visually detect paraquat under irradiation with a UV lamp. These results indicate that Tb-MOF can be used as a potential sensor for the practical detection of paraquat in the environment and agricultural products.

The effects of synthetic methods, modulator types, content of modulator, and reaction time on the size and morphology of a microscale Zn-MOF containing dual Lewis basic amino and carbonyl groups,...

Lewis basic site-functionalized porous Cd(ii)-MOF as a bi-functional fluorescent sensor of glyphosate and Cr3+ with exceptional LODs.

No abstract

Water-stable Eu-MOF as a fluorescent probe for detecting tetracycline antibiotics and dihydrogen phosphate in real samples and visualization of latent fingerprints.

DNA methylation is an epigenetic alteration that results in 5-methylcytosine (5-mC) through the addition of a methyl group to the fifth carbon of a cytosine (C) residue. The methylation level, the ratio of 5-mC to C, in urine might be related to the whole-body epigenetic status and the occurrence of common cancers. To date, never before have any nanomaterials been developed to simultaneously determine C and 5-mC in urine samples. Herein, a dual-responsive fluorescent sensor for the urinary detection of C and 5-mC has been developed. This assay relied on changes in the optical properties of nitrogen-doped carbon quantum dots (CQDs) prepared by microwave-assisted pyrolysis. In the presence of C, the blue-shifted fluorescence intensity of the CQDs increased. However, fluorescence quenching was observed upon the addition of 5-mC. This was primarily due to photoinduced electron transfer as confirmed by the density functional theory calculation. In urine samples, our sensitive fluorescent sensor had detection limits for C and 5-mC of 43.4 and 74.4 μM, respectively, and achieved satisfactory recoveries ranging from 103.5 to 115.8%. The simultaneous detection of C and 5-mC leads to effective methylation level detection, achieving recoveries in the range of 104.6−109.5%. Besides, a machine learningenabled smartphone was also developed, which can be effectively applied to the determination of methylation levels (0−100%). These results demonstrate a simple but very effective approach for detecting the methylation level in urine, which could have significant implications for predicting the clinical prognosis.

We develop an easy-to-use, highly selective, and real-time smartphone-based quantitative test to monitor the water content in organic solvents utilizing CDs@HKUST-1.