The safety of drinking water is vital for human health. In recent years, organic micropollutants (OMPs) in water have attracted much attention because they are toxic, non-degradable, easily migratable and have wide sources. Since 2017, inspired by the pioneering work on the adsorption removal of OMPs from water by porous polymerized β-cyclodextrins, the adsorption of OMPs in water by macrocycle-crosslinked polymers (MCPs) has received widespread attention. Classical macrocyclic hosts such as cyclodextrin, calixarene, pillararene and other emerging macrocycles have been employed for this purpose. This review encompasses the advancements on the removal of OMPs from water by MCPs, involving the building blocks of polymers, types of OMPs, the preparation and performance of each MCP. An overview of challenges and future research directions in this regard are also discussed.
Uranium is one of the most important radionuclides but could also cause potential health risks to human beings due to its radioactive and chemical toxicity. It is an urgent task to develop a simple but efficient sensing platform for UO22+, the main existing form of uranium in environment. Herein, a rhodamine-functionalized carbon dots (o -CDs-Rho) was synthesized and applied for UO22+ sensing through a simple but novel aggregation-enhanced FRET strategy. The weak FRET efficiency (16.2%) of o-CDs-Rho in dispersed solution is significantly enhanced (>77.2%) after UO22+ triggered aggregation due to the increased number of rhodamine acceptors around each CDs from dispersed 80 to aggregated 2800. This is the first ratiometric fluorescence sensor with an inverse change of fluorescence intensity at dual emission wavelengths under single-wavelength excitation for UO22+. Under optimized experiment conditions, o-CDs-Rho nanosensor shows a low detection limit of 53 nM and excellent selectivity. Meanwhile, the as-prepared nanosensor also shows high reliability and stability. These excellent properties make it successful in detecting uranium content in real samples.
Prevalent contamination of water by cadmium ion (Cd2+) brings environmental risk, which threatening to human health including renal dysfunction, reduced lung capacity, and some cancers. It calls for rapid, sensitive and selective protocol to analyze Cd2+ on field. In this work, specific Raman probe is rationally designed by gold nanoparticles (AuNPs) functionalized with tripeptide glutathione (GSH) and Rhodamine 6G (R6G) (denoted as R6G/GSH/AuNPs), which is explored for indirectly determining trace Cd2+ in river water. Based on chelating interaction between GSH and Cd2+ to form tetrahedral Cd(SG)4, which trends easy detachment from R6G/GSH/AuNPs. With increasing Cd2+ concentration, the Raman probe without protection of GSH happens due aggregation and Raman signal of R6G increases correspondingly. The R6G/GSH/AuNPs-based Raman detection of Cd2+ in river water shows rapidness, excellent sensitivity, selectivity and good repeatability. Limit of detection of 10 ppb with a widely linear range of 0.5–20 ppm could be achieved. It could be perspective that such Raman probe could be extended to be used for on-site monitoring trace Cd2+ in river water system.
For real application, it is an urgent demand to fabricate stable and flexible surface-enhanced Raman scattering (SERS) substrates with high enhancement factors in a large-scale and facile way. Herein, by using the electrospinning technique, a hydrophobic and flexible poly(styrene-co-butadiene) (SB) fibrous membrane is obtained, which is beneficial for modification of silver nanoparticles (Ag NPs) colloid in a small region and then formation of more “hot spots” by drying; the final SERS substrate is designated as Ag/SB. Hydrophobic Ag/SB can efficiently capture heterocyclic molecules into the vicinity of hot spots of Ag NPs. Such Ag/SB films are used to quantitatively detect trace triazophos residue on fruit peels or in the juice, and the limit of detection (LOD) of 2.5 × 10−8 M is achieved. Ag/SB films possess a capability to resist heat. As a case, 6-mercaptopurine (6MP) that just barely dissolves in 90 °C water is picked for conducting Ag/SB-film-based experiments.