Highly-Efficient Sulfonated UiO-66(Zr) Optical Fiber for Rapid Detection of Trace Levels of Pb2

Constructing functional metal-organic frameworks by ligand design for environmental applications

Metal-organic frameworks (MOFs) with unique physical and chemical properties are composed of metal ions/clusters and organic ligands, including high porosity, large specific surface area, tunable structure and functionality, which have been widely used in chemical sensing, environmental remediation, and other fields. Organic ligands have a significant impact on the performance of MOFs. Selecting appropriate types, quantities and properties of ligands can well improve the overall performance of MOFs, which is one of the critical issues in the synthesis of MOFs. This article provides a comprehensive review of ligand design strategies for functional MOFs from the number of different types of organic ligands. Single-, dual- and multi-ligand design strategies are systematically presented. The latest advances of these functional MOFs in environmental applications, including pollutant sensing, pollutant separation, and pollutant degradation are further expounded. Furthermore, an outlook section of providing some insights on the future research problems and prospects of functional MOFs is highlighted with the purpose of conquering current restrictions by exploring more innovative approaches.

Metal organic frameworks as promising sensing tools for electrochemical detection of persistent heavy metal ions from water matrices: A concise review

Water bodies are being polluted rapidly by disposal of toxic chemicals with their huge entrance into drinking water supply chain. Among these pollutants, heavy metal ions (HMIs) are the most challenging one due to their non-biodegradability, toxicity, and ability to biologically hoard in ecological systems, thus posing a foremost danger to human health. This can be addressed by robust, sensitive, selective, and reliable sensing of metal ions which can be achieved by Metal organic frameworks (MOF) based electrochemical sensors. In the present era, MOFs have caught greater interest in a variety of applications including sensing of hazardous pollutants such as heavy metal ions. So, in this review article, types, synthesis and working mechanism of MOF based sensors is explained to give general overview with updated literature. First time, detailed study is done for sensing of metal ions such as chromium, mercury, zinc, copper, manganese, palladium, lead, iron, cadmium and lanthanide by MOFs based electrochemical sensors. The use of MOFs as electrochemical sensors has attractive success story along with some challenges of the area. Considering these challenges, we attempted to highlight the milestone achieved and shortcomings along with future prospective of the MOFs for employing it in electrochemical sensing devices for HMIs. Finally, challenges and future prospects have been discussed to promote the development of MOFs-based sensors in future.

Liquid Crystal@Nanosilver Catalytic Amplification-Aptamer Trimode Biosensor for Trace Pb2

Liquid crystals (LCs) are a very important display material. However, the use of LC, especially LC-loaded nanoparticles, as a catalyst to amplify the analytical signal and coupled with specific aptamer (Apt) as a recognition element to construct a highly sensitive and selective three-mode molecular spectral assay is rarely reported. In this article, five LCs, such as cholesteryl benzoate (CB), were studied by molecular spectroscopy to indicate the liquid crystal nanoparticles in the system, and highly catalytic and stable CB loaded-nanosilver (CB@AgNPs) sol was prepared. The slope procedure was used to study the catalysis of the five LCs and CB@AgNPs on the new indicator reaction between AgNO₃ and sodium formate (Fo) to produce silver nanoparticles (AgNPs) with a strong surface plasmon resonance absorption (Abs) peak at 450 nm, a resonance Rayleigh scattering (RRS) peak at 370 nm and a surface enhanced Raman scattering (SERS) peak at 1618 cm^-1 in the presence of molecular probes. By coupling the new CB@AgNPs catalytic indicator reaction with the Apt reaction, a new CB@AgNPs catalytic amplification-SERS/RRS/Abs trimode biosensoring platform was constructed for detecting inorganic pollutants, such as Pb²⁺, Cd²⁺, Hg²⁺ and As³⁺.

Solvent-Free Preparation of Tannic Acid Carbon Dots for Selective Detection of Ni2+ in the Environment

Carbon dots (CDs) are widely used nanomaterials that not only exhibit good biocompatibility and photostability, but also benefit from a simple preparation process and easy functionalization, making them promising for broad applications in the fields of heavy metal ion detection and optoelectronic devices. Based on the excellent optical properties of CDs and the current situation of increasing energy shortages, this paper selects the natural polyphenolic compound tannic acid (TA) found in biomass materials as the carbon source and innovatively adopts a simple and convenient solvent-free pyrolysis method without auxiliary reagents or solvents. The CDs with good water solubility and certain fluorescence properties were directly prepared under the condition of high temperature, and the obtained CDs exhibited blue fluorescence, and a high QY of 35.4% was obtained at 300 °C. The analysis and results demonstrate the selectivity of these CDs for the detection of various metal ion solutions. In particular, these CDs are sensitive to Ni²⁺ and can be used as fluorescent sensors for the efficient and sustainable detection of Ni²⁺, whereas previous sensors were often specific to Fe³⁺ and Hg²⁺. Thus, a new sensing technique has been developed for the detection of Ni²⁺ to achieve more sensitive and rapid detection.

Recent Progress in Metal-Organic Framework Based Fluorescent Sensors for Hazardous Materials Detection

Population growth and industrial development have exacerbated environmental pollution of both land and aquatic environments with toxic and harmful materials. Luminescence-based chemical sensors crafted for specific hazardous substances operate on host-guest interactions, leading to the detection of target molecules down to the nanomolar range. Particularly, the luminescence-based sensors constructed on the basis of metal-organic frameworks (MOFs) are of increasing interest, as they can not only compensate for the shortcomings of traditional detection techniques, but also can provide more sensitive detection for analytes. Recent years have seen MOFs-based fluorescent sensors show outstanding advantages in the field of hazardous substance identification and detection. Here, we critically discuss the application of MOFs for the detection of a broad scope of hazardous substances, including hazardous gases, heavy metal ions, radioactive ions, antibiotics, pesticides, nitro-explosives, and some harmful solvents as well as luminous and sensing mechanisms of MOF-based fluorescent sensors. The outlook and several crucial issues of this area are also discussed, with the expectation that it may help arouse widespread attention on exploring fluorescent MOFs (LMOFs) in potential sensing applications.