Fluorescent lanthanide metal-organic framework for rapid and ultrasensitive detection of methcathinone in human urine

Facile synthesis of nitrogen-doped carbon dots for ultrasensitive detection of anticancer drug gefitinib based on IFE

Gefitinib, a highly significant antitumor drug, is now commonly employed in clinical settings as a first-line treatment for patients with advanced or metastatic non-small cell lung cancer, colon cancer, and breast cancer. Herein, a convenient, rapid, and accurate fluorescence method based on nitrogen-doped carbon dots (NCDs) was designed for ultrasensitive detection of gefitinib. The NCDs were easily synthesized through one-pot hydrothermal process using p-phenylenediamine and D-glutamic acid as the precursors. The sensing strategy relied on the fluorescence of NCDs at 345 nm, which was selectively reduced by gefitinib based on the inner filter effect (IFE). With a broad linear range of 0.025-30 μg/mL and a low limit of detection of 5.5 ng/mL, the probe was successfully applied to the detection of gefitinib in human serum samples, demonstrating strong practicality, affordability, and high accuracy. The proposed sensor is simple in design, fast in detection and cost-effective, and exhibits promising application in drug real-time analysis.

Highly sensitive ratiometric fluorescence detection of tetracycline residues in food samples based on Eu/Zr-MOF

The development of a simple, rapid, and sensitive method for monitoring antibiotic residues is crucial for maintaining food safety. Herein, a ratiometric fluorescence probe based on bimetallic organic framework (Eu/Zr-MOF) was developed for the detection of tetracycline (TC). The Eu/Zr-MOF was synthesized by the coordination of Eu3+ and Zr4+ with 2-APDC, which exhibited a grape-like cluster morphology and dual-emitting fluorescence at 430 nm/616 nm. Based on the internal filtering effect (IFE), significant fluorescence quenching was observed at 430 nm, whereas only slight changes occurred at 616 nm. The ratiometric sensing offered two broad linear ranges (0.5-8 μg/mL; 10-60 μg/mL) and a low detection limit (26.7 ng/mL). The proposed method was applied to the determination of TC in pork and water samples. Fluorescent sensors have the advantages of simple design, fast response, and high sensitivity, thus providing a promising means for evaluating the safety of food contaminated with TC.

Ratiometric fluorescence sensor based on europium-organic frameworks for selective and quantitative detection of cerium ions

BACKGROUND

Due to the unavoidable use of cerium in daily life, the accumulation of cerium in the environment increases health risks for humans. Therefore, it is crucial to develop a chemical sensing technology for the rapid, sensitive, and selective detection of cerium ions.

RESULTS

In this research work, a novel two-dimensional chain structure of a europium-based metal organic framework (Eu-MOF) [Eu2(tcpa)(Htcpa)2] was synthesized by using 3,4,5,6-tetrachloro-1,2-benzenedicarboxylic acid (H2TCPA) as the ligand and europium nitrate as the metal source. The results of powder X-ray diffraction and thermogravimetric analysis show that the synthesized Eu-MOF has excellent chemical and thermal stability. When the Eu-MOF suspension was excited by ultraviolet light at 292 nm, four fluorescence emissions were observed at 420, 595, 620 and 705 nm. It was particularly interesting that when cerium ions (Ce3+/Ce4+) were added to the Eu-MOF suspension, the fluorescence intensity at 420 nm was enhanced, while the fluorescence at 620 nm was quenched. On this basis, a ratiometric fluorescent sensor for detecting cerium ions was constructed, which has a good linear relationship in the range of 0.05-15 μM and a detection limit of 16 nM. The plausible mechanism of the change in the fluorescence characteristics of Eu-MOF caused by cerium ions was discussed in detail. Through the study of fluorescence lifetime and ultraviolet absorption, it was proven that the mechanism of Ce3+-quenching Eu-MOF fluorescence is the inner filter effect. Photoinduced electron transfer and internal filtering effects lead to fluorescence quenching at 620 nm, while redox reactions lead to fluorescence enhancement of the ligand at 420 nm.

SIGNIFICANCE

The proposed ratiometric fluorescence sensor was successfully employed for the detection of cerium ions in real water samples, confirming that it can be used as an alternative method for the detection of Ce3+ and Ce4+ in environmental samples.

Hg2+ detection and information encryption of new [1+1] lanthanide cluster

The sensing of heavy metal ion and information encryption are two very important research areas. Therefore, developing multi-functional materials capable of sensing heavy metal ions and encrypting information is highly important. In this work, three [1 + 1] lanthanide clusters [Ln(TFBA)3(dmp) (H2O)2]2 (Ln = Tb3+Tb1+1, Eu3+Eu1+1, Gd3+Gd1+1, HTFBA = 2,3,4,5-tetrafluorobenzoic acid, dmp = 4,7-dimethyl-1,10-phenanthroline) were designed and synthesized. Among them, Tb1+1 shows excellent luminescence sensing towards Hg2+ (Ex = 350 nm, Em = 545 nm). Results demonstrates the sensing with high selectivity, strong anti-interference, 20-s response time, high accuracy, excellent linear relationship in 0-20.0 μM, and a very low limit of detection (0.02 ppb). Furthermore, paper strips based on Tb1+1 is fabricated for visual detection of Hg2+ in real samples of tap water, lake water, human urine, and human serum. More interestingly, a new method for confidentiality of information is realized through multi-color anti-counterfeiting patterns with the [1 + 1] lanthanide cluster ink, based on the luminescence "on-off" sensing towards Hg2+.

Europium metal-organic frameworks: Synthesis, characterization, and application as fluorescence sensors for the detection of Cu2+, Ni2+ cations and T3, T4 hormones

The solvothermal approach was used to create a novel Eu metal-organic framework (Eu-MOF) based on 1,4-benzendicarboxylic acid (TPA), 1,10-phenanthroline, and N,N-dimethylformamide (DMF)/H2O. Structural analysis of Eu-MOF, Fluorescence spectrometry, Fourier Transform Infrared Spectrometer (FTIR), Scanning Electron Microscopy (SEM), Energy dispersive X-ray (EDX) mapping, Thermo-gravimetric analysis (TGA), and Single Crystal X-Ray Diffraction (PXRD) methods. Using the fluorescence properties of the synthesized Eu-MOF, its use as a fluorescence sensor in the determination of different analytes, such as organic molecules (T3-T4 hormone, ascorbic acid, and glucose) and metal ions (Na+, K+, Ca2+, Mg2+, Cu2+, Mn2+, Hg2+, Pb2+, Ni2+, Cr3+, Al3+, Fe3+), was investigated. Fluorescence experiments revealed that Cu2+, Ni2+ cations, as well as T3 and T4 hormones, quenched the fluorescence of Eu-MOF. Turn-off luminescence can be induced by 10 μM Cu2+, 30 μM Ni2+ cations, 500 nM T3, and 800 nM T4 hormones. Fluorescence quenching efficiencies were calculated for Cu2+, Ni2+, T3, and T4 99.7%, 99.6%, 98.7%, and 98.2%, respectively.

Fully Integrated Ratiometric Fluorescence Enrichment Platform for High-Sensitivity POC Testing of Salivary Cancer Biomarkers

The point-of-care (POC) testing of cancer biomarkers in saliva with both high sensitivity and accuracy remains a serious challenge in modern clinical medicine. Herein, we develop a new fully integrated ratiometric fluorescence enrichment platform that utilizes acoustic radiation forces to enrich dual-emission sandwich immune complexes for a POC visual assay. As a result, the color signals from red and green fluorescence (capture probe and report probe, respectively) are enhanced by nearly 10 times, and colorimetric sensitivity is effectively improved. When illuminated using a portable UV lamp, the fluorescence color changing from red to green can be clearly seen with the naked eye, which allows a semiqualitative assessment of the carcinoembryonic antigen (CEA) level. In combination with a homemade smartphone-based portable device, cancer biomarkers like CEA are quantified, achieving a limit of detection as low as 0.012 ng/mL. We also directly quantify CEA in human saliva samples to investigate the reliability of this fully integrated platform, thus validating the usefulness of the proposed strategy for clinical diagnosis and home monitoring of physical conditions.

Sensors in the Detection of Abused Substances in Forensic Contexts: A Comprehensive Review

Forensic toxicology plays a pivotal role in elucidating the presence of drugs of abuse in both biological and solid samples, thereby aiding criminal investigations and public health initiatives. This review article explores the significance of sensor technologies in this field, focusing on diverse applications and their impact on the determination of drug abuse markers. This manuscript intends to review the transformative role of portable sensor technologies in detecting drugs of abuse in various samples. They offer precise, efficient, and real-time detection capabilities in both biological samples and solid substances. These sensors have become indispensable tools, with particular applications in various scenarios, including traffic stops, crime scenes, and workplace drug testing. The integration of portable sensor technologies in forensic toxicology is a remarkable advancement in the field. It has not only improved the speed and accuracy of drug abuse detection but has also extended the reach of forensic toxicology, making it more accessible and versatile. These advancements continue to shape forensic toxicology, ensuring swift, precise, and reliable results in criminal investigations and public health endeavours.

Smartphone-integrated ratiometric fluorescence sensing platform based on bimetallic metal-organic framework nanowires for anthrax biomarker detection

Developing an intelligent, sensitive, and visual strategy for quickly identifying anthrax biomarkers is crucial for ensuring food safety and preventing disease outbreaks. Herein, a smartphone-integrated ratiometric fluorescent sensing platform based on bimetallic metal-organic framework (Eux/Tb1-x-MOF) nanowires was designed for specific recognition of pyridine-2,6-dicarboxylic acid (DPA, anthrax biomarker). The Eux/Tb1-x-MOF was prepared by coordinating Eu3+ and Tb3+ with BBDC ligands, which exhibited a uniform fibrous morphology and dual-emission fluorescence at 543 and 614 nm. After the introduction of DPA, the red emission at 614 nm displayed obvious fluorescence quenching, while the green emission at 543 nm was gradually enhanced. The ratiometric sensing offered a wide linear equation in the range of 0.06-15 µg/mL and a low detection limit (LOD) of 20.69 ng/mL. Furthermore, a portable smartphone installing the color recognition application can achieve sensitive, real-time, and visual detection of DPA. As a simple and effective smartphone-assisted sensing platform, this work holds admirable promise to broaden the applications in biomarker real-time determinations and other fields.

Luminescence-based detection and identification of illicit drugs

Luminescence-based sensing is capable of being used for the sensitive, rapid, and in some cases selective detection of chemicals. Furthermore, the method is amenable to incorporation into handheld low-power portable detectors that can be used in the field. Luminescence-based detectors are now commercially available for explosive detection with the technology built on a strong foundation of science. In contrast, there are fewer examples of luminescence-based detection of illicit drugs, despite the pervasive and global challenge of combating their manufacture, distribution and consumption and the need for handheld detection systems. This perspective describes the relatively nascent steps that have been reported in the use of luminescent materials for the detection of illicit drugs. Much of the published work has focused on detection of illicit drugs in solution with less work on vapour detection using thin luminescent sensing films. The latter are better suited for handheld sensing devices and detection in the field. Illicit drug detection has been achieved via different mechanisms, all of which change the luminescence of the sensing material. These include photoinduced hole transfer (PHT) leading to quenching of the luminescence, disruption of Förster energy transfer between different chromophores by a drug, and chemical reaction between the sensing material and a drug. The most promising of these is PHT, which can be used for rapid and reversible detection of illicit drugs in solution and film-based sensing of drugs in the vapour phase. However, there are still significant knowledge gaps, for example, how vapours of illicit drugs interact with the sensing films, and how to achieve selectivity for specific drugs.

AIE-doped Poly(Ionic Liquid) Photonic Spheres for the Discrimination of Psychoactive Substances

Drugs of abuse has drawn intense attention due to increasing concerns to public health and safety. The construction of a sensing platform with the capability to identify them remains a big challenge because of the limitations of synthetic complexity, sensing scope and receptor extendibility. Here a kind of poly(ionic liquid) (PIL) photonic crystal spheres doped with aggregation-induced emission (AIE) luminogens was developed. As diverse noncovalent interactions involve in PIL moieties, the single sphere shows different binding affinity to a broad range of psychoactive substances. Furthermore, the dual-channel signals arising from photonic crystal structures and sensitive AIE-luminogens provide high-dimensional information for discriminative detection of targets, even for molecules with slight structural differences. More importantly, such single sphere sensing platform could be flexibly customized through ion-exchange, showing great extendibility to fabricate high-efficiency/high-throughput sensing arrays without tedious synthesis.

An Overview of the Design of Metal-Organic Frameworks-Based Fluorescent Chemosensors and Biosensors

Taking advantage of high porosity, large surface area, tunable nanostructures and ease of functionalization, metal-organic frameworks (MOFs) have been popularly applied in different fields, including adsorption and separation, heterogeneous catalysis, drug delivery, light harvesting, and chemical/biological sensing. The abundant active sites for specific recognition and adjustable optical and electrical characteristics allow for the design of various sensing platforms with MOFs as promising candidates. In this review, we systematically introduce the recent advancements of MOFs-based fluorescent chemosensors and biosensors, mainly focusing on the sensing mechanisms and analytes, including inorganic ions, small organic molecules and biomarkers (e.g., small biomolecules, nucleic acids, proteins, enzymes, and tumor cells). This review may provide valuable references for the development of novel MOFs-based sensing platforms to meet the requirements of environment monitoring and clinical diagnosis.