Metal-organic Framework Sensor Research Articles

Fluorescence Turn-on Detection of Perfluorooctanoic Acid (PFOA) by Perylene Diimide-Based Metal-Organic Framework.

A novel, water-stable, perylene diimide (PDI) based metal-organic framework (MOF), namely, U-1, has been synthesized for selective and sensitive detection of perfluorooctanoic acid (PFOA) in mixed aqueous solutions. The MOF shows highly selective fluorescence turn-on detection via the formation of a PFOA-MOF complex. This PFOA-MOF complex formation was confirmed by various spectroscopic techniques. The detection limit of the MOF for PFOA was found to be 1.68 μM in an aqueous suspension. Upon coating onto cellulose paper, the MOF demonstrated a significantly lower detection limit, down to 3.1 nM, which is mainly due to the concentrative effect of solid phase extraction (SPE). This detection limit is lower than the fluorescence sensors based on MOFs previously reported for PFAS detection. The MOF sensor is regenerable and capable of detecting PFOA in drinking and tap water samples. The PDI-MOF-based sensor reported herein represents a novel approach, relying on fluorescence turn-on response, that has not yet been thoroughly investigated for detecting per- and polyfluoroalkyl substances (PFAS) until now.

Portably and Visually Sensing Cytisine through Smartphone Scanning Based on a Post-Modified Luminescence Center Strategy in Zinc-Organic Frameworks.

Cytisine (CTS) is a useful medicine for treating nervous disorders and smoking addiction, and exploring a convenient method to detect CTS is of great significance for long-term/home medication to avoid the risk of poisoning, but it is full of challenges. Here, a modified metal-organic framework sensor Tb@Zn-TDA-80 with dual emission centers was prepared using a post-modified luminescence center strategy. The obtained Tb@Zn-TDA-80 can serve as a CTS sensor with high sensitivity and selectivity. To achieve portable detection, Tb@Zn-TDA-80 was further fabricated as a membrane sensor, M-Tb@Zn-TDA-80, which displayed an obvious CTS-responsive color change by simply dropping a CTS solution onto its surface. Benefiting from this unique functionality, M-Tb@Zn-TDA-80 successfully realized the visual detection and quantitative monitoring of CTS in the range of 5.26-52.6 mM by simply scanning the color with a smartphone. The results of nuclear magnetic resonance spectroscopy and theoretical computation illustrated that the high sensing efficiency of Tb@Zn-TDA-80 for CTS was attributed to the N-H⋅⋅⋅π and π⋅⋅⋅π interactions between the ligand and CTS. And luminescence quenching may result from the intramolecular charge transfer. This study provides a convenient method for ensuring long-term medication safety at home.

Metal-Organic Frameworks Based Sensor Platforms for Rapid Detection of Contaminants in Wastewater.

Metal-organic frameworks (MOFs) are a type of multifunctional material with organic-inorganic doped metal complexes that have a lot of unsaturated metal sites and a consistent network structure. MOFs work has great performance for enhancing the mass transfer, signal, and sensitivity as well as analyte enrichment. This study highlights the recent advancements of MOFs-based sensors for pollutant detection in a water environment and summarizes the effect of various synthetic materials on the performance of MOFs-based sensors. The related challenges and optimization techniques have been discussed. Then the research results of various MOFs sensors in the detection of wastewater pollutants are analyzed. Finally, the challenges facing MOFs-based water sensor development and the outlook for future research are discussed.

Second near-infrared fluorescent Metal–Organic framework sensors for in vivo extracellular adenosine triphosphate monitoring

Plant nanobionic sensors enable real-time monitoring of signaling molecules in plants by interfacing them with specifically designed nanoprobes, which have been acknowledged as species-independent analytical tools. In this study, we developed a plant nanobionic sensor for in vivo detection of extracellular adenosine triphosphate (eATP) in living plants by designing a novel second near-infrared (NIR-II) fluorescent metal–organic framework (MOF) nanoprobe. The NIR-II fluorescent nanoprobe (IR-1061 micelle@ZIF-90) with a sandwich structure was synthesized by successive encapsulation of the hydrophobic NIR-II dye IR-1061 with the amphipathic polymer DSPE-mPEG 2000 and MOF ZIF-90. Interestingly, coating ZIF-90 around IR-1061 micelles increased the NIR-II fluorescence 16.6-fold. Utilizing the ultrahigh NIR-II fluorescent emission of the designed nanoprobes and specific recognition of ZIF-90 to ATP, the nanoprobes were applied to spatial and temporal monitoring eATP in model and non-model plants under environmental stress.

Intelligent Identification of Cerebrospinal Fluid for the Diagnosis of Parkinson's Disease.

Cerebrospinal fluid (CSF) biomarkers are more sensitive than the Movement Disorder Society (MDS) criteria for detecting prodromal Parkinson's disease (PD). Early detection of PD provides the best chance for successful implementation of disease-modifying treatments, making it crucial to effectively identify CSF extracted from PD patients or normal individuals. In this study, an intelligent sensor array was built by using three metal-organic frameworks (MOFs) that exhibited varying catalytic kinetics after reacting with potential protein markers. Machine learning algorithms were used to process fingerprint response patterns, allowing for qualitative and quantitative assessment of the proteins. The results were robust and capable of discriminating between PD and non-PD patients via CSF detection. The k-nearest neighbor regression algorithm was used to predict MDS scores with a minimum mean square error of 38.88. The intelligent MOF sensor array is expected to promote the detection of CSF biomarkers due to its ability to identify multiple targets and could be used in conjunction with MDS criteria and other techniques to diagnose PD more sensitively and selectively.

Ultrathin MOF nanosheets and their mixed-matrix membranes for ammonia and aliphatic amine sensing in water.

Ultrathin 2D metal-organic frameworks (MOFs) exhibit a myriad of unparalleled properties, rendering them extensively applicable across various fields. Despite this, developing a 2D MOF sensor for detecting hazardous amines in water remains a formidable challenge. To address this issue, we synthesized Ni-btc MOF ultrathin nanosheets with a thickness of approximately 4.15 nm for the detection of amines in water. These nanosheets demonstrated a notable "turn-on" fluorescence response in the presence of ammonia and aliphatic amines. The detection limit for aliphatic amines ranged from 297 to 424 nM, while for ammonia, it reached an impressive low limit of around 42 nM, which is an excellent value compared to other reported MOFs for ammonia sensing in water. Density functional theory calculations elucidated the mechanism underlying fluorescence enhancement. Additionally, a mixed matrix membrane based on MOF nanosheets was fabricated for real-time sensing that exhibits an immediate color change in the presence of ammonia and aliphatic amines.

Ni-based metal-organic framework sensor material for urea detection: Mechanistic insights and performance

A mechanistic study of the metal-organic framework nickel-hexahydroxytriphenylene [Ni3(HHTP)2]n as an active catalyst material for electrochemical urea sensing is reported, together with the evaluation of its performance. Urea sensing is a crucial technology for the life quality of people facing kidney disease. Through the quantification of urea in saliva, the monitoring of the progress of kidney disease could be enabled. [Ni3(HHTP)2]n can detect urea via urea electro-oxidation reaction. The urea electro-oxidation on [Ni3(HHTP)2]n follows an EC’ mechanism. [Ni3(HHTP)2]n is electrochemically transformed into Ni(OH)2, the catalytic intermediate of Ni in alkaline electrolyte, and the reduction step of Ni3+ to Ni2+ limited by the urea electro-oxidation reaction. The transformation leads to a disintegration of the metal-organic framework due to oxygen evolution. As urea inhibits oxygen evolution, the degradation is also inhibited. Our results demonstrated a competitive sensor when compared to the benchmarking, with a sensitivity of 1.797 mA/cm2∙mM Urea, the limit of detection of 3.5 µM, linear range between 0.01 mM and 1 mM with a correlation coefficient of 0.991 and selectivity towards Na+, K+, Cl−, creatinine, uric acid, and low concentrations of glucose.

Towards an E-nose: Metal-organic frameworks based quartz crystal microbalance array for fruit ripeness indexing

Ethylene is a hormone for fruit ripening control, and for the purpose of maintaining plant quality, ethylene monitoring is crucial. Due to the simple structure and limited functionality, the technical realization of ethylene detection by an artificial sensor remains a challenge. In this paper, we present a metal-organic frameworks (MOFs) array based electronic nose (e-nose) for rapid and accurate determination of ethylene. Six zirconium-based MOFs with systematically modified pore sizes and π-π binding sites have been prepared and fabricated into a sensor array using quartz crystal microbalance (QCM) technology. By virtue of the synergistic features of six MOF sensors, selectivity detection of ethylene has been achieved. The detection limit reaches to 0.27 ± 0.02 ppm, and high selectivity and stability (98.29 % ± 0.88 %) could also be confirmed. By submitting data to machine learning algorithm, an e-nose system could be established for discriminating ethylene from mixtures with a qualitative accuracy of 90.30 % and quantitative accuracy of 98.89 %. Practical evaluation suggests that the e-nose could index the fruit quality based on the accurate detection of ethylene released during fruit ripeness. This work demonstrates the promising potential of fabricating MOFs based e-nose systems for practical monitoring applications by selectively detecting challengeable target molecules.

Selective and Rapid Detection of 4-Nitrophenol in River and Treated Industrial Wastewater by a Luminescent Lanthanide Metal-Organic Framework Sensor.

Phenolic organic compounds are widely used industrial chemicals that exist extensively in the environment and have a significant impact on human health. 4-Nitrophenol (4-NP) is a typical phenolic organic compound found in aqueous environments. Efficient detection of 4-NP in wastewater is highly challenging due to the complexity of testing environmental samples. Herein, a luminescent lanthanide metal-organic framework (MOF) sensor based on the Eu3+ ion {[Eu(HL)(L)(H2O)]·2H2O}n (EuMOF; H2L = 5-(4H-1,2,4-triazol-4-yl)benzene-1,3-dicarboxylic acid) was successfully synthesized for efficient 4-NP detection in wastewater. Fluorescence sensing experiments revealed that 4-NP could greatly quench the EuMOF fluorescence. Subsequently, EuMOF was applied to 4-NP detection in distilled water, tap water, river water, and treated industrial wastewater, exhibiting high sensitivity, a fast response within 30 s, high selectivity, excellent reusability, and a low detection limit. Finally, the fluorescence quenching mechanism was explored and attributed to competitive absorption of irradiated light between 4-NP and the ligand.

An efficient dual-response luminescent metal-organic framework sensor constructed by new photochromic ligand

Photochromic materials have shown very promising applications. However, developing new photochromic materials remains a huge challenge. In this work, a new photochromic organic molecule, namely 6,13-bis(di(pyridin-4-yl)methylene)-6,13-dihydropentacene (L), has been successfully synthesized. Its photochromic mechanism has been elucidated. The dihydropentacene-based photochromic organic molecule was firstly applied as functional ligands to construct LMOF-based sensor {Zn(L)(TPA)·H2O}n (1; LMOF = luminescent metal-organic framework; H2TPA = terephthalic acid). 1 exhibits a three-dimensional (3-D) two-fold interpenetrated architecture, excellent stabilities, luminescent and photochromic properties. 1 can highly sensitively detect Cu2+ and MnO4− in aqueous medium by luminescent quenching effect. Notably, the quenching constants of 1′ (1 after photochromism) towards Cu2+ and MnO4− are 6.4 and 6.5 times higher than those of 1, respectively, which demonstrates significantly enhanced sensing sensitivities for 1′. Furthermore, 1′ can effectively identify MnO4− from similar strong oxidizing anions CrO42− and Cr2O72−. This dual-response luminescent sensor exhibits good recyclability, and its quenching sensing mechanisms have been discussed in detail. This work will contribute to the development of efficient photochromic luminescent sensors.

Preparation and Characterization of Fe-Gallic acid MOF for determination of antiviral Molnupiravir as inhibitor for RNA Corona virus replication

Fe-Gallic acid metal organic framework (MOF) was synthetized and characterized by acquired qualitative and quantitative micro analytical tools such as: FE-SEM/EDX, XPS analysis, XRD analysis, FT-IR, and Fluorescence spectroscopy. Fe-Gallic acid MOF is used as a sensor for the determination of antiviral Molnupiravir (MOL) in pharmaceutical formulations, urine and serum samples. The existence of adequate functional groups in (MOL) solution in DMSO induces the interaction with the Fe- Gallic acid MOF complex that absorb energy at the characteristic wavelength of the organic ligand (λex = 290 nm) and emits radiation at 357 nm over a working range of 1 × 10−5 − 1 × 10−9 mol/L. The Fe-Gallic acid MOF sensor is a sensitive and cost-effective method for the detection of Molnupiravir. It has a detection limit of 2.24 × 10−9 mol/L, which is lower than other methods for the detection of Molnupiravir. The Fe-Gallic acid MOF sensor is also easy to use and does not require any special equipment. It is a promising new method for the detection of Molnupiravir, and it could be used in a variety of settings, including clinical laboratories and point-of-care settings.

Hf-Based MOF for Rapid and Selective Sensing of a Nerve Agent Simulant and an Aminophenol: Insights from Experiments and Theory.

The metal-organic framework (MOF) Hf-DUT-52 was prepared with diamino functionality by the solvothermal method. This material displayed fluorometric sensing ability toward a nerve agent simulant (diethyl chlorophosphate (DCP)) and 3-diethylaminophenol (3-DEAP). It is the first-ever reported fluorescent MOF sensor for DCP and 3-DEAP. Apart from a fast response (<5 s), the sensor had a very low detection limit for both DCP and DEAP (limit of detection (LOD) values for DCP and 3-DEAP sensing were 9 and 125 nM, respectively). The obtained detection limit is the second lowest among all of the reported optical sensors for DCP. The sensor also displayed its capability to identify the presence of trace amount of DCP in various natural water specimens with good selectivity. Moreover, MOF@cotton composites were developed for visual, on-site, nanomolar-level detection of both targeted analytes. Furthermore, a MOF@PVA thin film was fabricated and successfully utilized for the detection of highly volatile and deadly poisonous DCP in the vapor phase. The sensor was also recyclable for up to five cycles without losing appreciable efficiency. Density functional theory (DFT)-based periodic and cluster calculations were performed to shed light on the sensing ability of the MOF by studying the interactions of DCP and DEAP with the MOF. Our theoretical results reveal the importance of linker defects and water chemisorption on the adsorption/complexation of the analytes at uncoordinated Hf sites.

Gold nanoparticles embedded Fe-BTC (AuNPs@Fe-BTC) metal-organic framework as a fluorescence sensor for the selective detection of As(III) in contaminated waters

In this article, a new off-mode fluorescent platform based on the metal-organic framework (MOF) is introduced as a highly selective and rapid chemical sensor for the detection of As(III) in water and wastewater samples. A typical Fe-BTC (BTC = 1,3,5-benzenetricarboxylate or trimesic acid) MOF was used as a porous template for loading gold nanoparticles (AuNPs@Fe-BTC MOF). The physicochemical properties of AuNPs@Fe-BTC MOF were characterized by Fourier-transform infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EAX), element mapping (MAP) and X-ray diffraction (XRD) analysis. This sensing method for As(III) ions is based on the fact that the fluorescence intensity of AuNPs@Fe-BTC MOF sensor decreases in proportion to the increase in As(III) concentration. The main effective factors on the performance of the sensor signal such as MOF dosage, sonication time, pH and reaction time were optimized. Under optimized conditions, the calibration graph was linear in the concentration range of 0.5–380 ng mL−1 of As(III) and the limit of detection was 0.2 ng mL−1. The proposed method was successfully validated by addition/recovery experiments by the determination of As(III) in four river water and two wastewater effluent samples.

Electrochemical Sensor for Food Monitoring Using Metal-Organic Framework Materials

Feeding the world’s increasing inhabitants requires considerable quantities of food, whose quality is essential to personal and economic health. Food quality parameters are mandatory to control throughout the fresh produce supply chain to meet consumer requests. Until now, different analytical techniques have been employed in food safety control. However, most of these are laboratory needed, expensive, and time-consuming. To address these obstacles, many researchers have concentrated on developing electrochemical sensors (ECSs) as a powerful method with great sensitivity and reliability for food evaluation. Metal-organic frameworks (MOFs) with surprisingly porous morphology provide uniform yet tunable features, a high specific surface, and established practical applications in various fields. MOF-based ECSs present novel routes for the fast and effective detection of food contaminants or nutrients. In this current review, we concentrate on the MOF-based ECSs for food evaluation by first overviewing the library of available MOF sensors from pristine to MOF-bio composites and then exploiting recent application fields, with an emphasis on how this novel material unlocks new opportunities to monitor food nutrients or hazards.

Recent Progress in MOF-Based Electrochemical Sensors for Non-Enzymatic Glucose Detection

In recent years, substantial advancements have been made in the development of enzyme-free glucose sensors utilizing pristine metal-organic frameworks (MOFs) and their combinations. This paper provides a comprehensive exploration of various MOF-based glucose sensors, encompassing monometallic MOF sensors as well as multi-metal MOF combinations. These approaches demonstrate improved glucose detection capabilities, facilitated by the augmented surface area and availability of active sites within the MOF structures. Furthermore, the paper delves into the application of MOF complexes and derivatives in enzyme-free glucose sensing. Derivatives incorporating carbon or metal components, such as carbon cloth synthesis, rGO-MOF composites, and core–shell structures incorporating noble metals, exhibit enhanced electrochemical performance. Additionally, the integration of MOFs with foams or biomolecules, such as porphyrins, enhances the electrocatalytic properties for glucose detection. Finally, this paper concludes with an outlook on the future development prospects of enzyme-free glucose MOF sensors.

Metal-organic framework-based nanomaterials as opto-electrochemical sensors for the detection of antibiotics and hormones: A review.

Increasing trace levels of antibiotics and hormones in the environment and food samples are concerning and pose a threat. Opto-electrochemical sensors have received attention due to their low cost, portability, sensitivity, analytical performance, and ease of deployment in the field as compared to conventional expensive technologies that are time-consuming and require experienced professionals. Metal-organic frameworks (MOFs) with variable porosity, active functional sites, and fluorescence capacity are attractive materials for developing opto-electrochemical sensors. Herein, the insights into the capabilities of electrochemical and luminescent MOF sensors for detection and monitoring of antibiotics and hormones from various samples are critically reviewed. The detailed sensing mechanisms and detection limits of MOF sensors are addressed. The challenges, recent advances, and future directions for the development of stable, high-performance MOFs as commercially viable next-generation opto-electrochemical sensor materials for the detection and monitoring of diverse analytes are discussed.

Fluorescence Ratiometric Antibiotic Detection with a Single Lanthanide Metal‐Organic Framework

AbstractAntibiotic residues are currently an increasing threat for human health and the ecosystem, and specific and rapid real‐time sensing of antibiotics is a big challenge. To realize specific sensing by rapid fluorescent sensors, a lanthanide metal‐organic framework (MOF) containing dual emissive centers has been developed with high sensing selectivity and sensitivity. Owing to the self‐calibration ability, the dual‐center Tb‐MOF exhibits higher selectivity towards furazolidone (FZD) and nitrofural (NZF) among the reported MOF sensors. Additionally, the corresponding ratiometric detection mode also realized specific sensing of other tested antibiotics. Besides, the single‐Tb3+‐based dual‐emission MOF in this work is expected to support the development of fluorescent sensors with high sensitivity and selectivity for environmental safety purposes.

Amine-decorated Zirconium Based Metal Organic Framework for Ultrafast Detection of 2,4,6-Trinitrophenol in Aqueous Samples.

An amine-decorated zirconium based metal organic framework (MOF) UiO-66-NH2 with rod shape morphology was synthesized by solvothermal process using 2-aminoterephthalic acid as an organic linker. Crystallinity of synthesized MOF material was confirmed with PXRD technique. MOF was employed as selective and sensitive sensor for ultra-trace detection of 2,4,6-trinitrophenol (TNP) in aqueous matrix, even in coexistence with other competitive nitroaromatic analytes. High value of Stern-Volmer quenching constant Ksv (1.106 × 105M- 1), plausible photoluminescent quenching efficiency (97.8%) and lower detection limit (0.95 µM/217ng mL- 1) ascertained extraordinary sensitivity of developed MOF for TNP. Density functional theory calculations and electrostatic interactions (i.e. ionic interaction, H-bonding and π-π interaction) indicated that electron and energy transfer processes play a key role in turn-off quenching response of UiO-66-NH2 sensor. Spiked real samples were analysed to validate the developed method, which satisfactorily established the developed MOF sensor as an efficient tool for analysis.

Ultra-low limit of luminescent detection of gossypol by terbium(III)-based metal-organic framework

The widespread use of gossypol-containing animal feed and cottonseed oil poses a great threat to water quality and livestock and human health, and there is an urgent need for a sensor for the rapid detection of trace amounts of gossypol in aqueous solutions and cottonseed oil. As a result, an unprecedented three-dimensional metal-organic framework sensor based on terbium(III) and a flexible ligand 4-(3,5-dicarboxyphenoxy)isophthalic acid (H4L) was developed. Tb-MOF, {[Tb(H2O)(HL)]·0.5MeCN·0.25 H2O}n, is highly stable in water and polar organic solvents and exhibits terbium-centered luminescence with 44% quantum yield. Suspensions of MOF in water and ethanol demonstrate a luminescence quenching response to cotton phytotoxicant gossypol with an unprecedented low detection limit of 0.76 nM and 1.89 nM, correspondingly, without interference from the components of cottonseed oil and blood plasma, making it suitable for the detection and determination of gossypol in real-life water and oil samples. Significantly, Tb-MOF is the first highly efficient sensor that uses water as a solvent to detect trace amounts of gossypol, and it can visualize and quantify gossypol in edible-grade cottonseed oil as well, which proves its great potential for practical application. In addition, Tb-MOF exhibited a detection limit for Fe3+ (0.23 μM) among the lowest reported for lanthanide-based MOFs in aqueous solutions so far.

Metal–Organic Frameworks as Sensors for Human Amyloid Diseases

Metal-organic frameworks (MOFs) are versatile compounds with emergent applications in the fabrication of biosensors for amyloid diseases. They hold great potential in biospecimen protection and unprecedented probing capabilities for optical and redox receptors. In this Review, we summarize the main methodologies employed in the fabrication of MOF-based sensors for amyloid diseases and collect all available data in the literature related to their performance (detection range, limit of detection, recovery, time of analysis, among other parameters). Nowadays, MOF sensors have evolved to a point where they can, in some cases, outperform technologies employed in the detection of several amyloid biomarkers (amyloid β peptide, α-synuclein, insulin, procalcitonin, and prolactin) present in biological fluids, such as cerebrospinal fluid and blood. A special emphasis has been given by researchers on Alzheimer's disease monitoring to the detriment of other amyloidosis that are underexploited despite their societal relevance (e.g., Parkinson's disease). There are still important obstacles to overcome in order to selectively detect the various peptide isoforms and soluble amyloid species associated with Alzheimer's disease. Furthermore, MOF contrast agents for imaging peptide soluble oligomers in living humans are also scarce (if not nonexistent), and action in this direction is unquestionably required to clarify the contentious link between the amyloidogenic species and the disease, guiding research toward the most promising therapeutic strategies.