Luminescent Metal-organic Framework Research Articles

CLICK-FLISA Based on Metal-Organic Frameworks for Simultaneous Detection of Fumonisin B1 (FB1) and Zearalenone (ZEN) in Maize.

Mycotoxins are secondary products produced primarily by fungi and are pathogens of animals and cereals, not only affecting agriculture and the food industry but also causing great economic losses. The development of rapid and sensitive methods for the detection of mycotoxins in food is of great significance for livelihood issues. This study employed an amino-functionalized zirconium luminescent metal-organic framework (LOF) (i.e., UiO-66-NH2). Click chemistry was utilized to assemble UiO-66-NH2 in a controlled manner, generating LOF assemblies to serve as probes for fluorescence-linked immunoassays. The proposed fluoroimmunoassay method for Zearalenone (ZEN) and Fumonisin B1 (FB1) detection based on the UiO-66-NH2 assembled probe (CLICK-FLISA) afforded a linear response range of 1-20 μmol/L for ZEN, 20 μmol/L for FB1, and a very low detection limit (0.048-0.065 μmol/L for ZEN; 0.048-0.065 μmol/L for FB1). These satisfying results demonstrate promising applications for on-site quick testing in practical sample analysis. Moreover, the amino functionalization may also serve as a modification strategy to design luminescent sensors for other food contaminants.

Charting a Path to Tumor Therapy: Mastery of Luminescent Metal–Organic Frameworks for Precise Spatiotemporal Control

AbstractThe field of drug delivery has significantly advanced tumor therapy, yet challenges such as the predictability of treatment outcomes and the real‐time monitoring of tumor progression, such as recurrence or metastasis. Luminescent metal–organic frameworks (L‐MOFs) are a promising solution to overcome these issues. This review offers a comprehensive exploration of the design and synthesis of L‐MOFs, presenting their crucial optical properties. The review highlights the pivotal role of L‐MOFs in enabling precision medicine for tumor treatment driven by their performance. Through strategically harnessing light‐manipulated metal–organic frameworks (MOFs), real‐time therapeutic monitoring and precise spatiotemporal control in tumor treatment can be achieved. Moreover, this review meticulously examines the influence of photomanipulating MOFs on in situ drug synthesis, introducing the catalytic role in light‐manipulated gas therapy. Additionally, the role of L‐MOFs as gene therapy vectors that utilize light to trigger gene expression responses is also comprehensively explored in the article, aiming to highlight their role in enabling tumor therapy through gene therapy. The review concludes by proposing an artificial intelligence (AI)‐mediated blueprint for tumor treatment with L‐MOFs, aiming to pave the way for innovative approaches through light manipulation.

A luminescent metal–organic framework composite as a turn-on sensor for the selective determination of monosodium glutamate in instant noodles

This work reports the development and application of a new fluorescent nanoprobe sensor depending on using luminescent metal organic framework (LMOF). The developed sensor composed of hybridized Ca 1,3,5-benzenetricarboxylic acid metal organic framework with microcrystalline cellulose (Ca-BTC/MCC MOF) as a fluorescent probe for the determination of the monosodium glutamate (MSG), a non-chromophoric food additive. The developed sensor was characterized using a high-resolution scanning electron microscope (HR-SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The Ca-BTC/MCC MOF hybrid, examined under the HR-SEM, showed morphological features different from the MCC and the Ca-BTC MOF. The diffraction patterns of Ca-BTC/MCC composites clearly displayed the characteristic Ca-BTC MOF diffraction bands, indicating that MCC was successfully incorporated in the formation of crystalline MOF hybrids. The FTIR spectra show the bands of MCC, as well as the bands of Ca-BTC MOFs. The prepared nanoprobe was successfully applied as a sensitive sensor for the determination of MSG in food sample. The method was validated following the International ICH (Q2)R2 guidelines in terms of precision, trueness and other main analytical figures of merit, comprised the green profile and practicability metrics. A wide linearity range was achieved (5–50 µg/mL) with good correlation coefficient (R2 ≥ 0.9993). The recoveries (%) were found in the range of 100.0 to 101.5 and the RSDs (%) were in the range of 0.1 to 0.9 %.These results show that the developed nanoprobe was selective, and highly accurate to determine this important food additive in the seasonings of instant noodles, also showing a reduced environmental impact based on the metrics currently accepted for the evaluation of the green profile and practicability.

Reusable MOF-Coated Chitosan@Paper Strip Composite for Real-Time Monitoring of Pesticide Pendimethalin and Organoarsenic Feed Additive Roxarsone Levels in Environmental Water, Food, and Vegetable Samples.

An alarming increase in the use of pesticides and organoarsenic compounds and their toxic impacts on the environment have inspired us to develop a selective and highly sensitive sensor for the detection of these pollutants. Herein, a bio-friendly, low-cost Al-based luminescent metal-organic framework (1')-based fluorescent material is demonstrated that helps in sustaining water quality by rapid monitoring and quantification of a long-established pesticide (pendimethalin) and a widely employed organoarsenic feed additive (roxarsone). A pyridine-functionalized porous aluminum-based metal-organic framework (Al-MOF) was solvothermally synthesized. After activation, it was used for fast (<10 s) and selective turn-off detection of roxarsone and pendimethalin over other competitive analytes. This is the first MOF-based recyclable sensor for pendimethalin with a remarkably low limit of detection (LOD, 14.4 nM). Real-time effectiveness in detection of pendimethalin in various vegetable and food extracts was successfully verified. Moreover, the aqueous-phase recyclable detection of roxarsone with an ultralow detection limit (13.1 nM) makes it a potential candidate for real-time application. The detection limits for roxarsone and pendimethalin are lower than the existing luminescent material based sensors. Furthermore, the detection of roxarsone in different environmental water and a wide pH range with a good recovery percentage was demonstrated. In addition, a cheap and bio-friendly 1'@chitosan@paper strip composite was prepared and successfully employed for the hands-on detection of pendimethalin and roxarsone. The turn-off behavior of 1' in the presence of pendimethalin and roxarsone was examined systematically, and plausible mechanistic pathways were proposed with the help of multiple experimental evidences.

A Recyclable Luminescent MOF Sensor for On-Site Detection of Insecticide Dinotefuran and Anti-Parkinson's Drug Entacapone in Various Environmental and Biological Specimens.

The monitoring and precise determination of pesticides and pharmaceutical drugs and their residues have become increasingly important in the field of food safety and water contamination issues. Herein, a fluorescent aluminium MOF-based sensor (1) was developed for the selective recognition of neonicotinoid insecticide dinotefuran and anti-Parkinson's drug entacapone. Guest-free MOF 1' exhibited ultra-fast response (<5 s) and ultra-low detection limits of 2.3 and 7.6 nM for dinotefuran and entacapone, which are lower than the previously reported MOF-based sensors. In the presence of other competitive analytes, great selectivity was achieved towards both analytes. The probe was recyclable up to five cycles. The sensing ability was explored towards entacapone in human serum, urine and dinotefuran in real soil, rice, honey samples, different fruits, vegetables, real water specimens and a wide range of pH media. A low-cost, handy MOF-based polymer thin-film composite (1'@PVDF-PVP) was developed for the on-site detection of dinotefuran and entacapone. Mechanistic studies involving analytical techniques and theoretical calculations suggested that FRET and PET are the probable reasons for entacapone sensing whereas IFE is responsible for dinotefuran detection. The entire work presents a low cost, multi-use photoluminescent sensor of entacapone and dinotefuran to address the environmental pollution.

Metal-Organic framework incorporated luminescent PTCA combined with novel co-reactant accelerator for ultra-sensitive electrochemiluminescence detection of CA19-9

Polycyclic aromatic hydrocarbons (PAHs) are commonly used as electrochemiluminescence (ECL) luminophores. However, PAHs are limited by the aggregation-caused quenching (ACQ) effect, which reduces ECL emission. Therefore, developing an ECL system from PAHs with efficient luminescence is a significant challenge. In this work, a two-ligand strategy was proposed to assemble 3, 4, 9, 10-perylenetetracarboxylic acid (PTCA) into zeolitic imidazole framework-8 (ZIF-8). The ACQ effect of PTCA was inhibited by participating in the formation of metal–organic frameworks (MOFs) and a luminescent ZIF-8-PTC (Z8P) composite was obtained. Satisfactorily, conceptual experiments demonstrated that the significantly higher ECL efficiency of Z8P was achieved compared with PTCA monomers and aggregates. On the sensing substrate, a novel co-reactant accelerator (Au@MFNC) was used to achieve continuous catalysis of the persulfate (K2S2O8) with the Prussian blue analogues (PBAs) as a template under the efficient synergistic effect of MoS2. Through the reversible transformation of the transition metal valence states, a sufficient amount of sulfate radicals (SO4•−), again amplifying the ECL signal of Pd@Z8P. Under ideal conditions, the constructed dual-MOFs ECL immunosensor had a wide response range (1 × 10−4 − 1 × 102 U/mL) and a low limit of detection (LOD) (6 × 10−5 U/mL), which provided an alternative method for CA19-9 ultrasensitive detection, and broadened a new idea for the development of high-performance luminescent MOFs.

Linker Engineering toward Tunable Emission Behavior of Porous Interpenetrated Zr-Organic Frameworks.

Conjugated molecules with donor-acceptor-donor (D-A-D) moieties have garnered significant attention for their ability to form luminescent metal-organic frameworks (LMOFs). D-A-D molecules feature tunable bandgaps, which can be varied systematically to control the fluorescence wavelength of LMOFs. In this study, we prepared and characterized the fluorescence properties of two porous interpenetrated Zr-organic frameworks (PIZOFs) constructed using 4,4'-(benzo[c][1,2,5]selenadiazole-4,7-diylbis(ethyne-2,1-diyl))dibenzoic acid (L-Se) or 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diylbis(ethyne-2,1-diyl))dibenzoic acid (L-S) as linkers. The corresponding MOFs are denoted as PIZOF-Se and PIZOF-S, respectively. Through our investigation, we explored the correlation between the structure of the frameworks and their respective optical properties. Our findings revealed that there are distinct differences in the fluorescence properties of the two PIZOFs. Specifically, the fluorescence of PIZOF-S is red-shifted from that characteristic of the corresponding linker, L-S. By contrast, the fluorescence of PIZOF-Se is substantially blue-shifted from that of linker L-Se. The emission of mixed-linker MOFs is explored by combining L-S or L-Se with structurally analogous, but nonfluorescent linker, 4,4'-((perfluoro-1,4-phenylene)bis(ethyne-2,1-diyl))dibenzoic acid (L-F). Based on steady-state and time-resolved photoluminescence experiments, as well as confocal fluorescence microscopy combined with fluorescence lifetime imaging (FILM), we demonstrated that linker engineering is an effective method to tune the emission behavior of LMOFs.

Morphology Control of Zr-Based Luminescent Metal-Organic Frameworks for Aflatoxin B1 Detection.

Metal-organic frameworks (MOFs) have gained significant prominence as sensing materials owing to their unique properties. However, understanding the correlation between the morphology, properties, and sensing performance in these MOF-based sensors remains a challenge, limiting their applications and potential for improvement. In this study, Zr-MOF was chosen as an ideal model to explore the impact of the MOF morphology on the sensing performance, given its remarkable stability and structural variability. Three luminescent MOFs (namely rod-like Zr-LMOF, prismoid-like Zr-LMOF, and ellipsoid-like Zr-LMOF) were synthesized by adjusting the quantities of the benzoic acid and the reaction time. More importantly, the sensing performance of these Zr-LMOFs in response to aflatoxin B1 (AFB1) was thoroughly examined. Notably, the ellipsoid-like Zr-LMOF exhibited significantly higher sensitivity compared to other Zr-LMOFs, attributed to its large specific surface area and pore volume. Additionally, an in-depth investigation into the detection mechanism of AFB1 by Zr-LMOFs was conducted. Building upon these insights, a ratiometric fluorescence sensor was developed by coordinating Eu3+ with ellipsoid-like Zr-LMOF, achieving a remarkably lower detection limit of 2.82 nM for AFB1. This study contributes to an improved comprehension of the relationship between the MOF morphology and the sensing characteristics while presenting an effective approach for AFB1 detection.

The impact of Activation on the Performance of Optical Oxygen Sensing with the Luminescent Metal–Organic Framework MOF‐76(Eu)

AbstractThe influence of activation as key parameter for oxygen sensing by luminescent metal–organic frameworks has been investigated and quantified for the archetype MOF‐76(Eu). Activation at different conditions (regarding temperature and solvent‐exchange for distinct vacuum pressure and heating time), shows an influence on the overall quenching, response time and cyclability due to different pore accessibility and surface area and therefore on the overall performance of the sensor. The optical sensing process is based on luminescence quenching, analyzed from high vacuum (10−7 bar) to ambient pressure by dosing oxygen from 0.01 bar to 1 bar. Strong influence of the different activation parameters is observed, as MOF‐76(Eu) activated at 50 °C shows limited quenching of the luminescence intensity within 30 min, while methanol‐exchange and subsequent activation at 250 °C leads to a quenching rate of 98.6 %. In addition, the sensor response occurs more than 1000 times faster within 0.2 s. These results correlate well with physisorption data, which reveal a significant change in porosity and surface area according to the degree of activation. For a better understanding of the involved processes, adsorption isotherms were recorded, surface areas determined and correlated to the photophysical parameters, including Stern‐Volmer kinetics and cycling experiments for the differently activated MOF sensors.

Luminescent nanotherapeutics system for Real-Time imaging and Membrane-Mitochondria stepwise targeted drug delivery in ovarian cancer

Considerable attention has been devoted to developing anti-cancer treatments targeted mitochondria. However, there is a dearth of literature on using luminescent metal–organic frameworks for the transportation of anti-cancer drugs to organelles. A luminescent nanotherapeutic platform known as UiO-DOX@FA/TPP has been engineered with a membrane-mitochondrial stepwise targeting strategy for the delivery of doxorubicin (DOX). DOX administration caused mitochondrial dysfunction, increased Caspase-3 activity, and cell apoptosis. The UiO-DOX@FA/TPP system improved drug sensitivity, requiring only 10.8 % of the free DOX dose. It showed strong anti-tumor effects in vivo, with over 98 % tumor growth inhibition and commendable biocompatibility. The system also enabled in vivo imaging by emitting fluorescence at around 500 nm, highlighting its transport and targeted distribution to tumor sites. Furthermore, treating cells with UiO-DOX@FA/TPP nanosystem led to extensive gene expression changes, primarily enriched in Ca2+ signaling and autophagy regulation. The stepwise targeted luminescent UiO-DOX@FA/TPP nanosystem allow for the precise identification and delineation of ovarian cancer boundaries, monitoring of drug transport in real-time, and targeted delivery to mitochondria for inducing apoptosis. This innovative approach provides a theoretical and methodological basis for integrating ovarian cancer diagnosis and treatment.

A Zn/Cd/Ni Metal-Organic Framework-Based Solid and Flexible Fluoroprobes for Highly Selective Detection of 4-Nitroaniline in Real Water Samples.

The combination of diazabicyclic compound i.e. 1,4-diazabicyclo[2.2.2]octane (DABCO) and dicarboxylate linker 1,4-dicarboxylic acid are employed to self-assemble with three divalent metal ions such as Zn2+, Cd2+, Ni2+ led to the formation of highly stable pillar layered luminescent metal-organic frameworks. The emissive response of as-synthesized MOFs was studied in organic solvents with different functionalities resulting in the development of fluoroprobes having excellent recognition ability for 4-nitroaniline with detection limit upto micromolar. All the MOFs display a good linear relation between the fluorescence intensity and concentration of 4-NA in the range of 10-90µmol L-1. The values of Ksv for Zn-MOF, Cd-MOF, and Ni-MOF are found to be 1.75 × 104mol-1L, 1.25 × 104mol-1L, and 28.0 × 104mol-1L, respectively. The calculated detection limit values are 19.7µmol L-1, 27.6µmol L-1, and 1.19µmol L-1 respectively. Moreover, the study was further extended to fabricate the solid membrane-based fluoroprobe using a linear chitosan polysaccharide and act as an efficient solid fluoroprobe for the detection of 4-NA. This proposed synthesis of polymeric membrane facilitates the MOF@chitosan fluorophore to transfer its fluorescence-emissive nature to a solid state.

Fluorescent probe for Fe3+ detection based on a guest molecular luminescent metal–organic framework

The zinc(II) bis-(8-hydroxyquinoline) (Znq2) has excellent photoluminescence properties, and its fluorescence emission can be significantly quenched by Fe3+ in water. To accelerate the detection response of Znq2 to Fe3+, a luminescent metal–organic framework Znq2@ZIF-8 based on guest molecular luminescence was constructed by growing zeolite imidazolate framework-8 (ZIF-8) on the outer surface of Znq2. The results show that the prepared Znq2@ZIF-8 has an octahedral core–shell structure, a particle size of approximately 1–3 μm, an enhanced specific surface area of 1105.41 m2 g−1, and with a stable green luminescence at 495 nm. A fluorescence analytical method was developed for the detection of Fe3+ in water, the correlation coefficients were significant in the Fe3+ concentration range of 0–600 μmol L−1, and the limit of detection was as low as 3.89 μmol L−1. The spiked recoveries of tap water samples demonstrated that the method could be applied to practical applications. The mechanism of fluorescence detection is that Fe3+ participates in the competitive coordination of Znq2@ZIF-8 metal centers, leading to the collapse of the crystal structure, meanwhile, Fe3+ produces a certain degree of competitive absorption of the excitation light of Znq2@ZIF-8. This method was applied for the detection of Fe3+ in water with good selectivity, anti-interference ability, and has the potential to be used as a rapid detection method.

Strategic Design of Non-d10 Luminescent Metal-Organic Frameworks as Dual-Mode Ultrafast and Selective Sensing Platforms for Aldehydes at the ppb Level.

Utilizing a cautious design of luminescent MOFs of non-d10 divalent transition metals based on two factors (metal nodes in an octahedral geometry to minimize nonradiative energy dissipation and tailored organic chromophores), this work reports {[Ni2(oxdz)2(tpbn)]}n (1), {[Ni2(oxdz)2(tphn)]}n (2), and {[Ni2(oxdz)2(tpon)]}n (3), synthesized at room temperature, varying the spacer length of tpbn/tphn/tpon (four, six, and eight CH2 groups, respectively). This subtle change in 1-3 is correlated to their hydrophobicity and polarizing power via water vapor sorption and selective and sensitive detection of aldehydes at the ppb level, respectively. A decrease in water vapor uptake (14.8, 8.95, and 3.19 mmol g-1 for 1-3, respectively) is observed with an increase in their hydrophobicity. On the other hand, the solution phase detection limits of acetaldehyde and benzaldehyde (2.42 and 6.71 ppb for 1, 2.77 and 4.08 ppb for 2, and 10.35 and 10.4 ppb for 3, respectively) show a similar trend for their polarizing power. The best performance of 1 is expanded to the vapor-phase detection of acetaldehyde (297% luminescence enhancement) under different pH conditions. The second mode of detection of acetaldehyde via the metal-centered electrochemical behavior of 1 provides detection limits of 38.2 and 71.5 ppb at pH 7 and 13, respectively.

Probing ligand conformation and net dimensionality in a series of tetraphenylethene-based metal-organic frameworks.

Tetraphenylethene-based ligands with lowered symmetry are promising building blocks for the construction of novel luminescent metal-organic frameworks (MOFs). However, few examples have been reported, and predicting the ligand conformation and the dimensionality of the resulting MOF remains challenging. In order to uncover how synthetic conditions and accessible ligand conformations may affect the resulting MOF structure, four new MOF structures were synthesized under solvothermal conditions using the meta-coordinated tetraphenylethene-based ligand m-ETTC and paddlewheel SBUs composed of Co(II), Cu(II), and Zn(II). WSU-10 (WSU = Washington State University) is formed with either Zn or Cu comprising stacked psuedo-2D layers. The dimensionality of WSU-10 can be intentionally increased through the addition of pyrazine as a pillar ligand into the synthesis, forming the 3D structure WSU-11. The third structure, WSU-20, is formed by the combination of Zn or Co with m-ETTC and is intrinsically 3D without the use of a pillar ligand; interestingly, this is the result of a distortion in the paddlewheel SBU. Finally, Cu was also found to form a new structure (WSU-12), which displays an m-ETTC conformation unique from that found in the other isolated MOFs. Structural features are compared across the series and a mechanistic relationship between WSU-10 and -20 is proposed, providing insight into the factors that can encourage the generation of frameworks with increased dimensionality.

Two AIE-Ligand-Based 2-D Luminescent Metal-Organic Frameworks as Fe3+ Sensors.

The design and synthesis of high-performance sensors are very important but remain great challenges. In this work, a new aggregation-induced-emission (AIE) molecule 4,4'-(((9H-fluoren-9-ylidene)methylene)bis(4,1-phenylene))dipyridine (L) was successfully synthesized and first developed as a functional ligand to construct two isomorphic metal-organic frameworks (MOFs) [M(L)(OBBA)]n [M2+ = Cd2+ (1), Co2+ (2); H2OBBA = 4,4'-oxybisbenzoic acid]. They adopt [M2(COO)4] flywheel clusters, OBBA2- bridges, and terminal L ligands as building units to form isomorphic 2-D networks with Lewis base active cites (uncoordinated pyridyl N). Both 1 and 2 exhibit excellent water, pH, and thermal stabilities and extremely efficient Fe3+ sensing abilities in the water environment. The quenching constants and detection limits reach the best levels reported so far. The sensing mechanism of 1 and 2 toward Fe3+ is studied in depth, and the difference in their sensing performance is also explained.

MOF-based ratiometric fluorescent nanoprobe for quantitative detection of hydrogen sulfide in acute pancreatitis

The timely detection of acute pancreatitis (AP) is crucial for mitigating its severe complications, including pancreatic necrosis and multi-system organ failure. In this work, we developed LMOF-BR, an innovative luminescent metal–organic framework (LMOF)-based ratiometric fluorescent nanoprobe, specifically designed for the sensitive and selective detection of hydrogen sulfide (H2S) in AP. This nanoprobe employs a synthesized LMOF to provide a stable reference signal, and a fluorescent dye (BR) as the target recognizer and signal output unit, enabling H2S detection through single-excitation dual fluorescence emission. The LMOF-BR nanoprobe demonstrates significant advantages, including improved water solubility, superior photostability, a high signal-background ratio, and a low limit of detection (LOD), all of which are crucial for accurate detection in complex biological environments. Successful quantification of H2S in serum samples and AP mouse plasma has been achieved by LMOF-BR nanoprobe, showcasing notable accuracy and precision. The LMOF-BR nanoprobe holds great promise in advancing biosensing technology, particularly for the timely and reliable diagnosis of AP.

Luminescent metal–organic frameworks for ultrasensitive detection of pesticide and biomarker: In situ imaging and real field application

Frequent uses of pesticides for agricultural led to the environmental pollution and ultimately threaten the human body. On the other hand, the monitoring of the biomarker at the optimum level is also very imperative for human health. So the investigation of smart materials is very essential for visual and on‐site monitoring of pesticide and biomarker. In this regard, we have synthesized highly fluorescent MOF (ZnATA, 1) oriented with free‐NH2 functionality as a guest functional moiety. Framework 1 showed the selective and sensitive ratiometric detection of biomarker riboflavin (RBF). Further, sensor 1 exhibited the discriminating recognition of pesticide 2,6‐dichloro‐4‐nitroaniline (DCNA). The detection limit for both RBF and DCNA is very excellent, and the values are 0.13 and 0.07 ppm, respectively. The detection of RBF and DCNA is very fast (within 3 s) and has been realized through colorimetric response and by cost‐effective paper strip method. Interestingly, the sensor displayed the visual and on‐site (in situ imaging by using real fruit and vegetable) recognition of “DCNA” within 3 s. Sensor 1 further demonstrated the recognition of DCNA in different real field sample (environmental water sample) and RBF in food samples (milk and vitamin B2 tablet). The mechanism of sensing for DCNA and RBF has been comprehended through the occurrence of photo‐induced electron transfer, forster resonance energy transfer, and inert filter effect. Further, the recognition mechanism is justified by the theoretical study. The presence of free‐NH2 moiety in the linker of MOF is possibly to establish a strong supramolecular interaction with the analytes.

Cellulose nanofiber-templated metal-organic frameworks for fluorescent detection of methyl parathion pesticides

Methyl parathion is a typical organophosphorus pesticide that poses threats to the global environment and human health. In this study, we developed a portable 2D sensing pad for monitoring methyl parathion based on the aggregation-induced emission (AIE) properties of an innovated hybrid material that integrates cellulose nanofibers (CNFs) with luminescent metal-organic frameworks (LMOFs). The hybrid material enhanced the flexibility and moldability of LMOFs and significantly improved the scalability of sensing material. The resulting CNF/LMOF material was shaped into a 2D pad, exhibiting fluorescent properties under UV exposure. The fluorescence of the pad was quenchable upon exposure to methyl parathion. This host-guest interaction enabled the precise quantification of the pesticide’s concentration by monitoring the intensity variation of the fluorescence at 405 nm wavelength. We further engineered these hybrid pads into a user-friendly and portable sensing prototype, and then validated them with real sample testing. Time-dependent Density Functional Theory calculations were employed to elucidate the underlying fluorescence quenching mechanism triggered by methyl parathion. This work introduces a practical and sustainable sensing platform for pesticide detection.

Strong aggregation-induced electrochemiluminescence of pyrene-coordination metal-organic frameworks coupled with zero-valent iron as novel accelerator for ultrasensitive immunoassay

Polycyclic aromatic hydrocarbons (PAHs) are excellent alternative luminophores for electrochemiluminescence (ECL) immunoassays. However, they are inevitably limited by the aggregation-caused quenching effect. In this study, aimed at eliminating the aggregation quenching of PAHs, luminescent metal–organic frameworks (MOFs) with 1,3,6,8-tetra(4-carboxybenzene)pyrene (H4TBAPy) as the ligand were exploited as a novel nano-emitter for the construction of ECL immunoassays. The luminophore exhibits efficient aggregation-induced emission enhancement, good acid-base resistance property and unusual ECL reactivity. In addition, the simultaneous use of potassium persulfate and hydrogen peroxide as dual co-reactants resulted in a synergistic enhancement of the cathodic ECL efficiency. The use of magnetic iron-nickel alloys as the multifunctional sensing platform can further enhance the ECL activity, and its enriched zero-valent iron as a co-reactant accelerator effectively drives ECL analytical performance. Profiting from the excellent characteristics, signal-on ECL immunoassays have been constructed. With carcinoembryonic antigen as the model analysis target, a detection limit of 0.63 pg/mL was obtained within the linear range of 1 pg/mL to 50 ng/mL, accompanied by excellent analytical performance. This report opens a new window for the rational design of efficient ECL illuminators, and the proposed ECL immunoassays may find promising applications in the detection of disease markers.

Insights into dual-emitting Eu-doped Mn–organic framework with 1D helical chain SBUs as a ratiometric thermometer for temperature sensing

The development and construction of smart luminescent MOF materials are highly desired. For the construction of luminescent MOF with new network and smart responsiveness, the introduction of Ln3+ into porous materials by the post-synthetic modification approach is one of the most effective strategies. Herein, a new anionic Mn–organic framework with 1D helical chain SBUs, [(CH3)2NH2][Mn3(OH)(TATB)2] (SQNU-24, H3TATB = 4,4′,4″-s-triazine-2,4,6-triyltribenzoic acid, SQNU = Shangqiu Normal University), was successfully prepared under a DMF/CH3CN solvent system. Benefitting from the anionic skeleton, high porosity, double-walled structure and 1D helical chain SBUs within SQNU-24, the dual-emitting Eu@SQNU-24 was successfully constructed by a post-synthetic modification approach. This work demonstrates the TATB3− ligand as an “antenna” can effectively sensitize Eu3+ ions. Interestingly, the dual-emitting Eu@SQNU-24 as a ratiometric thermometer exhibits a good temperature-responsive property.