Multiresponsive luminescent metal-organic framework for cooking oil adulteration detection and gallium(III) sensing

A new 3D metal-organic framework {[Cd16(tr2btd)10(dcdps)16(H2O)3(EtOH)]∙15DMF}n (MOF 1, tr2btd = 4,7-di(1,2,4-triazol-1-yl)benzo-2,1,3-thiadiazole, H2dcdps = 4,4'-sulfonyldibenzoic acid) was obtained and its luminescent properties were studied. MOF 1 exhibited bright blue-green luminescence with a high quantum yield of 74 % and luminescence quenching response to a toxic natural polyphenol gossypol and luminescence enhancement response to some trivalent metal cations (Fe3+, Cr3+, Al3+ and Ga3+). The limit of gossypol detection was 0.20 µM and the determination was not interfered by the components of the cottonseed oil. The limit of detection of gallium(III) was 1.1 µM. It was demonstrated that MOF 1 may be used for distinguishing between the genuine sunflower oil and oil adulterated by crude cottonseed oil through qualitative luminescent and quantitative visual gossypol determination.

Eu(III) functionalized ZnMOF based efficient dual-emission sensor integrated with self-calibrating logic gate for intelligent detection of epinephrine

The rapid detection of epinephrine (EPI) in serum holds immense importance in the early disease diagnosis and regular monitoring. On the basis of the coordination post-synthetic modification (PSM) strategy, a Eu3+ functionalized ZnMOF (Eu3+@ZnMOF) was fabricated by anchoring the Eu3+ ions within the microchannels of ZnMOF as secondary luminescent centers. Benefiting from two independent luminescent centers, the prepared Eu3+@ZnMOF shows great potential as a multi-signal self-calibrating luminescent sensor in visually and efficiently detecting serum EPI levels, with high reliability, fast response time, excellentrecycleability, and low detection limits of 17.8 ng/mL. Additionally, an intelligent sensing system was designed in accurately and reliably detecting serum EPI levels, based on the designed self-calibrating logic gates. Furthermore, the possible sensing mechanisms were elucidated through theoretical calculations as well as spectral overlaps. This work provides an effective and promising strategy for developing MOFs-based self-calibrating intelligent sensing platforms to detect bioactive molecules in bodily fluids.

A stable and highly luminescent 3D Eu(III)-organic framework for the detection of colchicine in aqueous environment

The metal-organic framework materials have an important application as sensors. In this work, a microporous three-dimensional (3D) Eu(III)-organic framework (Eu-MOF), [Eu₂(3,5-bct)(phen)₂(ox)₂(H₂O)]·H₂O, was constructed from 3,5-bis(3'-carboxyphenyl)-1,2,4-triazole (3,5-H₂bct), oxalate (ox) and 1,10-phenanthroline (phen) as a luminescent sensor. The free volume was found to be 15.7% per unit volume ignoring the free water molecules. The Eu-MOF showed bright red light due to the emission at 622 nm (⁵D₀ → ⁷F₂ transition) of the Eu(III) with high quantum yield (QY, 52.51%). The Eu-MOF exerted high luminescence stability in common organic solvents as well as aqueous solutions within a wide pH range from 4 to 11. Based on the luminescent Eu-MOF, the sensing behavior for colchicine in the aqueous environment was studied. Highly selective and sensitive detection (LOD = 2.43 × 10^-5 mol L^-1) of colchicine was observed by the Eu-MOF even in the presence of potential interfering components. The sensing mechanism for colchicine was investigated by experimental and theoretical results. It is worth noting that a film (Film@Eu-MOF) prepared by loading Eu-MOF showed intense characteristic red light emission under UV light. The luminescence color changed immediately from red to colorless when the Film@Eu-MOF came in contact with colchicine. Highly sensitive and rapid detection of colchicine in wastewater was achieved using this Film@Eu-MOF, which could be identified by the naked eye. The experimental results suggest that the synthesized Eu-MOF has potential application as a luminescent sensing material for pollutants in the environmental system.

Highly sensitive sensing device based on highly luminescent lanthanide nanocluster for biomarker in human urine and serum

The level of L-kynurenine (L-kyn) can reflect the health state of human body, and the determination of L-kyn can be used for the medical diagnosis of several cancers and neurological diseases. In this work, a series of air-, water-, and thermo-stable dinuclear lanthanide nanoclusters [Ln₂(2,5-DFBA)₆(phen)₂] (Tb 1, Eu 2, Gd 3, 2,5-DFBA = 2,5-difluorobenzoic acid, phen = 1,10-phenanthroline) are obtained by a facial method. 1 and 2 show very high luminescence quantum yields (QYs) of 71.7% and 81.8%, respectively. Interestingly, investigation reveals that 1 is a quick, highly sensitive and selective sensor for L-kyn in real samples of urine and serum. Furthermore, transmission electron microscope (TEM) results reveal that nanocluster 1 is stable in solution and can be uniform distributed on the base, suggesting it can be deposited on various supports to fabricate sensing devices. Thus, 1 is fabricated into a sensitive test paper for the eye-readable detection of L-kyn in real samples of human urine and serum. The limit of detection (LOD) as low as 0.3 μM, which is enough to rapidly determine L-kyn in human body liquor (usually 5 μM in healthy human body).

A copper-based metal-organic framework for ratiometric detection of hydrogen sulfide with high sensitivity and fast response

Metal-organic framework (MOF) is a class of crystalline porous solid materials which could be designed as sensors for bioactive molecules. In this study, charge transition between the ligand and the metal ions related emission and the ligand-based emission were formed simultaneously within a novel luminescent MOF with the copper reactive site as nodes. It can serve as a rare example of MOFs implicated ratiometric sensor for selective luminescent detection of H₂S. The luminescent detection limitations for H₂S is 0.21 μM, and it possesses a fast response of 30 s. The sensing mechanism is also discussed.

A dual luminescent sensor coordination polymer for simultaneous determination of ascorbic acid and tryptophan

Simultaneous high sensitivity detection of biomolecules is important for research in medicine, living cells and environmental samples. In this work, a water stable coordination polymer, [Cd₂(bptc)(4,4'-bpy)(H₂O)₃]ˑH₂O 1 (H₄bptc = 2,3,3',4'-biphenyl tetracarboxylic acid, 4,4'-bpy = 4,4'-bipyridine), was designed and successfully synthesized as a luminescent sensor for simultaneous recognition of Ascorbic Acid (AA) and L-Tryptophan (L-Trp) based on luminescent -OFF and -ON, respectively. Importantly, the proposed sensing system showed an excellent performance with high K_SV values of 4.85 × 10⁴ M^-1, 9.60 × 10⁷ M^-1 and low limit of detection (LOD) of 0.28 nM, 63 nM, respectively. In addition, the probable mechanisms are also discussed. The luminescent quenching behavior by AA can be mainly attributed to the static resonance energy transfer between complex 1 and the analytes. Whereas the enhancing effect of L-Trp comes from the intrinsic strong luminescence for L-Trp itself and photo-competitive mechanism between CP 1 sensor and L-Trp, supposedly. In addition, the repeatability of both systems were also investigated.

A Bifunctional Coordination Polymer for Al3+ Ion Detection and its Treatment Effect on Nonalcoholic Fatty Liver Disease by Promoting Lipoxygenases and Reducing Intrahepatic Triglyceride Content

In this study, a new Cd(II)-bearing coordination polymer with the chemical formula of {[Cd₄(meda)₃(dpe)₄(H₂O)₄]·(NO₃)₂·2(H₂O)}_n (1, H₂meda = 3,3'-methylenedibenzoic acid, dpe = 1,2-di(pyridin-4-yl)ethane) has been successfully prepared by reaction of Cd(NO₃)·4H₂O with a V-shape carboxyl ligand H₂meda along with the linear dipyridine ligand dpe under the hydrothermal conditions. Due to its intensive luminescence, complex 1 could be utilized as the sensor of detecting Al³⁺ ion, and its detection limit is 4 × 10^-6 M. Firstly, the toxicity of the compound on the normal liver cells was determined with Cell Counting Kit-8 detection kit. The triglyceride in liver cells was detected by detection kit after compound treatment and the relative expression of 15-lox and 12-lox in L02 cells was also measured by RT-PCR after compound treatment. In addition, multiple functional groups that provided by the synthesized Cd(II) complex have been studied by using molecular docking simulation for the confirmation of possible binding modes that formed between ligand and receptor.

Two cadmium(II) coordination polymers as multi-functional luminescent sensors for the detection of Cr(VI) anions, dichloronitroaniline pesticide, and nitrofuran antibiotic in aqueous media

Two ternary cadmium(II) coordination polymers, with the formulas being {[Cd(tptc)_0.5(bpz)(H₂O)]·0.5H₂O}_n (CP 1), and [Cd(tptc)_0.5(bpy)]_n (CP 2), were designed through mixed ligands strategy. Benefiting from the excellent chemical stability and luminescent property, two Cd(II) CPs possessing efficient multi-functional fluorescent responses toward Cr(VI) anions, 2,6-dichloro-4-nitroaniline pesticide, and nitrofuran antibiotic in aqueous media with high sensitivity, selectivity, and excellent recyclable behaviors with the detection limits (LODs) are 235 ppb for CrO₄^2- anion, 343 ppb for Cr₂O₇^2- anion, 112 ppb for DCN pesticide, 62 ppb for NFT antibiotic for CP 1, and 173 ppb for CrO₄^2- anion, 270 ppb for Cr₂O₇^2- anion, 638 ppb for DCN pesticide, 184 ppb for NFT antibiotic for CP 2, respectively. Besides, the mechanisms of luminescence quenching were revealed from the viewpoint of internal filter effect (IFE) and photoinduced electron transfer (PET).

Selective sensing of Fe3+ ions in aqueous solution by a biodegradable platform based lanthanide metal organic framework

As a significant metal ion in the environmental and biological systems, excess or shortage of Fe³⁺ from the organism can cause a host of diseases. So it is very urgent to explore an explicit, rapid and recoverable method for the detection of Fe³⁺ ions. Herein, a novel and flexible ligand containing 12 carboxyl groups (BHM-COOH) is used for the structure of a series of luminescent Eu³⁺/Tb³⁺-metal-organic frameworks (MOFs). A reliable and convenient luminescent detection platform is constructed by combining polylactic acid (PLA) film with Eu_0.24Tb_0.76-BHM-COOH. More importantly, the luminescent platform can highly sensitive to sense Fe³⁺ ions through fluorescence quenching (Stern-volmer constant Ksv = 1.27 × 10⁴ M^-1 for Fe(NO₃)₃), and detection limit can be as low as 4.47 μM. The sensing mechanism is ascribed to the fluorescence quenching caused by the competitive absorption between Eu_0.24Tb_0.76-BHM-COOH and Fe³⁺ ion. At the same time, the sensor can be reused many times. These exciting results indicate that Eu_0.24Tb_0.76-BHM-COOH film can serve as a promising multi-responsive luminescent sensor for environmental pollutant monitoring.

Rational design and synthesis of a stable pillar-layer NaI-organic framework as a multi-responsive luminescent sensor in aqueous solutions

A stable pillar-layer Na^I-organic framework, [Na₂(DCPB)∙(H₂O)₂]_n (namely 1), was rationally designed and synthesized by the assemble process of Na^I and 1,3-di(4'-carboxyl-phenyl)benzene (H₂DCPB). Benefiting from the luminescent property and high stability in water, the as-synthesized 1 is a potential multi-responsive luminescent sensor material toward Cr₂O₇^2-, Fe³⁺, and nitrofurazone (NFZ) in water. Ground 1 not only has the excellent detectability and selectivity but also possesses outstanding stability and circularity. The calculated K_sv values of 1 are 8.8×10³ for Fe³⁺, 9.9×10³ for Cr₂O₇^2-, and 2.7×10⁴ M^-1 for NFZ in aqueous solutions, respectively. Furthermore, 1 is able to accurately detect NFZ in real bovine serum samples through luminescence detection technology.

Genetically-encoded sensors to detect fatty acid production and trafficking

OBJECTIVE

Fatty acids are important for biological function; however, in excess, they can cause metabolic dysregulation. Methods to image and detect fatty acids in real time are lacking. Therefore, the current study examined the dynamics of fatty acid trafficking and signaling utilizing novel fluorescent and luminescent approaches.

METHODS

We generated fluorescent and luminescent-based genetically-encoded sensors based upon the ligand-dependent interaction between PPARα and SRC-1 to image and detect cellular dynamics of fatty acid trafficking.

RESULTS

The use of a fluorescent sensor demonstrates that fatty acids traffic rapidly from lipid droplets to the nucleus. Both major lipases ATGL and HSL contribute to fatty acid signaling from lipid droplet to nucleus, however, their dynamics differ. Furthermore, direct activation of lipolysis, independent of receptor-mediated signaling is sufficient to promote lipid droplet to nuclear trafficking of fatty acids. A luminescent-based sensor that reports intracellular fatty acid levels is amenable to high-throughput analysis.

CONCLUSIONS

Fatty acids traffic from lipid droplets to the nucleus within minutes of stimulated lipolysis. Genetically-encoded fluorescent and luminescent based sensors can be used to probe the dynamics of fatty acid trafficking and signaling.

The functionalized ruthenium(II) polypyridine complexes for the highly selective sensing of mercury ions

A series of new ruthenium(II) polypyridine complexes appending with thioether groups were designed, synthesized and characterized. The sensing ability of the complexes toward mercury ions were studied by electronic absorption and emission spectra, and the reaction of the complexes with mercury ions were also confirmed by ESI mass spectroscopy and ¹HNMR spectroscopy. The thioether groups would react with mercury ion fast to form aldehyde group leading to the significant change in the spectra. The color of the complex changed from yellow to orange after addition of mercury ions, and the color of the emission changed from red orange to dark red with a large red shift (~80 nm). Importantly, these kinds of ruthenium(II) complexes show a unique recognition of mercury ions over other metal ions. The complexes with more thioether groups also showed a better sensitivity toward mercury ions, this is good strategy for the further design of the new phosphorescent probes for sensing of mercury ions.