Luminescent Probes Research Articles

A Water-Soluble Wavy Coordination Polymer of Cu(II) as a Turn-On Luminescent Probe for Histidine and Histidine-Rich Proteins/Peptides.

Histidine plays an essential role in most biological systems. Changes in the homeostasis of histidine and histidine-rich proteins are connected to several diseases. Herein, we report a water-soluble Cu(II) coordination polymer, labeled CuCP, for the fluorimetric detection of histidine and histidine-rich proteins and peptides. Single-crystal structure determination of CuCP revealed a two-dimensional wavy network structure in which a carboxylate group connects the individual Cu(II) dimer unit in a syn-anti conformation. The weakly luminescent and water-soluble CuCP shows turn-on blue emission in the presence of histidine and histidine-rich peptides and proteins. The polymer can also stain histidine-rich proteins via gel electrophoresis. The limits of quantifications for histidine, glycine-histidine, serine-histidine, human serum albumin (HSA), bovine serum albumin, pepsin, trypsin, and lysozyme were found to be 300, 160, 600, 300, 600, 800, 120, and 290 nM, respectively. Utilizing the fluorescence turn-on property of CuCP, we measured HSA quantitatively in the urine samples. We also validated the present urinary HSA measurement assay with existing analytical techniques. Job's plot, 1H NMR, high-resolution mass spectrometry (HRMS), electron paramagnetic resonance (EPR), fluorescence, and UV-vis studies confirmed the ligand displacement from CuCP in the presence of histidine.

Plasmon-emitter coupling in cytosine-rich hairpin DNA-templated silver nanoclusters: Thermal reversibility, white light emission, and dynamics inside live cells.

Bio-templated luminescent noble metal nanoclusters (NCs) have attracted great attention for their intriguing physicochemical properties. Continuous efforts are being made to prepare NCs with high fluorescence quantum yield (QY), good biocompatibility, and tunable emission properties for their widespread practical applications as new-generation environment-friendly photoluminescent materials in materials chemistry and biological systems. Herein, we explored the unique photophysical properties of silver nanoclusters (AgNCs) templated by cytosine-rich customized hairpin DNA. Our results indicate that a 36-nucleotide containing hairpin DNA with 20 cytosine (C20) in the loop can encapsulate photostable red-emitting AgNCs with an absolute QY of ∼24%. The luminescent properties in these DNA-templated AgNCs were found to be linked to the coupling between the surface plasmon and the emitter. These AgNCs exhibited excellent thermal sensitivity and were employed to produce high-quality white light emission with an impressive color rendering index of 90 in the presence of dansyl chloride. In addition, the as-prepared luminescent AgNCs possessing excellent biocompatibility can effectively mark the nuclear region of HeLa cells and can be employed as a luminescent probe to monitor the cellular dynamics at a single molecular resolution.

Luminescence-Monitored Progressive Chemical Pressure Implementation Realized through Successive Y3+ and Mg2+ Doping into Ca10.5(PO4)7:Eu2.

Chemical pressure generated through ion doping into crystal lattices has been proven to be conducive to exploration of new matter, development of novel functionalities, and realization of unprecedented performances. However, studies are focusing on one-time doping, and there is a lack of both advanced investigations for multiple doping and sophisticated strategies to precisely and quantitatively track the gradual functionality evolution along with progressive chemical pressure implementation. Herein, high-valent Y3+ and equal-valent Mg2+ is successively doped to replace multiple Ca sites in Ca10.5(PO4)7:Eu2+. The luminescence evolution of Eu2+ serves as an optical probe, allowing step-by-step and atomic-level tracking of the site occupation of Y3+ and Mg2+, interassociation of Ca sites, and ultimately functionality improvement. The resulting Ca8MgY(PO4)7:Eu2+ displays a record-high relative sensitivity for optical thermometry. Utilization of the environment-sensitive emission of Eu2+ as a luminescent probe has offered a unique approach to monitoring structure-functionality evolution in vivo with atomic precision, which shall also be extended to optimization of other functionalities such as ferroelectricity, conductivity, thermoelectricity, and catalytic activity through precise control over atomic diffusion in other types of substances.

A waterborne polyurethane‐based fluorescent tunable carbon quantum dot

AbstractFluorescent tunable materials have potential applications in lighting, display, anti‐counterfeiting, biological probes, and so on. Herein, carbon quantum dots (CQDs) with blue fluorescence (BCDs), and yellow fluorescence (YCDs) were synthesized by solvothermal method using bio‐based citric acid and lignin as carbon sources, respectively. BCDs and YCDs were anchored on polyurethane chains to prepare waterborne polyurethane‐based blue fluorescent carbon quantum dots (BCDs1.0‐WPU) and waterborne polyurethane‐based yellow fluorescent carbon quantum dots (YCDs1.0‐WPU), respectively. Compared with the corresponding BCDs and YCDs, the fluorescence intensity of both BCDs1.0‐WPU and YCDs1.0‐WPU is markedly enhanced, and the emission peaks obviously show a hypochromatic shift. A waterborne polyurethane‐based fluorescent tunable carbon quantum dots (BCDsxYPDs1‐x‐WPU) is prepared by mixing the ratio of BCDs1.0‐WPU and YCDs1.0‐WPU with the RGB method. It is noteworthy that BCDsxYCDs1‐x‐WPU not only achieves a fluent change of fluorescence from blue to yellow but also emits strong white fluorescence (CIE coordinates: X = 0.28, Y = 0.32). The absolute value of the Zeta potential of BCDsxYCDs1‐x‐WPU is greater than 40, indicating good storage stability. Furthermore, the thermal decomposition temperature is above 225 °C, implying good thermal stability. Furthermore, BCDsxYCDs1‐x‐WPU uses water as a continuous phase and has potential applications in environmentally friendly luminescence, anti‐counterfeiting and biological probes.

Functional fluorescent probe based on amide condensation of coumarin and melatonin for the turn-on detection of calcium ion in vitro and living cell

Due to a physiological significant role of calcium ion, it is essential to develop ways of detecting and monitor the level of Ca2+ ions in living cell. Herein, we rationally designed and synthesized a functional blue fluorescent compound CM based on amide condensation of coumarin and melatonin. Interestingly, it could exhibit an “On-OFF” fluorescence response for Ca2+ in an aqueous environment with 80-fold enhancement in bright blue emission, which is also free from interference of other co-existing cations of high concentration. A detection limit of 0.28 ppm was obtained, and the binding ratio of CM and Ca2+ is further investigated by Job’s plot. After coordination of CM with calcium ion, a significant “Tyndall Effect” can be observed, and blue emissive nanowires induced by aggregation of complex of CM and Ca2+ were further investigated by Dynamic Light Scattering, analysis of Zeta potential, and confocal imaging. The molecular docking of CM with melatonin receptor 1A is also conducted. MTT assay reveals that CM ligand and the corresponding Ca2+ complex are non-cytotoxic. Moreover, CM shows good membrane permeability, and the relative cellular uptake mechanism is mainly dominated by an energy-dependent process. CM and its complex of Ca2+ can be further used as intracellular luminescent imaging probes and their localization in cell organelles is also revealed.

Utilization of Schiff base-Co(II) complex as a stable luminescent probe for the highly selective detection of 2,4,6-trinitrophenol in an aqueous medium

In this study, the fluorescence properties of Co(II) Schiff base complex (Co(II) complex) were examined. The sensor properties of the Co(II) complex nitroaromatic compounds [(DNB, TNT, DNT, 2-NP, 4-nitrophenol (NP), 2,4-dintrophenol (DNP) and 1,3,5-trinitrophenol (TNP) e.g.,] were investigated by fluorescence spectroscopy. Compound has high sensitivity for the sensing of 1,3,5-trinitrophenol (TNP) (Ksv: 4.74 × 104 M−1) with low LOD of 0.034 μM. It was revealed that the complex ([CoLCl(H2O)2]∙2H2O) exhibited strong fluorescence properties. Additionally, the synthesized Co(II) complex was utilized for fluorescence quenching-based TNP detection in water solution with high selectivity and sensitivity. The stoichiometry of the compound and TNP was found to be 1:1 (ligand/TNP) via fluorescence titrations (Job's plot).

Unveiling the dual functionality of dimeric Cu(I)/(II) crystal as luminescence and electrochemical probe for Zn2+ and glucose detection—Structural, sensing and molecular docking studies

A new crystalline dinuclear Cu(I)/(II) complex (E.F: C32H28Cu2N6O14) (1) of terephthalic acid (TERE) and 1, 10‐Phenathroline (PHEN) was synthesized under one‐pot approach. Structure identification of the complex was carried out using the single crystal XRD technique, which revealed the penta coordination nature of Cu(I)/(II) in a square pyramidal environment. Further, the structural data was supported by employing other spectroscopic studies (UV, ESR, FT‐IR). In addition, the thermal stability and morphology of the complex were elucidated using TGA and SEM‐EDAX analysis. Photoluminescence experiments revealed the capability of 1 to act as a “turn‐off” sensor towards Zn2+ sensing. This luminescence quenching of 1 exhibited a threefold quenching in intensity by achieving a static quenching process corresponding to a limit of detection (LOD) of 3.7 μM. Further, considering the electroactive nature of Cu(I)/(II) complex, the cyclic voltammetric experiments were performed to study its competence to act as a modifier of GCE for the detection of glucose and its excellent potency to act as an effective electroactive material in the detection of glucose solutions. Also, molecular docking of 1 with human bovine serum (HSA) and bovine serum albumin (BSA) was investigated to prove their ability to act as pharmacological agents.

A novel iridium(III) complex-based ratiometric luminescence probe for monitoring hydrogen sulfide in living cells and zebrafish

Hydrogen sulfide exhibits crucial functions in many biological and physiological processes. The abnormal levels of H2S have been revealed to be associated with numerous human diseases. The majority of existing fluorescent probes toward H2S may still need to be improved in terms of single output signal, water solubility, biotoxicity and photostability. The construction of a ratiometric fluorescent probe based on metal complex is one effective strategy for avoiding the mentioned problems for precisely detecting H2S. Herein, we report an iridium(III) complex-based ratiometric luminescence probe (Ir-PNBD), which is designed by coupling the 7-nitro-2,1,3-benzoxadiazoles (NBD) to one of the bipyridine ligands of Ir (III) complex luminophore through a piperazition moiety. Ir-PNBD owns high selectivity and sensitivity toward H2S, and an excellent ability to target mitochondria. Moreover, Ir-PNBD was further successfully utilized to visualize exogenous and endogenous H2S in HeLa cells and zebrafish. Our work offers new opportunities to gain deeper insights into the construction of transition metal complex-based ratiometric luminescent probes and expands their applications in biomedical imaging and disease diagnosis.

Bispecific aptamer-decorated and light-triggered nanoparticles targeting tumor and stromal cells in breast cancer derived organoids: implications for precision phototherapies

BackgroundBased on the established role of cancer-stroma cross-talk in tumor growth, progression and chemoresistance, targeting interactions between tumor cells and their stroma provides new therapeutic approaches. Dual-targeted nanotherapeutics selectively acting on both tumor and stromal cells may overcome the limits of tumor cell-targeting single-ligand nanomedicine due to the complexity of the tumor microenvironment.MethodsGold-core/silica-shell nanoparticles embedding a water-soluble iridium(III) complex as photosensitizer and luminescent probe (Iren-AuSiO2_COOH) were efficiently decorated with amino-terminated EGFR (CL4) and PDGFRβ (Gint4.T) aptamers (Iren-AuSiO2_Aptamer). The targeting specificity, and the synergistic photodynamic and photothermal effects of either single- and dual-aptamer-decorated nanoparticles have been assessed by confocal microscopy and cell viability assays, respectively, on different human cell types including mesenchymal subtype triple-negative breast cancer (MES-TNBC) MDA-MB-231 and BT-549 cell lines (both EGFR and PDGFRβ positive), luminal/HER2-positive breast cancer BT-474 and epidermoid carcinoma A431 cells (only EGFR positive) and adipose-derived mesenchymal stromal/stem cells (MSCs) (only PDGFRβ positive). Cells lacking expression of both receptors were used as negative controls. To take into account the tumor-stroma interplay, fluorescence imaging and cytotoxicity were evaluated in preclinical three-dimensional (3D) stroma-rich breast cancer models.ResultsWe show efficient capability of Iren-AuSiO2_Aptamer nanoplatforms to selectively enter into target cells, and kill them, through EGFR and/or PDGFRβ recognition. Importantly, by targeting EGFR+ tumor/PDGFRβ+ stromal cells in the entire tumor bulk, the dual-aptamer-engineered nanoparticles resulted more effective than unconjugated or single-aptamer-conjugated nanoparticles in either 3D spheroids cocultures of tumor cells and MSCs, and in breast cancer organoids derived from pathologically and molecularly well-characterized tumors.ConclusionsOur study proposes smart, novel and safe multifunctional nanoplatforms simultaneously addressing cancer-stroma within the tumor microenvironment, which are: (i) actively delivered to the targeted cells through highly specific aptamers; (ii) localized by means of their luminescence, and (iii) activated via minimally invasive light, launching efficient tumor death, thus providing innovative precision therapeutics. Given the unique features, the proposed dual targeted nanoformulations may open a new door to precision cancer treatment.

A pyridyl-benzimidazole based ruthenium(II) complex as optical sensor: Targeted cyanide detection and live cell imaging applications

An extreme toxicity of cyanide (CN−) ion in diverse environmental media has encouraged significant attention for scheming well-organised molecular probes for its selective and sensitive detection. Keeping in mind, we present here a monometallic Ru(II) complex (Ru-1) based on 2-(pyridin-2-yl)-1H-benzo[d]imidazole moiety acting as a highly selective luminescent probe for CN− recognition in pure water. Besides, Ru-1 also acted as an efficient sensor for F−, AcO− and H2PO4− ions along with CN− when acetonitrile was chosen as solvent system. The binding constant (Kb) and detection limit (LoD) for CN− have been depicted as 3.05 × 106 M−1 and 12.8 nM, respectively, in water. The close proximity of N-H site with Ru(II) centre along with its remarkable acidity were identified as mainly responsible for the high selectivity of Ru-1 toward CN− in water. Job’s plot and DFT analyses were carried out to support the anion binding mechanism. Furthermore, the time-resolved fluorescence (TRF) spectroscopy was performed to assess the cyanide-induced emission lifetime change of Ru-1 in aqueous medium. In order to investigate applied potential, the probe Ru-1 was notably developed into paper-based strips that could readily detect CN− ion in mM range via naked eye under 365 nm light illumination, and also adequately employed to detect CN− in human breast cancer MCF-7 cell lines and natural food sources (such as apple seeds and sprouting potatoes).

Fluorinated complexes doped nanodot with high brightness and dual emission for ratiometric detection of glucose-related enzymes

Fluorescence detection of enzymes have attracted considerable interest due to their promise in biological applications, while suffering from the limitation of rigorous demand on the structure design of enzyme substrates. Herein, we report a simple and convenient approach for fluorescence detection of multiple enzymes by developing a fluorescence/phosphorescence dual-emissive nanodot, which is composed of fluorinated organic dyes and fluorinated Pt (II) porphyrin complexes, and exhibits ratiometric luminescence response toward oxygen. We characterized the optical properties of the nanodot, which showed high brightness and sensitive oxygen-response luminescence. Based on the oxygen-consumed enzymatic reaction of glucose oxidase and the glucose-generated enzymatic reaction of the enzymes related to glucose metabolism, and using this presented nanodot, the concentration of glucose and the enzymatic activity of invertase, β-galactosidase, and maltase in aqueous solution were successfully determined quantitatively. To the best of our knowledge, the strategy proposed here for enzyme detection is the first demonstration of an optical probe for monitoring the enzymatic activity of multiple enzymes. Significantly, the strategy presented here may provide a general design principle to develop a kind of luminescent probe for detecting various enzymes.

Fluorescent Vitamin B12–Platinum(II) Derivatives as Potential Metallotheranostic Agents for the Treatment and Imaging of Tumors

Vitamin B12 (cyanocobalamin) is an essential nutrient with very low bioavailability. Compared with normal cells, tumor cells show an increased demand for vitamin B12 to support their abnormal proliferation, which is a feature that can be exploited for the tumor-specific delivery of therapeutic and/or diagnostic agents by functionalizing vitamin B12 with suitable metallodrugs and/or luminescent probes. In this context, we report on the design of fluorescent vitamin B12–metal conjugates of the type [FLUO–B12–{M}] in which cyanocobalamin is functionalized at the 5′-site of the ribose unit with a fluorophore (FLUO: rhodamine 6G), whereas the Co(III)–cyano moiety is N-coordinated to a metal-based anticancer scaffold ({M}: Pt(II) substrate bearing enantiopure phenylamino-oxime ligands derived from R- or S-limonene). Two novel fluorescent cyanocobalamin–platinum(II) derivatives and their corresponding non-fluorescent counterparts were successfully generated and fully characterized, including the evaluation of their lipophilicity and luminescent properties. Although they exhibit low antiproliferative activity (IC50 = 40–70 μM), both fluorescent vitamin B12–platinum(II) conjugates showed an enhanced capability to inhibit cell viability compared with the inactive metal precursors and the non-fluorescent vitamin B12–platinum(II) analogues, confirming the beneficial effect of functionalization with the rhodamine 6G scaffold not only for imaging purposes but also with the aim of improving their biological activity.

Colorimetric recognition of a biomarker of trichloroethylene in human urine and photocatalytic dye degradation employing unprecedented Co(II) MOF luminescent probe

The Co(II) ion was combined with the ligand Bis(2-Carboxyethyl)isocyanurate at room temperature to form a new MOF, [Co(Cei)]n. This polymer was then characterised using various techniques including FT-IR analysis, Powder X-ray diffraction, thermal analysis, and SEM-EDAX analysis. Single crystal X-ray analysis reveals that the compound [Co(Cei)]n forms a 12-c connected uninodal net with a point symbol of {324.436.56}. This net has an underlying net with face-centred cubic (fcu) topology, which can effectively detect TCA in human urine. Furthermore, it demonstrates exceptional specificity by detecting concentrations as low as 1.09 ppm in real human urine. Extensive study has been conducted on the recyclability and photocatalytic effectiveness of [Co(Cei)]n for the degradation of organic dyes. Out of the 13 dyes studied, the photocatalytic breakdown efficiency of [Co(Cei)]n is highest for the potentially dangerous organic dyes Neutral Red (NR), with highest percentages of degradation i.e. 93.44 %.

Unveiling the negative correlation of formaldehyde and hydrogen sulfide in Parkinson’s disease models using a dual-responsive ruthenium(II) complex probe

Parkinson’s disease (PD) is one of the most common neurodegenerative diseases caused by various complicated pathological processes. Recent studies have revealed that formaldehyde (FA) and hydrogen sulfide (H2S) are essential signal molecules closely linked to central nervous systems. Therefore, understanding the physiological functions and relationship of FA and H2S in PD is beneficial for the early diagnosis and treatment of PD. However, an effective tool that could detect and visualize FA and H2S simultaneously in PD is still lacking. Herein we report the design and synthesis of a novel dual-responsive ruthenium(II) complex-based luminescent probe, Ru-aza-NBD, for the discriminatory detection of FA and H2S in aqueous media and PD models of living cells and mouse brains. Notably, using Ru-aza-NBD as a probe, the increased level of FA and the decreased level of H2S in PD models were discovered, which revealed the negative correlation of FA and H2S in PD for the first time. Collectively, Ru-aza-NBD could be an excellent tool for further investigating the biological functions of FA and H2S in pathological processes of PD, which offers a promising approach for the exploration of the pathogenic mechanism, diagnosis and treatment of this disease.

Copper(I) photosensitizer-silica nanoparticle assembly towards enhanced aqueous photoluminescence

Harnessing the luminescence potential of Cu(I) complexes in aqueous media is typically hindered by their poor photostability and altered properties. Here, we report the synthesis, engineering and morphological characterization of a hydrophobic homoleptic copper(I) complex entrapped into silica nanoparticles, Cu-I@SiO2 (where “Cu-I” designates [Cu(2,9-diiodo-1,10-phenanthroline)2]+), as a promising stabilisation strategy towards water-compatible, Cu(I) complex-based luminescence. The polyether chain-decorated nano-objects are spherical with an average diameter of ca. 10.8 ± 1.9 nm. Upon dispersion in water, clear solution-like suspensions were obtained. Significantly, the aqueous suspensions photo-luminesce (Φem = 5×10-4) upon excitation through the Metal-to-Ligand Charge-Transfer transition (MLCT) of the embedded copper(I) complexes. In contrast, the corresponding silica-free molecular complex dissolved in an aqueous environment revealed fully quenched emission. Finally, the use of Cu-I@SiO2 suspensions as luminescent probes is reported, first by assessing their potential use as electrochemiluminescent probes, and second by monitoring the photoluminescence from Cu-I@SiO2 in the presence of whole blood.

Glutathione ligand self-assembly enables luminescence from Au15 nanoclusters for highly sensitive and selective monitoring of blood Pb(II) ions

Lead Pb(II) ions is a cumulative toxicant that impacts several biological systems and poses severe harm to young children. Accurate Pb(II) ions monitoring is thus of paramount importance. Here, we present the synthesis and application of glutathione-capped Au15 nanoclusters (Au15(SG)13) as a luminescence probe for the accurate and selective monitoring of blood Pb(II). The introduction of Pb(II) ions triggers orderly self-assembly of Au15 nanoclusters, resulting in the formation of rigid shell around Au nuclei. This limits the localized vibration of the glutathione ligands and their interaction with water molecules, greatly reducing non-radiative energy loss, and thereby enhancing the photoluminescence signal. Consequently, Au15(SG)13 nanoclusters exhibit high sensitivity for Pb(II) detection. The detection signal displays a linear relationship with Pb(II) over a wide detection range (0–800 μg/L), demonstrating a substantial sensitivity of 35.29 μg/L. Moreover, the developed nanoclusters show superior selectivity for Pb(II) ions, distinguishing them from other prevalent heavy metals. This work pave the way for the development of advanced Pb(II) sensors with high sensitivity and selectivity.

A highly sensitive and selective Zn-based luminescent MOF for specific detection of trinitrotoluene in aqueous phase

The existence of nitroaromatic compounds, specifically 2,4,6-trinitrotoluene (TNT), in water reservoirs poses significant health risks, necessitating robust detection and monitoring strategies. In this study, we leverage the exceptional properties of the previously synthesized metal-organic framework (MOF), PUC2 as a highly luminescent probe for selective and sensitive detection of TNT in aqueous media. PUC2 exhibits remarkable luminescence, emitting a vivid blue light, making it an ideal candidate for TNT detection. Our investigations reveal that PUC2 demonstrates outstanding sensitivity, achieving an impressive detection limit of 0.145 μM towards TNT which can be attributed to the robust probe-analyte interactions evident from the quenching constant (Ksv) value of 0.18 × 104M−1. An intriguing aspect of PUC2 is its adaptability to a wide pH range, maintaining its sensing capabilities effectively in aqueous phase with pH levels ranging from 4 to 11. The predominant quenching mechanism in this context appears to be photoinduced electron transfer (PET), with an additional enhancement through Forster resonance energy transfer (FRET). The unique combination of structural features and exceptional sensing capabilities of PUC2 opens up new avenues for environmental monitoring and security applications, highlighting its potential as a highly effective luminescent sensor for detecting hazardous substances like TNT.

Ratiometric luminescence detection of H2O2 in food samples using a terbium coordination polymer sensitized with 3-carboxyphenylboronic acid

A ratiometric luminescent probe was fabricated using adenosine monophosphate (AMP) as a bridging ligand and 3-carboxyphenylboronic acid (3-CPBA) as the sensitizer and functional ligand that allowed the probe to recognize hydrogen peroxide (H2O2). The probe was labeled AMP-Tb/3-CPBA. Adding H2O2 caused the nonluminescent 3-CPBA to be converted into 3-hydroxybenzoic acid, which strongly luminesces at 401 nm. This meant that adding H2O2 decreased the AMP-Tb/3-CPBA luminescence intensity at 544 nm and caused luminescence at 401 nm. The 401 and 544 nm luminescence intensity ratio (I401/I544) was strongly associated with the H2O2 concentration between 0.1 and 60.0 μM, and the detection limit was 0.23 μM. Dual emission reverse-change ratio luminescence sensing using the probe allowed environmental effects to be excluded and the assay to be very selective. We believe that the results pave the way for the development of new functionalized lanthanide coordination polymers for use in luminescence assays.

Two multifunctional coordination polymers based on 1,4-bis(imidazole-1-ylmethyl) benzene: Synthesis, crystal structure and sensitive detection of enrofloxacin and ciprofloxacin

In this paper, we have successfully obtained two novel compounds, namely, the Cd-based compound [Cd0.5L0.5(BA)(H2O)] n1 (L = 1,4-bis(imidazole-1-ylmethyl) benzene; BA = benzoic acid) and the Co-based compound [Co1.5L1.5(OX)1.5] n2 (H2OX = Oxalic acid) by using the hydrothermal methods. The Cd ion in 1 and the Co ion in 2 have the same coordination number. However, due to the different second ligands, namely benzoic acid in 1 and oxalic acid in 2, 1 is the 1D chain structure and 2 is the 2D layer structure, thus the second ligand also plays an important role in the structure of compound. Two CPs can be used as multifunctional luminescent probes to detect the enrofloxacin and ciprofloxacin with high selectivity and sensitivity.

A NIR iridium(III) complex-based reversible probe for assessing AD progression and screening anti-AD drugs through visualization of the “Cu2+-H2S seesaw” phenomenon in Alzheimer’s disease

The progression of Alzheimer’s disease (AD) is accompanied by the increase of copper ions (Cu2+) concentration and decrease of hydrogen sulfide (H2S) level in brain tissue, thus, reversible detection of Cu2+ and H2S is regarded as an important strategy for the diagnosis and intervention of AD. However, reliable tools for reversible tracking of Cu2+ and H2S and demonstrate their dynamic changes in AD are still lacking. Herein, this work developed a novel NIR Ir(III) complex-based probe, named NIR-Ir-DA, for reversible tracking of Cu2+ and H2S in AD cells and brain tissues. The newly prepared NIR luminescence probe exhibited fast response, high sensitivity and selectivity, good biocompatibility, which makes it to be used for reversible sensing of Cu2+ and H2S in multiple cycles in living cells and assessing AD progression in vitro and in vivo. Furthermore, using NIR-Ir-DA as a probe, we screened the theaflavin-3,3′-digallate (TF3) from polyphenols with an outstanding ability to reduce neuroinflammation, which would be greatly beneficial for AD therapy. These results indicated that NIR-Ir-DA could be a useful tool for understanding the role of “Cu2+-H2S seesaw” phenomenon in amyloid-β deposition, as well as for assessing AD progression and screening anti-AD drugs.