Sm(â ¢), Gd(â ¢), and Eu(â ¢) complexes with 8-hydroxyquinoline derivatives as potential anticancer agents via inhibiting cell proliferation, blocking cell cycle, and inducing apoptosis in NCI-H460 cells.

Four lanthanide complexes with 8-hydroxyquinoline-2-aldehyde-2-hydrazinopyridine (H-L1), 8-hydroxyquinoline-2-aldehyde-2-hydrazimidazole (H-L2): [Sm(L1)2][Sm(L1)(NO3)3]·CHCl3·2CH3OH (1), [Gd(L1)2][Gd(L1)(NO3)3]·CHCl3·2CH3OH (2), [Sm(L2)(NO3)2]2·CH3OH (3), and [Eu(L2)(NO3)2]2·CH3OH (4) were synthesized and characterized. In vitro cytotoxicity evaluation showed that the ligands and four lanthanide complexes exhibited cytotoxicity to the five tested tumor cell lines. Among them, complex 1 showed the best antiproliferative activity against NCI-H460 tumor cells. Mechanistic studies demonstrated that complex 1 arrested the cell cycle of NCI-H460 cells in G1 phase and induced mitochondria-mediated apoptosis, which resulted in the loss of mitochondrial membrane potential, enhanced intracellular Ca2+ levels and reactive oxygen species generation. In addition, complex 1 affected the expression levels of intracellular apoptosis-related proteins and activated the caspase-3/9 in NCI-H460 cells. Therefore, complex 1 is a potential anticancer agent.

Research Progress of Deep-Red to Near-Infrared Electroluminescent Materials Based on Organic Cyclometallated Platinum(II) Complexes.

In recent years, the near-infrared (NIR) light-emitting materials have attracted increasing attention due to the broad application prospects in the fields of military industry, aerospace, lighting, display and wearable devices. As the transition metal complexes, platinum(II) complexes have been shown to emit luminescence efficiently in NIR organic light-emitting diodes because of the unique d8 electron structure. This structure ensures that the platinum(II) complex molecules exhibit a high planarity, variety of excited states, and strong intermolecular interactions. This review summarizes the research progress of deep red to NIR organic light-emitting materials based on platinum(II) complexes in recent years and provides a certain reference for the further design and synthesis of NIR platinum(II) complex luminescent materials with superior performance.

Fluorine-18 incorporation and radiometal coordination in macropa ligands for PET imaging and targeted alpha therapy.

The development of theranostic agents for radiopharmaceuticals based on therapeutic alpha emitters marks an important clinical need. We describe a strategy for the development of theranostic agents of this type via the functionalization of the ligand with the diagnostic radionuclide fluorine-18. An analogue of macropa, an 18-membered macrocyclic chelator with high affinity for alpha therapeutic radiometals, was synthesized and its complexation properties with metal ions were determined. The new macropa-F ligand was used for quantitative radiometal complexation with lead-203 and bismuth-207, as surrogates for their alpha-emitting radioisotopes. As a diagnostic partner, a radiofluorinated macropa ligand was used for quantitative bismuth(III) and lead(II) complexation. All fluorine-18 and radiometal complexes are highly stable in human serum over several days. This study presents a new proof-of-principle approach for developing theranostic agents based on alpha-emitting radionuclides and fluorine-18.

Bioinorganic Chemistry Meets Microbiology: Copper(II) and Zinc(II) Complexes Doing the Cha-Cha with the C-t-CCL-28 Peptide, Dancing till the End of Microbes.

The necessity to move away from conventional antibiotic therapy has sparked interest in antimicrobial peptides (AMPs). One fascinating example is human CCL-28 chemokine produced by acinar epithelial cells in the salivary glands. It can also be released into the oral cavity with saliva, playing a crucial role in oral protection. The C-terminal domain of CCL-28 possesses antifungal and antibacterial properties, which are likely linked to membrane disruption and enzyme leakage. Studies suggest that AMPs can become more potent after they have bound Cu(II) or Zn(II). In many cases, these ions are essential for maximizing effectiveness by altering the peptides' physicochemical properties, such as their local charge or structure. The examined peptide binds Cu(II) and Zn(II) ions very effectively, forming equimolar complexes. Metal ion binding affinity, coordination mode, and antimicrobial activity strongly depend on the pH of the environment. Coordination modes have been proposed based on the results of potentiometric titrations, spectroscopic studies (UV-visible, electron paramagnetic resonance and circular dichroism at different path lengths), and mass spectrometry. The antimicrobial properties of the Cu(II) and Zn(II) complexes with the C-terminal fragment of CCL-28 chemokine have been assessed against fungal and bacterial strains, demonstrating exceptional activity against Candida albicans at pH 5.4. Moreover, the complex with Zn(II) ions shows the same activity against theStreptococcus mutans bacterium as chloramphenicol, a commonly used antibiotic. Cyclic voltammetry proposed a probable antimicrobial mechanism of the studied Cu(II) complex through the formation of reactive oxygen species, which was also confirmed by tests with ascorbic acid in UV-vis and fluorescence spectroscopic studies.

Pyrene-Based Metal-Organic Frameworks with Coordination-Enhanced Electrochemiluminescence for Fabricating a Biosensing Platform.

Enhancing the electrochemiluminescence (ECL) properties of polycyclic aromatic hydrocarbons (PAHs) is a significant topic in the ECL field. Herein, we elaborately chose PAH derivative luminophore 1,3,6,8-tetrakis(p-benzoic acid)pyrene (H4TBAPy) as the organic ligand to synthesize a new Ru-complex-free ECL-active metal-organic framework Dy-TBAPy. Interestingly, Dy-TBAPy exhibited a more brilliant ECL emission and higher ECL efficiency than H4TBAPy aggregates. On the one hand, TBAPy luminophores were assembled into rigid MOF skeleton via coordination bonds, which not only enlarged the distance between pyrene cores to eliminate the aggregation-caused quenching (ACQ) effect but also obstructed the intramolecular motions of TBAPy to diminish the nonradiative relaxation, thus realizing a remarkable coordination-enhanced ECL. On the other hand, the ultrahigh porosity of Dy-TBAPy was beneficial to the diffusion of electrons, ions, and coreactant (S2O82-) in the skeleton, which efficiently boosted the excitation of interior TBAPy luminophores and led to a high utilization ratio of TBAPy, further improving ECL properties. More intriguingly, the ECL intensity of the Dy-TBAPy/S2O82- system was about 4.1, 87.0-fold higher than those of classic Ru(bpy)32+/TPrA and Ru(bpy)32+/S2O82- systems. Considering the aforementioned fabulous ECL performance, Dy-TBAPy was used as an ECL probe to construct a supersensitive ECL biosensor for microRNA-21 detection, which showed an ultralow detection limit of 7.55 aM. Overall, our study manifests that coordinatively assembling PAHs into MOFs is a simple and practicable way to improve ECL properties, which solves the ACQ issue of PAHs and proposes new ideas for developing highly efficient Ru-complex-free ECL materials, therefore providing promising opportunities to fabricate high-sensitivity ECL biosensors.

Bis(amino acidato)copper(II) compounds in blood plasma: a review of computed structural properties and amino acid affinities for Cu2+ informing further pharmacological research.

Neutral bis(amino acidato)copper(II) [Cu(aa)2] coordination compounds are the physiological species of copper(II) amino acid compounds in blood plasma taking the form of bis(l-histidinato)copper(II) and mixed ternary copper(II)-l-histidine complexes, preferably with l-glutamine, l-threonine, l-asparagine, and l-cysteine. These amino acids have three functional groups that can bind metal ions: the common α-amino and carboxylate groups and a side-chain polar group. In Cu(aa)2, two coordinating groups per amino acid bind to copper(II) in-plane, while the third group can bind apically, which yields many possibilities for axial and planar bonds, that is, for bidentate and tridentate binding. So far, the experimental studies of physiological Cu(aa)2 compounds in solutions have not specified their complete geometries. This paper provides a brief review of my group's research on structural properties of physiological Cu(aa)2 calculated using the density functional theory (DFT) to locate low-energy conformers that can coexist in aqueous solutions. These DFT investigations have revealed high conformational flexibility of ternary Cu(aa)2 compounds for tridentate or bidentate chelation, which may explain copper(II) exchange reactions in the plasma and inform the development of small multifunctional copper(II)-binding drugs with several possible copper(II)-binding groups. Furthermore, our prediction of metal ion affinities for Cu2+ binding with amino-acid ligands in low-energy conformers with different coordination modes of five physiological Cu(aa)2 in aqueous solution supports the findings of their abundance in human plasma obtained with chemical speciation modelling.

Strategy of Constructing Ratio-Dependent Coordination Polymer probes and Their Film Application with a Smart Phone for Detection of Lomefloxacin Hydrochloride and Sodium Salicylate.

Lomefloxacin hydrochloride (LMFX) and sodium salicylate (SS) are important targets for real-time detection due to their widespread uses in daily life; accurate and portable monitoring of LMFX and SS is crucial for human health concerns accordingly. Developing a precise and smart platform for determination of the above analytes remains a significant challenge. Herein, a high-sensitivity platform incorporating a luminescence electrospinning film, self-designed smart-phone app, and portable 3D printing device has been developed to identify LMFX and SS. In this work, two heterometallic coordination polymers with two-dimensional layer structures have been synthesized based on 2,2'-oxidiacetic acid ligand (H2oda), namely, [LnPb(oda)2(CH3COO)]n [Ln = Eu (IMU-1); Tb (IMU-2)]. IMU-1 and IMU-2 were ratio-dependent luminescence probes, which could selectively and sensitively sense with LMFX and SS, respectively. Additionally, the synthesized electrospinning films incorporating IMU-1 and IMU-2 were employed to identify LMFX and SS. Both films could rapidly photograph and color-capture through a portable 3D printing device, along with a self-designed smart-phone app that enabled convenient and quick determination of the concentrations of the above analytes. Remarkably, the mechanism exploration indicated that electron transfer from ligands to analytes affected the antenna effect and further utilized the intrinsic luminescence of analytes along with the luminescence quenching of Ln3+ ions. Furthermore, a strategy for constructing ratio-based fluorescent probes by exploiting the luminescence of analytes and Ln3+ ions in host coordination polymers is proposed. This work provides a new insight by combining luminescence probes, portable devices, and a smart-phone app for real-time detection of drugs and food additives.

Bombesin-Targeted Delivery of ß-Carboline-Based Ir(III) and Ru(II) Photosensitizers for a Selective Photodynamic Therapy of Prostate Cancer.

Despite advances in Ir(III) and Ru(II) photosensitizers (PSs), their lack of selectivity for cancer cells has hindered their use in photodynamic therapy (PDT). We disclose the synthesis and characterization of two pairs of Ir(III) and Ru(II) polypyridyl complexes bearing two ß-carboline ligands (N^N') functionalized with -COOMe (L1) or -COOH (L2), resulting in PSs of formulas [Ir(C^N)2(N^N')]Cl (Ir-Me: C^N = ppy, N^N' = L1; Ir-H: C^N = ppy, N^N' = L2) and [Ru(N^N)2(N^N')](Cl)2 (Ru-Me: N^N = bpy, N^N' = L1; Ru-H: N^N = bpy, N^N' = L2). To enhance their selectivity toward cancer cells, Ir-H and Ru-H were coupled to a bombesin derivative (BN3), resulting in the metallopeptides Ir-BN and Ru-BN. Ir(III) complexes showed higher anticancer activity than their Ru(II) counterparts, particularly upon blue light irradiation, but lacked cancer cell selectivity. In contrast, Ir-BN and Ru-BN exhibited selective photocytoxicity against prostate cancer cells, with a lower effect against nonmalignant fibroblasts. All compounds generated ROS and induced severe mitochondrial toxicity upon photoactivation, leading to apoptosis. Additionally, the ability of Ir-Me to oxidize NADH was demonstrated, suggesting a mechanism for mitochondrial damage. Our findings indicated that the conjugation of metal PSs with BN3 creates efficient PDT agents, achieving selectivity through targeting bombesin receptors and local photoactivation.

Group VA Aromatic Thiosemicarbazone Complexes: Synthesis, Characterization, Biological Activity, and Topological Studies.

The antiproliferative and antibacterial activities of thiosemicarbazones increase markedly with the presence of metal ions. One of the factors determining the activity of metal thiosemicarbazone complexes is the coordination structure. In this study, the biological effects of new antimony (III) and bismuth (III) thiosemicarbazone complexes with different binding modes and geometrical structures were demonstrated. Three new complexes, with the formulae {[SbCl3(µ2-S-Hacptsc)(η1-S-Hacptsc)], 2/3H2O,1/3CH2Cl2}, {[SbCl3(κ2-S,N-Hacpmtsc)(η1-S-Hacpmtsc)2CH2Cl2]}, and{[BiCl3(η1-S-Hbzmtsc)3]·C2H5OH}, where Hacptsc: acetophenone thiosemicarbazone, Hacpmtsc: acetophenone-N-methyl thiosemicarbazone, Hbzmtsc: benzaldehyde-N-methyl thiosemicarbazone) were elucidated by different methods and deeply analyzed in accordance with their structure by X-ray structure analysis and Atoms-In-Molecules topological analysis. This analysis provided a deeper understanding of the coordination spheres of the Sb/Bi complexes. For instance, the first reported two binding modes of the same ligand are observed in a single crystal structure of antimony (III) halide complexes. Additionally, in one of the complexes, a solid-to-solid phase transition was detected and analyzed in detail. Those complexes, very unique in terms of their geometry, have also been tested for their in vitro cytotoxic activity against human adenocarcinoma cervical cancer (HeLa) cells, whereas antimony (III) complex 1is the most active complex of this study. Further, the antibacterial activity of the complexes has been screened against two Gram-negative (Pseudomonas aeruginosa and Escherichia coli) and two Gram-positive (Staphylococcus epidermidis and Staphylococcus aureus) pathogenic bacteria. From the results, it is found that all the complexes exhibited significant activity against the Gram-negative pathogenic bacteria.

Establishing Composition of Solid Solution Based on Single Crystal and Powder X-ray Measurement: The Case of Halogenated Bismuth(III) Complexes with Acetophenone-4-methyl-3-thiosemicarbazone.

New bismuth (III) complexes with acetophenone-4-methyl-3-thiosemicarbazone (L) and halogens (Cl and Br) in both bridging and terminal positions have been synthesized and structurally characterized using single-crystal X-ray diffraction. The pure complexes (Cl or Br) were found to be highly isostructural, which motivated our attempts to create solid solutions of these complexes. A series of such compounds was prepared using various procedures and stoichiometries. A method for determining the mutual concentrations of different halogens, based on the positions of selected peaks in powder diffraction patterns, was tested and compared with other methods.

Synthesis and Preliminary Studies for In Vitro Biological Activity of Two New Water-Soluble Bis(thio)carbohydrazones and Their Copper(II) and Zinc(II) Complexes.

Research in the field of metallodrugs is continually increasing. However, it is often limited by the poor solubility in water of the metal complexes. To try to overcome this problem, the two new ligands bis-(sodium 3-methoxy-5-sulfonate-salicylaldehyde)thiocarbohydrazone (bis-TCH, Na2H4L1) and bis-(sodium 3-methoxy-5-sulfonate-salicylaldehyde)carbohydrazone (bis-CH, Na2H4L2) were synthesized and characterized, both achieving high solubility in water. The speciation of the ligands and their coordinating behaviour towards the biologically relevant Cu(II) and Zn(II) ions were studied spectroscopically and potentiometrically, determining the pKas of the ligands and the formation constants of the complex species. The monometallic and bimetallic Cu(II) and Zn(II) complexes were isolated, and the single-crystal X-ray structure of [Cu2(NaHL1)(H2O)7].3.5H2O was discussed. Finally, preliminary studies of the in vitro cytotoxic properties of the new compounds were started on normal (Hs27) and cancer (U937) cell lines. bis-TCH was able to induce a growth inhibition effect between 40% and 45% in both cell lines; bis-CH did not produce a reduction in cell viability in Hs27 cells but revealed mild antiproliferative activity after 72 h of treatment in U937 cancer cells (GI50 = 46.5 ± 4.94 µg/mL). Coordination of the Cu(II) ions increased the toxicity of the compounds, while, in contrast, Zn(II) complexes were not cytotoxic.

Creation of Metal-Complex-Integrated Tensegrity Triangle DNA Crystals.

Structural DNA nanotechnology is an emerging field and is expected to be used for various applications in materials science. In this study, we designed a DNA tensegrity triangle to accommodate the bipyridine complexes with metal ions (Ni2+ and Fe2+) at the center of the space within the triangle. A metal-bipyridine-incorporated DNA tensegrity triangle was crystalized, and the presence of metals within it was confirmed through X-ray crystal structure analysis. A signal of the anomalous dispersion effect derived from metal was observed in the center of the DNA triangle.

Advances in Chiral Pincer Complexes: Insights and Applications in Catalytic Asymmetric Reactions.

Chiral pincer complexes, characterized by their rigid tridentate coordination framework, have emerged as powerful catalysts in asymmetric synthesis. This review provides a comprehensive overview of recent advancements in the development of chiral pincer-type ligands and their corresponding transition metal complexes. We highlight the latest progress in their application across a range of catalytic asymmetric reactions, including the (transfer) hydrogenation of polar and non-polar bonds, hydrophosphination, alkynylation, Friedel-Crafts reactions, enantioselective reductive cyclization of alkynyl-tethered cyclohexadienones, enantioselective hydrosilylation, as well as Aza-Morita-Baylis-Hillman reactions. The structural rigidity and tunability of chiral pincer complexes enable precise control over stereoselectivity, resulting in high enantioselectivity and efficiency in complex molecular transformations. As the field advances, innovations in ligand design and the exploration of new metal centers are expected to expand the scope and utility of these catalysts, bearing significant implications for the synthesis of enantioenriched compounds in pharmaceuticals, materials science, and beyond.

DNA-Directed Activation of Photocatalytic Labeling at Cell-Cell Contact Sites.

Cell-cell interactions govern diverse biological activities, necessitating molecular tools for understanding and regulating these interactions. Photoredox chemistry can detect cell-cell interactions by anchoring photocatalysts on cellular membranes to generate reactive species that tag closely contacting cells. However, the activation of photocatalysts lacks precise spatial resolution for selectively labeling intercellular interfaces. Herein, we report a DNA-based approach to selectively activate photocatalytic reactions at cell-cell contacts. Two cell populations are coated with distinct DNA strands, which interact at intercellular contacts, mediating the site-specific turn-on of a Ru(bpy)3-type photocatalyst. We demonstrate high spatial specificity for intercellular chemical labeling in cultured mammalian cells. Furthermore, as a proof of concept, we activate the dynamic DNA catalyst at cell-cell contacts in response to customized DNA triggers. This study lays the foundation for designing versatile chemical tools with high spatial precision and programmable responsiveness, along with the temporal resolution afforded by photoirradiation, to investigate and manipulate cell-cell interactions.

Synthesis, Characterization, and Biological Evaluation of Novel [M(η6-arene)2]+ (M = Re, 99mTc) Hosted Terpyridines and Copper Complexes Thereof.

We report the synthesis, characterization, and in vitro biological activities of [Re(η6-arene)2]+-terpyridine conjugates and their CuII complexes. The terpyridine (terpy) chelators were attached to the [Re(η6-arene)2]+ scaffold via secondary amine linkers allowing for heteroleptic mono- and homoleptic bis-terpyridine-substituted chelators. Complexation with CuCl2 afforded the respective square pyramidal [Cu(terpy)Cl2] complexes hosted on the [Re(η6-arene)2]+ scaffold. The chelator conjugates and their respective complexes were found to be remarkably cytotoxic against malignant HT29 and A549 human cancer cell lines in vitro with IC50 values in the low micromolar range. Mitochondrial respiration disruption was identified as a possible mode of action of these novel drug candidates. Crucially, the [Re(η6-arene)2]+ hosts delivered water solubility of the otherwise insoluble [Cu(terpy)Cl2] motif. Importantly, the homoleptic [99mTc(η6-arene)2]+-terpyridine conjugate is available in a single step, which enables the presented system to be used as a theranostic approach to modern medicinal inorganic chemistry.

Computational Exploration of the Mechanism of Action of a Sorafenib-Containing Ruthenium Complex as an Anticancer Agent for Photoactivated Chemotherapy.

Ruthenium(II) polypyridyl complexes are being tested as potential anticancer agents in different therapies, which include conventional chemotherapy and light-activated approaches. A mechanistic study on a recently synthesized dual-action Ru(II) complex [Ru(bpy)2(sora)Cl]+ is described here. It is characterized by two mono-dentate leaving ligands, namely, chloride and sorafenib ligands, which make it possible to form a di-aquo complex able to bind DNA. At the same time, while the released sorafenib can induce ferroptosis, the complex is also able to act as a photosensitizer according to type II photodynamic therapy processes, thus generating one of the most harmful cytotoxic species, 1O2. In order to clarify the mechanism of action of the drug, computational strategies based on density functional theory are exploited. The photophysical properties of the complex, which include the absorption spectrum, the kinetics of ISC, and the character of all the excited states potentially involved in 1O2 generation, as well as the pathway providing the di-aquo complex, are fully explored. Interestingly, the outcomes show that light is needed to form the mono-aquo complex, after releasing both chloride and sorafenib ligands, while the second solvent molecule enters the coordination sphere of the metal once the system has come back to the ground-state potential energy surface. In order to simulate the interaction with canonical DNA, the di-aquo complex interaction with a guanine nucleobase as a model has also been studied. The whole study aims to elucidate the intricate details of the photodissociation process, which could help with designing tailored metal complexes as potential anticancer agents.

Force Fields, Quantum-Mechanical- and Molecular-Dynamics-Based Descriptors of Radiometal-Chelator Complexes.

Radiopharmaceuticals are currently a key tool in cancer diagnosis and therapy. Metal-based radiopharmaceuticals are characterized by a radiometal-chelator moiety linked to a bio-vector that binds the biological target (e.g., a protein overexpressed in a particular tumor). The right match between radiometal and chelator influences the stability of the complex and the drug's efficacy. Therefore, the coupling of the radioactive element to the correct chelator requires consideration of several features of the radiometal, such as its oxidation state, ionic radius, and coordination geometry. In this work, we systematically investigated about 120 radiometal-chelator complexes taken from the Cambridge Structural Database. We considered 25 radiometals and about 30 chelators, featuring both cyclic and acyclic geometries. We used quantum mechanics methods at the density functional theoretical level to generate the general AMBER force field parameters and to perform 1 µs-long all-atom molecular dynamics simulations in explicit water solution. From these calculations, we extracted several key molecular descriptors accounting for both electronic- and dynamical-based properties. The whole workflow was carefully validated, and selected test-cases were investigated in detail. Molecular descriptors and force field parameters for the complexes considered in this study are made freely available, thus enabling their use in predictive models, molecular modelling, and molecular dynamics investigations of the interaction of compounds with macromolecular targets. Our work provides new insights in understanding the properties of radiometal-chelator complexes, with a direct impact for rational drug design of this important class of drugs.

Hybrid Hydroxyapatite-Metal Complex Materials Derived from Amino Acids and Nucleobases.

Calcium phosphates (CaPs) and their substituted derivatives encompass a large number of compounds with a vast presence in nature that have aroused a great interest for decades. In particular, hydroxyapatite (HAp, Ca10(OH)2(PO4)6) is the most abundant CaP mineral and is significant in the biological world, at least in part due to being a major compound in bones and teeth. HAp exhibits excellent properties, such as safety, stability, hardness, biocompatibility, and osteoconductivity, among others. Even some of its drawbacks, such as its fragility, can be redirected thanks to another essential feature: its great versatility. This is based on the compound's tendency to undergo substitutions of its constituent ions and to incorporate or anchor new molecules on its surface and pores. Thus, its affinity for biomolecules makes it an optimal compound for multiple applications, mainly, but not only, in biological and biomedical fields. The present review provides a chemical and structural context to explain the affinity of HAp for biomolecules such as proteins and nucleic acids to generate hybrid materials. A size-dependent criterium of increasing complexity is applied, ranging from amino acids/nucleobases to the corresponding macromolecules. The incorporation of metal ions or metal complexes into these functionalized compounds is also discussed.

Ratiometric Imaging Detection of Amyloid-ß Fibrils by a Dual-Emissive Tris-Heteroleptic Ruthenium Complex.

Two dual fluorescent/phosphorescent tris-heteroleptic mononuclear Ru(ΙΙ) complexes (2 and 3) were designed and applied in amyloid-ß (Aß) sensing. These complexes have a general formula of [Ru(phen)(dppz)(L)](PF6)2, where L is (2-pyrazinyl)(2-pyridyl)(methyl)amine (H-L) with different substituents (-OMe for 2, -H for 3), phen is 1,10-phenanthroline, and dppz is dipyridophenazine, respectively. Compared with the previously reported ratiometric probe 1 with a di(pyrid-2-yl)(methyl)amine ligand, complex 2 can be employed for not only ratiometric emissive detection of Aß aggregation but also ratiometric imaging detection of Aß fibrils. In ratiometric emissive detection, as the incubation time of the Aß sample (Aß40 and Aß42) was prolonged, a new phosphorescence emission band appeared with gradual enhancement of the emission intensity, while the fluorescence emission was basically unchanged, which could be treated as an intrinsic internal reference signal. In comparison, a larger ratiometric photoluminescence enhancement (I640/I440) was observed for Aß40 aggregation with respect to Aß42. In ratiometric imaging detection, the imaging signals obtained from the phosphorescence emission are much brighter than the fluorescence emission in both Aß40 and Aß42 fibrils. As indicated by molecular docking results, stronger interactions were found between complex 2 with Aß40 fibrils, which included π/π, π/C-H, and π/H interactions between bidentate ligands dppz and phen with amino acid residues. Moreover, computational calculations were carried out to assist the interpretation of these experimental findings.

A smartphone-assisted electrochemiluminescent biosensor for highly sensitive detection of miRNA-21 based on Ru(bpy)2(L)4+@MOF-5.

A smartphone-assisted electrochemiluminescence (ECL) strategy based on Ru(bpy)2(L)4+ as chromophores confined with metal - organic frameworks (Ru(bpy)2(L)4+@MOF-5) for the signal-amplified detection of miRNA-21 was developed. We synthesized a derivative of tris(2,2'-bipyridyl)ruthenium(II) complex (Ru(bpy)2(L)4+) with high charges, which can be loaded into the MOF-5 by strong electrostatic interaction to prevent from leakage. In addition, nucleic acid cycle amplification was used to quench the signal of Ru(bpy)2(L)4+@MOF-5 by ferrocene. This method was applied to detect the concentration of miRNA-21 ranging from 1.0 × 10-14-1.0 × 10-9 M with a low LOD of 7.2 fM. This work demonstrated the construction of a signal quenching strategy ECL biosensor for miRNA using Ru(bpy)2(L)4+@MOF-5 systems and its application in smartphone-assisted ECL detection.