Automated ECL Aptasensing Platform from an Intrarticular Radical Annihilation Route for Distinguishing Glioma Stages.

Nowadays, continuous efforts have been devoted to designing stable and high-efficiency electrochemiluminescence (ECL) emitters as alternatives for tris(2,2'-bipyridine)-ruthenium(II) (Ru(bpy)32+) in medical research. Herein, a novel ECL emitter was obtained by coordinating crystalline covalent triazinyl frameworks (cCTFs) with Ru2+ (termed Ru-cCTFs), which exhibited strong ECL emission by the ligand to metal charge transfer (LMCT) route. After its integration with 4-mercaptopyridine (SH-Py), the resultant SH-Py-Ru-cCTFs achieved 2.3-fold enhancement in the ECL efficiency by employing Ru(bpy)32+ as a standard, which involved a dynamic "intrarticular radical annihilation" ECL pathway. On such foundation, an automated ECL (A-ECL) aptasensor was constructed with an "on-off-on" model and magnetic separation upon linkage of the SH-Py-Ru-cCTFs with streptavidin (SA) magnetic beads (MBs). This automatic assay of miRNA-182 showed a wider linear range from 1.0 to 100.0 fM with a correlation coefficient (R2) of 0.994, a lower limit of detection (LOD) down to 0.28 fM, and faster operation within 41 min. Impressively, this bioassay facilely distinguished the stages of glioma disease from clinical blood samples with high accuracy. Hence, this research sheds light on how to develop advanced ECL luminophores and an automatic method, showing substantial insights into pathogenesis research of gliomas.

Photodynamic-Assisted Electrochemiluminescence Enhancement toward Advanced BODIPY for Precision Diagnosis of Parkinson.

Nowadays, signal enhancement is imperative to increase sensitivity of advanced ECL devices for expediting their promising applications in clinic. In this work, photodynamic-assisted electrochemiluminescence (PDECL) device was constructed for precision diagnosis of Parkinson, where an advanced emitter was prepared by electrostatically linking 2,6-dimethyl-8-(3-carboxyphenyl)4,4'-difluoroboradiazene (BET) with 1-butyl-3-methylimidazole tetrafluoroborate ([BMIm][BF4]). Specifically, protoporphyrin IX (PPIX) can trigger the photodynamic reaction under light irradiation with a wavelength of 450 nm to generate lots of singlet oxygen (1O2), showing a 2.43-fold magnification in the ECL responses. Then, the aptamer (Apt) was assembled on the functional BET-[BMIm] for constructing a "signal off" ECL biosensor. Later on, the PPIX was embedded into the G-quadruplex (G4) of the Apt to magnify the ECL signals for bioanalysis of α-synuclein (α-syn) under light excitation. In the optimized surroundings, the resulting PDECL sensor has a broad linear range of 100.0 aM ∼ 10.0 fM and a low limit of detection (LOD) of 63 aM, coupled by differentiating Parkinson patients from normal individuals according to the receiver operating characteristic (ROC) curve analysis of actual blood samples. Such research holds great promise for synthesis of other advanced luminophores, combined with achieving an early clinical diagnosis.

Palladium nanospheres-embedded metal-organic frameworks to enhance the ECL efficiency of 2,6-dimethyl-8-(3-carboxyphenyl)4,4'-difluoroboradiazene in aqueous solution for ultrasensitive Cu2+ detection.

Nowadays, organic emitters suffer from insufficient electrochemiluminescence (ECL) efficiency in aqueous solutions, and their practical applications are severely restricted in the bio-sensing field. In this work, palladium nanospheres-embedded metal-organic frameworks (Pd@MOFs) were exploited to enhance the ECL efficiency of 2,6-dimethyl-8-(3-carboxyphenyl)4,4'-difluoroboradiazene (BET) prepared by a one-pot method in aqueous environment. First, the Pd@MOFs were generated via in situ reduction of Pd nanospheres anchored onto the MOFs, and fabricated by orderly coordination of palladium chloride (PdCl2) with 1,2,4,5-benzenetetramine (BTA) tetrahydrochloride. Then, the influence of protons on the ECL response of BET was studied in detail to obtain stronger ECL emission using potassium persulfate (K2S2O8) as co-reactant in aqueous environment. As a result, a 1.47-fold ECL efficiency enlargement of BET/K2S2O8 was harvested at the Pd@MOFs/GCE, where Ru(bpy)32+ behaved as a standard. Based on the fact that the ECL signals of the BET-covered Pd@MOFs modified glassy carbon electrode (simplified as BET/Pd@MOFs/GCE) can be quenched by Cu2+, the as-built ECL sensor showed a wide linear range (1.0-100.0 pM) and a limit of detection (LOD) as low as 0.12 pM. Hence, such research offers huge potential to promote the development of organic emitters in ECL biosensors and environmental monitoring.

Hydrogen Bond Organic Frameworks as Radical Reactors for Enhancement in ECL Efficiency and Their Ultrasensitive Biosensing.

Nowadays, electrochemiluminescence (ECL) efficiency of an organic emitter is closely related with its potential applications in food safety and environmental monitoring fields. In this work, 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (TATB) was self-assembled to form hydrogen bond organic frameworks (HOFs), which worked as ideal reactors to generate highly active oxygen-containing radicals, followed by linking with isoluminol (ILu) via amide bond (termed ILu-HOFs). After covalent assembly with aminated indium-tin oxide electrode (labeled NH2-ITO), the ECL efficiency of the ILu-HOFs NH2-ITO showed about a 23.4-time increase over that of ILu itself in the presence of H2O2. Meanwhile, the enhanced ECL mechanism was mainly studied by electron paramagnetic resonance, theoretical calculation, and electrochemistry. On the above foundation, an aptamer "sandwich" ECL biosensor was constructed for detecting isocarbophos (ICP) via in situ elimination of H2O2 with catalase-linked palladium nanocubes (CAT-Pd NCs). The as-built sensor showed a broad linear range (1 pM to 100 nM) and a low limit of detection (LOD) down to 0.4 pM, coupled with efficient assays of ICP in lake water and cucumber juice samples. This strategy provides an effective way for the synthesis of advanced ECL emitter, coupled by showing promising applications in environmental and food analysis.

Efficient Electrochemical Detection of Hydrogen Peroxide Based on Silver-Centered Preyssler-Type Polyoxometalate Hybrids.

Four polyoxometalate (POM)-based organic-inorganic hybrid compounds, namely, (H2bimb)6H8[((Mn(H2O)3(µ-bimb))0.5(Mn(H2O)4)(Mn(H2O)5)0.5(AgP5W30O110))2]·29H2O (1), [(Cu(Hbimb)(H2O)2(µ-bimb)Cu(Hbimb)(H2O))(Cu(H2O)2(µ-bimb)Cu(H2O)3)((Cu(H2O)2)0.5(µ-bimb)(Cu(H2O)3)0.5)H2(AgP5W30O110)]·12.5H2O (2), (H2bimb)2H[(Zn(Hbimb)(H2O)4(Zn(Hbimb)(H2O)2)0.5)2(AgP5W30O110)]·12H2O (3), and (H2bimb)3H2[(Ag(H2O)2)0.5(Ag(Hbimb)Ag(Hbimb)(µ-bimb)Ag)(Ag(H2O)2)0.5(AgP5W30O110)]·7H2O (4) (bimb = 1,4-bis(1H-imidazol-1-yl)benzene), were hydrothermally synthesized using a silver-centered Preyssler-type POM K14[AgP5W30O110]·18H2O (abbreviated as K-{AgP5W30}) as a precursor. In 1-4, {AgP5W30} clusters integrating the merits of Ag+ and {P5W30} units are modified by different transition metal (TM)-organic fragments to extend the structures into three-dimensional frameworks. As nonenzymatic electrochemical sensor materials, 1-4 show good electrocatalytic activity, high sensitivity, and a low detection limit for detecting hydrogen peroxide (H2O2); 4 possesses the highest sensitivity of 195.47 µA·mM-1·cm-2 for H2O2 detection. Most importantly, the average level of H2O2 detection of these {AgP5W30}-based materials outperforms that of Na-centered Preyssler-type {NaP5W30} and most Keggin-type POM-based materials. The performances of such {AgP5W30} materials mainly stem from the unique advantage of high-negatively charged {AgP5W30} clusters together with the good synergistic effect between {AgP5W30} and TMs. This work expands on the research of high-efficiency POM-based nonenzymatic electrochemical H2O2 sensors using Ag-containing POMs with high negative charges, which is also of great theoretical and practical significance to carry out health monitoring and environmental analysis.

Self-assembly of a unique triangle-like tungstovanadate containing pentagonal {(WO7)W3(SnR)2} cluster.

In aqueous solution, a novel triangle-like tungstovanadate estertin derivative K10H10.5[(W4O15(H2O)2){(SnCH2CH2COO)2(V0.75W10.75/V0.25O39)}{{(SnCH2CH2COO)2(µ-OH)}2(SnCH2CH2COO)(VW10O37)}2]·31H2O ((SnR)8-V3W35, R = CH2CH2COO) was assembled by a conventional synthetic method. (SnR)8-V3W35 is composed of one [VW11O39]7- ({VW11}) and two [VW10O37]9- ({VW10}) units connected by eight [Sn(CH2)2COO]2+ groups and a {W4O19} cluster. Interestingly, there exists a pentagonal bipyramid WO7 polyhedral center surrounded by two SnCO5 and three WO6 octahedra, forming a pentagonal {(WO7)W3(SnR)2} cluster in this polyoxometalate (POM), which is also the first example of a pentagonal structure formed by transition metals (TMs) and main group organometals in the POM family. Furthermore, the structure of this organic-inorganic hybrid POM also exhibits the largest number of organotin groups introduced into the POM system. It was characterized with various physico-chemical and spectroscopic methods, including X-ray single crystal and powder diffraction analysis, 119Sn and 51V NMR, IR, thermal gravimetric analysis (TGA), etc. In addition, the catalytic activity of (SnR)8-V3W35 as a mimic of peroxidase was evaluated using o-phenylenediamine (OPD) as a peroxidase substrate. The major factors influencing the oxidation reaction such as pH, the dosage of (SnR)8-V3W35, and concentrations of OPD and H2O2 were mainly studied. (SnR)8-V3W35 exhibits good peroxidase-like catalytic activity. From another perspective, the successful acquisition of (SnR)8-V3W35 further proves the instability and easy reassembly characteristics of TM-sandwich-type tungstovanadates, which also provides a new assembly strategy for synthesizing POM-estertin derivatives.

The dual ECL signal enhancement strategy of Pd nanoparticles attached covalent organic frameworks and exonuclease cycling reaction for the ultrasensitive detection of progesterone.

Nowadays, novel and efficient signal amplification strategy in electrochemiluminescence (ECL) platform is urgently needed to enhance the sensitivity of biosensor. In this work, the dual ECL signal enhancement strategy was constructed by the interactions of Pd nanoparticles attached covalent organic frameworks (Pd NPs@COFs) with tris (bipyridine) ruthenium (RuP) and Exonuclease III (Exo.III) cycle reaction. Within this strategy, the COFs composite was generated from the covalent reaction between 2-nitro-1,4-phenylenediamine (NPD) and trialdehyde phloroglucinol (Tp), and then animated by glutamate (Glu) to attach the Pd NPs. Next, the "signal on" ECL biosensor was constructed by the coordination assembly of thiolation capture DNA (cDNA) onto the Pd NPs@COFs modified electrode. After the aptamer recognition of progesterone (P4) with hairpin DNA 1 (HP1), the Exo. III cycle reaction was initiated with HP2 to generate free DNA, which hybridized with cDNA to form double-stranded DNA (dsDNA). For that, the RuP was embedded into the groove of dsDNA and achieved the ultrasensitive detection of P4 with a lower limit of detection (LOD) down to 0.45 pM, as well as the excellent selectivity and stability. This work expands the COFs-based materials application in ECL signal amplification and valuable DNA cyclic reaction in biochemical testing field.

Two-dimensional ultrathin surfactant-encapsulating polyoxometalate assemblies as carriers for monodispersing noble-metal nanoparticles with high catalytic activity and stability.

Noble metal nanoparticles (NMNPs) with excellent catalytic activity and stability play an important role in the field of environmental governance. A uniform distribution and a strong binding force with the carriers of the noble metal nanoparticles are important, but avoidance of the use of additional reducing agents is a promising direction of research. Herein, 2D ultrathin surfactant-encapsulating polyoxometalate (SEP) nanosheets constructed by the self-assembly of dodecyldimethylammonium bromide (DODA) and molybdophosphate (H3PMo12O40, PMo12) are designed to be versatile carriers for Ag nanoparticles. Under the synergistic effect of the well-arranged PMo12 units, encapsulating hydrophobic oleic acid (OA) and reductive molybdophosphate under Xe lamp irradiation, the silver oleate (AgOA)-derived Ag nanoparticles (5 ± 2 nm) are monodispersed on the DODA-PMo12 assemblies and form the Agx/DODA-PMo12 composite. The optimized Ag4.89/DODA-PMo12 composite exhibits high catalytic activity and stability in the degradation of 4-nitrophenol (4-NP), which reaches a superior rate constant of 6.49 × 10-3 s-1 and without significant deterioration after three recycles. This technique can be facilely promoted to other noble metal nanoparticles with excellent catalytic activity and stability.

Pt-O bond as an active site superior to Pt0 in hydrogen evolution reaction.

The oxidized platinum (Pt) can exhibit better electrocatalytic activity than metallic Pt0 in the hydrogen evolution reaction (HER), which has aroused great interest in exploring the role of oxygen in Pt-based catalysts. Herein, we select two structurally well-defined polyoxometalates Na5[H3Pt(IV)W6O24] (PtW6O24) and Na3K5[Pt(II)2(W5O18)2] (Pt2(W5O18)2) as the platinum oxide model to investigate the HER performance. Electrocatalytic experiments show the mass activities of PtW6O24/C and Pt2(W5O18)2/C are 20.175 A mg-1 and 10.976 A mg-1 at 77 mV, respectively, which are better than that of commercial 20% Pt/C (0.398 A mg-1). The in situ synchrotron radiation experiments and DFT calculations suggest that the elongated Pt-O bond acts as the active site during the HER process, which can accelerate the coupling of proton and electron and the rapid release of H2. This work complements the knowledge boundary of Pt-based electrocatalytic HER, and suggests another way to update the state-of-the-art electrocatalyst.

An open chain carboxyethyltin functionalized sandwich-type tungstophosphate based on a trivacant Dawson subunit: synthesis, characterization and properties.

A Dawson sandwich-type polyoxometalate {C(NH2)3}12H4[αßßα-{(Sn(C3H4O2))2Mn2(P2W15O56)2}]·22H2O (abbreviated as SnR-Mn-P2W15), functionalized by open chain carboxyethyltin groups, was first prepared in aqueous solution under conventional reaction conditions, and then structurally characterized by physicochemical and spectroscopic methods. Single crystal X-ray diffraction analysis revealed that two Mn(2+) cations and two [Sn(CH2CH2COO)](2+) groups are located in the internal and external positions in the so-called equatorial region of SnR-Mn-P2W15, respectively. Intriguingly, two exposed carboxyl groups act as stretching-arm brackets, which provide a favorable structure for potential further functionalization. The electrocatalytic activity of SnR-Mn-P2W15 towards the reduction of hydrogen peroxide and nitrite was studied. Additionally, its acid catalysis and oxidation catalysis activities in organic synthesis were investigated.