Highly stable Ru-complex-based metal-covalent organic frameworks as novel type of electrochemiluminescence emitters for ultrasensitive biosensing.

Developing novel types of high-performance electrochemiluminescence (ECL) emitters is of great significance for constructing ultrasensitive ECL sensors. Herein, a highly stable metal-covalent organic framework (MCOF), termed Ru-MCOF, has been devised and synthesized by employing a classic ECL luminophore, tris(4,4'-dicarboxylicacid-2,2'-bipyridyl)ruthenium(II) (Ru(dcbpy)32+), as building unit and applied as a novel ECL probe to construct an ultrasensitive ECL sensor for the first time. Impressively, the topologically ordered and porous architectures of the Ru-MCOF not only allow Ru(bpy)32+ units to precisely locate and homogeneously distribute in the skeleton via strong covalent bonds but also facilitate the transport of co-reactants and electrons/ions in channels to promote the electrochemical activation of both external and internal Ru(bpy)32+ units. All these features endow the Ru-MCOF with excellent ECL emission, high ECL efficiency, and outstanding chemical stability. As expected, the constructed ECL biosensor based on the Ru-MCOF as a high-efficiency ECL probe accomplishes the ultrasensitive detection of microRNA-155. Overall, the synthesized Ru-MCOF not only enriches the MCOF family but also displays excellent ECL performance and thus expands the application of MCOFs in bioassays. Considering the structural diversity and tailorability of MCOFs, this work opens a new horizon to design and synthesize high-performance ECL emitters, therefore paving a new way to develop highly stable and ultrasensitive ECL sensors and motivating further research on MCOFs.

Ruthenium(II) complex-grafted conductive metal-organic frameworks with conductivity- and confinement-enhanced electrochemiluminescence for ultrasensitive biosensing application.

Improving the electrochemiluminescence (ECL) performance of luminophores is an ongoing research hotspot in the ECL realm. Herein, a high-performance metal-organic framework (MOF)-based ECL material (Ru@Ni3(HITP)2, HITP = 2,3,6,7,10,11-hexaiminotriphenylene) with conductivity- and confinement-enhanced ECL was successfully constructed by using conductive MOF Ni3(HITP)2 as the carrier to graft Ru(bpydc)34- (H2bpydc = 2,2'-bipyridine-4,4'-dicarboxylic acid) into the channels of Ni3(HITP)2. Compared to Ru@Cu3(HITP)2 and Ru@Co3(HITP)2 with relatively low conductivity, the ECL intensity of Ru@Ni3(HITP)2 was prominently increased about 6.76 times and 18.8 times, respectively, which demonstrated that the increase in conductivity induced the ECL enhancement of the MOF-based ECL materials. What's more, the hydrophobic and porous Ni3(HITP)2 can not only effectively enrich the lipophilic tripropylamine (TPrA) coreactants in its channels to enhance the electrochemical oxidation efficiency of TPrA, but also provide a conductive reaction micro-environment to boost the ECL reaction between Ru(bpydc)33- intermediates and TPrA• in confined spaces, thus realizing a remarkable confinement-enhanced ECL. Considering the excellent ECL performance of Ru@Ni3(HITP)2, an ultrasensitive ECL biosensor was prepared based on the Ru@Ni3(HITP)2 ECL indicator combining an exonuclease I-aided target cycling amplification strategy for thrombin determination. The constructed ECL biosensor showcased a wide linear range from 1 fM to 1 nM with a low detection limit of 0.62 fM. Overall, the conductivity- and confinement-enhanced ECL based on Ru@Ni3(HITP)2 provided effective and feasible strategies to enhance ECL performance, which paved a promising avenue for exploring high-efficient MOF-based ECL materials and thus broadened the application scope of conductive MOFs.

In situ growth of metal-organic layer on ultrathin Ti3C2Tx MXene nanosheet boosting fast electron/ion transport for electrochemiluminescence enhancement.

Ultrathin metal-organic layers (MOLs) have attracted substantial attention in fabricating highly efficient electrochemiluminescence (ECL) materials due to their porous structure, small diffusion blockage, and short electron/ion-diffusion pathway, yet MOLs suffer from the inherent poor electrical conductivity that astricted the electrochemical activation, resulting in the unsatisfactory utilization ratio of ECL emitters. Herein, to address this limitation, we in situ hybridized Zr-based ultrathin MOL (Zr-TCBPE-MOL, H4TCBPE = 1,1,2,2-tetra(4-carboxylbiphenyl)ethylene) with the highly conductive Ti3C2Tx MXene nanosheet to obtain a unique 2D-2D hybrid nanocomposite (Zr-TCBPE-MOL/MXene). Benefiting from the above-mentioned attractive virtues of ultrathin MOLs and the superior conductivity of Ti3C2Tx MXene nanosheet, the resulting Zr-TCBPE-MOL/MXene nanocomposite permitted fast electron/ion transport across the whole framework of Zr-TCBPE-MOL/MXene, which efficiently boosted the electrochemical activation of TCBPE luminophores and thus improved the utilization ratio of luminophores to realize a remarkable ECL emission. Gratifyingly, we found that the ECL signal of Zr-TCBPE-MOL/MXene nanocomposite was greatly enhanced by around 4.1 times in contrast to that of pure Zr-TCBPE-MOL. On basis of the prominent ECL performance of Zr-TCBPE-MOL/MXene nanocomposite, a novel "off-on" ECL biosensor was proposed to sensitively analyze microRNA-141, which possessed a wide response range (100 aM-1 nM) and a low detection limit of 16.2 aM. Overall, this work puts forward a rational strategy to construct high-performance ECL materials and sheds new light on developing sensitive ECL sensing platforms.

Pyrene-Based Hydrogen-Bonded Organic Frameworks as New Emitters with Porosity- and Aggregation-Induced Enhanced Electrochemiluminescence for Ultrasensitive MicroRNA Assay.

Exploring new electrochemiluminescence (ECL) luminophores with strong ECL emission is highly desirable for developing ultrasensitive ECL sensors. Herein, a pyrene-based hydrogen-bonded organic framework (Py-HOF) featuring prominent ECL performance was prepared by utilizing 1,3,6,8-tetrakis(p-benzoic acid) pyrene (H4TBAPy) with an aggregation-induced enhanced emission (AIEE) property as a building block, exhibiting a stronger ECL emission than those of H4TBAPy monomers, H4TBAPy aggregates, the low-porosity Py-HOF-210 °C and Py-HOF-180 °C. We have coined the term "the porosity- and aggregation-induced enhanced ECL (PAIE-ECL)" for this intriguing phenomenon. The Py-HOF displayed superb and stable ECL intensity, not only because the luminophore H4TBAPy was assembled into the Py-HOF via four pairs of O-H···O hydrogen bonds, which constrained the intramolecular movements to reduce nonradiative transition, but also because the H4TBAPy in Py-HOF was stacked in a slipped face-to-face mode to form J-aggregates that benefited the ECL enhancement. Furthermore, the high porosity of Py-HOF allowed the enrichment of coreactants and facilitated the migration of ions, electrons, and coreactants, which made it possible for the inner and outer H4TBAPy to be electrochemically excited. Considering the remarkable ECL performance, Py-HOF was first employed as an ECL probe combined with a 3D DNA nanomachine amplification strategy to assemble a hypersensitive "on-off" ECL sensor for the microRNA-141 assay, presenting a satisfactory linear range (100 aM to 1 nM) with a detection limit of 14.4 aM. The PAIE-ECL manifested by Py-HOF provided a bright avenue for the design and synthesis of outstanding HOF-based ECL materials and offered new opportunities for the development of ECL biosensors with excellent sensitivity.

Properties and Structure of In Situ Transformed PAN-Based Carbon Fibers.

Carbon fibers in situ prepared during the hot-pressed sintering in a vacuum is termed in situ transformed polyacrylonitrile-based (PAN-based) carbon fibers, and the fibrous precursors are the pre-oxidized PAN fibers. The properties and structure of in situ transformed PAN-based carbon fibers are investigated by Nano indenter, SEM, TEM, XRD, and Raman. The results showed that the microstructure of the fiber surface layer was compact, while the core was loose, with evenly-appearing microvoids. The elastic modulus and nanohardness of the fiber surface layer (303.87 GPa and 14.82 GPa) were much higher than that of the core (16.57 GPa and 1.54 GPa), and its interlayer spacing d002 and crystallinity were about 0.347 nm and 0.97 respectively. It was found that the preferred orientation of the surface carbon layers with ordered carbon atomic arrangement tended to be parallel to the fiber axis, whereas the fiber core in the amorphous region exhibited a random texture and the carbon atomic arrangement was in a disordered state. It indicates that the in situ transformed PAN-based carbon fibers possess significantly turbostratic structure and anisotropy.

The role of fenhexamid on the proliferation of ovarian cancer BG-1 cells.

To study the influence of fenhexamid in pesticide residue to the human ovarian cancer BG-1 cell proliferation. Detecting the effectiveness of 17ß-estradiol, fenhexamid and Fulvestrant to BG-1 cell proliferation by MTT, and detecting the expression levels of cyclin D1 and cyclin E by Western blot. Fenhexamid can promote BG-1 cell proliferation for its estrogen-like effect. On the other hand, it can help to improve the expression levels of cyclin D1 and cyclin E in BG-1 cells which is regulated by ER-dependent pathway. And 17ß-estradiol is also regulated by the same way. The existence of fenhexamid can promote ovarian cancer cell proliferation, so for patients with ovarian cancer, fenhexamid in pesticide residue may make medical conditions worse.