Covalent Organic Frameworks-Based Fluorescence Sensor Array and QSAR Study for Identification of Energetic Heterocyclic Compounds.

The accurate identification of energetic heterocyclic compounds (EHCs) is of great significance in munition assessment, environmental monitoring, and biosafety but remains largely underexplored. Herein, a covalent organic frameworks-based fluorescence sensor array (COFx sensor array) for efficient screening of EHCs is reported. The topologies of the COFs were rationally designed by modulating the pore sizes and linkage strategies to achieve the simplified sensor array. Eighteen EHC representatives, including single-, dual-, and three-ring EHCs with multivariate substructures, were successfully discriminated ranging from 10 µM to 1 mM. The sensor array showed robust selectivity against a wide range of interferences. The quantitative structure-activity relationship (QSAR) analysis has been conducted for the mechanistic study of the sensor array. Three multiple linear regression models have been established using molecular descriptors to evaluate and predict Stern-Volmer coefficient values, achieving explicit correlation between EHC structures and the signal outputs of the sensor array. Five molecular descriptors are retained to reveal the governing factors of the sensor array resolution. The QSAR analysis facilitates the design and development of the COFx sensor array, offering a new approach for customized multivariate analysis.

Selenium Supplementation Sensor Based on Direct Electrochemistry of Urinary Selenosugar and Total Selenium.

Emerging point-of-care testing methods are extremely beneficial for personalized assessments of trace element metabolism including selenium (Se). Given the lack of timely evaluation methods for well-received Se fortification, an electrochemical solution was developed based on the recently identified urinary selenosugar (Sel) as a marker. The Se content of crude urine was rapidly determined (∼5 min), and the square-wave voltammetric responses of a Se-selective probe (SeSE) composed of liquid metal amalgam demonstrated comparable performance (e.g., detection limit: 19 nM) to central lab benchtop equipment within the physiological range. Meanwhile, SeSE enabled total urinary Se detection via a mere one-step oxidation. Additionally, SeSE was utilized to jointly assess the apparent internalization and utilization rate of two typical nutrients, selenite and selenomethionine, in a rat nutrition model, demonstrating consistent results with those obtained by HPLC-MS and ICP-MS. Upon systematic standardization directed by Ramaley's theory, SeSE was integrated into a battery-operated portable kit (dubbed "SeEye") with a micro electrochemical drive and tablet PC console for one-stop service trials in a local commercial scenario. This study establishes (1) a nutritive value classifier in a low-cost consumer electronic format and (2) noninvasive diagnostic technology for Se supplementation.

Sub-Second Electrochemiluminescence Imaging Assay of SARS-CoV-2 Nucleocapsid Protein Based on Reticulation of Endo-Coreactants.

The nonphotodriven electrochemiluminescence (ECL) imageology necessitates concentrated coreacting additives plus longtime exposures. Seeking biosafe and streamlined ensembles can help lower the bar for quality ECL bioimaging to which call the crystallized endo-coreaction in nanoreticula might provide a potent solution. Herein, an exo-coreactant-free ECL visualizer was fabricated out in one-pot, which densified the dyad triethylamine analogue: 1,4-diazabicyclo-[2.2.2]octane (DABCO) in the lamellar hive of 9,10-di(p-carboxyphenyl)anthracene (DPA)-Zn2+. This biligated non-noble metal-organic framework (m-MOF) facilitated a self-contained anodic ECL with a yield as much as 70% of Ru(bPy)32+ in blank phosphate buffered saline. Its featured two-stage emissions rendered an efficient and endurant CCD imaging at 1.0 V under mere 0.5 s swift snapshots and 0.1 s step-pulsed stimulation. Upon structural and spectral cause analyses as well as parametric set optimization, simplistic ECL-graphic immunoassay was mounted in the in situ imager to enact an ultrasensitive measurement of coronaviral N-protein in both signal-on and off modes by the privilege of straight surface amidation on m-MOFs, resulting in a wide dynamic range (10-4-10 ng/mL), a competent detection limit down to 56 fg/mL, along with nice precision and parallelism in human saliva tests. The overall work manifests a rudimentary endeavor in self-sufficient ECL visuality for brisk, biocompatible, and brilliant production of point-of-care diagnostic "Big Data".

Point-of-Care Diagnosis on Selenium Nutrition Based on Time-Resolved Fluorometric Glycoaffinity Chromatography.

Given the lack of timely evaluation of the well-received selenium fortification, a neat lateral-flow chromatographic solution was constructed here by using the recently identified urinary selenosugar (Sel) as a strongly indicative marker. As there are no ready-made receptors for this synthetic standard, phenylboronic acid (PBA) esterification and Dolichos biflorus agglutinin (DBA) affinity joined up to pinch and pin down the analyte into a sandwich-type glycol complex. Pilot lectin screening on homemade glycan microarrays verified such a new pairing between dual recognizers as PBA-Sel-DBA with a firm monosaccharide-binding constant. To quell the sample autofluorescence, europium nanoparticles with efficient long-life afterglow were employed as conjugating probes under 1 µs excitation. After systematic process optimizations, the prepared Sel-dipstick achieved swift and sensitive fluorometry over the physiological level of the target from 0.1 to 10 µM with a detection limit down to 0.06 µM. Further efforts were made to eliminate matrix effects from both temperature and pH via an approximate formula. Upon completion, the test strips managed to quantify the presence of Sel in not just imitated but real human urine, with comparable results to those in the references. As far as we know, this would be the first in-house prototype for user-friendly and facile diagnosis of Se nutrition with fair accuracy as well as selectivity. Future endeavors will be invested to model a more traceable Se-supplementary plan based on the rhythmic feedback of Sel excretion.

Amplification of an Electrochemiluminescence-Emissive Aptamer into DNA Nanotags for Sensitive Fecal Calprotectin Determination.

The precision additive manufacturing and tessellated multitasking out of the structural DNA nanotechnology enable a configurable expression of densified electrochemiluminescent (ECL) complexes, which would streamline the bioconjugation while multiplying signals. Herein, a completely DNA-scaffold ECL "polyploid" was replicated out via the living course of rolling circle amplification. The amplicon carried the aptameric sequences of ZnPPIX/TSPP porphyrin as photoreactive centers that rallied at periodical intervals of the persistent extension into a close-packed nanoflower, ZnPDFI/II. Both microscopies and electrophoresis proved the robust nesting of guests at their deployed gene loci, while multispectral comparisons among cofactor substituents pinpointed the pivotal roles of singlet seclusion and Zn2+-chelation for the sake of intensive ECL irradiation. The adversity-resilient hydrogel texture made lipoidal filmogens as porphyrinic ECL prerequisites to be of no need at all, thus not only simplifying assay flows but also inspiring an in situ labeling plan. Upon bioprocessing optimization, an enriched probe ZnPDFIII was further derived that interpolated the binding motif related to calprotectin as validated by molecular docking and affinity titration. With it being a strongly indicative marker of inflammatory bowel disease (IBD), a competitive ECL aptasensing strategy was contrived, managing a signal-on and sensitive detection in mild conditions with a subnanogram-per-milliliter limit of detection by 2 orders of magnitude lower than the standard method as well as a comparable accuracy in clinical stool sample testing. Distinct from those conventional chemophysical rebuilding routes, this de novo biosynthetic fusion demonstrated a promising alternative toward ECL-source bioengineering, which may intrigue vibrant explorations of other ECL-shedding fabrics and, accordingly, a new bioanalytic mode downstream.

Electrochemiluminescent Ion-Channeling Framework for Membrane Binding and Transmembrane Activity Assays.

Recent upgrades in the electrochemiluminescence (ECL) technique showcased its brilliant knack in probing microscopic biointerfacial events, many of which were actually underlain by the ionotropic membrane processes, yet not being ostensive. Here, by modeling an artificial lipoid-supported porin ensemble, we explore and establish the ECL potency in profiling ion-channel activities. A lipophilic hollowed construct dubbed ZnPC was made out of the dynamic covalent chemistry, and its unique geometry was characterized that configured stoichiometric ECL-emissive units in a cubic stance; while the aliphatic vertices of ZnPC helped it safely snorkel and steadily irradiate in a biofilm fusion. After expounding basic ECL properties, the brightness was traced out in response to halogen contents that was lit up by F-/Cl- but down by Br-/I-. The overall pattern fitted the Langmuir isotherm, from which the membrane-binding strengths of the four were analyzed, compared, and collaterally examined in impedimetrics. On the other hand, one could derive anionic transmembrane kinetics from the time-dependent ECL statistics that pinpointed the ECL signaling via the nanocage-directed mass-transfer pathway. More data mining unveiled an ECL-featured Hofmeister series and the thermodynamic governing force behind all scenes. Finally, combining with halide-selective fluorometry, the synthetic conduit was identified as an ECL symporter. In short, this work develops a novel ECL model for the evaluation of life-mimicking membrane permeation. It might intrigue the outreach of ECL applications in the measurement of diverse surface-confined transient scenarios, e.g., in vitro gated ion or molecule trafficking, which used to be handled by nanopore and electrofluorochromic assays.

Sorting and Screening of Quaternary Ammonium Lipoids for Membrane-Binding Assays Based on Electrochemiluminescent Cocrystalline Nanosheets.

Being synthetic supplements to natural lipids, lipoids now play an increasingly significant role in nanopore sequencing, olfactory sensing, and nanoimpact electrochemistry. Yet, systematic comparisons to sort and screen qualified lipoids are lacking for specific scenario applications. Here, taking the merits of electrochemiluminescence (ECL) in probing biointerfacial events, a new metric was proposed for the evaluation of substrate candidacy in the pool of hyamine bromides (ABs), that are used to cohere with electron-rich porphyrins for deep eutectics-like ECL matrices. Using a state-of-the-art framework emitter, the cocrystalline nanosheet of C70 and zinc meso-tetraphenylporphine (ZnTPP) via simple liquid-liquid interfacial deposition, 6 out of 20 ABs were inspected and identified as not only amenable filmogens but excitonic sensitizers in key terms of ECL strength as well as voltammetric characteristics. Among them, the methyltrioctyl (MTOAB) headgroup stood out; while the ECL activity at ZnTPP-C70@MTOAB was proven to be dictated by ionophoresis across multilamellar lipoidal layers. Thus, target-induced membrane deformation would let coreactant scavengers in to quench ECL, which enabled assays on two less visited bioprocesses regarding (1) the lipid solubility of ipratropium bromide, an aerosol medication for rhinitis treatment; and (2) the resorption of selenosugar as the central metabolite of Se-proteins on kidney glomerular basement barrier. Both resulted in nice membrane-binding measurements with comparable dissociation constants to reported microfluidic ELISA methods. By and large, though still being rudimentary, such parametrization of ECL-able biofilm would set up a basic ECL toolbox for archiving and resourcing multilipoidal even lipid-lipoid combos to handle the realistic (sub)cytomembrane processes in the future.

Zippering DNA Tetrahedral Hyperlink for Ultrasensitive Electrochemical MicroRNA Detection.

Pluripotency of a DNA tetrahedron (DNATT) has made the iconic framework a compelling keystone in biosensors and biodevices. Herein, distinct from the well-tapped applications in substrate fabrication, we focus on exploring their tracing and signaling potentials. A homologous family of four isostructural DNATT, i.e., DNATTα/ß/γ/δ, was engineered to form a sensor circuitry, in which a target-specific monolayer of thiolated DNATTγ pinned down the analyte jointly with the reciprocal DNATTδ into a sandwich complex; the latter further rallied an in situ interdigital relay of biotinylated DNATTα/ß into a microsized hyperlink dubbed polyDNATT. Its scale and growth factors were illuminated rudimentarily in transmission electron microscopy and confocal laser scanning microscopy. Using a nonsmall-cell lung cancer-related microRNA (hsa-miR-193a-3p) as the subject, a compound DNA-backboned construct was synthesized, fusing all building blocks together. Its superb tacticity and stereochemical conformality avail the templating of a horseradish peroxidase train, which boosted the paralleled catalytic surge of proton donors, resulting in an attomolar detection limit and a broad calibration range of more than seven orders of magnitude. Such oligomerization bested the conventional hybridization chain reaction laddering at both biomechanical stability and stoichiometric congruency. More significantly, it demonstrates the flexibility of DNA architectures and their multitasking ability in biosensing.

Electrochemiluminescence-Repurposed Abiological Catalysts in Full Protein Tag for Ultrasensitive Immunoassay.

Being announced as one of the "2019 Top Ten Emerging Technologies in Chemistry" by IUPAC, the directed evolution of artificial metalloenzymes has led to a broad scope of abiotic processes. Here, inspired by those key proteins in bioluminescence, a rudimentary expression of bio-electrochemiluminescent (ECL) macromolecules was achieved via the complexation of zinc proto-porphyrin IX (ZnPPIX) within apo-hemoglobin (apo-Hb). A high-yield monochromic irradiation at 644 nm could be provoked potentiostatically from the reconstituted holo-HbZnPPIX in solutions. Its secondary structure integrity was elucidated by UV and circular dichroism spectrometry, while voltammetry-hyphenated surface plasmon resonance authenticated its ligation conservativeness in electrical fields. Further conjugation with streptavidin rendered a homogeneous Janus fusion of both receptor and reporter domains, enabling a new abiological catalyst-linked ECL bioassay. On the other hand, singular ZnPPIX inside each tetrameric subunit of Hb accomplished an overall signal amplification without the bother of luminogenic heterojunctions. This pH-tolerant and non-photobleaching optics was essentialized to be the unique configuration interaction between Zn and O2, by which the direct electrochemistry of proteins catalyzed the transient progression of O2 → O2·- → O2* + hυ selectively. Such principle was implemented as a signal-on strategy for the determination of a characteristic cancer biomarker, the vascular endothelial growth factor, resulting in competent performance at a low detection limit of 0.6 pg·mL-1 and a wide calibration range along with good stability and reliability in real practices. This simple mutation repurposed the O2-transport Hb in the erythrocytes of almost all vertebrates into a cluster of oxidoreductases with intrinsic ECL activity, which would enrich the chromophore library. More importantly, its genetically engineered variants may come in handy in biomedical diagnosis and visual electrophysiology.

Enhanced electrochemiluminescent brightness and stability of porphyrins by supramolecular pinning and pinching for sensitive zinc detection.

Ultrasensitive electrochemiluminescence (ECL) detection can benefit substantially from the rational configuration of emitter-enhancer stereochemistry. Here, using zinc(II) meso-5,10,15,20-tetra(4-sulfonatophenyl)porphyrin (ZnTSPP) as a model, we demonstrate that both the ECL intensity and the photostability of this emitter were significantly improved when it was trapped in pyridyl-bridged ß-cyclodextrin dimer (Py(CD)2); a synthetic enhancer that is ECL inactive. Through NMR characterization, we confirmed that ZnTSPP formed a clam-like inclusion complex involving pinning and pinching forces from the biocompatible container Py(CD)2. Up to a threefold increase in the ECL brightness of ZnTSPP was witnessed when it was encapsulated in ß-CD. Absorption and emission spectroscopic data revealed that both the extended excitation lifetime and the restricted mobility of the guest contributed to the observed improvement in signal transduction within the host molecule. This bioinspired entrapment also led to a marked boost in ECL stability. With the aid of the newly identified coreactant H2O2, the hollow TSPP@Py(CD)2 system was employed to create a Zn2+-selective probe that was capable of sensitive and accurate zinc detection. The observed increase in ECL conversion and enhanced photophysical properties of this compact supramolecular assembly render it a novel template for enhancing ECL in analytical applications. Graphical abstract ᅟ.

Detection of zinc finger protein (EGR1) based on electrogenerated chemiluminescence from singlet oxygen produced in a nanoclay-supported porphyrin environment.

Early growth response protein 1 (EGR1), as a characteristic example of zinc finger proteins, acts as a transcription factor in eukaryotic cells, mediating protein-protein interactions. Here, a novel electrochemiluminescence (ECL)-based protocol for EGR1 assay was developed with a new eco-friendly emitter: singlet oxygen produced in the vicinity of nanoclay-supported zinc proto-porphyrin IX (ZnPPIX). Its electrochemical reduction stimulates an intense monochromic CL irradiation at 644 nm from the dissolved oxygen as endogenous coreactant in the aqueous solution. This ECL derivation was rationalized via hyphenated spectroscopy and theoretical calculation. To promote hydrophilicity and solid-state immobilization of porphyrins, the lamellar artificial laponite was employed as a nanocarrier owning to its large specific area without the blackbody effect. The facile exfoliation of laponite produced quality monolayered nanosheets and facilitated the adsorption and flattening of PPIX upon the surface, resulting in a highly efficient ECL emission. Based on the release of Zn(2+) in zinc finger domains of EGR1 upon contact with the ECL-inactive PPIX, which was monitored by circular dichroism and UV-absorption, a sensitive Zn(2+)-selective electrode for the "signal-on" detection of EGR1 was prepared with a detection limit down to 0.48 pg mL(-1) and a linearity over 6 orders of magnitude. The proposed porphyrin-based ECL system thus infused fresh blood into the traditional ECL family, showing great promise in bioassays of structural Zn(II) proteins and zinc finger-binding nucleotides.

Magnetic zirconium hexacyanoferrate(II) nanoparticle as tracing tag for electrochemical DNA assay.

Novel multifunctional magnetic zirconium hexacyanoferrate nanoparticles (ZrHCF MNPs) were prepared, which consisted of magnetic beads (MBs) inner core and zirconium hexacyanoferrate(II) (ZrHCF) outer shell. As an artificial peroxidase, the ZrHCF MNPs exhibited remarkable electrocatalytic properties in the reduction of H2O2 at 0.2 V vs saturated calomel electrode (SCE). On the basis of the bonding interaction between Zr (IV) of the shell ZrHCF framework and phosphonate groups, the 5'-phosphorylated ssDNA probes with a consecutive stretch of guanines as a spacer could be incorporated in ZrHCF MNPs easily. Thus, DNA-grafted ZrHCF MNPs could be simply obtained by magnetic separation. The prepared nanoelectrocatalyst was further used as signal nanoprobe for the ultrasensitive electrochemical DNA assay. Under optimal conditions, the proposed biosensor presents high sensitivity for detecting target DNA with a linear range from 1.0 fM to 1.0 nM and a low detection limit of 0.43 fM. Moreover, it exhibits good performance with excellent selectivity, high stability, and acceptable fabrication reproducibility.

DNA Framework-Based Programmable Atom-Like Nanoparticles for Non-Coding RNA Recognition and Differentiation of Cancer Cells.

The cooperative diagnosis of non-coding RNAs (ncRNAs) can accurately reflect the state of cell differentiation and classification, laying the foundation of precision medicine. However, there are still challenges in simultaneous analyses of multiple ncRNAs and the integration of biomarker data for cell typing. In this study, DNA framework-based programmable atom-like nanoparticles (PANs) are designed to develop molecular classifiers for intra-cellular imaging of multiple ncRNAs associated with cell differentiation. The PANs-based molecular classifier facilitates signal amplification through the catalytic hairpin assembly. The interaction between PAN reporters and ncRNAs enables high-fidelity conversion of ncRNAs expression level into binding events, and the assessment of in situ ncRNAs levels via measurement of the fluorescent signal changes of PAN reporters. Compared to non-amplified methods, the detection limits of PANs are reduced by four orders of magnitude. Using human gastric cancer cell lines as a model system, the PANs-based molecular classifier demonstrates its capacity to measure multiple ncRNAs in living cells and assesses the degree of cell differentiation. This approach can serve as a universal strategy for the classification of cancer cells during malignant transformation and tumor progression.

Antidiabetic Close Loop Based on Wearable DNA-Hydrogel Glucometer and Implantable Optogenetic Cells.

Diabetes mellitus and its associated secondary complications have become a pressing global healthcare issue. The current integrated theranostic plan involves a glucometer-tandem pump. However, external condition-responsive insulin delivery systems utilizing rigid glucose sensors pose challenges in on-demand, long-term insulin administration. To overcome these challenges, we present a novel model of antidiabetic management based on printable metallo-nucleotide hydrogels and optogenetic engineering. The conductive hydrogels were self-assembled by bioorthogonal chemistry using oligonucleotides, carbon nanotubes, and glucose oxidase, enabling continuous glucose monitoring in a broad range (0.5-40 mM). The optogenetically engineered cells were enabled glucose regulation in type I diabetic mice via a far-red light-induced transgenic expression of insulin with a month-long avidity. Combining with a microchip-integrated microneedle patch, a prototyped close-loop system was constructed. The glucose levels detected by the sensor were received and converted by a wireless controller to modulate far-infrared light, thereby achieving on-demand insulin expression for several weeks. This study sheds new light on developing next-generation diagnostic and therapy systems for personalized and digitalized precision medicine.

Electrochemiluminescent quenching of quantum dots for ultrasensitive immunoassay through oxygen reduction catalyzed by nitrogen-doped graphene-supported hemin.

A hemin functionalized graphene sheet was prepared via the noncovalent assembly of hemin on nitrogen-doped graphene. The graphene sheet could act as an oxygen reduction catalyst to produce sensitive electrochemiluminescent (ECL) quenching of quantum dots (QDs) due to the annihilation of dissolved oxygen, the ECL coreactant, by its electrocatalytic reduction. With the use of the catalyst with high loading of hemin as a signal tag of the secondary antibody, a novel ultrasensitive immunoassay method for biomarker detection was proposed. In an air-saturated pH 8.0 buffer, the immunosensor constructed by a stepwise immobilization of bidentate-chelated CdTe QDs and capture antibody showed an intensive cathodic ECL irradiation, which could be scavenged upon the formation of the catalyst-bound sandwich immunocomplex. With the use of the carcinoembryonic antigen as a model analyte, the immunoassay method showed a linear range from 0.1 pg mL(-1) to 10 ng mL(-1) and a detection limit of 24 fg mL(-1). The immunosensor exhibited good stability, acceptable fabrication reproducibility, and practicability. The electrocatalytic reduction-based ECL quenching strategy provided a powerful avenue for the design of the ultrasensitive detection method, showing great promise for clinical application.

Electrogenerated chemiluminescence of nanomaterials for bioanalysis.

Since the electrogenerated chemiluminescence (ECL) of silicon nanoparticles (NPs) was reported in 2002, miscellaneous nanomaterials with various sizes and shapes have been employed as ECL nanoemitters for bioanalysis. Elucidation of the ECL derivation from these nanoemitters and pertinent biofunctionalization with multitudinous biomolecules can offer excellent ECL signal-transduction platforms for fabricating novel biosensing devices. In this review, we comprehensively describe retrospective and recent advances in NPs-based ECL and related biosensing methodologies, and review their analytical applications in the detection of small biological molecules, enzymatic sensing, immunoassay, DNA analysis and cytosensing.

A fully π-conjugated covalent organic framework with dual binding sites for ultrasensitive detection and removal of divalent heavy metal ions.

Covalent organic frameworks (COFs) have become a promising candidate for the remediation of heavy metal pollution. However, researches on COF adsorbents still have challenges on maintaining good optical properties and adsorption performance under harsh conditions. Herein, a fully π-conjugated COF with dual binding sites (Bpy-sp2c-COF) is reported for rapid fluorescence recognition and enhanced adsorption towards divalent heavy metal ions. The vinylene-linkage lattice shows strong luminescence and excellent stability in both strong acidity and basicity. Bpy-sp2c-COF demonstrates not only nanomolar-scale detection of divalent heavy metal ions, but also good adsorption capacity (Hg2+ 718.48, Ni2+ 278.64, Cu2+ 260.11, and Co2+ 126.23 mg/g). Experimental and theoretical studies reveal the intramolecular charge transfer as the fluorescence quenching mechanism. Further simulation results demonstrate the cyano and bipyridine groups on the lattice can act as dual binding sites for divalent heavy metal ions. Experimental results confirmed the adsorption capacity of Bpy-sp2c-COF superior to that of COFs with either cyano groups (Hg2+ 415.34, Ni2+ 165.60, Cu2+ 160.55, and Co2+ 73.14 mg/g), or bipyridine groups (Hg2+ 369.25, Ni2+ 133.41, Cu2+ 133.32, and Co2+ 69.23 mg/g). Besides, robust regeneration of the adsorbent could be achieved over 10 cycles. The fully π-conjugated COF with dual binding sites provides a new approach for designing next-generation sensors and adsorbents with excellent performances.

Controllable mitochondrial aggregation and fusion by a programmable DNA binder.

DNA nanodevices have been feasibly applied for various chemo-biological applications, but their functions as precise regulators of intracellular organelles are still limited. Here, we report a synthetic DNA binder that can artificially induce mitochondrial aggregation and fusion in living cells. The rationally designed DNA binder consists of a long DNA chain, which is grafted with multiple mitochondria-targeting modules. Our results indicated that the DNA binder-induced in situ self-assembly of mitochondria can be used to successfully repair ROS-stressed neuron cells. Meanwhile, this DNA binder design is highly programmable. Customized molecular switches can be easily implanted to further achieve stimuli-triggered mitochondrial aggregation and fusion inside living cells. We believe this new type of DNA regulator system will become a powerful chemo-biological tool for subcellular manipulation and precision therapy.

Effect of divalent cations on electrochemiluminescence of metal-organic frameworks in bioassay.

The structural characteristics of electrochemiluminescent (ECL) microreticula enabled flexible designs for probing specific molecules. However, bioanalysts paid little attention to the impact of concomitant electrolytic carriers on ECL responsiveness of these grids. Our previous finding confirmed the collisional quenching of ECL radiative secondary building units from polarized Br- and I-. To further address this concern, herein typical cationic commonplaces including Na+, K+, Ca2+, … in buffer plus regular transition metals - their influences upon the ECL performance of a well-defined zinc porphyrin-organic framework (ZnPOF) were inspected in a one-by-one manner. Except for Na+/K+, a dozen of divalent metal chlorides exerted an adverse effect in the form of Stern-Volmer quenching on the ECL brightness, which was illuminated to be cation channeling in open voids of ZnPOFs and bonding with O2-reactive sites as exemplified by the model Ca2+ via systematic compositional investigation. Following this principle, a simplistic Ca2+-sensitive sensor was developed for quantitative evaluation of health-care calcium supplements with high precision. Above all, this work highlighted the non-negligible interference from those Mn + requisites to the susceptible MOF-based ECL, which should be paid extra attention in bioassays and mechanistic analyses.

Disposable electrochemiluminescent biosensor using bidentate-chelated CdTe quantum dots as emitters for sensitive detection of glucose.

A novel disposable solid-state electrochemiluminescent (ECL) biosensor was fabricated by immobilizing glucose oxidase and surface-unpassivated CdTe quantum dots (QDs) on a screen-printed carbon electrode (SPCE). The surface morphology of the biosensor was characterized with scanning electron microscopy and atomic force microscopy. With dissolved O(2) as an endogenous coreactant, QDs/SPCE showed strong ECL emission in pH 9.0 HCl-Tris buffer solution with low ECL peak potential at -0.89 V. The ECL intensity was twice that with hydrogen peroxide as coreactant at the same concentration. This phenomenon meant the ECL decreased upon consumption of dissolved O(2) and thus could be applied to the construction of oxidase-based ECL biosensors. With glucose oxidase as a model enzyme, the biosensor showed rapid response to glucose with a linear range of 0.8 to 100 µM and a detection limit of 0.3 µM. Further detection of glucose contained in human serum samples showed acceptable sensitivity and selectivity. This work provided a promising application of QDs in ECL-based disposable biosensors.