A High-Efficiency Autocatalysis-Oriented Cascade Circuit via Reciprocal Hug-Amplification for Assay-to-Treat Application.

Developing a DNA autocatalysis-oriented cascade circuit (AOCC) via reciprocal navigation of two enzyme-free hug-amplifiers might be desirable for constructing a rapid, efficient, and sensitive assay-to-treat platform. In response to a specific trigger (), seven functional DNA hairpins were designed to execute three-branched assembly (TBA) and three isotropic hybridization chain reaction (3HCR) events for operating the AOCC. This was because three new inducers were reconstructed in TBA arms to initiate 3HCR (TBA-to-3HCR) and periodic repeats were resultantly reassembled in the tandem nicks of polymeric nanowires to rapidly activate TBA in the opposite direction (3HCR-to-TBA) without steric hindrance, thereby cooperatively manipulating sustainable AOCC progress for exponential hug-amplification (1:3).

A bivariate fluorescence biosensor based on Janus DNA nanoarchitecture-loaded dual-emissive Ag nanoclusters as bi-responsive signaling reporters.

Constructing label-free bivariate fluorescence biosensor would be intriguing and desired for the recognizable and accurate detection of two specific DNA segments, yet the design of functional DNA structures with low overlapped interference might be challenging. Herein in this work, a double-faced Janus DNA nanoarchitecture (JDNA) with bi-responsive recognition regions on opposite sides was assembled, which consisted of two substrate strands and two template strands for loading green-/red-emissive Ag nanoclusters (gAgNC and rAgNC) as bivariate signaling reporters. Of note, the hybridized double helix in the middle rationally oriented two flank faces and stabilized the rigid conformation of JDNA, while the template sequences of bicolor clusters were blocked to minimize non-specific background leakage.

Stimulus-Responsive Four-Stranded DNA Nanoring Assembly to Host Multiple Nanosilver Clusters for Cooperatively Enhanced Fluorescence Biosensing.

Exploring the ability of four-stranded DNA nanorings (DNRs) to host multiple nanosilver clusters (NAgCs) for cooperatively amplifiable fluorescence biosensing to a specific initiator () is fascinating. By designing three DNA single strands and three analogous stem-loop hairpins, we developed a functional DNR through sequential cross-opening and overlapped hybridization. Note that a substrate strand (SS) was programmed with six modules: two severed splits (sT and sT') of NAgCs template, two sequestered segments by a middle unpaired spacer, and a partition for -recognizable displacement, while sT and sT' were also tethered in two ends of three hairpins.

De Novo Design of a Highly Stable Ratiometric Probe for Long-Term Continuous Imaging of Endogenous HClO Burst.

Long-term continuous imaging of endogenous HClO burst is of great importance for the elucidation of various physiological or pathological processes. However, most of the currently reported HClO probes have failed to achieve this goal due to their insufficient photobleaching resistance under a laser source. Herein, a highly stable ratiometric probe, HFTC-HClO 1, which is capable of continuously monitoring endogenous HClO burst over a long period of time, has been judiciously developed.

Short-stranded DNA segment-modulated LAMP/H as signal transducer to guide CHA-cooperated amplifiable electrochemical biosensing.

Background: Modulating loop-mediated isothermal amplification (mLAMP) by short-stranded DNA segment trigger (T) to generate byproducts H ions (mLAMP/H) as signal transducer is intriguing for developing catalytic hairpin assembly (CHA)-cooperated amplifiable electrochemical biosensors. This would be a big challenge for traditional LAMP that is basically suitable for amplifying long-stranded oligonucleotides up to 200-300 nt. To address this inherent limitation of traditional LAMP, many researchers have put in efforts to explore improvements in this that would allow LAMP to be used for a wider range of target species amplification.

Fluorescence Biosensing Based on Bifurcated DNA Scaffold-Aggregated Ag Nanocluster via Responsive Conformation Switch of Quasi-Molecular Beacon.

To address the limitations of typical hairpin-structural molecular beacons, exploring the ability of a quasi-molecular beacon (MB) to create label-free fluorescence biosensors is intriguing and remains a challenge. Herein, we propose the first example of modular MB with the feature of a stimulation-responsive conformation switch to develop an aggregated Ag nanocluster (AgNC) in a bifurcated DNA scaffold for fluorescently sensing a specific initiator (*). This MB was well designed to program four functional modules: *-recognizable element adopting metastable stem-loop bihairpin structure and two DNA splits (exposed CGT and locked CACT) of AgNC template that is separated by a tunable hairpin spacer for the customized combination of selective recognition and signaling readout.

Ratiometric Fluorescence Biosensing of Tandem Biemissive Ag Clusters Boosted by Confined Catalytic DNA Assembly.

The reaction kinetics and yield of traditional DNA assembly with a low local concentration in homogeneous solution remain challenging. Exploring confined catalytic DNA assembly (CCDA) is intriguing to boost the reaction rate and efficacy for creating rapid and sensitive biosensing platforms. A rolling circle amplification (RCA) product containing multiple tandem repeats is a natural scaffold capable of guiding the periodic assembly of customized functional probes at precise sites.

Fluorescent Features and Applicable Biosensing of a Core-Shell Ag Nanocluster Shielded by a DNA Tetrahedral Nanocage.

The DNA frame structure as a natural shell to stably shield the sequence-templated Ag nanocluster core (AgNC) is intriguing yet challenging for applicable fluorescence biosensing, for which the elaborate programming of a cluster scaffold inside a DNA-based cage to guide AgNC nucleation might be crucial. Herein, we report the first design of a symmetric tetrahedral DNA nanocage (TDC) that was self-assembled in a one-pot process using a C-rich AgNC template strand and four single strands. Inside the as-constructed soft TDC architecture, the template sequence was logically bridged from one side to another, not in the same face, thereby guiding the in situ synthesis of emissive AgNC.

Cooperative Amplification of Au@FeCo as Mimetic Catalytic Nanozymes and Bicycled Hairpin Assembly for Ultrasensitive Electrochemical Biosensing.

Exploring the cooperative amplification of peroxidase-like metal nanocomposites and cycled hairpin assembly is intriguing for sensitive bioanalysis. Herein, we report the first design of a unique electrochemical biosensor based on mimicking Au@FeCo nanozymes and bicycled hairpin assembly (BHA) for synergistic signal amplification. By loading the enzyme-like FeCo alloy in Au nanoparticles (AuNPs), the as-synthesized Au@FeCo hybrids display great improvement of electronic conductivity and active surface area and excellent mimic catalase activity to HO decomposition into OH radicals.

Homoadamantane-Fused Tetrahydroquinoxaline as a Robust Electron-Donating Unit for High-Performance Asymmetric NIR Rhodamine Development.

Rhodamines have emerged as a useful class of dye for bioimaging. However, intrinsic issues such as short emission wavelengths and small Stokes shifts limit their widespread applications in living systems. By taking advantage of the homoadamantane-fused tetrahydroquinoxaline (HFT) moiety as an electron donor, we developed a new class of asymmetric NIR rhodamine dyes, NNR1-7.

A Reciprocal-Amplifiable Fluorescence Sensing Platform via Replicated Hybridization Chain Reaction for Hosting Concatenated Multi-Ag Nanoclusters as Signal Reporter.

Exploring the replication of hybridization chain reaction HCR (HCR) for reciprocal amplification is intriguing in biosensing and bioanalysis. Herein, we develop a HCR-based fluorescence platform that is manipulated by the combination of a specific DNA trigger () and a -analogous amplicon (), thereby concatenating multi green-emissive Ag nanoclusters (AgNCs) for amplifiable signal readout. Four well-designed hairpins (H1 recognizing , H2, H3, and H4) with sequential complements are executed to operate HCR.

Target DNA-Activating Proximity-Localized Catalytic Hairpin Assembly Enables Forming Split-DNA Ag Nanoclusters for Robust and Sensitive Fluorescence Biosensing.

Proximity-localized catalytic hairpin assembly (CHA) is intriguing for rapid and sensitive assay of an HIV-specific DNA segment (*). Using template-integrated green Ag nanoclusters (AgNCs) as emitters, herein, we report the first design of a *-activated CHA circuit that is confined in a three-way-junction architecture (3WJA) for the fluorescence sensing of *. To this end, the *-recognizable complement is programmed in a stem-loop hairpin (H1), and two split template sequences of AgNCs are separately overhung contiguous to the paired stems of H1 and another hairpin (H2).

Modulating the Fluorescence of Silver Nanoclusters Wrapped in DNA Hairpin Loops via Confined Strand Displacement and Transient Concatenate Ligation for Amplifiable Biosensing.

It is intriguing to modulate the fluorescence emission of DNA-scaffolded silver nanoclusters (AgNCs) via confined strand displacement and transient concatenate ligation for amplifiable biosensing of a DNA segment related to SARS-CoV-2 (DNA). Herein, three stem-loop structural hairpins for signaling, recognizing, and assisting are designed to assemble a variant three-way DNA device (3WDD) with the aid of two linkers, in which orange-emitting AgNC (AgNC) is stably clustered and populated in the closed loop of a hairpin reporter. The presence of DNA initiates the toehold-mediated strand displacement that is confined in this 3WDD for repeatable recycling amplification, outputting numerous hybrid DNA-duplex conformers that are implemented for a transient "head-tail-head" tandem ligation one by one.

Target Deoxyribonucleic Acid-Recycled Lighting-Up Amplifiable Ratiometric Fluorescence Biosensing of Bicolor Silver Nanoclusters Hosted in a Switchable Deoxyribonucleic Acid Construct.

Ratiometric assays of label-free dual-signaling reporters with enzyme-free amplification are intriguing yet challenging. Herein, yellow- and red-silver nanocluster (H-AgNC and H-AgNC) acting as bicolor ratiometric emitters are guided to site-specifically cluster in two template signaling hairpins (H and H), respectively, and originally, both of them are almost non-fluorescent. The predesigned complement tethered in H is recognizable to a DNA trigger () related to SARS-CoV-2.

Amplifiable ratiometric fluorescence biosensing of nanosilver multiclusters populated in three-way-junction DNA branches.

To explore the fluorescence bio-responsiveness of emissive silver nanoclusters (AgNCs) populated in DNA-branched scaffolds is intriguing yet challenging. In response to a desired targeting model (T*) as a vehicle, herein a customized three-way-junction DNA construct (TWJDC) is assembled via competitive hybridizing cascade among three stem-loop hairpins with specific base sequences, where the repeated recycling of T* enables the exponentially amplifiable output of rigid TWJDC. As designed, these stable hybridization products are highly T*-stimulated responsive and constructing-directional.

A Domain Gap Aware Generative Adversarial Network for Multi-Domain Image Translation.

Recent image-to-image translation models have shown great success in mapping local textures between two domains. Existing approaches rely on a cycle-consistency constraint that supervises the generators to learn an inverse mapping. However, learning the inverse mapping introduces extra trainable parameters and it is unable to learn the inverse mapping for some domains.

Antibody-Responsive Ratiometric Fluorescence Biosensing of Biemissive Silver Nanoclusters Wrapped in Switchable DNA Tweezers.

Exploring the ratiometric fluorescence biosensing of DNA-templated biemissive silver nanoclusters (AgNCs) is significant in bioanalysis, yet the design of a stimuli-responsive DNA device is a challenge. Herein, using the anti-digoxin antibody (anti-Dig) with two identical binding sites as a model, a tweezer-like DNA architecture is assembled to populate fluorescent green- and red-AgNCs (g-AgNCs and r-AgNCs), aiming to produce a ratio signal via specific recognition of anti-Dig with two haptens (Dig). To this end, four DNA probes are programmed, including a reporter strand (RS) dually ended with a g-/r-AgNC template sequence, an enhancer strand (ES) tethering two same G-rich tails (), a capture strand (CS) labeled with Dig at two ends, and a help strand (HS).

Amplified electrochemical biosensing based on bienzymatic cascade catalysis confined in a functional DNA structure.

Herein, an amplified and renewable electrochemical biosensor was developed via bienzymatic cascade catalysis of glucose oxidase (GOx) and horseradish peroxidase (HRP), which were confined in a functional Y-shaped DNA nanostructure oriented by a dual-thiol-ended hairpin probe (dSH-HP) with a paired stem as a rigid scaffold and unpaired loop as enclosed binding platform. For proof-of-concept assay of sequence-specific biomarker DNA related to Alzheimer's disease (aDNA), GOx and redox ferrocene-modified HRP (Fc@HRP) were chemically conjugated in two enzyme strands (GOx-ES1 and Fc@HRP-ES2), respectively. The repeated recycling of aDNA was powered by the displacement of GOx-ES1 by aDNA and exonuclease III (ExoIII)-assisted cleavage reaction for amplified output of numerous GOx-ES1 as dependent transducers, together with Fc@HRP-ES2 which was simultaneously hybridized with dSH-HP to assemble this DNA structure.

Antibody-powered DNA switches to initiate the hybridization chain reaction for the amplified fluorescence immunoassay.

Designing antibody-powered DNA nanodevice switches is crucial and fascinating to perform a variety of functions in response to specific antibodies as regulatory inputs, achieving highly sensitive detection by integration with simple amplified methods. In this work, we report a unique DNA-based conformational switch, powered by a targeted anti-digoxin mouse monoclonal antibody (anti-Dig) as a model, to rationally initiate the hybridization chain reaction (HCR) for enzyme-free signal amplification. As a proof-of-concept, both a fluorophore Cy3-labeled reporter hairpin (RH) in the 3' terminus and a single-stranded helper DNA (HS) were individually hybridized with a recognition single-stranded DNA (RS) modified with Dig hapten, while the unpaired loop of RH was hybridized with the exposed 3'-toehold of HS, isothermally self-assembling an intermediate metastable DNA structure.

Guanine-Lighting-Up Fluorescence Biosensing of Silver Nanoclusters Populated in Functional DNA Constructs by a pH-Triggered Switch.

Dark or weak-emissive DNA-harbored silver nanoclusters (AgNCs) can be remarkably lighted up when approaching to guanine bases. The resultant bright AgNCs acting as a fluorescent reporter are fascinating in biosensing. To explore the applicable guanine-enhanced emission of AgNCs for biosensing microRNA-155 (miR-155) as a model, here we designed a unique stem-loop hairpin beacon (HB) encoding with an miR-155-recognizable sequence and a AgNCs-nucleable template, as well as a hairpin helper tethering a partially locked guanine-rich (15-nt) tail (GH), while two identical cytosine-rich segments were inserted in HB and GH to merge for folding/unfolding of i-motif at changed pHs.

Targeted DNA-driven catalytic assembly light-up ratiometric fluorescence of biemissive silver nanoclusters for amplified biosensing.

The isothermal assembly of a target-recognizable hairpin and a catalytic hairpin was driven by specific HIV-related DNA (hDNA) as a test model, outputting amplified duplexes to open a functional hairpin beacon (HB) tethering the templates of biemissive (green and red) silver nanoclusters (G-AgNCs and R-AgNCs). As such, their ratiometric fluorescence was remarkably lit up, achieving rapid, specific and sensitive biosensing with potential for disease diagnosis and biomolecule detection.

The catadromous teleost Anguilla japonica has a complete enzymatic repertoire for the biosynthesis of docosahexaenoic acid from α-linolenic acid: Cloning and functional characterization of an Elovl2 elongase.

The Japanese eel Anguilla japonica is a catadromous fish species with considerable farming scale. Previous studies showed that dietary α-linolenic acid (18:3n-3) and linoleic acid (18:2n-6) satisfied essential fatty acid requirements in eel, which suggested that Japanese eel should have a complete pathway for the biosynthesis of long-chain polyunsaturated fatty acids (LC-PUFA). However, existing knowledge was insufficient to explain the molecular basis of LC-PUFA biosynthetic capacity in eel.