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Synthetic biochemical circuits (e.g., DNA circuits) remain at the forefront of intracellular biosensing tasks yet are hindered by the undesired off‐site activation and the accompanying signal leakage. Herein, the study attempts to overcome this limitation by developing a simple‐yet‐powerful endogenous glutathione (GSH)‐regulating tactic that permits robust and distinguishable on‐site microRNA (miRNA) imaging under disturbed redox homeostasis. Specifically, a hierarchically activated catalytic DNA (HAD) circuit is fabricated by grafting the disulfide linkage within entropy‐driven DNA circuitry (EDC) reactants. It is exemplified that this HAD system promises the spatiotemporally selective microRNA‐21 (miR‐21) imaging in living cells and the robust differentiation of tumor cells from normal cells. The correlationship between GSH and miRNA is extensively explored in live cells, and can substantially expand the toolbox of DNA circuits for profiling intracellular biochemical processes. [ABSTRACT FROM AUTHOR]

The precise regulation of cellular behaviors within a confined, crowded intracellular environment is highly amenable in diagnostics and therapeutics. While synthetic circuitry system through a concatenated chemical reaction network has rarely been reported to mimic dynamic self‐assembly system. Herein, a catalytic self‐defined circuit (CSC) for the hierarchically concatenated assembly of DNA domino nanostructures is engineered. By incorporating pre‐sealed symmetrical fragments into the preying hairpin reactants, the CSC system allows the hierarchical DNA self‐assembly via a microRNA (miRNA)‐powered self‐sorting catalytic hybridization reaction. With minimal strand complexity, this self‐sustainable CSC system streamlined the circuit component and achieved localization‐intensified cascaded signal amplification. Profiting from the self‐adaptively concatenated hybridization reaction, a reliable and robust method has been achieved for discriminating carcinoma tissues from the corresponding para‐carcinoma tissues. The CSC‐sustained self‐assembly strategy provides a comprehensive and smart toolbox for organizing various hierarchical DNA nanostructures, which may facilitate more insights for clinical diagnosis and therapeutic assessment. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: A label‐free deoxyribozyme (DNAzyme) biosensor for m6A demethylase activity detection is developed. When demethylase FTO (Fat mass and obesity‐associated protein), an important m6A demethylase of ALKBH demethylase family is present, the m6A group is specifically demethylated, and the cleavage activity of DNAzyme is restored. This allows the cleavage product that contains G‐quadruplex sequence to bind to thioflavin T (ThT) and generate fluorescence signals. The biosensor shows high specificity and sensitivity, and fast reaction speed. Our study demonstrates a new design of allosteric DNAzyme for sensing. This method represents the first label‐free nucleic acid biosensor for FTO assay, providing a feasible route towards inhibitors screening. [ABSTRACT FROM AUTHOR]

Nucleic acids in biofluids are emerging biomarkers for the molecular diagnostics of diseases, but their clinical use has been hindered by the lack of sensitive detection assays. Herein, we report the development of a sensitive nucleic acid detection assay named SPOT (sensitive loop‐initiated DNAzyme biosensor for nucleic acid detection) by rationally designing a catalytic DNAzyme of endonuclease capability into a unified one‐stranded allosteric biosensor. SPOT is activated once a nucleic acid target of a specific sequence binds to its allosteric module to enable continuous cleavage of molecular reporters. SPOT provides a highly robust platform for sensitive, convenient and cost‐effective detection of low‐abundance nucleic acids. For clinical validation, we demonstrated that SPOT could detect serum miRNAs for the diagnostics of breast cancer, gastric cancer and prostate cancer. Furthermore, SPOT exhibits potent detection performance over SARS‐CoV‐2 RNA from clinical swabs with high sensitivity and specificity. Finally, SPOT is compatible with point‐of‐care testing modalities such as lateral flow assays. Hence, we envision that SPOT may serve as a robust assay for the sensitive detection of a variety of nucleic acid targets enabling molecular diagnostics in clinics. [ABSTRACT FROM AUTHOR]

The progression of osteoarthritis (OA) requires the involvement of inflammation, in which chondrocyte damage plays a significant role. Hydroxysafflor yellow A (HSYA), the main active component in the medical and edible dual‐purpose plant safflower, has previously shown anti‐inflammatory effects in various diseases. However, the specific impact of HSYA on OA remains unclear. Here, we investigate the potential role and underlying mechanism of HSYA in chondrocyte damage during the progression of OA. The viability of C28/I2 and iCell‐0092a chondrocytes was measured by CCK8 assay at different concentrations (2.5, 10, 40, and 160 μM). The gene expression of the extracellular matrix was revealed by q‐PCR 24 h after IL‐1β treatment. ROS production and levels of pro‐inflammatory cytokines in C28/I2 cells treated with HSYA were measured by immunoflurescence stating and q‐PCR. The impact of HSYA on the extracellular matrix and inflammation in IL‐1β‐induced OA were detected by western blot, q‐PCR, and immunofluorescence staining. We assessed the effect of HSYA and NF‐κB signaling pathway‐related genes by bioinformatics analysis and conducted molecular docking to assess the interaction of HSYA with a combined protein residue molecule ligand. Western blot was employed to investigate NF‐κB transcription factors in chondrocyte metabolism. HSYA was found to reduce excessive ROS production induced by IL‐1β stimuli, inhibit the expression of matrix metalloproteinase 13, interleukin 6, and tumor necrosis factor‐α, and increase the expression of Type II collagen and SRY‐box transcription factor 9 (p <.05). Mechanistically, HSYA interacted with nuclear factor κB, inhibiting the nuclear translocation and phosphorylation level of NF‐κB p65, and decreasing the phosphorylation and degradation of IκBα (p <.05). In conclusion, HSYA ameliorates inflammation and cartilage damage in OA by inhibiting the NF‐κB pathway, suggesting its potential application as a therapeutic agent for OA treatment. [ABSTRACT FROM AUTHOR]

The isothermal enzyme‐free nucleic acid amplification method plays an indispensable role in biosensing by virtue of its simple, robust, and highly efficient properties without the assistance of temperature cycling or/and enzymatic biocatalysis. Up to now, enzyme‐free nucleic acid amplification has been extensively utilized for biological assays and has achieved the highly sensitive detection of various biological targets, including DNAs, RNAs, small molecules, proteins, and even cells. In this Review, the mechanisms of entropy‐driven reaction, hybridization chain reaction, catalytic hairpin assembly and DNAzyme are concisely described and their recent application as biosensors is comprehensively summarized. Furthermore, the current problems and the developments of these DNA circuits are also discussed. [ABSTRACT FROM AUTHOR]

Non‐invasive cell regulation represents a promising approach for on‐site cell modulation, but is confronted with inaccuracy or poor cell selectivity. Herein, by virtue of the interfacial‐activated concatenate DNA circuit, an activated recombination‐to‐modulation (ARM) machinery is developed to achieve accurate membrane imaging and effective cell modulation. Bioorthogonal signal transduction through the catalytic hairpin assembly circuit can continuously regenerate triggers for activating the subsequent circuit, with no activator consumption and occupation. The ARM strategy utilizes the amplified hybridization chain reaction to sensitively rearrange membrane receptors for blocking the related signaling pathways and indirectly modulating cell behaviors. Based on these two membrane receptor inputs, the controllably‐activated ARM strategy enables the identification of target cells among similar interfering cells with high accuracy and sensitivity. This machinery has demonstrated good performance in the efficient inhibition of tumor metastasis via the disruption of HGF/c‐Met‐signaling pathway. The modular‐designed ARM machinery provides a general platform for non‐invasive and specific cell modulation, suggesting a broad opportunity for advanced exploration of cellular metabolism behaviors. [ABSTRACT FROM AUTHOR]

Synthetic catalytic DNA circuits have been recognized as a promising signal amplification toolbox for sensitive intracellular imaging, yet their selectivity and efficiency are always constrained by uncontrolled off‐site signal leakage and inefficient on‐site circuitry activation. Thus, the endogenously controllable on‐site exposure/activation of DNA circuits is highly desirable for achieving the selective imaging of live cells. Herein, an endogenously activated DNAzyme strategy was facilely integrated with a catalytic DNA circuit for guiding the selective and efficient microRNA imaging in vivo. To prevent the off‐site activation, the circuitry constitute was initially caged without sensing functions, which could be selectively liberated by DNAzyme amplifier to guarantee the high‐contrast microRNA imaging in target cells. This intelligent on‐site modulation strategy can tremendously expand these molecularly engineered circuits in biological systems. [ABSTRACT FROM AUTHOR]

Laser‐free photodynamic therapy (PDT) is a promising noninvasive therapeutic modality for deep‐seated tumor, yet is constrained by low efficiency due to the limited stimulation strategies. Herein, a novel miRNA‐responsive laser‐free PDT was developed through metal‐organic frameworks (MOFs)‐mediated chemiluminescence resonance energy transfer (CRET) nanoplatform. The photosensitizer chlorin e6 (Ce6)‐loaded MOFs were functionalized with hairpin nucleic acids for sensitive responsiveness of tumor biomarker miRNA through catalytic hairpin assembly (CHA), which enabled the amplified assembly of horseradish peroxidase (HRP)‐mimicking hemin/G‐quadruplex DNAzyme on MOFs. Simultaneously, the on‐MOF assembled DNAzymes efficiently catalyzed chemiluminescence reaction to stimulate adjacent Ce6 in the presence of luminol and H2O2, thus allowing the CRET‐mediated Ce6 luminescence and reactive oxygen species (ROS) generation for self‐illuminating PDT. The CRET nanoplatform achieved significant malignant cell apoptosis and tumor inhibition effects without external laser irradiation. It is envisioned that the miRNA‐amplified CRET nanoplatform might be a selective and highly efficient antitumor nanomedicine for precise theranostic. [ABSTRACT FROM AUTHOR]

Background: Ossification of the posterior longitudinal ligaments (OPLL) is common disorder characterized by heterotopic ossification of the spinal ligaments. Mechanical stimulation (MS) plays an important role in OPLL. DLX5 is an essential transcription factor required for osteoblast differentiation. However, the role of DLX5 during in OPLL is unclear. This study aims to investigate whether DLX5 is associated with OPLL progression under MS. Methods: Stretch stimulation was applied to spinal ligaments cells derived from OPLL (OPLL cells) and non‐OPLL (non‐OPLL cells) patients. Expression of DLX5 and osteogenesis‐related genes were determined by quantitative real‐time polymerase chain reaction and Western blot. The osteogenic differentiation ability of the cells was measured using alkaline phosphatase (ALP) staining and alizarin red staining. The protein expression of DLX5 in the tissues and the nuclear translocation of NOTCH intracellular domain (NICD) was examined by immunofluorescence. Results: Compared with non‐OPLL cells, OPLL cells expressed higher levels of DLX5 in vitro and vivo (p < 0.01). Upregulated expression of DLX5 and osteogenesis‐related genes (OSX, RUNX2, and OCN) were observed in OPLL cells induced with stretch stimulation and osteogenic medium, whereas there was no change in the non‐OPLL cells (p < 0.01). Cytoplasmic NICD protein translocated from the cytoplasm to the nucleus inducing DLX5 under stretch stimulation, which was reduced by the NOTCH signaling inhibitors (DAPT) (p < 0.01). Conclusions: These data suggest that DLX5 play a critical role in MS‐induced progression of OPLL through NOTCH signaling, which provides a new insight into the pathogenesis of OPLL. [ABSTRACT FROM AUTHOR]

The wide extracellular‐intracellular distribution of microRNA requires the on‐site, robust and efficient activation of catalytic DNA circuits inside live cells. Herein, we develop an efficient non‐enzymatic circuitry activation strategy to realize the orthogonally controlled catalytic DNA (CCD) circuit for achieving high‐fidelity in vivo microRNA imaging through multiply guaranteed molecular recognition and progressively accelerated signal amplification. For predictable on‐site activation and useful catalytic efficiency, the dominating circuitry fuel strand was initially split into inactive fuel subunits that were grafted into an auxiliary catalytic circuit. There, the in‐cell‐specific mRNA triggered the orthogonal amplification of the active fuel strands for sensitive target detection through the chief entropy‐driven catalytic DNA circuit. We believe that the on‐site orthogonal circuitry activation method can contribute to clinical diagnosis and prognosis. [ABSTRACT FROM AUTHOR]

Programmable DNA materials hold great potential in biochemical and biomedical researches, yet the complicated synthesis, and the low stability and targeting efficacy in complex biological milieu limit their clinical translations. Here we show a one‐pot assembly of DNA‐protein superstructures as drug vehicles with specifically high affinity and stability for targeted therapy. This is achieved by biomimetic assembly of programmable polymer DNA wire into densely packed DNA nanosphere with an alkaline protein, protamine. Multivalent DNA nanostructures encoded with different types and densities of aptamers exhibit high affinity to targeted cells through polyvalent interaction. Our results show high cancer cell selectivity, reduced side effect, excellent therapeutic efficacy, and sensitive tumor imaging in both subcutaneous and orthotopic non‐small‐cell lung cancer murine models. This biomimetic assembly approach provides practical DNA nanomaterials for further clinical trials and may advance oligonucleotide drug delivery. [ABSTRACT FROM AUTHOR]

Lowly expressed analyte in complex cytoplasmic milieu necessitates the development of non‐enzymatic autocatalytic DNA circuits with high amplification and anti‐interference performance. Herein, we engineered a versatile and robust stimuli‐responsive autocatalytic hybridization assembly (AHA) circuit for high‐performance in vivo bioanalysis. Under a moderately confined condition, the initiator motivated the autonomous and cooperative cross‐activation of cascade hybridization reaction and catalytic DNA assembly for generating an exponentially amplified readout without the parasite steric hindrance and random diffusion side effects. The AHA circuit was systematically investigated by a series of experimental studies and theoretical simulations. The successively guaranteed target recognition and synergistically accelerated signal‐amplification enabled the sensitive and selective detection of analyte, and realized the robust miRNA imaging in living cells and mice. This autocatalytic DNA circuit could substantially expand the toolbox for accurate diagnosis and programmable therapeutics. [ABSTRACT FROM AUTHOR]

The direct visualization of vaccine fate is important to investigate its immunoactivation process to elucidate the detailed molecular reaction process at single‐molecular level. Yet, visualization of the spatiotemporal trafficking of vaccines remains poorly explored. Here, we show that quantum dot (QD) nanomaterials allow for monitoring vaccine dynamics and for amplified immune response. Synthetic QDs enable efficient conjugation of antigen and adjuvants to target tissues and cells, and non‐invasive imaging the trafficking dynamics to lymph nodes and cellular compartments. The nanoparticle vaccine elicits potent immune responses and anti‐tumor efficacy alone or in combination with programmed cell death protein 1 blockade. The synthetic QDs showed high fluorescence quantum yield and superior photostability, and the reliable and long‐term spatiotemporal tracking of vaccine dynamics was realized for the first time by using the synthetic QDs, providing a powerful strategy for studying immune response and evaluating vaccine efficacy. [ABSTRACT FROM AUTHOR]

Nanozymes hold great potential in nanomedicine, yet biotoxicity limits their clinical translation because of their uncontrolled catalytic activity, artificial inorganic components, and harsh synthesis conditions. Herein, a peroxidase‐like bionanozyme with ultrahigh and photocontrolled catalytic activity through the self‐assembly of biomolecules, hemin, and in situ polymerization of pyrrole in an aqueous solution is reported. Such bionanozymes leverage the specific cues of the tumor microenvironment and precise light‐induced photothermal heating for spatiotemporally controlled reactive oxygen species generation in tumors. The tunable catalytic activity and excellent biocompatibility of the bionanozyme result in high cancer cell apoptosis and tumor growth inhibition in murine models with negligible biotoxicity. This work highlights the potential of biomolecule‐based nanozymes for cancer‐specific therapy. Bionanozymes with ultrahigh and tunable catalytic activity may lay the important foundation for more advanced nanomedicine and biosensing. [ABSTRACT FROM AUTHOR]

DNAzyme‐based gene therapy holds immense prospects for effectively treating severe diseases, yet is constrained with inefficient delivery and unconditional activation. Herein, we designed a bioinspired self‐catabolic DNA nanocapsule for sustaining tumor‐specific cascade activation of therapeutic DNAzyme. The exquisite DNAzyme was temporarily masked by the self‐excising DNAzyme in the hierarchical rolling circle replication (RCR) nanostructures, thus stayed in an inactive state in physiological fluids. Through the multivalent tumor‐anchoring aptamer strands, the RCR nanocapsule was specifically accumulated in cancer cells and was sequentially activated for motivating the ultimate DNAzyme‐mediated gene silencing via the intelligent stimuli‐responsive cascade DNAzyme activation. By virtue of the programmable RCR assembly strategy, our compact DNAzyme nanoplatform shows great promise for developing versatile smart gene therapeutics and personalized nanomedicines. [ABSTRACT FROM AUTHOR]

DNA nanostructures have recently attracted increasing interest in biological and biomedical applications by virtue of their unique properties, such as structural programmability, multi‐functionality, stimuli‐responsive behaviors, and excellent biocompatibility. In particular, the intelligent responsiveness of smart DNA nanostructures to specific stimuli has facilitated their extensive development in the field of high‐performance biosensing and controllable drug delivery. This minireview begins with different self‐assembly strategies for the construction of various DNA nanostructures, followed by the introduction of a variety of stimuli‐responsive functional DNA nanostructures for assembling metastable soft materials and for facilitating amplified biosensing. The recent achievements of smart DNA nanostructures for controllable drug delivery are highlighted. Finally, the current challenges and possible developments of this promising research are discussed in the fields of intelligent nanomedicine. [ABSTRACT FROM AUTHOR]

The therapeutic performance of DNAzyme‐involved gene silencing is significantly constrained by inefficient conditional activation and insufficient cofactor supply. Herein, a self‐sufficient therapeutic nanosystem was realized through the delicate design of DNAzyme prodrugs and MnO2 into a biocompatible nanocapsule with tumor‐specific recognition/activation features. The indocyanine green (ICG)‐modified DNA prodrugs are designed by splitting the DNAzyme and then reconstituted into the exquisite catalyzed hairpin assembly (CHA) amplification circuit. Based on the photothermal activation of ICG, the nanocapsule was disassembled to expose the MnO2 ingredient which was immediately decomposed into Mn2+ ions to supplement an indispensable DNAzyme cofactor on‐demand with a concomitant O2 generation for enhancing the auxiliary phototherapy. The endogenous microRNA catalyzes the amplified assembly of DNA prodrugs via an exquisite CHA principle, leading to the DNAzyme‐mediated simultaneous silencing of two key tumor‐involved mRNAs. This self‐activated theranostic nanocapsule could substantially expand the toolbox for accurate diagnosis and programmable therapeutics. [ABSTRACT FROM AUTHOR]

DNAzymes have been recognized as promising transducing agents for visualizing endogenous biomarkers, but their inefficient intracellular delivery and limited amplification capacity (including insufficient cofactor supply) preclude their extensive biological application. Herein, an autocatalytic DNAzyme (ACD) biocircuit is constructed for amplified microRNA imaging in vivo based on a hybridization chain reaction (HCR) and DNAzyme biocatalysis, sustained by a honeycomb MnO2 nanosponge (hMNS). The hMNS not only delivers DNA probes, but also supplies Mn2+ as a DNAzyme cofactor and magnetic resonance imaging (MRI) agent. Through the subsequent cross‐activation of HCR and DNAzyme amplicons, the ACD amplifies the limited signal resulting from miRNA recognition. The hMNS/ACD system was used to image microRNA in vivo, thus demonstrating its great promise in cancer diagnosis. [ABSTRACT FROM AUTHOR]

DNAzymes have been recognized as potent therapeutic agents for gene therapy, while their inefficient intracellular delivery and insufficient cofactor supply precludes their practical biological applications. Metal–organic frameworks (MOFs) have emerged as promising drug carriers without in‐depth consideration of their disassembled ingredients. Herein, we report a self‐sufficient MOF‐based chlorin e6‐modified DNAzyme (Ce6‐DNAzyme) therapeutic nanosystem for combined gene therapy and photodynamic therapy (PDT). The ZIF‐8 nanoparticles (NPs) could efficiently deliver the therapeutic DNAzyme without degradation into cancer cells. The pH‐responsive ZIF‐8 NPs disassemble with the concomitant release of the guest DNAzyme payloads and the host Zn2+ ions that serve, respectively, as messenger RNA‐targeting agent and required DNAzyme cofactors for activating gene therapy. The auxiliary photosensitizer Ce6 could produce reactive oxygen species (ROS) and provide a fluorescence signal for the imaging‐guided gene therapy/PDT. [ABSTRACT FROM AUTHOR]

Abstract: The development of effective strategies for sensitive and specific detection of microRNAs will facilitate clinical diagnostics. Here, we utilize cascade hybridization chain reaction as an enzyme‐free isothermal amplified strategy, and construct label‐free electrochemical biosensors for microRNAassay. MicroRNA initiated autonomous assembly of DNA nanostructures through the toehold‐mediated strand displacement reaction. The assembly behavior was examined by gel electrophoresis and morphology of branched DNA nanostructure was verified by atomic force microscope. This cascade hybridization chain reaction leads to extended growth of DNA chains and higher amplification efficiency compared with the regular hybridization chain reaction. The performance of the sensors was characterized by electrochemical impedance spectroscopy, differential pulse voltammetry, and chronocoulometric analysis. The prepared biosensor exhibits high sensitivity and a lower detection limit of 11 pM for the determination of microRNA‐21. This electrochemical assay based on cascade hybridization chain reaction is specific and can distinguish between highly homologous targets such as fully complementary target microRNA‐21, single, or two‐base mismatched sequences and other family members. These findings open the possibility of using cascade hybridization chain reaction as possible amplified electrochemical sensing platforms. [ABSTRACT FROM AUTHOR]

DNA Circuit, Fluorescence, RNA, Signal Amplification, Tumor Imaging Der am Wirkort aktivierte CCD-Schaltkreis hat erhebliches Potenzial für die hochpräzise In-vivo-Bildgebung von microRNA. Keywords: DNA Circuit; Fluorescence; RNA; Signal Amplification; Tumor Imaging EN DNA Circuit Fluorescence RNA Signal Amplification Tumor Imaging 1 1 1 11/03/22 20221107 NES 221107 B Eine nicht-enzymatische b Aktivierungsstrategie mittels multipler molekularer Erkennungsereignisse und progressiv beschleunigter Signalverstärkung führte zu einem orthogonal gesteuerten katalytischen DNA-Schaltkreis (CCD), wie Fuan Wang et al. in ihrem Forschungsartikel berichten (e202206529). [Extracted from the article]

Back Cover: On-Site Non-enzymatic Orthogonal Activation of a Catalytic DNA Circuit for Self-Reinforced In Vivo MicroRNA Imaging (Angew. Keywords: DNA Circuit; Fluorescence; RNA; Signal Amplification; Tumor Imaging EN DNA Circuit Fluorescence RNA Signal Amplification Tumor Imaging 1 1 1 11/03/22 20221107 NES 221107 B A non-enzymatic circuitry b activation strategy can realize an orthogonally controlled catalytic DNA (CCD) circuit through multiple molecular recognition events and progressively accelerated signal amplification, as reported by Fuan Wang and co-workers in their Research Article (e202206529). DNA Circuit, Fluorescence, RNA, Signal Amplification, Tumor Imaging. [Extracted from the article]

We demonstrate the single-molecule imaging of the catalytic reaction of a Zn2+-dependent DNAzyme in a DNA origami nanostructure. The single-molecule catalytic activity of the DNAzyme was examined in the designed nanostructure, a DNA frame. The DNAzyme and a substrate strand attached to two supported dsDNA molecules were assembled in the DNA frame in two different configurations. The reaction was monitored by observing the configurational changes of the incorporated DNA strands in the DNA frame. This configurational changes were clearly observed in accordance with the progress of the reaction. The separation processes of the dsDNA molecules, as induced by the cleavage by the DNAzyme, were directly visualized by high-speed atomic force microscopy (AFM). This nanostructure-based AFM imaging technique is suitable for the monitoring of various chemical and biochemical catalytic reactions at the single-molecule level. [ABSTRACT FROM AUTHOR]

The base sequence of nucleic acid encodes structural and functional properties into the biopolymer. Structural information includes the formation of duplexes, G-quadruplexes, i-motif, and cooperatively stabilized assemblies. Functional information encoded in the base sequence involves the strand-displacement process, the recognition properties by aptamers, and the catalytic functions of DNAzymes. This Review addresses the implementation of the information encoded in nucleic acids to develop DNA switches. A DNA switch is a supramolecular nucleic acid assembly that undergoes cyclic, switchable, transitions between two distinct states in the presence of appropriate triggers and counter triggers, such as pH value, metal ions/ligands, photonic and electrical stimuli. Applications of switchable DNA systems to tailor switchable DNA hydrogels, for the controlled drug-release and for the activation of switchable enzyme cascades, are described, and future perspectives of the systems are addressed. [ABSTRACT FROM AUTHOR]

Die Basensequenz der Nukleinsäuren verschlüsselt strukturelle und funktionelle Eigenschaften in einem Biopolymer. Strukturelle Informationen beinhalten die Bildung von Duplexen, G ‐ Quadruplexen, i ‐ Motiven und kooperativ stabilisierten Anordnungen. Funktionelle Informationen betreffen z. B. den Prozess der Strangverdrängung, Erkennungseigenschaften von Aptameren und die katalytische Funktion von DNAzymen. Dieser Aufsatz befasst sich mit der Implementierung der in Nukleinsäuren kodierten Informationen zur Entwicklung von DNA ‐ Schaltern. Ein DNA ‐ Schalter ist eine supramolekulare Nukleinsäureanordnung, die in Gegenwart geeigneter Auslöser und Gegenauslöser wie pH, Metallionen/Liganden, photonischen und elektrischen Stimuli zyklische, schaltbare Übergänge zwischen zwei Zuständen eingeht. Anwendungen von schaltbaren DNA ‐ Systemen umfassen maßgeschneiderte DNA ‐ Hydrogele für die kontrollierte Wirkstofffreisetzung und die Aktivierung schaltbarer Enzymkaskaden. Intelligente DNA: Die reizgesteuerte, reversible Rekonfiguration von i ‐ Motiven, G ‐ Quadruplexen und Duplex ‐ DNA ‐ Strukturen oder von DNA ‐ Bausteinen wie Pinzetten, Nanofedern und Walkern ist die Grundlage für die Entwicklung schaltbarer DNA ‐ Nanostrukturen mit Auslösern wie pH ‐ Wert, Metallionen oder elektrochemischen Signalen. Potenzielle Anwendungen von DNA ‐ Schaltern umfassen die kontrollierte Wirkstoff ‐ Freisetzung, das Öffnen/Schließen von Poren und schaltbare Katalyse. [ABSTRACT FROM AUTHOR]

Mimicking cellular transformations and signal transduction pathways by means of biocatalytic cascades proceeding in organized media is a scientific challenge. We describe two DNA machines that enable the 'ON/OFF' switchable activation and deactivation of three-component biocatalytic cascades. One system consists of a reconfigurable DNA tweezers-type structure, whereas in the second system the catalytic cascade proceeds on a switchable DNA clamp scaffold. The three-component catalytic cascades consist of β-galactosidase (β-Gal), glucose oxidase (GOx), and the K+-ion-stabilized hemin-G-quadruplex horseradish peroxidase (HRP)-mimicking DNAzyme. The hemin-G-quadruplex-bridged closed structure of the tweezers or clamp allows the biocatalytic cascades to operate (switched 'ON′′), whereas separation of the hemin-G-quadruplex by means of 18-crown-6-ether opens the tweezers/clamp structures, thus blocking the catalytic cascade (switched 'OFF'). This study is complemented by two-component, switchable biocatalytic cascades composed of GOx and hemin-G-quadruplex assembled on hairpin-bridged DNA tweezers or clamp nanostructures. [ABSTRACT FROM AUTHOR]

The K+-induced formation of G-quadruplexes provides a versatile motif to lock or unlock substrates trapped in the pores of mesoporous SiO2 nanoparticles, MP-SiO2 NPs. In one system, the substrate is locked in the MP-SiO2 NPs by K+-ion-stabilized G-quadruplex units, and the pores are unlocked by the elimination of K+ ions using Kryptofix [2.2.2] (KP) or 18-crown-6-ether (CE) from the G-quadruplexes. In the second system, the substrate is locked in the pores by means of K+-stabilized aptameric G-quadruplex/thrombin units. Unlocking of the pores is triggered by the dissociation of the aptamer/thrombin complexes through the KP- or CE-mediated elimination of the stabilizing K+ ions. In the third system, duplex DNA units lock the pores of MP-SiO2 NPs, and the release of the entrapped substrate is stimulated by the K+-ion-induced dissociation of the duplex caps through the formation of the K+-stabilized G-quadruplexes. The latter system is further implemented to release the anti-cancer drug, doxorubicin, in the presence of K+ ions, from the MP-SiO2 NPs. Preliminary intracellular experiments reveal that doxorubicin-loaded MP-SiO2 NPs lead to effective death of breast cancer cells. [ABSTRACT FROM AUTHOR]

The Cu2+-dependent ligation DNAzyme is implemented as a biocatalyst for the colorimetric or chemiluminescence detection of Cu2+ ions, Hg2+ ions, or cocaine. These sensing platforms are based on the structural tailoring of the sequence of the Cu2+-dependent ligation DNAzyme for specific analytes. The tethering of a subunit of the hemin/G-quadruplex DNAzyme to the ligation DNAzyme sequence, and the incorporation of an imidazole-functionalized nucleic-acid sequence, which acts as a co-substrate for the ligation DNAzyme that is tethered to the complementary hemin/G-quadruplex subunit. In the presence of different analytes, Cu2+ ions, Hg2+ ions, or cocaine, the pretailored Cu2+-dependent ligation DNAzyme sequence stimulates the respective ligation process by combining the imidazole-functionalized co-substrate with the ligation DNAzyme sequence. These reactions lead to the self-assembly of stable hemin/G-quadruplex DNAzyme nanostructures that enable the colorimetric analysis of the substrate through the DNAzyme-catalyzed oxidation of 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid), ABTS2−, by H2O2 into the colored product ABTS.−, or the chemiluminescence detection of the substrate through the DNAzyme-catalyzed oxidation of luminol by H2O2. The detection limits for the sensing of Cu2+ ions, Hg2+ ions, and cocaine correspond to 1 n M, 10 n M and 2.5 μ M, respectively. These different sensing platforms also reveal impressive selectivities. [ABSTRACT FROM AUTHOR]

Polymerase/nicking enzymes and nucleic-acid scaffolds are implemented as DNA machines for the development of amplified DNA-detection schemes, and for the design of logic gates. The analyte nucleic acid target acts, also, as input for the logic gates. In the presence of two DNA targets, acting as inputs, and appropriate DNA scaffolds, the polymerase-induced replication of the scaffolds, followed by the nicking of the replication products, are activated, leading to the autonomous synthesis of the Mg2+-dependent DNAzyme or the Mg2+-dependent DNAzyme subunits. These biocatalysts cleave a fluorophore/quencher-functionalized nucleic-acid substrate, thus providing fluorescence signals for the sensing events or outputs for the logic gates. The systems are used to develop OR, AND, and Controlled-AND gates, and the DNA-analyte targets represent two nucleic acid sequences of the smallpox viral genome. [ABSTRACT FROM AUTHOR]

DNA, drug delivery, nanostructures, self-assembly, stimuli-responsive Keywords: DNA; drug delivery; nanostructures; self-assembly; stimuli-responsive EN DNA drug delivery nanostructures self-assembly stimuli-responsive 1 1 1 02/26/21 20210224 NES 210224 B Intelligent stimuli-responsive DNA b nanostructures have attracted increasing attention for biological and biomedical research owing to their promising native biocompatibility, programmability, multifunctionality, responsiveness to biological cues, and easy implementation for designing new materials. Frontispiece: Construction of Smart Stimuli-Responsive DNA Nanostructures for Biomedical Applications. [Extracted from the article]