A facile, low-cost bimetallic iron-nickel MOF nanozyme-propelled ratiometric fluorescent sensor for highly sensitive and selective uric acid detection and its smartphone application.

As a kind of well-known disease biomarker, uric acid (UA) is closely associated with normal metabolism and health. Despite versatile nanozymes facilitating the analysis of UA, most previous works could only generate single-signal outputs with unsatisfactory detection performance. Exploring a novel ratiometric fluorescent UA sensor with high sensitivity, reliability and portable sensing ability based on facile, low-cost nanozymes is still challenging. Herein, we report the first metal-organic-framework (MOF) nanozyme-originated ratiometric fluorescent UA sensor based on Fe3Ni-MOF-NH2 propelled UA/uricase/o-phenylenediamine tandem catalytic reaction. Different from previous reports, the peroxidase-like property and fluorescence of Fe3Ni-MOF-NH2 were simultaneously employed. In the absence of UA, only the MOF's fluorescence at 430 nm (FI430) can be observed, while the addition of UA will initiate UA/uricase catalytic reaction, and the generated H2O2 could oxidize o-phenylenediamine into highly fluorescent 2,3-diaminophenazine (DAP) (emission at 565 nm, FI565) under the catalysis of the MOF nanozyme. Coincidently, MOF's fluorescence can be quenched by DAP via the inner filter effect, resulting in a low FI430 value and high FI565 value, respectively. Therefore, H2O2 and UA can be alternatively detected through monitoring the above contrary fluorescence changes. The limit of detection for UA is 24 nM, which is much lower than those in most previous works, and the lowest among nanozyme-based ratiometric fluorescent UA sensors reported to date. Moreover, the portable sensing of UA via smartphone-based RGB analysis was facilely achieved by virtue of the above nanozyme-propelled tandem catalytic system, and MOF nanozyme-based molecular contrary logic pairs were further implemented accordingly.

An intelligent ratiometric fluorescent assay based on MOF nanozyme-mediated tandem catalysis that guided by contrary logic circuit for highly sensitive sarcosine detection and smartphone-based portable sensing application.

As the well-known test-indicator for early prostate cancer (PCa), sarcosine (SA) is closely related to the differential pathological process, which makes its accurate determination increasingly significant. Herein, we for the first time expanded the peroxidase (POD)-like property of facile-synthesized Zn-TCPP(Fe) MOF to fluorescent substrates and exploited it to ratiometric fluorescent (RF) sensing. By harnessing the effective catalytic oxidation of MOF nanozyme toward two fluorescent substrates (Scopoletin, SC; Amplex Red, AR) with contrary changes, and target-responsive (SA + SOx)/MOF/(SC + AR) tandem catalytic reaction, we constructed the first MOF nanozyme-based RF sensor for the quantitative determination of SA. Superior to previous works, the operation of this RF sensor is under the guidance of AND-(AND^NAND) contrary logic circuit. The dual-channel binary output changes (from 1/0 to 0/1) not only enable the intelligent logical recognition of SA, bringing strengthened reliability and accuracy, but also manifest the proof-of-concept discrimination of PCa individuals and healthy ones. Through recording the fluorescence alterations of SC (F465) and AR (F585), two segments of linear relationships between ratiometric values (F585/F465) and varied contents of SA are realized successfully. The LOD for SA could reach to as low as 39.98 nM, which outperforms all nanozyme-originated SA sensors reported till now. Moreover, this sensor also demonstrates high selectivity and satisfactory performance in human serum samples. Furthermore, the portable sensing of SA is realized under the assistance of smartphone-based RGB analysis, demonstrating the potential of point-of-care diagnostics of PCa in the future.

Toward Minute-Level DNA Computing: An Ultrafast, Cost-Effective, and Universal System for Lighting Up Various Concurrent DNA Logic Nanodevices (CDLNs) and Concatenated Circuits.

DNA logic nanodevices are powerful tools for both molecular computing tasks and smart bioanalytical applications. Nevertheless, the hour-level operation time and high cost caused by the frequent redesign/reconstruction of gates, tedious strand-displacement reaction, and expensive labeled probes (or tool enzymes) in previous works are ineluctable drawbacks. Herein, we report an ultrafast and cost-effective system for engineering concurrent DNA logic nanodevices (CDLNs) by combining polythymine CuNCs with SYBR Green I (SG I) as universal dual-output producers. Particularly, benefiting from the concomitant minute-level quick response of both unlabeled illuminators and the exquisite strand-displacement-free design, all CDLNs including contrary logic pairs (YES∧NOT, OR∧NOR, and Even∧Odd number classifier), noncontrary ones (IDE∧IMP, OR∧NAND), and concatenated circuits are implemented in just 10 min via a "one-stone-two-birds" method, resulting in only 1/12 the operation time and 1/4 the cost needed in previous works, respectively. Moreover, all of them share the same threshold value, and the dual output can be easily visualized by the naked eye under a portable UV lamp, indicating the universality and practicality of this system. Furthermore, by exploiting the "positive/negative cross-verification" advantages of concurrent contrary logic, the smart in vitro analysis of the polyadenine strand and its polymerase is realized, providing novel molecular tools for the early diagnosis of cancer-related diseases.

The one/two atom size-reduction of [Au23SCy16]- induced by the [Au6(dppp)4]2+ cluster.

The recent progress in atomically precise metal (Au, Ag etc.) nanoclusters has greatly enriched the molecular-level mechanistic understanding of metal nanomaterials. Herein, using two meta-stable (easy formation, easy transformation) clusters, i.e. [Au23SCy16]- and [Au6(dppp)4]2+ (HSCy and dppp denote cyclohexanethiol and 1,3-bis(diphenylphosphino)propane), as the reaction precursors, the etching of Au23 occurs smoothly, giving the one/two-atom size-reduced [Au21SCy12(dppp)2]+ and [Au22SCy14(dppp)]2+ as the major products. Structural analysis and DFT calculations indicate that the active reaction site of Au23 lies in the core-shell interference of the bi-capped icosahedral Au15 core and the AuS2 motifs. The fluorescence, band gap, and thermostability of the Au21 cluster products are improved compared to that of the Au23 precursors.

Integration of G-Quadruplex and Pyrene as a Simple and Efficient Ratiometric Fluorescent Platform That Programmed by Contrary Logic Pair for Highly Sensitive and Selective Coralyne (COR) Detection.

The effective and accurate detection of the anticancer drug coralyne (COR) is highly significant for drug quality control, medication safety and good health. Although various COR sensors have been reported in recent years, previous ones can only exhibit single-signal output (turn ON or turn OFF) with poor reliability and anti-interference ability. Therefore, exploring novel platform with dual-signal response for COR detection is urgently needed. Herein, we reported the first ratiometric fluorescent platform for highly sensitive and selective COR detection by integrating G-quadruplex (G4) and Pyrene (Py) as signal probes and harnessing A-COR-A interaction. In the absence of COR, the platform shows a low fluorescence signal of PPIX (F642) and a high one of Py monomer (F383). With the addition of COR, two delicately designed poly-A ssDNAs will hybridize with each other via A-COR-A coordination to form complete G4, yielding the increased fluorescence signal of PPIX and the decreased one of Py due to the formation of Py excimer. Based on the above mechanism, we constructed a simple and efficient sensor that could realize the ratiometric fluorescent detection of COR with high sensitivity and selectivity. A linear relationship between F642/F383 and COR's concentration is obtained in the range from 1 nM to 8 µM. And the limit of detection of COR could reach to as low as 0.63 nM without any amplification, which is much lower than that of most COR sensors reported so far. Notably, the logical analysis of COR can be carried out under the control of a "YES-NOT" contrary logic pair, enabling the smart dual-channel response with an adequate S/N ratio and improved reliability and anti-interference ability. Moreover, this system also presents satisfactory performance in fetal bovine serum (FBS) samples.

Recent advancements in coralyne (COR)-based biosensors: Basic principles, various strategies and future perspectives.

As a kind of protoberberine alkaloid heterocyclic analogues, coralyne (COR) has been reported to exhibit superior antileukemic ability and used as anticancer drug agent. While, the severe hazards and side effects caused by unreasonable use have made its accurate detection more and more important. Although scientists have explored various methods to sense COR and other related targets, a systematical review which could not only elaborate recent developments and analyze current challenges of COR-based biosensors, but also present future perspective has not been reported and is urgently needed. In this review, we attempt to summarize latest advancements in COR-based biosensors in recent decade. Firstly, the operating principles, advantages and disadvantages of various strategies for COR detection (colorimetric, fluorescent, electrochemical and other ones) are comprehensively demonstrated and reviewed. Secondly, COR-assisted biosensors for detection of different non-COR targets (heparin, toxins, nucleic acids and other small molecules) are further discussed. Finally, we analyze current challenges and also suggest potential perspectives for this area.

An Oligopeptide-Protected Ultrasmall Gold Nanocluster with Peroxidase-Mimicking and Cellular-Imaging Capacities.

Recent decades have witnessed the rapid progress of nanozymes and their high promising applications in catalysis and bioclinics. However, the comprehensive synthetic procedures and harsh synthetic conditions represent significant challenges for nanozymes. In this study, monodisperse, ultrasmall gold clusters with peroxidase-like activity were prepared via a simple and robust one-pot method. The reaction of clusters with H2O2 and 3,3',5,5'-tetramethylbenzidine (TMB) followed the Michaelis-Menton kinetics. In addition, in vitro experiments showed that the prepared clusters had good biocompatibility and cell imaging ability, indicating their future potential as multi-functional materials.

Evaluation of Macular and Retinal Ganglion Cell Count Estimates for Detecting and Staging Glaucoma.

Purpose: To investigate the clinical significance of macular estimated retinal ganglion cell (mRGC) and estimated retinal ganglion cell (eRGC) in the diagnosis and staging of glaucoma. Methods: This is a cross-section study. All enrolled subjects underwent standard automated perimetry (SAP) and optical coherence tomography (OCT) examination. Swedish Interactive Threshold Algorithm (SITA)-FAST detection strategy and 24-2, 10-2 detection programs were employed in SAP assessment. The visual-field parameters and OCT parameters were calculated according to three formulas to obtain the eRGC and mRGC1 or mRGC2. The efficiency of eRGC, mRGC1, and mRGC2 estimates for the staging of glaucoma was compared. The sensitivity and specificity of each parameter for diagnosis of glaucoma were analyzed using the receiver operating characteristic (ROC) curve. Results: A total of 119 eyes were included in the analysis. Compared with the healthy controls, eRGC, mRGC1, and mRGC2 estimates were significantly decreased in patients with glaucoma. As glaucoma progressed, eRGC, mRGC1, and mRGC2 estimates were gradually reduced. In preperimetric glaucoma, mRGC1, mRGC2, and eRGC were reduced by 13.2, 14.5, and 18%, respectively. In the mild stage of glaucoma, mRGC1, mRGC2, and eRGC were reduced by 28, 34, and 38%, respectively. In the advanced stage of glaucoma, mRGC1, mRGC2, and eRGC were reduced by 81, 85, and 92% respectively. The proportion of retinal ganglion cell (RGC) loss in the macula was close to that outside the macula. The specificity at 95% gave a sensitivity of 95.51, 86.52, and 87.64% for eRGC, mRGC1, and mRGC2, respectively. The sensitivity of structural parameters macular ganglion cell complex thickness and retinal nerve fiber layer (RNFL) were 98.88 and 95.51%, respectively. The sensitivity of functional parameters mean deviation (24-2) and visual field index (VFI) were 80.90 and 73.03%, respectively. The area under ROC curve of mRGC1, mRGC2, and eRGC were 0.982, 0.972, and 0.995 (P < 0.0001), respectively. Conclusion: Estimated retinal ganglion cell, mRGC1, and mRGC2 provide value to the staging of glaucoma and better diagnostic performance. Macular RGC estimatesthat integration of both structural and functional damages in macular may serve as a sensitive indicator for assessing macular damage in glaucoma and are of importance for the diagnosis and progression management of glaucoma.

Triggered Dimerization and Trimerization of DNA Tetrahedra for Multiplexed miRNA Detection and Imaging of Cancer Cells.

The reversible and switchable triggered reconfiguration of tetrahedra nanostructures from monomer tetrahedra structures into dimer or trimer structures is introduced. The triggered bridging of monomer tetrahedra by K+ -ion-stabilized G-quadruplexes or T-A•T triplexes leads to dimer or trimer tetrahedra structures that are separated by crown ether or basic pH conditions, respectively. The signal-triggered dimerization/trimerization of DNA tetrahedra structures is used to develop multiplexed miRNA-sensing platforms, and the tetrahedra mixture is used for intracellular sensing and imaging of miRNAs.

Propelling DNA Computing with Materials' Power: Recent Advancements in Innovative DNA Logic Computing Systems and Smart Bio-Applications.

DNA computing is recognized as one of the most outstanding candidates of next-generation molecular computers that perform Boolean logic using DNAs as basic elements. Benefiting from DNAs' inherent merits of low-cost, easy-synthesis, excellent biocompatibility, and high programmability, DNA computing has evoked substantial interests and gained burgeoning advancements in recent decades, and also exhibited amazing magic in smart bio-applications. In this review, recent achievements of DNA logic computing systems using multifarious materials as building blocks are summarized. Initially, the operating principles and functions of different logic devices (common logic gates, advanced arithmetic and non-arithmetic logic devices, versatile logic library, etc.) are elaborated. Afterward, state-of-the-art DNA computing systems based on diverse "toolbox" materials, including typical functional DNA motifs (aptamer, metal-ion dependent DNAzyme, G-quadruplex, i-motif, triplex, etc.), DNA tool-enzymes, non-DNA biomaterials (natural enzyme, protein, antibody), nanomaterials (AuNPs, magnetic beads, graphene oxide, polydopamine nanoparticles, carbon nanotubes, DNA-templated nanoclusters, upconversion nanoparticles, quantum dots, etc.) or polymers, 2D/3D DNA nanostructures (circular/interlocked DNA, DNA tetrahedron/polyhedron, DNA origami, etc.) are reviewed. The smart bio-applications of DNA computing to the fields of intelligent analysis/diagnosis, cell imaging/therapy, amongst others, are further outlined. More importantly, current "Achilles' heels" and challenges are discussed, and future promising directions of this field are also recommended.

Modeling Gene Expression Instability by Programmed and Switchable Polymerization/Nicking DNA Nanomachineries.

Models for gene expression instability by noncanonical DNA-nanostructures are introduced. The systems consist of a promoter-template scaffold that acts as a polymerization/nicking machinery that models, in the presence of polymerase/Nt.BbvCI and dNTPs, the autonomous synthesis of displaced strands mimicking the native "genes". Incorporation of noncanonical DNA structures into the scaffolds consisting of Sr2+-ion-stabilized G-quadruplexes, T-A·T triplexes, or ATP-aptamer complexes results in the perturbation of the polymerization/nicking DNA machineries and the synthesis of displaced strands-"genes" exhibiting other structures. By the dissociation of the noncanonical blockage units, the regeneration of the synthesis of the original intact displaced strands-"genes" is demonstrated. The study introduces conceptual means to eliminate destructive gene expression instability pathways.

Illuminating Diverse Concomitant DNA Logic Gates and Concatenated Circuits with Hairpin DNA-Templated Silver Nanoclusters as Universal Dual-Output Generators.

Exquisite administration of a new type of hairpin DNA-templated silver nanoclusters (H-AgNCs) as universal dual-output generators in DNA-based logic systems is reported. Diverse concomitant contrary logic gates (CCLGs) with opposite functions (YES^ NOT, OR^ NOR, INHIBIT^ IMPLICATION, XOR^ XNOR, and MAJORITY^ MINORITY) and extended concatenated logic circuits are presented and some of them perform specific functions, such as parity generators and checkers. The introduction of H-AgNCs as noncovalent signal reporters avoids tedious and high-cost labeling procedures. Of note, the concomitant feature of CCLGs attributed to the dual-emitter AgNCs conduces to reducing the time and cost to devise multiple logic gates. As compared to previous ones, this design eliminates numerous substances (e.g., organic dyes) and unstable components (hydrogen peroxide), which not only decreases the complexity of logic performs and improves repeatability of operation, but also makes it convenient to connect distinct DNA-based logic gates. It is worthy to anticipate that the cost-effective strategy will inspire researchers to develop much more complex logic systems and contribute to the field of molecular computing.

A Janus-inspired amphichromatic system that kills two birds with one stone for operating a "DNA Janus Logic Pair" (DJLP) library.

Although DNA computing has exhibited a magical power across diverse areas, current DNA logic gates with different functions are always separately operated and can only produce hard-to-visualize output. The fussy/obligatory gates' redesign/reconstruction and the non-intuitive output cause the wastage of time and costs, low efficiency and practicality. Herein, inspired by the ancient Roman mythical God Janus, for the first time, we propose the concept of "DNA Janus Logic Pair" (DJLP) to classify the DNA logic gates with contrary functions into "Positive + Negative" gates (DJLP = Pos + Neg). Based on the biocatalytic property of G-quadruplex DNAzyme (G4zyme) and the luminescence quenching ability of oxidized 3,3',5,5'-tetramethylbenzidine (OxTMB) towards the upconversion (UC) particles, we fabricated a universal amphichromatic platform that kills two birds with one stone for operating a versatile DJLP library. Different from the previous DNA logic systems, the "Pos + Neg" gates of each DJLP in this study were concomitantly achieved via the same one-time DNA reaction, which avoided the gates' redesign/reoperation and reduced the operating costs/time of the DNA gates by at least half. Besides, both the amphichromatic outputs (Visual-blue and UC luminescent-green) can be visualized under harmless-NIR, thus bringing greatly enhanced practicality to the method. Moreover, we constructed various concatenated logic circuits via logically modulating the G4zyme's biocatalytic property with glutathione, thus enabling the largely improved computing complexity. Furthermore, taking the circuit "YES-INH-1-2 decoder" as the "computing core", we designed an "antioxidant indicator" with ratiometric logical responses that could recognize the presence of antioxidants smartly (output changed from "10" to "01"), which provided a typical prototype for potential intelligent bio-applications.

Chemiluminescence of CsPbBr3 Perovskite Nanocrystal on the Hexane/Water Interface.

All-inorganic halide perovskite CsPbBr3 nanocrystals (NCs) have attracted more attention in recent years due to the unique optical feature. To date, most of the research was mainly focused on the photoluminescence (PL) and electrochemiluminescence (ECL) of the perovskite NCs. In this work, the strong chemiluminescence (CL) emission of CsPbBr3 NCs was observed for the first time on the hexane/water interface with the assistance of ammonium persulfate-(NH4)2S2O8 as coreactant. Different coreactants were investigated to demonstrate the effect on the CL behavior and it was found that CL intensity achieved the maximum in the presence of (NH4)2S2O8. In this system, electron transfer took place on the surface of the CsPbBr3 NCs, and the excited CsPbBr3 NCs was originated from the direct chemical oxidation of (NH4)2S2O8. The CL spectrum of CsPbBr3 NCs was also collected and was consistent with their PL and ECL spectra, indicating that CsPbBr3 NCs played a role of luminophor during the CL process. The discovery of monochromatic CL of highly crystallized CsPbBr3 NCs not only extends the applications of halide perovskite materials in the analytical field but also provides a new route for the exploration of the physical chemistry properties.

A simple, label-free, electrochemical DNA parity generator/checker for error detection during data transmission based on "aptamer-nanoclaw"-modulated protein steric hindrance.

Versatile DNA logic devices have exhibited magical power in molecular-level computing and data processing. During any type of data transmission, the appearance of erroneous bits (which have severe impacts on normal computing) is unavoidable. Luckily, the erroneous bits can be detected via placing a parity generator (pG) at the sending module and a parity checker (pC) at the receiving module. However, all current DNA pG/pC systems use optical signals as outputs. In comparison, sensitive, facilely operated, electric-powered electrochemical outputs possess inherent advantages in terms of potential practicability and future integration with semiconductor transistors. Herein, taking an even pG/pC as a model device, we construct the first electrochemical DNA pG/pC system so far. Innovatively, a thrombin aptamer is integrated into the input-strand and it functions as a "nanoclaw" to selectively capture thrombin; the electrochemical impedance changes induced by the "nanoclaw/thrombin" complex are used as label-free outputs. Notably, this system is simple and can be operated within 2 h, which is comparable with previous fluorescent ones, but avoids the high-cost labeled-fluorophore and tedious nanoquencher. Moreover, taking non-interfering poly-T strands as additional inputs, a cascade logic circuit (OR-2 to 1 encoder) and a parity checker that could distinguish even/odd numbers from natural numbers (0 to 9) is also achieved based on the same system. This work not only opens up inspiring horizons for the design of novel electrochemical functional devices and complicated logic circuits, but also lays a solid foundation for potential logic-programmed target detection.

Introducing Ratiometric Fluorescence to MnO2 Nanosheet-Based Biosensing: A Simple, Label-Free Ratiometric Fluorescent Sensor Programmed by Cascade Logic Circuit for Ultrasensitive GSH Detection.

Glutathione (GSH) plays crucial roles in various biological functions, the level alterations of which have been linked to varieties of diseases. Herein, we for the first time expanded the application of oxidase-like property of MnO2 nanosheet (MnO2 NS) to fluorescent substrates of peroxidase. Different from previously reported fluorescent quenching phenomena, we found that MnO2 NS could not only largely quench the fluorescence of highly fluorescent Scopoletin (SC) but also surprisingly enhance that of nonfluorescent Amplex Red (AR) via oxidation reaction. If MnO2 NS is premixed with GSH, it will be reduced to Mn2+ and lose the oxidase-like property, accompanied by subsequent increase in SC's fluorescence and decrease in AR's. On the basis of the above mechanism, we construct the first MnO2 NS-based ratiometric fluorescent sensor for ultrasensitive and selective detection of GSH. Notably, this ratiometric sensor is programmed by the cascade logic circuit (an INHIBIT gate cascade with a 1 to 2 decoder). And a linear relationship between ratiometric fluorescent intensities of the two substrates and logarithmic values of GSH's concentrations is obtained. The detection limit of GSH is as low as 6.7 nM, which is much lower than previous ratiometric fluorescent sensors, and the lowest MnO2 NS-based fluorescent GSH sensor reported so far. Furthermore, this sensor is simple, label-free, and low-cost; it also presents excellent applicability in human serum samples.

A DNA-based parity generator/checker for error detection through data transmission with visual readout and an output-correction function.

During any type of binary data transmission, the occurrence of bit errors is an inevitable and frequent problem suffered. These errors, which have fatal effects on the correct logic computation, especially in sophisticated logic circuits, can be checked through insertion of a parity generator (pG) at the transmitting end and a parity checker (pC) at the receiving end. Herein, taking even pG/pC as a model device, we constructed the first DNA-based molecular parity generator/checker (pG/pC) for error detection through data transmission, on a universal single-strand platform according to solely DNA hybridization. Compared with previous pG/pC systems, the distinct advantage of this one is that it can present not only fluorescence signals but also visual outputs, which can be directly recognized by the naked eye, using DNA inputs modulated split-G-quadruplex and its DNAzyme as signal reporters, thus greatly extending its potential practical applications. More importantly, an "Output-Correction" function was introduced into the pC for the first time, in which all of the erroneous outputs can be adequately corrected to their normal states, guaranteeing the regular operation of subsequent logic devices. Furthermore, through negative logic conversion towards the constructed even pG/pC, the odd pG/pC with equal functions was obtained. Furthermore, this system can also execute multi-input triggered concatenated logic computations with dual output-modes, which largely fulfilled the requirements of complicated computing.

Exploiting Polydopamine Nanospheres to DNA Computing: A Simple, Enzyme-Free and G-Quadruplex-Free DNA Parity Generator/Checker for Error Detection during Data Transmission.

Molecular logic devices with various functions play an indispensable role in molecular data transmission/processing. However, during any kinds of data transmission, a constant and unavoidable circumstance is the appearance of bit errors, which have serious effects on the regular logic computation. Fortunately, these errors can be detected via plugging a parity generator (pG) at the transmitting terminal and a parity checker (pC) at the receiving terminal. Herein, taking advantage of the efficient adsorption/quenching ability of polydopamine nanospheres toward fluorophore-labeled single-stranded DNA, we explored this biocompatible nanomaterial to DNA logic computation and constructed the first simple, enzyme-free, and G-quadruplex-free DNA pG/pC for error detection through data transmission. Besides, graphene oxide (GO) was innovatively introduced as the "corrective element" to perform the output-correction function of pC. All the erroneous outputs were corrected to normal conditions completely, ensuring the regular operation of later logic computing. The total operation of this non-G4 pG/pC system (error checking/output-correction) could be completed within 1 h (about 1/3 of previous G4 platform) in a simpler and more efficient way. Notably, the odd pG/pC with analogous functions was also achieved through negative logic conversion to the fabricated even one. Furthermore, the same system could also perform three-input concatenated logic computation (XOR-INHIBIT), enriching the complexity of PDs-based logic computation.

Tyramine Hydrochloride Based Label-Free System for Operating Various DNA Logic Gates and a DNA Caliper for Base Number Measurements.

DNA is believed to be a promising candidate for molecular logic computation, and the fluorogenic/colorimetric substrates of G-quadruplex DNAzyme (G4zyme) are broadly used as label-free output reporters of DNA logic circuits. Herein, for the first time, tyramine-HCl (a fluorogenic substrate of G4zyme) is applied to DNA logic computation and a series of label-free DNA-input logic gates, including elementary AND, OR, and INHIBIT logic gates, as well as a two to one encoder, are constructed. Furthermore, a DNA caliper that can measure the base number of target DNA as low as three bases is also fabricated. This DNA caliper can also perform concatenated AND-AND logic computation to fulfil the requirements of sophisticated logic computing.

Cascaded multiple amplification strategy for ultrasensitive detection of HIV/HCV virus DNA.

Ultrasensitive detection of HIV and HCV virus DNA is of great importance for early accurate diagnostics and therapy of HIV virus-infected patients. Herein, to our best knowledge, it is the first to use DNA cascaded multiple amplification strategy for ultrasensitive detection of HIV virus DNA with G-quadruplex-specific fluorescent or colorimetric probes as signal carriers. The developed strategy also exhibited universal applicability for HCV virus DNA detection. After reaction for about 4h, high sensitivity and specificity can be achieved at both fluorescent and colorimetric strategies (limit of detection (LOD) of 10 fM and 0.5pM were reached for fluorescent and colorimetric detection, respectively). And the single-based mismatched DNA even can be distinguished by naked eyes. It is believed that the cascaded multiple amplification strategy presents a huge advance in sensing platform and potential application in future clinical diagnosis.