Boron-Doped Ti3C2Tx MXene for Effective and Durable High-Current-Density Ammonia Synthesis.

Ammonia (NH3) synthesis via the nitrate reduction reaction (NO3RR) offers a competitive strategy for nitrogen cycling and carbon neutrality; however, this is hindered by the poor NO3RR performance under high current density. Herein, it is shown that boron-doped Ti3C2Tx MXene nanosheets can highly efficiently catalyze the conversion of NO3RR-to-NH3 at ambient conditions, showing a maximal NH3 Faradic efficiency of 91% with a peak yield rate of 26.2 mgh-1 mgcat. -1, and robust durability over ten consecutive cycles, all of them are comparable to the best-reported results and exceed those of pristine Ti3C2Tx MXene. More importantly, when tested in a flow cell, the designed catalyst delivers a current density of ‒1000 mA cm-2 at a low potential of ‒1.18 V versus the reversible hydrogen electrode and maintains a high NH3 selectivity over a wide current density range. Besides, a Zn-nitrate battery with the catalyst as the cathode is assembled, which achieves a power density of 5.24 mW cm-2 and a yield rate of 1.15 mgh-1 mgcat. -1. Theoretical simulations further demonstrate that the boron dopants can optimize the adsorption and activation of NO3RR intermediates, and reduce the potential-determining step barrier, thus leading to an enhanced NH3 selectivity.

Flexible Self-Powered Sensing System Based on Novel DNA Circuit Strategy and Graphdiyne for Thalassemia Gene by Rapid Naked-Eye Tracking and Open-Circuit Voltage.

Based on the controllable instantaneous self-assembly ability of long-chain branched DNA nanostructures and the synergistic effect between nucleic acid amplification without enzymes, a highly sensitive and highly specific self-powered biosensing platform is developed. Two-dimensional graphdiyne is prepared, modified on flexible carbon cloth, and then functionalized with gold nanoparticles. When DNA mi-tubes are applied on it, target thalassemia gene CD122 triggers a dual-catalytic hairpin assembly reaction. The generated nanoscale DNA is precisely captured by the DNA mi-tube, exposing binding sites and activating the hybridization chain reaction to form long-chain branched DNA. Double-stranded DNA, along with dendritic DNA carrying a large number of guanine bases, precisely captures the signal molecule methylene blue (MB), generating a significant electrochemical signal. The redox reaction of MB also causes a proportional change in the system's color, achieving a colorimetric detection functionality. An efficient dual-mode self-powered sensing platform, therefore, is established for detecting the thalassemia gene CD122. The linear response range of target concentration to open-circuit voltage and RGB Blue value is 0.0001-10,000 pM. The detection limit under electrochemical mode is 36.3 aM (S/N = 3), and under colorimetric mode, it is as low as 12.1 aM (S/N = 3). The new method exhibits high sensitivity, excellent selectivity, and high accuracy, providing a universal strategy for designing novel biosensing platforms that can be extended to the detection of other biomolecules.

Smart Target-Initiated Catalytic DNA Junction Circuit Amplification Strategy for the Ultrasensitive Electrochemiluminescence Detection of MicroRNA.

One of the highly attractive research directions in the electrochemiluminescence (ECL) field is how to regulate and improve ECL efficiency. Quantum dots (QDs) are highly promising ECL materials due to their adjustable luminescence size and strong luminous efficiency. MoS2 NSs@QDs, an ECL emitter, is synthesized via hydrothermal methods, and its ECL mechanism is investigated using cyclic voltammetry and ECL-potential curves. Then, a stable and vertical attachment of a triplex DNA (tsDNA) probe to the MoS2 nanosheets (NSs) is applied to the electrode. Next, an innovative ECL sensor is courageously empoldered for precise and ultrasensitive detection of target miRNA-199a through the agency of ECL-resonance energy transfer (RET) strategy and a dextrous target-initiated catalytic three-arm DNA junction assembly (CTDJA) based on a toehold strand displacement reaction (TSDR) signal amplification approach. Impressively, the ingenious system not only precisely regulates the distance between energy donor-acceptor pairs leave energy less loss and more ECL-RET efficiency, but also simplifies the operational procedure and verifies the feasibility of this self-assembly process without human intervention. This study can expand MoS2 NSs@QDs utilization in ECL biosensing applications, and the proposed nucleic acid amplification strategy can become a miracle cure for ultrasensitive detecting diverse biomarkers, which helps researchers to better study the tumor mechanism, thereby unambiguously increasing cancer cure rates and reducing the risk of recurrence.

An all-graphdiyne electrochemiluminescence biosensor for the ultrasensitive detection of microRNA-21 based on target recycling with DNA cascade reaction for signal amplification.

Graphdiyne oxide quantum dots (GDYO QDs), as derivatives of graphdiyne (GDY), have excellent electroconductibility and luminous properties and can be applied as a new ECL emitter. Herein, an electrochemiluminescence (ECL) biosensor for miRNA-21 ultrasensitive determination is constructed based on AuNPs/GDY, GDYO QD and oligonucleotide signal amplification strategy that integrates DNA walker and hybridization chain reaction (HCR) amplification. As electrode substrate material, AuNPs/GDY can not only bond with the aptamer CP but can also enhance the conductivity of the interface. When miRNA-21 exists, the DNA walker process is initiated, and the signaling probes are introduced on the electrode surface, producing abundant double-stranded H1/H2; then, H3/H4 undergoes complementary base pairing with H1/H2 through HCR. With the increase in miRNA-21, the 3D DNA nanomachine is actively manipulated, resulting in a gradual increase in ECL signal. This ECL biosensor demonstrates outstanding performance in the determination of miRNA-21 in the linear range from 0.1 fM to 1 nM. This study offers a new sensitive idea for the clinical analysis of cancer biomarkers.

A carbon dot-based nanoscale covalent organic framework as a new emitter combined with a CRISPR/Cas12a-mediated electrochemiluminescence biosensor for ultrasensitive detection of bisphenol A.

Exploring new highly efficient electrochemiluminescence (ECL) luminophores is a necessary condition for developing ultrasensitive ECL biosensors. Therefore, a luminescent carbon dot-based covalent organic framework (CD-COF) was prepared using aldehyde-based carbon dots (CDs) and 1,3,5-tris (4-aminophenyl) benzene (TPB). Because the CD-COF made the regular arrangement of CDs conducive to improving the ECL response, CD-COF had a higher ECL intensity and efficiency than CDs. What's more, the ECL intensity of the CD-COF/S2O82-/Bu4N+ system was about 2.98, 7.50, and 28.08 times higher than those of the CD-COF/S2O82-, CDs/S2O82- and S2O82- systems, respectively. Considering the remarkable ECL performance, the CD-COF/S2O82-/Bu4N+ system was employed combined with the CRISPR/Cas12a trans-cutting strategy to construct an "off-on" ECL biosensor for BPA detection. The proposed ECL biosensor exhibited excellent performance with a wide linear range from 1.0 × 10-14 mol L-1 to 1.0 × 10-5 mol L-1 with a low detection limit of 2.21 fM (S/N = 3) under the optimized conditions. The biosensor demonstrated that CD-COF can be used as an efficient ECL emitter, thus expanding the application field of COFs. In addition, the good stability and specificity of the biosensor enabled the rapid detection of BPA, which will provide valuable insights into promising ultrasensitive ECL biosensors.

Superior performance of a graphdiyne self-powered biosensor with exonuclease III-assisted signal amplification for sensitive detection of microRNAs.

Graphdiyne (GDY) is an sp and sp2 co-hydrocarbon allotrope whose particular structure endows it with many fascinating properties, including abundant chemical bonds, high conjugation, natural pores, high carrier mobility, high conductivity and stability, etc. In this work, two-dimensional graphdiyne is prepared as an electrode substrate material coupling with an exonuclease III-assisted amplification strategy to construct a superior-performance self-powered biosensor based on enzymatic biofuel cells for highly sensitive detection of the tumour marker miRNA-21. Glucose oxidase (GOD) is first immobilized on the GDY/AuNP composite to prepare a bioconjugate. GDY/AuNP modified carbon cloth is used as an enzyme biofuel cell electrode, which is then modified with bilirubin oxidase as a biocathode. The bioconjugate binds to GOD through specific binding to the bioanode. When miRNA-21 is present, specific recognition by exonuclease III in the system results in cleavage of the capture probe, and miRNA-21 is recovered and involved in the cycle. The target miRNA-21 then causes corresponding changes in the open-circuit voltage of the self-powered system. Based on this, a sensitive detection method was constructed, within the scope from 0.1 fM to 0.1 nM with a shallow detection limit of 55.2 aM (S/N = 3). The new approach triumphantly has been used to detect miRNA-21 in serum, which provides a compelling new way for early diagnosis of related cancers.

Flexible photoelectrochemical sensor for highly sensitive chloramphenicol detection based on M-TiO2-CdTe QDs/CdS QDs composite.

Chloramphenicol (CAP) is widely used in the food industry and animal husbandry due to its effective antibiotic effect active against gram-positive and gram-negative microorganisms. However, research shows that it can cause serious adverse reactions and side effects in the human body. In order to effectively monitor the residues of CAP, a novel and simple photoelectrochemical (PEC) sensor for sensitive detection of CAP is fabricated based on M-TiO2-CdTe QDs/CdS QDs composite. The results show that the prepared M-TiO2 not only retains the original morphology and structure of MIL-125(Ti), but also exhibits more abundant pore structure and good photoelectrochemical properties. Compared with M-TiO2, the as-prepared M-TiO2-CdTe QDs/CdS QDs composite exhibits excellent PEC performances including about ninefold enhancement of photocurrent intensity, which is ascribed to the large surface of M-TiO2 and the introduction of CdTe QDs and CdS QDs. Based on the selective inhibitory effect of CAP in the photocurrent intensity of the M-TiO2-CdTe QDs/CdS QDs PEC system, a novel PEC sensor for CAP concentration determination is constructed. The designed PEC sensor demonstrates a linear range from 1 to 140 nmol L-1 with a detection limit of 0.14 nmol L-1 (S/N = 3). Moreover, the method is applied to real milk samples to quantify the CAP residues with spiked recoveries in the range of 96.3-106%, and the possible detection mechanism of the M-TiO2-CdTe QDs/CdS QDs PEC system is also discussed.

A novel signal amplified electrochemiluminescence biosensor based on MIL-53(Al)@CdS QDs and SiO2@AuNPs for trichlorfon detection.

An ultrasensitive electrochemiluminescence (ECL) biosensor was developed based on MIL-53(Al)@CdS QDs and SiO2@AuNPs for trichlorfon detection. Metal-organic frameworks (MOFs) were used as a loading platform that provided a large surface area to load targets and modified materials onto the electrode. At the same time, SiO2@AuNPs loaded plenty of AuNPs which effectively increased the ECL resonance energy transfer between the CdS QDs, so that the ECL signal was strongly quenched and resulted in an amplified response. In the range of 10-11-10-4 M, the ECL response showed a linear relationship with the concentration (logarithm) of trichlorfon, and the detection limit was 5.1 × 10-12 M (S/N = 3). When the biosensor was applied to detect trichlorfon in lettuce, broccoli, cucumber, and chives, the recoveries obtained from the spiked samples were 97%-105%, 102%-104%, 100%-104%, and 98%-104%, respectively. Thus, this novel ECL biosensor has potential applications for the analysis of trichlorfon in food samples.

An in situ growth approach to the fabrication of zeolite imidazolate framework-90 bonded capillary column for gas chromatography separation.

The unique properties of metal-organic frameworks, such as diversity in structures and pore sizes, high surface area, shape selectivity and available to functionality make them as potential materials of the stationary phase for gas chromatography. Here we show an in situ growth approach to the fabrication of zeolite imidazolate framework-90 (ZIF-90) bonded capillary column for gas chromatography separation. ZIF-90 was directly grown onto the inner wall of the carboxyl modified capillary via the coordination between Zn(II) and carboxyl group. The fabricated ZIF-90 bonded capillary column acted as a weak polar stationary phase. It not only exhibits high capacity in the separation of linear molecules, but also offers excellent features for the separation of 2- and 3-substituted ketones.

A sandwich-type dual-mode biosensor based on graphdiyne and DNA nanoframework for ultra-sensitive detection of CD142 gene.

Thalassemia is a globally prevalent single-gene blood disorder, with nearly 7% of the world's population being carriers. Therefore, the development of specific and sensitive methods for thalassemia detection holds significant importance. Herein, a sandwich-type electrochemical/colorimetric dual-mode biosensor is developed based on gold nanoparticles (AuNPs)/graphdiyne (GDY) and DNA nanoframeworks for ultra-sensitive detection of CD142 gene associated with sickle cell anemia. Utilizing AuNPs/GDY as the substrate electrode, the fabricated sandwiched DNA nanoframework not only improves selectivity but also introduces numerous signal probes to further amplify the output signal. In the electrochemical mode, glucose oxidase catalyzes the oxidation of glucose, generating electrons that are transferred to the biocathode for a reduction reaction, resulting in an electric signal proportional to the target concentration. In the colorimetric mode, glucose oxidase catalyzes the generation of H2O2 from glucose, and with the aid of horseradish peroxidase, H2O2 oxidizes 3,3',5,5'-tetramethylbenzidine to produce a colored product, enabling colorimetric detection of the target. The dual-mode biosensor demonstrates a detection range of 0.0001-100 pM in the electrochemical mode and a detection range of 0.0001-10,000 pM in the colorimetric mode. The detection limit in the electrochemical mode is determined to be 30.4 aM (S/N=3), while in the colorimetric mode is of 35.6 aM (S/N=3). This dual-mode detection achieves ultra-sensitive detection of CD142, demonstrating broad prospects for application.

FeCu bimetallic clusters for efficient urea production via coupling reduction of carbon dioxide and nitrate.

Urea electrosynthesis has appeared to meet the nitrogen cycle and carbon neutrality with energy-saving features. Copper can co-electrocatalyze among CO2 and nitrogen species to generate urea, however developing effective electrocatalysts is still an obstacle. Here, we developed a nitrogen-doped porous carbon loaded with FeCu clusters that convert CO2 and NO3- into urea, with the highest Faradaic efficiency of 39.8 % and yield rate of 1024.6 µg h-1 mgcat.-1, under optimized ambient conditions, exceeding that at the Fe or Cu homogeneous sites. Furthermore, a favorable CN coupling pathway originates from *NHCO and *NHCONO two intermediates with lower free energy barriers on FeCu dual active sites are verified through in-situ Fourier transform infrared spectroscopy and theoretical calculations. This research might provide deep insights into coupling mechanisms and investigation of efficient catalysts for green urea production.

Enhanced luminol electrochemiluminescence biosensing system based on highly dispersed bimetallic nanozyme coreaction accelerator and 3D DNA walker signal amplifier.

In this work, a platinum-nickel based nanozyme is prepared and used as a coreaction accelerator in the luminol-H2O2 electrochemiluminescence (ECL) system to construct an ECL biosensor for dimethyl phthalate (DMP) detection. The PtNi/NC nanozyme possesses dispersed metal active sites, and the synergistic effect of Pt and Ni endows it with excellent catalytic performance, which effectively converts H2O2 into more superoxide anions, and then significantly enhances the ECL intensity of the luminol system. The ECL mechanism is investigated by combining cyclic voltammetry and ECL with different types of free radical scavengers. Simultaneously, an "off-on" biosensor is constructed by integrating 3D DNA walker with enzyme-free recycling amplification for ultrasensitive detection of DMP. The biosensor based on PtNi/NC nanozyme mediated luminol-H2O2 system and 3D DNA walker exhibits a linear range of 1 × 10-16 to 1 × 10-6 M with a detection limit of 4.3 × 10-17 M (S/N = 3), and displays good stability and specificity. This study demonstrates the advantages of PtNi/NC nanozyme in enhancing the luminol-H2O2 ECL system, providing new strategy for designing efficient ECL emitter and offering a new method for detecting phthalate esters.

Multiple signal amplification strategy induced by biomarkers of lung cancer: A self-powered biosensing platform adapted for smartphones.

Lung cancer is a major malignant cancer with low survival rates, and early diagnosis is crucial for effective treatment. Herein, a biosensing platform that is self-powered derived from a capacitor-coupled EBFC has been developed for ultra-sensitive real-time identification of microRNA-21 (miRNA-21) with the assistance of a mobile phone. The flexible substrate of the platform is prepared on a carbon paper modified with graphdiyne and gold nanoparticles. The biosensor employs DNAzyme-mediated dual strand displacement amplification, which enhances the signal output intensity of the EBFC and improves selectivity. The coupling of the capacitor with the EBFC significantly amplifies the sensing signal, causing a 10.6-fold surge in current respond and further improving the sensitivity of the sensing platform. The established detection approach demonstrates a linear relationship varied from 0.0001 to 10,000 pM, with a sensitivity down to 32.3 aM as the minimum detectable limit, which has been effectively utilized for detecting miRNA-21 in practical samples. This sensing system provides strong support for the construction of portable detection devices, and the strategy of the platform construction provides an effective method for ultra-sensitive and accurate detection of miRNA, holding great potential in clinical diagnosis, prognosis evaluation, and drug screening for cancer.

CRISPR/Cas12a-triggered ordered concatemeric DNA probes signal-on/off multifunctional analytical sensing system for ultrasensitive detection of thalassemia.

Based on CRISPR/Cas12a triggered ordered concatemeric DNA probes, a "on/off" self-powered biosensor is developed to achieve highly sensitive detection of thalassemia gene CD142 through open-circuit potential-assisted visual signal output. The ingeniously constructed glucose oxidase (GOD)-functionalized ordered concatemeric DNA probe structure can significantly amplify signal output, while the coupled CRISPR/Cas12a system is served as a "signal switch" with excellent signal-transducing capabilities. When the ordered concatemeric DNA probe structure is anchored on electrode, the response signal of the sensing system is in the "signal on" mode. While, the presence of the target activates the non-specific cleavage activity of the CRISPR/Cas12a system, causing the sensing system to switch to the "signal off" mode. In the detection system, GOD catalyzes the oxidation of glucose to produce hydrogen peroxide, which further catalyzes the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to form a color product, enabling visual signal of the target through naked-eye color contrast. By employing a multifunctional analytical mode combining electrochemical and visual signal outputs, accurate determination of the target is achieved, with linear ranges of 0.0001-100 pM, and detection limits of 48.1 aM (S/N = 3). This work provides a reference method for sensitive detection of thalassemia genes and holds great diagnostic potential in biomedical applications.

Room-temperature phosphorescent discrimination of catechol from resorcinol and hydroquinone based on sodium tripolyphosphate capped Mn-doped ZnS quantum dots.

A room-temperature phosphorescence (RTP) strategy was developed for direct, additive-free discrimination of catechol from resorcinol and hydroquinone based on sodium tripolyphosphate capped Mn-doped ZnS quantum dots (STPP-Mn-ZnS QDs). The RTP response of STPP-Mn-ZnS QDs to the three isomers was pH-dependent, and the greatest difference in the RTP response to the isomers was observed at pH 8.0: catechol enhanced the RTP intensity of the QDs, while resorcinol and hydroquinone had little effect on the RTP intensity of the QDs. The enhanced RTP intensity of 1 µM catechol was not affected by the coexistence of 30 µM resorcinol and 50 µM hydroquinone at pH 8.0. The detection limit of this RTP method was 53 nM catechol, and the precision was 3.2% (relative standard deviation) for five replicate detections of 1 µM catechol. The discrimination mechanism was ascribed to the weak bonded ligand of STPP-Mn-ZnS QDs and the different interaction between the three isomers and STPP-Mn-ZnS QDs. The strong binding of catechol to Zn resulted in the extraction of Zn from the surface of STPP-Mn-ZnS QDs and the generation of holes that were trapped by Mn(2+) to form Mn(3+). Catechol also promoted the reduction of Mn(3+) into Mn(2+) excited state, thus ultimately inducing the enhanced RTP response of STPP-Mn-ZnS QDs.

Intra-brachial ergonovine, not acetylcholine, is associated with radial artery vasospasm in patients with coronary vasospasm.

BACKGROUND: The intracoronary provocation test is expensive and may cause complications. Therefore, we investigated the sensitivity, specificity and safety of different drug- and dose-peripheral artery provocation tests in the diagnosis of coronary artery spasm (CAS). METHODS: The patients who had repeated chest pain as well as both coronary and radial stenoses <50% were selected. These patients were divided into CAS group (n = 24) and control group (n = 33) after the intracoronary ergonovine provocation test. All patients underwent radial artery provocation tests at different dose-acetylcholine (200 µg, 400 µg and 800 µg) and ergonovine (60 µg, 100 µg and 160 µg). The predictive values of radial provocation tests for CAS diagnosis were analysed using receiver operator characteristic (ROC) curves. RESULTS: In radial acetylcholine provocation tests, 200 µg of acetylcholine failed to induce radial artery spasm, and the radial artery stenosis degree was not significantly different between the CAS group and control group at 400 µg and 800 µg of acetylcholine (all p > 0.05). In the radial artery ergonovine provocation tests, the radial artery stenosis degree was all significantly higher in the CAS group than in the control group at the three different doses (all p < 0.05). The specificity and sensitivity of radial ergonovine provocation tests were 90.91% and 50.00% at 60 µg, 96.97% and 66.67% at 100 µg, and 90.91% and 95.83% at 160 µg. Only the radial 160 µg-ergonovine provocation test caused CAS in one case. CONCLUSION: The radial acetylcholine provocation test has no diagnostic value for CAS. The radial 160 µg-ergonovine provocation test has higher sensitivity and specificity for CAS diagnosis, but its safety should be paid attention to.

A highly sensitive self-powered sensing method designed on DNA circuit strategy and MoS2 hollow nanorods for detection of thalassemia.

Thalassemia is one of the most common monogenic diseases, which seriously affects human growth and development, cardiovascular system, liver, etc. There is currently no effective cure for this disease, making screening for thalassemia particularly important. Herein, a self-powered portable device with high sensitivity and specificity for efficiently screening of low-level thalassemia is developed which is enabled with AuNPs/MoS2@C hollow nanorods and triple nucleic acid amplification technologies. It is noteworthy that AuNPs/MoS2@C electrode shows the advantages of high electrocatalytic activity, fast carrier migration rate and large specific surface area, which can significantly improve the stability and output signal of the platform. Using high-efficiency tetrahedral DNA as the probe, the target CD122 gene associated with thalassemia triggers a catalytic hairpin assembly reaction to achieve CD122 recycling while providing binding sites for subsequent hybridization chain reaction, greatly improving the detection accuracy and sensitivity of the device. A reliable electrochemical/colorimetric dual-mode assay for CD122 is then established, with a linear response range of 0.0001-100 pM for target concentration and open circuit voltage, and the detection limit is 78.7 aM (S/N = 3); a linear range of 0.0001-10000 pM for CD122 level and RGB Blue value, with a detection limit as low as 58.5 aM (S/N = 3). This method achieves ultra-sensitive and accurate detection of CD122, providing a new method for the rapid and accurate screening of thalassemia.

Smart enzyme-free amplification dual-mode self-powered platform designed on two-dimensional networked graphdiyne and DNA nanorods for ultra-sensitive detection of breast cancer biomarkers.

Research has shown that microRNAs exhibit regular dysregulation in cancers, making them potential biomarkers for cancer diagnosis. However, achieving specific and sensitive detection of microRNAs has been a challenging task. To address this issue, two-dimensional networked graphdiyne is used to fabricate a self-powered biosensor and establish a new approach for ultra-responsive dual-mode detection of miRNA-141, a breast cancer biomarker. This method detects miRNA-141 using both electrochemical and colorimetric modes by measuring the output electrical signal of an enzyme-based biofuel cell and the RGB blue value of the electrolyte solution. Tetrahedral DNA and DNA nanorods also are immobilized on the electrode as a biocathode and methylene blue is used as the electron acceptor, which is fixed in the DNA phosphate backbone through electrostatic adsorption. The bioanode catalyzes the oxidation of glucose to produce electrons, which reduces methylene blue to its reduced form, resulting in a high open-circuit voltage (EOCV) and a highger RGB Blue value, enabling dual-mode detection. A reliable linear correlation is observed between EOCV values and miRNA-141 concentrations ranging from 0.0001 to 100 pM, with a detection limit of 21.9 aM (S/N = 3). Additionally, the colorimetric mode also demonstrates a reliable linear correlation with a concentration range of 0.0001-10000 pM, and this method can detect a concentration of 22.2 aM (S/N = 3). This innovative research realizes sensitive and accurate determination of miRNA-141 and provides an important new method for cancer diagnosis.

Enhancing biosensing with fourfold amplification and self-powering capabilities: MoS2@C hollow nanorods-mediated DNA hexahedral framework architecture for amol-level liver cancer tumor marker detection.

Two-dimensional carbon-coated molybdenum disulfide (MoS2@C) hollow nanorods are combined with nucleic acid signal amplification strategies and DNA hexahedral nanoframework to construct a novel self-powered biosensing platform for ultra-sensitive dual-mode detection of tumor suppressor microRNA-199a. The nanomaterial is applied on carbon cloth and then modified with glucose oxidase or using as bioanode. A large number of double helix DNA chains are produced on bicathode by nucleic acid technologies including 3D DNA walker, hybrid chain reaction and DNA hexahedral nanoframework to adsorb methylene blue, producing high EOCV signal. Methylene blue also is reduced and an increased RGB Blue value is observed. For microRNA-199a detection, the assay shows a extensive linear range of 0.0001-100 pM with a low detection limit of 4.94 amol/L (S/N = 3). The method has been applied to the detection of actual serum samples, providing a novel method for the accurate and sensitive detection of tumor markers.

Self-powered dual-mode sensing strategy based on graphdiyne and DNA nanoring for sensitive detection of tumor biomarker.

MicroRNA-21 (miRNA-21) is currently the only known oncogenic miRNA that is upregulated in almost all malignant tumors and exhibits a broad spectrum of tumor recognition characteristics. It holds significant value in the early diagnosis, malignant degree assessment, and prognostic evaluation of tumors. In this study, a novel dual-mode self-powered sensing platform is developed using Au nanoparticles/graphdiyne as the electrode substrate and combined with DNA nanoring for highly sensitive and specific detection of miRNA-21. The DNA nanoring structure, which is easy to prepare and contains multiple recognition sites, induces significant electrochemical/colorimetric signal responses of the signaling molecule methylene blue. Under optimal conditions, the linear ranges of the electrochemical and colorimetric detection modes of this self-powered sensor are 0.1 fM-100 pM and 0.1 fM-10 nM, respectively, with the detection limits of 35.1 aM and 61.6 aM (S/N=3). This strategy provides a new reference for the sensitive detection of microRNA and has immense potential for application in the screening and detection of clinical nucleic acid diseases.