The role of non-coding RNAs in neuropathic pain.

Neuropathic pain (NPP) is a refractory pain syndrome, caused by damage or disease of the somatosensory nervous system and characterized by spontaneous pain, hyperalgesia, abnormal pain and sensory abnormality. Non-coding RNAs (ncRNAs), including microRNA (miRNA), long non-coding RNA (lncRNA), circular RNA (circRNA) and Piwi interacting RNA (piRNA), play a notable role in initiation and maintenance of NPP. In this review, we summarize the role of ncRNAs in NPP and their underlaying mechanism. Generally, ncRNAs are interacted with mRNA, protein or DNA to regulate the molecules and signals assciated with neuroinflammation, ion channels, neurotrophic factors and others, and then involved in the occurrence and development of NPP. Therefore, this review not only contributes to deepen our understanding of the pathophysiological mechanism of NPP, but also provides theoretical basis for the development of new therapy strategies for this disorder.

Multiarmed DNA jumper and metal-organic frameworks-functionalized paper-based bioplatform for small extracellular vesicle-derived miRNAs assay.

Small extracellular vesicle-derived microRNAs (sEV-miRNAs) have emerged as promising noninvasive biomarkers for early cancer diagnosis. Herein, we developed a molecular probe based on three-dimensional (3D) multiarmed DNA tetrahedral jumpers (mDNA-Js)-assisted DNAzyme activated by Na+, combined with a disposable paper-based electrode modified with a Zr-MOF-rGO-Au NP nanocomplex (ZrGA) to fabricate a novel biosensor for sEV-miRNAs Assay. Zr-MOF tightly wrapped by rGO was prepared via a one-step method, and it effectively aids electron transfer and maximizes the effective reaction area. In addition, the mechanically rigid, and nanoscale-addressable mDNA-Js assembled from the bottom up ensure the distance and orientation between fixed biological probes as well as avoid probe entanglement, considerably improving the efficiency of molecular hybridization. The fabricated bioplatform achieved the sensitive detection of sEV-miR-21 with a detection limit of 34.6 aM and a dynamic range from100 aM to 0.2 µM. In clinical blood sample tests, the proposed bioplatform showed results highly consistent with those of qRT-PCRs and the signal increased proportionally with the NSCLC staging. The proposed biosensor with a portable wireless USB-type analyzer is promising for the fast, easy, low-cost, and highly sensitive detection of various nucleic acids and their mutation derivatives, making it ideal for POC biosensing.

Catalytic Hairpin Assembly-Driven Ratiometric Dual-Signal Electrochemical Biosensor for Ultrasensitive Detection of MicroRNA Based on the Ratios of Fe-MOFs and MB-GA-UiO-66-NH2.

In this work, a novel ratio electrochemical biosensing platform based on catalytic hairpin assembly target recovery to trigger dual-signal output was developed for ultrasensitive detection of microRNA (miRNA). To achieve the ratiometric dual-signal strategy, methylene blue (MB), an electrochemical indicator, was ingeniously loaded into the pores of graphene aerogel (GA) and metal-organic framework (MOF) composites with high porosity and large specific surface area, and another electrochemical indicator Fe-MOFs with distinct separation of redox potential was selected as a signal probe. Concretely, with the presence of the target miRNA, the CHA process was initiated and the signal probe was introduced to the electrode surface, producing abundant double-stranded H1-H2@Fe-MOFs-NH2. Then, the measurement and analysis of the prepared ratiometric electrochemical biosensor by differential pulse voltammetry (DPV) showed that the introduction of the target miRNA led to an increase in the oxidation peak signal of Fe-MOFs (+0.8 V) and a decrease in the oxidation peak signal of MB (-0.23 V). Therefore, the peak current ratio of IFe-MOFs/IMB could be employed to accurately reflect the actual concentration of miRNA. Under optimal conditions, the detection limit of the proposed biosensor was down to 50 aM. It was worth noting that the proposed biosensor exhibited excellent detection performance in a complex serum environment and tumor cell lysates, showing great potential in biosensing and clinical diagnosis.

A disposable and sensitive non-enzymatic glucose sensor based on a 3D-Mn-doped NiO nanoflower-modified flexible electrode.

Herein, nanoflower-shaped Mn-doped NiO nano-enzyme composites with high catalytic performance and excellent conductivity were grown on 3D flexible carbon fiber cloth (CFC) via hydrothermal and calcination methods to construct an efficient flexible glucose-sensitive detection electrode. For electrochemical-based sensors, high conductivity is a prerequisite for reliable data acquisition. To avoid the problems associated with using insulating Nafion or paraffin binders, we adopted a strategy of directly growing Mn-doped NiO onto the electrode surface, thereby avoiding interference due to the oxidization of species present in real samples at higher redox potentials, since Ni2+/Ni3+ has low redox potential. Therefore, the electrode has a linear range of 3-5166 µM for glucose detection, with a detection limit as low as 0.28 µM, showing excellent selectivity and reproducibility. The composite-modified electrode provides accurate detection results with real human serum samples, which are in full agreement with those of commercial blood glucose meters. In addition, we tested the glucose content in tea and sorghum fermentation broth at different stages, further expanding the application range of the Mn-NiO sensors. The nano-enzyme sensor fabricated herein offers a new idea for further integration into wearable flexible electronic devices for accurate glucose detection.

A test strip electrochemical disposable by 3D MXA/AuNPs DNA-circuit for the detection of miRNAs.

The simple and reliable detection of microRNAs is of great significance for studying the biological functions, molecular diagnosis, disease treatment and targeted drug therapy of microRNA. In this study, we introduced a novel Ti3C2Tx (MXene) aerogels (denoted as MXA) composite gold nano-particles (AuNPs)-modified disposable carbon fiber paper (CFP) electrode for the label-free and sensitive detection of miRNA-155. Firstly, in the presence of MXene, graphene oxide (GO) and ethylenediamine (EDA), the 3D MXene hydrogel was formed by self-assembly method, and then adding the freeze-dried 3D MXA dropwise to CFP. Subsequently, electrodepositing AuNPs on the CFP/MXA was done to construct a 3D disposable DNA-circuit test strip with excellent interface. Under the optimum experimental conditions, the detection limit of 3D disposable DNA circuit strip for miRNA-155 was 136 aM (S/N = 3). The CFP/MXA/AuNPs (CMA) electrode also has a wide dynamic range (20 fM to 0.4 µM), with a span of 4 orders of magnitude. Notably, we also tested the practicality of the sensor in 8 clinical samples. The technological innovations in the detection and quantification of microRNA in this work may be helpful to the study new aspects of microRNA biology and the development of diagnosis.

Sandwich-type microRNA biosensor based on graphene oxide incorporated 3D-flower-like MoS2 and AuNPs coupling with HRP enzyme signal amplification.

A sandwich electrochemical biosensing strategy for ultrasensitive detection of miRNA-21 was developed by using graphene oxide incorporated 3D-flower-like MoS2 (3D MoS2-rGO) nanocomposites as the substrate and horseradish peroxidase (HRP)-functionalized DNA strand 1 (S1)-gold nanoparticles (S1-AuNPs-HRP) as signal amplification probes. Herein, 3D MoS2-rGO nanocomposites not only had a large specific surface area and excellent conductivity, but also provided more attachment sites for electrodepositing AuNPs. In the presence of target miRNA, a sandwich structure was formed, and the determination of the miRNA-21 was carried out by measuring the DPV response of H2O2 mediated by hydroquinone (HQ) at a potential of + 0.052 V (vs AgCl reference electrode). Under the optimal experimental conditions, the as-prepared biosensor enabled the ultrasensitive detection of miRNA-21 from 5 fM to 0.5 µM with the low detection limit of 0.54 fM (S/N = 3), comparable or lower than previous reported methods for miRNA-21 detection, which benefited from the synergistic amplification of 3D MoS2-rGO and AuNPs-HRP. The prepared biosensor showed satisfactory selectivity, reproducibility, and stability towards miRNA-21 detection. The biosensor was feasible for accurate and quantitative detection of miRNA-21 in normal human serum samples with RSD below 5.86%, which showed a great potential in clinical analysis and disease diagnosis.

Disposable 3D GNAs/AuNPs DNA-Circuit Strip for miRNAs Dynamic Quantification.

Real-time quantitative monitoring of miRNAs plays an essential role in diagnosis and therapeutics. Herein, a DSN-coupled graphene nanoarray/gold nanoparticles (GNAs/AuNPs) carbon paper (CP) electrode for the dynamic, sensitive, and real-time analysis of miRNAs is reported. GNAs are vertically grown on the conductive CP by radio frequency plasma enhanced chemical vapor deposition, and AuNPs are electrodeposited on CP/GNAs to build a 3D ultrasensitive sensing interface with large specific surface area, good conductivity and biocompatibility. The dynamic quantitative monitoring of microRNA-21 (miR-21) is realized by cyclic voltammetry with a series of different concentrations within 16 min, and this 3D GNAs/AuNPs DNA-circuit strip shows good performance for the simultaneous detection of miR-21 and miR-155, and the detection limits are as low as 21.4 and 30.3 am, respectively. Moreover, comparable detection results are achieved for clinical samples between the proposed sensor and qRT-PCR, suggesting the reliability of the constructed sensor. This ultrasensitive sensing and disposable DNA-circuit strip with 3D structure can efficiently shorten the diffusion distance between reactive biomolecules and the sensing interface, enhance the hybridization of probes and improve the sensitivity of the biosensor, holding great promise for the rapid, quantitative and dynamic monitoring of multiple low concentrations of biomolecules in point-of-care clinical analysis.

Simultaneous detection of dihydroxybenzene isomers in the environment by a free-standing flexible ZnCo2O4 nanoplate arrays/carbon fiber cloth electrode.

The simultaneous determination of dihydroxybenzene isomers is highly valuable for early environmental monitoring, but it is still a challenge. In this work, a free-standing flexible electrode was prepared for the simultaneous detection of hydroquinone (HQ), catechol (CC), and resorcinol (RC). The bimetallic zinc/cobalt zeolitic imidazolate frameworks nanoplate arrays (Zn/Co-ZIF NPAs) grown in situ on the carbon fiber cloth (CFC) was fabricated by a facile static synthesis method, and the porous ternary ZnCo2O4 NPAs derived from Zn/Co-ZIF NPAs were formed by annealing in air. Due to the fast electron transmission, abundant active sites and excellent electrocatalytic properties with enzyme-like kinetic performance of the ZnCo2O4/CFC electrode, the as-proposed sensor showed a wilder linear response (2-500 µM), a lower detection limits (0.03 µM HQ, 0.06 µM CC and 0.15 µM RC) and a higher sensitivity (23.58 µA µM-1 cm-2 HQ, 17.72 µA µM-1 cm-2 CC, and 15.18 µA µM-1 cm-2 RC), respectively. More importantly, the proposed electrochemical sensor exhibited excellent detection performance in complex water samples, providing a strategy for the detection of other toxic substances in the ecological environment.

A portable sensor for glucose detection in Huangshui based on blossom-shaped bimetallic organic framework loaded with silver nanoparticles combined with machine learning.

In this work, we propose a blossom-like Ni, Co bimetallic metal-organic framework (NiCo-MOF) synthesized hydrothermally and decorated with silver nanoparticles (AgNPs) via chemical reduction for electrochemical enzyme-free glucose sensing. The NiCo-MOF nanostructures had large specific surface area and good sensing performance. The AgNPs enhanced the electrochemical performance of the MOF, resulting in excellent electrochemical activity. The sensor exhibited sensitivities of 1191.84 and 271.19 µA mM-1 cm-2 in the linear ranges of 0.005-1.125 and 1.525-5.325 mM, respectively, with a detection limit of 2.3 µM. The sensor was successfully applied for glucose determination in Huangshui (HS) using an artificial neural network as machine learning (ML) model. The R2 value near 1, low RMSE, and high RPD values of the proposed ML model demonstrate its excellent fitting and prediction performance. This will provide a fast and portable intelligent sensing analysis technology for the detection of glucose in HS.

An ultrasensitive electrochemical biosensor for microRNA-21 detection via AuNPs/GAs and Y-shaped DNA dual-signal amplification strategy.

Herein, a gold nanoparticles/graphene aerogels (AuNPs/GAs) modified electrochemical biosensor with catalytic hairpin assembly (CHA) and Y-shaped DNA nanostructure dual-signal amplification approaches for ultrasensitive microRNA-21 (miR-21) detection was successfully constructed, which displayed an ultra-wide detection linear range from 5 fM to 50 nM, as well as a relatively low detection limit (LOD) of 14.70 aM (S/N = 3). Furthermore, the sensing strategy had excellent specificity among highly homologous miRNA family members and exhibited satisfactory analytical performance for miRNA detection.

Duplex-specific nuclease powered 3D DNA walker and quantum dots barcodes for homogeneous electrochemical detection of microRNAs.

Multiplex microRNAs (miRNAs) detection is beneficial for early diagnosis and prognosis of cancer. Herein, duplex-specific nuclease (DSN) powered 3D DNA walker and quantum dots (QDs) barcodes were designed for the simultaneous detection of miRNAs in a homogeneous electrochemical sensor. In the proof-of-concept experiment, the effective active area of the as-prepared graphene aerogel-modified carbon paper (CP-GAs) electrode was ∼14.30 times larger than that of the traditional glassy carbon electrode (GCE), endowing the enhanced capability of loading more metal ions for ultrasensitive detection of miRNAs. In addition, DSN-powered target recycling and DNA walking strategy assured the sensitive detection of miRNAs. After the introduction of magnetic beads (MNs) and electrochemical double enrichment strategies, the integration of triple signal amplification methods yielded good detection results. Under optimal conditions, towards simultaneous detection of microRNA-21 (miR-21) and miRNA-155 (miR-155), a linear range of 10-16-10-7 M and a sensitivity of 10 aM (miR-21) and 2.18 aM (miR-155) were achieved, respectively. It was worth mentioning that the prepared sensor can detect miR-155 down to 0.17 aM, which was also extremely advantageous among the sensors reported so far. What's more, through verification, the prepared sensor had good selectivity and reproducibility, and exhibited good detection ability in complex serum environments, showing great potential in early clinical diagnosis and screening.

Flexible carbon fiber cloth supports decorated with cerium metal- organic frameworks and multi-walled carbon nanotubes for simultaneous on-site detection of Cd2+ and Pb2+ in food and water samples.

The widespread heavy metal pollution endangers human health; hence, accurate on-site detection and quantification of heavy metal content in the surroundings is a vital step in reversing the harmful effect. Herein, an electrochemical sensor based on flexible cerium metal-organic framework@multi-walled carbon nanotubes/carbon cloth (CeMOF@MWCNTs/CC) was constructed for simultaneous on-site detection of Cd2+ and Pb2+ in food and water samples. The rich carboxyl groups of MWCNTs provided abundant sites for the adsorption of Cd2+ and Pb2+, and the mutual conversion of Ce3+ and Ce4+ in CeMOF facilitated the reduction and reoxidation of metal ions. The prepared electrode showed excellent performance in the simultaneous measurement of Cd2+ and Pb2+, with detection limits of 2.2 ppb and 0.64 ppb, respectively. More importantly, the sensing platform has been successfully used to detect simultaneously Cd2+ and Pb2+ in grain and water samples, and the detection results were consistent with the standard methods, showing great potential in environmental monitoring and food safety.

A sensitive enzyme-free electrochemical sensor based on a rod-shaped bimetallic MOF anchored on graphene oxide nanosheets for determination of glucose in huangshui.

In this work, we propose a bimetallic Ni-Co based MOF attached to graphene oxide (GO) by a one-step hydrothermal approach which may be employed as an electrochemical enzyme-free glucose sensor. Due to the obvious synergistic catalysis of Ni and Co, as well as the combination of NiCo-MOF and GO, NiCo-MOF/GO not only enhances energy transfer and electrocatalytic performance but also provides a larger surface area and more active sites. Electrochemical studies show that NiCo-MOF/GO exhibits outstanding electrochemical activity, with a sensitivity of 11 177 µA mM-1 cm-2 and 4492 µA mM-1 cm-2 in the linear ranges of 1-497 µM and 597-3997 µM, a detection limit of 0.23 µM, and a response time of 2 seconds. More importantly, the newly fabricated sensor is successfully applied for glucose determination in huangshui. This method provides a novel strategy for the controlled fermentation process and product quality of Chinese baijiu.

Metal-organic framework-derived porous ternary ZnCo2O4 nanoplate arrays grown on carbon cloth for simultaneous electrochemical determination of ascorbic acid, dopamine, and uric acid.

Metal-organic frameworks derived from ternary metal oxide directly grown on the conductive substrate have attracted great interest in electrochemical sensing. In this work, metal-organic framework-derived ternary ZnCo2O4 nanoplate arrays that were grown on carbon cloth (ZnCo2O4 NA/CC) are fabricated and applied for the electrochemical determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA). Field emission scanning electron microscope (FESEM) reveals that a network-like CC substrate is covered with considerable nanoplate arrays, presenting a large specific area. X-ray photoelectron spectroscopy (XPS) demonstrates the nanoplate arrays to be composed of ZnCo2O4. Benefiting from the unique array morphology and ternary element composition, the ZnCo2O4 NA/CC shows desirable performances for simultaneous detection of AA, DA, and UA. The individual detection limits are 7.14 µM for AA, 0.25 µM for DA, and 0.33 µM for UA. Additionally, the ZnCo2O4 NA/CC is successfully applied for the quantitative determination of AA, DA, and UA in spiked serum samples, showing its great application potential.

MXene-MoS2 heterostructure collaborated with catalyzed hairpin assembly for label-free electrochemical detection of microRNA-21.

Abnormal expression of microRNAs is greatly associated with the occurrence of various cancer types, revealing great potential of microRNA as biomarkers for cancer diagnosis and prognosis. Herein, a MXene-MoS2 heterostructure enhancing electrochemical biosensor coupled with catalytic hairpin assembly (CHA) amplification approach for label-free determination of microRNA-21 (miR-21) was successfully assembled. In particular, the unique micro-nano heterostructure with large specific area and favorable electroconductivity exhibited the ability of excellent confinement effect. Thus, rendered the MXene-MoS2 heterostructure the ability to trigger more target recycling reaction, giving new vitality to the traditional CHA amplification method. Meanwhile, thionine (Thi) and gold nanoparticles (AuNPs) were anchoring at the surface of MXene-MoS2 heterostructure, respectively, empowered the sensor the capability of capture probes fixation and miR-21 label-free determination. When numerous electronegative double-stranded DNA generated, the electron transfer was greatly hindered, resulting in signal decrease. Accordingly, the design denoted a broad dynamic range from 100 fM to 100 nM and a detection limit of about 26 fM, comparable or lower than previous reported methods for miR-21 detection. Furthermore, the sensing platform supplied satisfactory selectivity, reproducibility and stability towards the miR-21 detection. The real sample determination also showed a promising performance under clinical circumstance. Finally, from the clinical standpoint, the proposed biosensor is a considerable platform toward early disease detection and monitoring.

A novel electrochemical sensor for simultaneous detection of Cd2+ and Pb2+ by MXene aerogel-CuO/carbon cloth flexible electrode based on oxygen vacancy and bismuth film.

Herein, a novel MXene aerogel-CuO/carbon cloth (MXA-CuO/CC) electrochemical sensor was constructed, and the synergistic adsorption of heavy metal ions by oxygen vacancies and Bi (III) was investigated with Cd2+ and Pb2+ as detection targets. The oxygen vacancies of CuO have a strong affinity for heavy metal ions, which promoted the adsorption of Cd2+ and Pb2+ on the electrode surface. In addition, the introduced Bi (III) can form alloys with heavy metal ions, which effectively enhanced the adsorption capacity of sensing electrodes for Cd2+ and Pb2+. Differential pulse anodic stripping voltammetry (DPASV) was used to study the performance of MXA-CuO/CC sensitive electrode for the detection of Cd2+ and Pb2+ separately and simultaneously. The constructed sensing electrode has excellent detection performance, and can detect Cd2+ (4 µg L-1- 800 µg L-1) and Pb2+ (4 µg L-1- 1200 µg L-1) simultaneously with detection limits of 0.3 µg L-1 (Cd2+) and 0.2 µg L-1 (Pb2+), respectively. The proposed sensor electrode also has good anti-interference performance, excellent stability and reproducibility. It is worth mentioning that the proposed method can accurately detect Cd2+ and Pb2+ in food and water samples, which is consistent with the detection results of inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectroscopy (AAS).

Flexible nickel-cobalt double hydroxides micro-nano arrays for cellular secreted hydrogen peroxide in-situ electrochemical detection.

It is critical to detect cellular secreted hydrogen peroxide (H2O2) in situ for clinical diagnosis, biomedical research and cancer treatment. Herein, the electrochemical determination of H2O2 released by cancer cells grown on the surface of carbon cloth supported NiCo-DH/AuPt micro-nano arrays to elevate the capability of in situ signal collection was achieved. NiCo-DH/AuPt @CC was successfully prepared using the cobalt based metal-organic framework (Co-MOF) as a presoma after in situ etching growth onto the CC and electrodeposition of gold and platinum nanoparticles (AuPt NPs). Under the optimal conditions, owing to the excellent catalytic efficiency of NiCo-DH and AuPt NPs, the designed sensor performs a relatively wider linear range to H2O2 concentration from 10 µM to 22.08 mM, and the limit of detection is 0.145 µM. Accordingly, the as-prepared sensing system was also applied to determine H2O2 secreted by living cells which grown on the surface of NiCo-DH/AuPt @CC with satisfactory consequences. In possession of the superior sensitivity, selectivity, reproducibility, the NiCo-DH/AuPt @CC is a luciferous platform for the real time detection of H2O2 in the area of biomedical and clinical diagnosis.

Au doped poly-thionine and poly-m-Cresol purple: Synthesis and their application in simultaneously electrochemical detection of two lung cancer markers CEA and CYFRA21-1.

The single tumor antigen does not have enough specificity and sensitivity to meet the accurate diagnostic criteria, and single antigen measurement is often prone to false negative and false positive perceptions. Therefore, simultaneous monitoring of multiple tumor antigens related to precise tumors in serum samples has become an interesting and encouraging analytical method. In this work, we demonstrated an electrochemical biosensor based on multiple signal amplification methods, and simultaneously detect two lung cancer markers, cytokeratin 19 fragment 21-1 (CYFRA21-1) and carcinoembryonic antigen (CEA). Large number of gold nanoparticles distributed on the surface of three-dimensional graphene (3D-G), poly-thionine (pThi) and poly-m-Cresol purple (pMCP) not only provide large number of binding sites for antigen and antibody, but also enhance the electrochemical signal of biosensor and greatly improves the sensitivity of the biosensor. The detection linear range extends from 0.5 to 200 ng/mL, with low detection limits (LOD) of 0.18 ng/mL and 0.31 ng/mL for CYFRA21-1 and CEA, respectively. Overall, this kind of immune-biosensor provides great potential for the simultaneous detection of multiple targets in early clinical diagnosis.

A disposable and sensitive non-enzymatic glucose sensor based on 3D graphene/Cu2O modified carbon paper electrode.

Herein, a three-dimensional graphene wall (GWs) and nano-Cu2O modified carbon fiber paper (CFP) electrode were used to develop a disposable and sensitive non-enzymatic glucose sensor. This sensing interface of GWs/Cu2O consists of an interlaced CFP on which intercrossed graphene walls (GWs) were vertically tethered in situ by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD), and Cu2O nanoparticles (NPs) were evenly grew on the 3D GWs layer and skeleton through the complete thermal decomposition of copper acetate (Cu (CH3COO)2) at high temperature. The CFP/GWs/Cu2O shows a large specific surface area and rich solution diffusion channels, which can expose more catalytic active sites without Nafion fixation film, thus greatly improving the electrocatalytic performance of this glucose sensor. The CFP/GWs/Cu2O sensor shows excellent catalytic performance to glucose with a linear detection range of 0.5 µM-5166 µM, LOD of 0.21 µM, and response time <4 s. This kind of disposable and sensitive electrode can capable of controlling uniform growth and accurate quantification, and has great development potential in the field of medical detection and the commercialization of wearable sensors.

An enzyme-free sensitive electrochemical microRNA-16 biosensor by applying a multiple signal amplification strategy based on Au/PPy-rGO nanocomposite as a substrate.

In present study, a sensitive and effective electrochemical microRNA (miRNA) sensing platform is successfully developed by integrating gold nanoparticles/polypyrrole-reduced graphene oxide (Au/PPy-rGO), catalyzed hairpin assembly (CHA) and hybridization chain reaction (HCR) multiple signal amplification strategy. Firstly, Au/PPy-rGO was employed onto a bare GCE by electrodeposition that can greatly enhanced conductivity and effectively immobilize probes. Then, the thiolated capture probes (SH-CP) were self-assembled on the Au/PPy-rGO modified GCE via Au-S bond. The target miRNA triggered the dynamic assembly of the two hairpin substrates (H1 and H2), leading to the cyclicality of the target miRNA and the formation of H1-H2 complexes without the assistance of enzyme. Subsequently, the newly emerging DNA fragment of H2 triggered the HCR when a mixture solution (hairpins H3 and H4) and produced dsDNA polymers. Finally, a substantial amount of methylene blue (MB) as signal indicator was intercalated into the minor groove of the long dsDNA polymers to achieve detected electrochemical signal. The fabricated sensor is able to detect miRNA-16 (model target) with concentration range from 10 fM to 5 nM with a low detection limit (LOD) of 1.57 fM (S/N = 3). Current research suggests that the developed multiple signal amplification platform has a great potential for the applications in the field of biomedical research and clinical analysis.