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.

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.

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.

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.

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.

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.

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.