A dual-amplification mode and Cu-based metal-organic frameworks mediated electrochemical biosensor for sensitive detection of microRNA

Development of an electrochemical sensor based on Ni-Bio-MOF and a molecular imprinted polymer for determination of diclofenac: electrochemical and DFT investigations

In this work, a metal-organic nickel framework (Ni-MOF) modified with a biological ligand (asparagine) (Ni-Bio-MOF) was synthesized by a hydrothermal method. Asparagine is believed to create defects on the surface of the MOF, thereby increasing its electrocatalytic activity. Then, a Diclofenac (DCF) polymer imprinted with l-methionine (PL-Met) was electrodeposited on a carbon paste electrode (CPE)/Ni-Bio-MOF and used as a new electrochemical sensor for highly selective and sensitive detection of DCF in biological and pharmaceutical samples. The Ni-Bio-MOF/MIP-PL-Met nanocomposite was characterized using the following techniques: FT-IR, FE-SEM, TEM, HR-TEM, XRD, XPS, and EDX. The electrochemical properties and performance of the sensor for the electrooxidation of DCF were assessed using CV, DPV, and EIS techniques. The electrochemical behavior of CPE/Ni-Bio-MOF/MIP-PL-Met and non-imprinted polymer (NIP) with an imprinting factor of 6.64 was investigated, and the influencing parameters in DCF measurement were optimized by cyclic voltammetry (CV). This modified sensor showed three dynamic ranges at 1.0-500.0 pM, 1.0-1000.0 nM, and 1.0-1000.0 μM of DCF with a limited detection (LOD) of 0.17 pM, sensitivity of 2015.5 μA μM-1 cm-2, relative standard deviation (RSD) of 3.3%, and reproducibility of 96.2%. Real samples of healthy human blood serum and DCF tablets were used to evaluate the practical application of the CPE/Ni-Bio-MOF/MIP-PL-Met electrochemical sensor. This method is simple, low-cost, with good limited detection, high sensitivity, and selectivity. The interactions of PL-Met with DCF were studied at the B3LYP/6-311++G(d,p) level of theory in both gaseous and aqueous phases. Additionally, the computational methodology investigated the thermodynamic stability of the proposed configurations and the role of hydrogen bonds in this system.

Dual-mode strategy for the determination of vanillin in milk-based products based on molecular-imprinted nanozymes

The inclusion of artificial food additives such as vanillin in infant formula should be strictly monitored to mitigate potential negative impacts on the dietary habits and health of infants. This raises a necessity of an accurate inspection and prompt feedback of vanillin in infant foods. In this study, colorimetric and fluorescent dual-mode assays based on CuNS/Fe3O4@MIPs were established to detect vanillin selectively and sensitively. Quantification of vanillin could be achieved with linear detection ranges of 1-100 μM and 1-150 μM for the colorimetric and fluorescent assays respectively. The corresponding detection limits were 0.11 and 0.10 μM respectively. The CuNS/Fe3O4@MIPs-based dual-mode assays exhibited good selectivity and stability for vanillin detection in infant formula and milk-based foods. Hence, this method can serve as a reliable tool for the cost-saving, effective and quantitative determination of vanillin in infant foods, with the potential to replace conventional instrumental analysis.

Machine Learning-Aided Intelligent Monitoring of Multivariate miRNA Biomarkers Using Bipolar Self-powered Sensors

Breast cancer has become the most prevalent form of cancer among women on a global scale. The early and timely diagnosis of breast cancer is of the utmost importance for improving the survival rate of patients with this disease. The occurrence of breast cancer is typically accompanied by the dysregulation of multiple microRNA (miRNA) expression profiles. Consequently, simultaneous detection of multiple miRNAs is vital for the early and accurate diagnosis of breast cancer. In this study, a bipolar self-powered sensor was developed for the simultaneous detection of miRNA-451 and miRNA-145 breast cancer biomarkers based on the specific catalytic properties of enzymes. Selenides with a microporous hollow cubic structure were designed and prepared, which can markedly enhance the enzyme load and activity, as well as detection sensitivity, due to their extensive surface area and three-dimensional porous channel. The designed bipolar self-powered sensor platform is integrated into the commercial chip, and the signal is presented in the smartphone interface, thereby enabling real-time and continuous monitoring. Furthermore, machine learning was utilized to predict miRNA detection, which encompasses numerous stages, including data collection, feature extraction, model training, and validation. In comparison to the limited sensing efficiency of self-powered biosensors driven by enzyme biofuel cells, our bipolar self-powered sensor achieved simultaneous quantitative analysis of multiple miRNA targets, thereby providing a robust tool for a more comprehensive understanding of miRNA function and its association with cancers.

A ratiometric electrochemical aptasensor for Ochratoxin A detection based on electroactive Cu-MOF and DNA conjugates resembling the structure of Bidens pilosa

BACKGROUND

Ochratoxin A (OTA) represents a naturally occurring mycotoxin with a serious hazard to the health of individuals because of carcinogenic and teratogenic properties. To date, various analytical methods have been developed for the detection of OTA, among which aptamer-based electrochemical sensing has attracted significant attention due to its rapidity and high sensitivity. As a subtype of aptamer-based electrochemical sensing, ratiometric electrochemical methods further exhibit excellent anti-interference capability. However, their analytical performance remains limited by the labor-intensive and resource-consuming modification of electroactive signal molecules, as well as the restricted specific surface area of the electrodes.

RESULT

Here, we develop a ratiometric electrochemical aptasensor functionalized with Bidens pilosa-like DNA-gold structures and copper-based metal-organic frameworks (Cu-MOFs) for OTA detection. Cu-MOFs served as a substrate for electrode modification, performing two key roles: 1) providing a large surface area for aptamer immobilization, and 2) generating one current signal. Double-stranded DNA-gold nanoparticles (dsDNA-AuNPs) were assembled through Au-S bonding. The dsDNA-AuNPs conjugates, structurally resembling Bidens pilosa, could load more dsDNA and connect to Cu-MOFs via π-π stacking. When OTA was present, the aptamer-OTA complex was stripped from the aptasensor, reducing the amount of Fc-Apt, thus decreasing the corresponding Fc current (IFc). Simultaneously, the decreased interfacial resistance caused an increase in the Cu-MOF current (ICu), providing the decreased IFc/ICu ratio as a quantitative indicator. The aptasensor exhibited a linear detection range from 0.01 ng mL-1 to 300 ng mL-1, with a detection limit of 0.002 ng mL-1 for OTA.

SIGNIFICANCE

The developed electrochemical ratiometric aptasensor demonstrated high reproducibility and stability, and it was successfully applied to maize sample analysis, underscoring its practical applicability. Moreover, it provides a promising strategy for the application of Cu-MOF-based electrochemical aptasensors. Furthermore, the modification procedures of the developed aptasensor were simplified by preparing dsDNA-AuNPs in solution rather than assembling them step-by-step on the electrode surface.

Magnetic MOF-based sensing platform integrated with graphene field-effect transistors for ultrasensitive detection of infectious disease

The development of highly sensitive methods for detecting infectious diseases is crucial for preventing disease spread. In this study, a novel sensing platform for detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pathogens was developed by combining a magnetic metal-organic framework (Fe3O4@MIL-100) with graphene field-effect transistors (GFET). The Fe3O4@MIL-100 magnetic MOF was functionalized with SARS-CoV-2-specific antibodies, enabling highly selective pathogen capture in a phosphate-buffered solution. Following magnetic separation, the captured pathogens were detected using GFETs, with a linear detection range of 1 ag/mL to 10 ng/mL and a detection limit as low as 8.60 ag/mL. Furthermore, the platform has been successfully applied to human serum samples, highlighting its remarkable potential for practical application.

Synergistic powering of DNA walker movement by endogenous dual enzymes for constructing dual-mode biosensors

To achieve highly sensitive and reliable detection of apurinic/apyrimidinic endonuclease 1 (APE1), a critical cancer diagnostic biomarker, we designed a DNA walker-based dual-mode biosensor, utilizing cellular endogenous dual enzymes (APE 1 and Flap endonuclease 1 (FEN 1)) to collaborate in activating and propelling DNA walker motion on DNA-functionalized Au nanoparticles. Incorporating both fluorescence and electrochemical detection modes, this system leverages signal amplification from DNA walker movement and cascade amplification through tandem hybridization chain reactions (HCR), achieving highly sensitive detection of APE 1. In the fluorescence mode, continuous DNA walker movement, initiated by APE1 and driven by FEN1, generates a robust signal response within a concentration range of 0.01-500 U mL-1, presenting a good linearity in the concentration range of 0.01-10 U mL-1, with a detection limit of 0.01 U mL-1. In the electrochemical detection module, the cascade upstream DNA walker and downstream HCR dual signal amplification strategy further enhances the sensitivity of APE1 detection, extending the linear range to 0.01-50 U mL-1 and reducing the detection limit to 0.002 U mL-1. Rigorous validation demonstrates the biosensor's specificity and anti-interference capability against multiple enzymes. Moreover, it effectively distinguishes cancer cells from normal cell lysates, exhibiting excellent stability and consistency in the dual-modes. Overall, our findings underscore the efficacy of the developed dual-mode biosensor for detecting APE1 in serum and cell lysates samples, indicating its potential for clinical applications in disease diagnosis.

Electrochemiluminescence Biosensor Based on a Duplex-Specific Nuclease and Dual-Output Toehold-Mediated Strand Displacement Cascade Amplification Strategy for Sensitive Detection of MicroRNA-499

The timely and accurate diagnosis of acute myocardial infarction (AMI) is of great significance to reduce mortality and morbidity associated with the condition. Herein, we developed an electrochemiluminescence (ECL) biosensor for the detection of the potential AMI biomarker microRNA-499 (miRNA-499), which was based on duplex-specific nuclease-assisted target recycling and dual-output toehold-mediated strand displacement (TMSD). First, miRNA-499 was converted into a large amount of single-stranded DNA through the DSN-assisted target recycling, which was further incubated with the DNA triple-stranded complex (S) to implement TMSD cycles. Thus, the Ru(bpy)32+-labeled signal strands were released and captured by the capture probe on the electrode surface, resulting in an intense ECL signal. Owing to the prominent cascade signal amplification, the constructed biosensor exhibited a good linear response to miRNA-499 within the range of 100 aM-100 pM with a detection limit of 69.99 aM. Furthermore, it demonstrated superior selectivity, stability, and reproducibility. In addition, the biosensor was successfully applied to detect miRNA-499 in real human serum samples, demonstrating its potential for nucleic acid detection in the early diagnosis of diseases.

An ultrasensitive electrochemical biosensor with dual-amplification mode and enzyme-deposited silver for detection of miR-205-5p

An electrochemical biosensor based on dual-amplified nucleic acid mode and biocatalytic silver deposition was constructed using catalytic hairpin assembly-hybrid chain reaction (CHA-HCR). The electrochemical detection of silver on the electrode by linear sweep voltammetry (LSV) can be utilized to quantitatively measure miR-205-5p since the amount of silver deposited on the electrode is proportional to the target nucleic acid. The current response values exhibit strong linearity with the logarithm of miR-205-5p concentrations ranging from 0.1 pM to 10 μM, and the detection limit is 28 fM. A consistent trend was found in the results of the qRT-PCR and electrochemical biosensor techniques, which were employed to determine the total RNA recovered from cells, respectively. Moreover, the constructed sensor was used to assess miR-205-5p on various cell counts, and the outcomes demonstrated the excellent analytical efficiency of the proposed strategy. The recoveries ranged from 97.85% to 115.3% with RSDs of 2.251% to 4.869% in human serum samples. Our electrochemical biosensor for miR-205-5p detection exhibits good specificity, high sensitivity, repeatability, and stability. It is a potentially useful sensing platform for tumor diagnosis and tumor type identification in clinical settings.

Recent Advances on the Metal-Organic Frameworks-Based Biosensing Methods for Cancer Biomarkers Detection

Sensitive and selective detection of cancer biomarkers is crucial for early diagnosis and treatment of cancer, one of the most dangerous diseases in the world. Metal-organic frameworks (MOFs), a class of hybrid porous materials fabricated through the assembly of metal ions/clusters and organic ligands, have attracted increasing attention in the sensing of cancer biomarkers, due to the advantages of adjustable size, high porosity, large surface area and ease of modification. MOFs have been utilized to not only fabricate active sensing interfaces but also arouse a variety of measurable signals. Several representative analytical technologies have been applied in MOF-based biosensing strategies to ensure high detection sensitivity toward cancer biomarkers, such as fluorescence, electrochemistry, electrochemiluminescence, photochemistry and colorimetric methods. In this review, we summarized recent advances on MOFs-based biosensing strategies for the detection of cancer biomarkers in recent three years based on the categories of metal nodes, and aimed to provide valuable references for the development of innovative biosensing platform for the purpose of clinical diagnosis.

Bioactive Metal-Organic Frameworks as a Distinctive Platform to Diagnosis and Treat Vascular Diseases

Vascular diseases (VDs) pose the leading threat worldwide due to high morbidity and mortality. The detection of VDs is commonly dependent on individual signs, which limits the accuracy and timeliness of therapies, especially for asymptomatic patients in clinical management. Therefore, more effective early diagnosis and lesion-targeted treatments remain a pressing clinical need. Metal-organic frameworks (MOFs) are porous crystalline materials formed by the coordination of inorganic metal ions and organic ligands. Due to their unique high specific surface area, structural flexibility, and functional versatility, MOFs are recognized as highly promising candidates for diagnostic and therapeutic applications in the field of VDs. In this review, the potential of MOFs to act as biosensors, contrast agents, artificial nanozymes, and multifunctional therapeutic agents in the diagnosis and treatment of VDs from the clinical perspective, highlighting the integration between clinical methods with MOFs is generalized. At the same time, multidisciplinary cooperation from chemistry, physics, biology, and medicine to promote the substantial commercial transformation of MOFs in tackling VDs is called for.

A new strategy based on a cascade amplification strategy biosensor for on-site eDNA detection and outbreak warning of crown-of-thorns starfish

Population outbreaks of the crown-of-thorns starfish (COTS) seriously threaten the sustainability of coral reef ecosystems. However, traditional ecological monitoring techniques cannot provide early warning before the outbreaks, thus preventing timely intervention. Therefore, there is an urgent need for a more accurate and faster technology to predict the outbreaks of COTS. In this work, we developed an electrochemical biosensor based on a programmed catalytic hairpin assembly (CHA) and hybridization chain reaction (HCR) cyclic amplification strategy for sensitive and selective detection of COTS environmental DNA (eDNA) in water bodies. This biosensor exhibited excellent electrochemical characteristics, including a low limit of detection (LOD = 18.4 fM), low limit of quantification (LOQ = 41.1 fM), and wide linear range (50 fM - 10 nM). The biosensing technology successfully allowed the detection of COTS eDNA in the aquarium environment, and the results also demonstrated a significant correlation between eDNA concentration and COTS number (r = 0.990; P < 0.001). The reliability and accuracy of the biosensor results have been further validated through comparison with digital droplet PCR (ddPCR). Moreover, the applicability and accuracy of the biosensor were reconfirmed in field tests at the COTS outbreak site in the South China Sea, which has shown potential application in dynamically monitoring the larvae before the COTS outbreak. Therefore, this efficient electrochemical biosensing technology offers a new solution for on-site monitoring and early warning of the COTS outbreak.

Signal amplification strategy of DNA self-assembled biosensor and typical applications in pathogenic microorganism detection

Biosensors have emerged as ideal analytical devices for various bio-applications owing to their low cost, convenience, and portability, which offer great potential for improving global healthcare. DNA self-assembly techniques have been enriched with the development of innovative amplification strategies, such as dispersion-to-localization of catalytic hairpin assembly, and dumbbell hybridization chain reaction, which hold great significance for building biosensors capable of realizing sensitive, rapid and multiplexed detection of pathogenic microorganisms. Here, focusing primarily on the signal amplification strategies based on DNA self-assembly, we concisely summarized the strengths and weaknesses of diverse isothermal nucleic acid amplification techniques. Subsequently, both single-layer and cascade amplification strategies based on traditional catalytic hairpin assembly and hybridization chain reaction were critically explored. Furthermore, a comprehensive overview of the recent advances in DNA self-assembled biosensors for the detection of pathogenic microorganisms is presented to summarize methods for biorecognition and signal amplification. Finally, a brief discussion is provided about the current challenges and future directions of DNA self-assembled biosensors.

DNAzyme-driven bipedal DNA walker and catalytic hairpin assembly multistage signal amplified electrochemical biosensor based on porous AuNPs@Zr-MOF for detection of Pb2

As a highly toxic and refractory heavy metal contaminant, Pb2+ seriously endangers human health. The problems of low sensitivity and high cost of signal labeling widely exist in common electrochemical biosensors. Herein, a Pb2+ electrochemical biosensor was constructed using a DNAzyme-driven bipedal DNA Walker and catalytic hairpin assembly as the multistage signal amplification strategy. Compared with Zr-MOF, AuNPs@Zr-MOF has a larger porosity and specific surface area, which can effectively load MB to amplify the current signal. Pb2+ can trigger a dual signal amplification reaction to gradually accumulate the signal of methylene blue/gold nanoparticle @ zirconium-based metal organic frameworks (MB/AuNPs@Zr-MOF) on the electrode. The ingeniously designed sensing strategy realized the analysis of Pb2+ with a wide linear range from 0.05 to 1000 nmol/L and a lower limit of detection (LOD) of 4.65 pmol/L. In addition, the sensor has strong anti-interference ability and can accurately detect Pb2+ in various food samples.

Ultrasensitive reporter DNA sensors built on nucleic acid amplification techniques: Application in the detection of trace amount of protein

The detection of protein is of great significance for the study of biological physiological function, early diagnosis of diseases and drug research. However, the sensitivity of traditional protein detection methods for detecting trace amount of proteins was relatively low. By integrating sensitive nucleic acid amplification techniques (NAAT) with protein detection methods, the detection limit of protein detection methods can be substantially improved. The DNA that can specifically bind to protein targets and convert protein signals into DNA signals is collectively referred to reporter DNA. Various NAATs have been used to establish NAAT-based reporter DNA sensors. And according to whether enzymes are involved in the amplification process, the NAAT-based reporter DNA sensors can be divided into two types: enzyme-assisted NAAT-based reporter DNA sensors and enzyme-free NAAT-based reporter DNA sensors. In this review, we will introduce the principles and applications of two types of NAAT-based reporter DNA sensors for detecting protein targets. Finally, the main challenges and application prospects of NAAT-based reporter DNA sensors are discussed.

Recent Advances in Metallic Nanostructures-assisted Biosensors for Medical Diagnosis and Therapy

The field of nanotechnology has witnessed remarkable progress in recent years, particularly in its application to medical diagnosis and therapy. Metallic nanostructures-assisted biosensors have emerged as a powerful and versatile platform, offering unprecedented opportunities for sensitive, specific, and minimally invasive diagnostic techniques, as well as innovative therapeutic interventions. These biosensors exploit the molecular interactions occurring between biomolecules, such as antibodies, enzymes, aptamers, or nucleic acids, and metallic surfaces to induce observable alterations in multiple physical attributes, encompassing electrical, optical, colorimetric, and electrochemical signals. These interactions yield measurable data concerning the existence and concentration of particular biomolecules. The inherent characteristics of metal nanostructures, such as conductivity, plasmon resonance, and catalytic activity, serve to amplify both sensitivity and specificity in these biosensors. This review provides an in-depth exploration of the latest advancements in metallic nanostructures-assisted biosensors, highlighting their transformative impact on medical science and envisioning their potential in shaping the future of personalized healthcare.

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.

Self-accelerated DNA walker mediated electrochemical biosensor for rapid and ultrasensitive detection of microRNA

Herein, we developed a novel three-dimensional (3D) self-accelerated DNA walker (SADW) which progressively expedite walking rate by unlocking the more walking arm continuously in walker process to construct electrochemical biosensor for ultrasensitive detection of microRNA. Particularly, we skillfully introduced a target analogue sequence in the double-loop hairpin, which could be released in the walking process of SADW, then rapidly activating more silenced walking strands to achieve the continuous self-acceleration, resulting in the expedited reaction rate. Surprisingly, the average reaction rate of SADW was quite higher than that of traditional 3D self-circulating DNA walkers (DW) under pretty low target miRNA concentration, which is ascribed to the outstanding acceleration process of the SADW, readily conquering the major predicaments of DW in detecting target with traces concentration: slow reaction rate and low sensitivity. This way, the elaborated SADW is favorably applied in the ultrasensitive and rapid detection of miRNA-21 in tumor cancer cell lysates with a detection limit down to 5.81 aM which was far from lower than the detection limit of DW. This approach develops the novel generation of widespread strategy for the applications in clinic diagnose, biosensing assay, and DNA nanobiotechnology.

Electrochemical detection of glycoproteins using boronic acid-modified metal-organic frameworks as dual-functional signal reporters

The sensitive analysis of glycoproteins is of great importance for early diagnosis and prognosis of diseases. In this work, a sandwich-type electrochemical aptasensor was developed for the detection of glycoproteins using 4-formylphenylboric acid (FPBA)-modified Cu-based metal-organic frameworks (FPBA-Cu-MOFs) as dual-functional signal probes. The target captured by the aptamer-modified electrode allowed the attachment of FPBA-Cu-MOFs based on the interaction between boronic acid and glycan on glycoproteins. Large numbers of Cu2+ ions in FPBA-Cu-MOFs produced an amplified signal for the direct voltammetric detection of glycoproteins. The electrochemical aptasensor showed a detection limit as low as 6.5 pg mL-1 for prostate specific antigen detection. The method obviates the use of antibody and enzymes for molecular recognition and signal output. The dual-functional MOFs can be extended to the design of other biosensors for the determination of diol-containing biomolecules in clinical diagnosis.

Biorecognition element-free electrochemical detection of recombinant glycoproteins using metal-organic frameworks as signal tags

Accurate and sensitive determination of recombinant glycoproteins is in great demand for the treatment of anemia-induced chronic kidney disease and the illegal use of doping agents in sports. In this study, an antibody and enzyme-free electrochemical method for the detection of recombinant glycoproteins was proposed via the sequential chemical recognition of hexahistidine (His₆) tag and glycan residue on the target protein under the cooperation interaction of nitrilotriacetic acid (NTA)-Ni²⁺complex and boronic acid, respectively. Specifically, NTA-Ni²⁺ complex-modified magnetic beads (MBs-NTA-Ni²⁺) are employed to selectively capture the recombinant glycoprotein through the coordination interaction between His₆ tag and NTA-Ni²⁺ complex. Then, boronic acid-modified Cu-based metal-organic frameworks (Cu-MOFs) were recruited by glycans on the glycoprotein via the formation of reversible boronate ester bonds. MOFs with abundant Cu²⁺ ions acted as efficient electroactive labels to directly produce amplified electrochemical signals. By using recombinant human erythropoietin as a model analyte, this method showed a wide linear detection range from 0.01 to 50 ng/mL and a low detection limit of 5.3 pg/mL. With the benefits from the simple operation and low cost, the stepwise chemical recognition-based method shows great promise in the determination of recombinant glycoproteins in the fields of biopharmaceutical research, anti-doping analysis and clinical 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 E^OCV 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.

A dual-targeting nanobiosensor for Gender Determination applying Signal Amplification Methods and integrating Fluorometric Gold and Silver Nanoclusters

A dual-targeting nanobiosensor has been developed for the simultaneous detection of AMELX and AMELY genes based on the different fluorescence signals emitted from gold and silver nanoclusters, AuNCs and AgNCs respectively. In our design, both catalytic hairpin assembly (CHA) and hybridization chain reaction (HCR) have been used as isothermal, enzyme-free and simple methods for signal's amplification. The working principle is based on the initiation of a cascade of CHA-HCR reactions when AMELX is present, in which AuNCs, synthesized on the third hairpin, are aggregated on the surface of the dsDNA product, performing the phenomenon of aggregation induced emission (AIE) and enhancing their fluorescence signal. On the other hand, the presence of the second target, AMELY, is responsible for the enhancement of the fluorescence signal corresponding to AgNCs by the same phenomenon, via hybridizing to the free end of the dsDNA formed and at the same time to the probe of silver nanoclusters fixing it closer to the surface of the dsDNA product. Such a unique design has the merits of being simple, inexpensive, specific and stable and presents rapid results. The detection limits of this assay for AMELX and AMELY are as low as 3.16 fM and 23.6 fM respectively. Moreover, this platform showed great performance in real samples. The design has great promise for the application of dual-targeting nanobiosensors to other biomarkers.

Polyhedral Au Nanoparticle/MoOx Heterojunction-Enhanced Ultrasensitive Dual-Mode Biosensor for miRNA Detection Combined with a Nonenzymatic Cascade DNA Amplification Circuit

A novel homologous surface-enhanced Raman scattering (SERS)-electrochemical (EC) dual-mode biosensor based on a 3D/2D polyhedral Au nanoparticle/MoO_x nanosheet heterojunction (PAMS HJ) and target-triggered nonenzyme cascade autocatalytic DNA amplification (CADA) circuit was constructed for highly sensitive detection of microRNA (miRNA). Mixed-dimensional heterostructures were prepared by in situ growth of polyhedral Au nanoparticles (PANPs) on the surface of MoO_x nanosheets (MoO_x NSs) via a seed-mediated growth method. As a detection substrate, the resulting PAMS HJ shows the synergistic effects of both electromagnetic and chemical enhancements, efficient charge transfer, and robust stability, thus achieving a high SERS enhancement factor (EF) of 4.2 × 10⁹ and strong EC sensing performance. Furthermore, the highly efficient molecular recognition between the target and smart lock probe and the gradually accelerated cascade amplification reaction further improved the selectivity and sensitivity of our sensing platform. The detection limits of miRNA-21 in SERS mode and EC mode were 0.22 and 2.69 aM, respectively. More importantly, the proposed dual-mode detection platform displayed excellent anti-interference and accuracy in the analysis of miRNA-21 in human serum and cell lysates, indicating its potential as a reliable tool in the field of biosensing and clinical analysis.

A novel detection of MicroRNA based on homogeneous electrochemical sensor with enzyme-assisted signal amplification

Rapid and sensitive detection of microRNAs is of great importance in biological researches and cancer diagnosis. Herein, we proposed a novel homogeneous electrochemical sensor to detect microRNA-21 (miRNA-21) using functionalized magnetic nanoparticles combined with enzyme-assisted signal amplification. The biotinylated capture probe (CP) labeled magnetic nanoparticles can capture miRNA-21 and introduce streptavidin-conjugated hydroxyapatite (HAP) nanoparticles. In the presence of miRNA-21, hybridization between RNA and DNA results in the formation of RNA/DNA duplexes, and then duplex-specific nuclease (DSN) cleave the duplexes to digest the capture chain and release the miRNA-21 in a loop. Meanwhile, the HAP nanoparticles strip from the magnetic nanoparticles and electrochemical signal by the reaction of HAP with molybdate is changed. The current variation before and after incubation with miRNA-21 is linearly correlated with the miRNA-21 concentration between 1 aM and 1 pM with a low detection limit (LOD) of 0.27 aM. Remarkably, the expression of miRNA-21 in human serum and different cell lysate was successfully performed, which fully demonstrates the great practical potentials in biomedical diagnostics and clinical therapeutics.

Dual-mode biosensor platform based on synergistic effects of dual-functional hybrid nanomaterials

Detection of biomarkers is very vital in the prevention, diagnosis and treatment of diseases. However, due to the poor accuracy and sensitivity of the constructed biosensors, we are now facing great challenges. In addressing these problems, nanohybrid-based dual mode biosensors including optical-optical, optical-electrochemical and electrochemical-electrochemical have been developed to detect various biomarkers. Integrating the merits of nanomaterials with abundant active sites, synergy and excellent physicochemical properties, many bi-functional nanohybrids have been reasonable designed and controllable preparation, which applied to the construction dual mode biosensors. Despite the significant progress, further efforts are still needed to develop dual mode biosensors and ensure their practical application by using portable digital devices. Therefore, the present review summarizes an in-depth evaluation of the bi-functional nanohybrids assisted dual mode biosensing platform of biomarkers. We are hoping this review could inspire further concepts in developing novel dual mode biosensors for possible detection application.

Recent Developments in the Design and Fabrication of Electrochemical Biosensors Using Functional Materials and Molecules

Electrochemical biosensors are superior technologies that are used to detect or sense biologically and environmentally significant analytes in a laboratory environment, or even in the form of portable handheld or wearable electronics. Recently, imprinted and implantable biosensors are emerging as point-of-care devices, which monitor the target analytes in a continuous environment and alert the intended users to anomalies. The stability and performance of the developed biosensor depend on the nature and properties of the electrode material or the platform on which the biosensor is constructed. Therefore, the biosensor platform plays an integral role in the effectiveness of the developed biosensor. Enormous effort has been dedicated to the rational design of the electrode material and to fabrication strategies for improving the performance of developed biosensors. Every year, in the search for multifarious electrode materials, thousands of new biosensor platforms are reported. Moreover, in order to construct an effectual biosensor, the researcher should familiarize themself with the sensible strategies behind electrode fabrication. Thus, we intend to shed light on various strategies and methodologies utilized in the design and fabrication of electrochemical biosensors that facilitate sensitive and selective detection of significant analytes. Furthermore, this review highlights the advantages of various electrode materials and the correlation between immobilized biomolecules and modified surfaces.

Recent progress of metal-organic frameworks as sensors in (bio)analytical fields: towards real-world applications

The deployment of metal-organic frameworks (MOFs) in a plethora of analytical and bioanalytical applications is a growing research area. Their unique properties such as high but tunable porosity, well-defined channels or pores, and ease of post-synthetic modification to incorporate additional functional units make them ideal candidates for sensing applications. This is possible because the interaction of analytes with a MOF often results in a change in its structure, eventually leading to a modification of the intrinsic physicochemical properties of the MOF which is then transduced into a measurable signal. The high porosity allows for the adsorption of analytes very efficiently, while the tunable pore sizes/nature and/or installation of specific recognition groups allow modulating the affinity towards different classes of compounds, which in turn lead to good sensor sensitivity and selectivity, respectively. Some figures are given to illustrate the potential of MOF-based sensors in the most relevant application fields, and future challenges and opportunities to their possible translation from academia (i.e., laboratory testing of MOF sensing properties) to industry (i.e., real-world analytical sensor devices) are critically discussed.

Recent Progress in Aptamer-Functionalized Metal-Organic Frameworks-Based Optical and Electrochemical Sensors for Detection of Mycotoxins

Mycotoxin contamination in foodstuffs and agricultural products has posed a serious hazard to human health and raised international concern. The progress of cost-effective, facile, rapid and reliable analytical tools for mycotoxin determination is in urgent need. In this regard, the potential utility of metal-organic frameworks (MOFs) as a class of crystalline porous materials has sparked immense attention due to their large specific surface area, adjustable pore size, nanoscale framework structure and good chemical stability. The amalgamation of MOFs with high-affinity aptamers has resulted in the progress of advanced aptasensing methods for clinical and food/water safety diagnosis. Aptamers have many advantages over classical approaches as exceptional molecular recognition constituents for versatile bioassays tools. The excellent sensitivity and selectivity of the MOF-aptamer biocomposite nominate them as efficient lab-on-chip tools for portable, label-free, cost-effective and real-time screening of mycotoxins. Current breakthroughs in the concept, progress and biosensing applications of aptamer functionalized MOFs-derived electrochemical and optical sensors for mycotoxins have been discussed in this study. We first highlighted an overview part, which provides some insights into the functionalization mechanisms of MOFs with aptamers, offering a foundation to create MOFs-based aptasensors. Then, we discuss various strategies to design high-performance MOFs-based aptamer scaffolds, which serve as either signal nanoprobe carriers or signal nanoprobes and their applications. We perceived that applications of optical aptamers are in their infancy in comparison with electrochemical MOFs-derived aptasensors. Finally, current challenges and prospective trends of MOFs-aptamer sensors are discussed.