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

Sensitive and accurate photoluminescent-multiphonon resonant Raman scattering dual-mode detection of microRNA-21 via catalytic hairpin assembly amplification and magnetic assistance

A novel dual-mode detection method for microRNA-21 was developed. Photoluminescent (PL) and multiphonon resonant Raman scattering (MRRS) techniques were combined by using ZnTe nanoparticles as signal probes for reliable detection. The catalytic hairpin assembly (CHA) strategy was integrated with superparamagnetic Fe3O4 nanoparticle clusters (NCs) to enhance sensitivity. A remarkable detection sensitivity was achieved, with an ultralow limit of detection (LOD) of 310 aM for PL and 460 aM for MRRS. A wide detection range spanning from 500 aM to 100 nM for PL and 500 aM to 10 nM for MRRS was demonstrated, showcasing the versatility and efficacy of the method. Comparing to current methods and our previous work, both sensitivity and detection range showed significant advancements. The consistency between the detection results of PL and MRRS modes highlights the reliability and robustness of our method, offering compelling internal validation. This work not only opens new avenues for achieving sensitive and accurate detection of miRNAs, but also shows significant promise for advancing diagnostic applications in disease management.

Detection of pesticide residues using flower-like silver SERS substrates based on flexible sponge

In response to the existing issues of cumbersome and time-consuming detection processes and limited application scope in current pesticide residue detection, this paper designed a novel flexible substrate for surface-enhanced Raman spectroscopy (SERS) by combining flower-like silver nanoparticles prepared by chemical reduction technology with a flexible sponge. The flexible substrate exhibits excellent SERS enhancement effects, with a minimum detection limit of 10-12 mol/L for the probe molecule rhodamine 6G (R6G) and an average enhancement factor of 6.63 × 105. For the commonly used pesticide thiram, the minimum detection limit is 0.1 mg/L, which is significantly lower than the maximum residue limits set by China and the USA for thiram. Further experiments confirmed the substrate's excellent uniformity and stability, and the use of finite difference time domain (FDTD) software revealed that the model combining flower-like silver nanoparticles with a sponge exhibited higher electromagnetic field intensity compared to the model without the sponge, resulting in abundant "hot spots". Additionally, the sparrow search algorithm (SSA) was used to optimize the backpropagation (BP) neural network for predicting the concentration of thiram pesticide. The experimental results indicated that the SSA-BP algorithm achieved a determination coefficient (R2) of 0.99974 and root mean square error (RMSE) of 300.321, demonstrating good network performance and meeting the requirements of actual detection needs.

A universal electrochemical-modulated surface-enhanced Raman scattering platform for the sensitive detection of charged molecules

Electrochemical-modulated surface-enhanced Raman scattering (EC-SERS) integrates the benefits of SERS with electrochemical techniques. By controlling the electrode potential, Raman spectroscopy allows for the analysis of molecules with enhanced sensitivity and selectivity. With its large volume and high sample consumption, the traditional three-electrode electrochemical cell constrains the widespread adoption of EC-SERS. This study developed a versatile EC-SERS platform based on Ag nanowires-modified screen-printed electrode (AgNWs-SPE). Taking advantage of the dual functionality of AgNWs-SPE, this platform facilitates the successful in situ collection and sensitive detection of charged molecules. Experimental findings and theoretical calculations validate the platform's high sensitivity and selectivity mainly regulated by the applied potential, providing a universal approach for the highly sensitive and accurate detection of charged molecules.

Dual amplification dynamic DNA network system for CRISPR/Cas12a based p53 gene detection

BACKGROUND

It is estimated that over 50 % of human cancers are caused by mutations in the p53 gene. Early sensitive and accurate detection of the p53 gene is important for diagnosis of cancers in the early stage. However, conventional detection techniques often suffer from strict reaction conditions, or unsatisfied sensitivity, so we need to develop a new strategy for accurate detection of p53 gene with smart designability, multiple signal amplification in mild reaction conditions.

RESULTS

In this study, CRISPR/Cas system is exploited in entropy-driven catalysis (EDC) and hybridization chain reaction (CHA) dual signal amplification sensing strategies. The products of both reactions can efficiently and separately activate CRISPR/Cas12a which greatly amplifies the fluorescent signal. The method has good linearity in p53 detection with the concentration ranged from 0.1 fM to 0.5 pM with ultra-low detection limit of 0.096 fM. It also showed good performance in serum, offering potentials for early disease detection.

SIGNIFICANCE

The designed dual amplification dynamic DNA network system exhibits an ultra-sensitive fluorescence biosensing for p53 gene identification. The method is simple to operate and requires only one buffer for the experiment, and meanwhile shows smart designability which could be used for a wide range of markers. Thus, we believe the present work will provide a potential tool for the construction and development of sensitive fluorescent biosensors for diseases.

Application of CRISPR/Cas12a in miRNA-155 detection: A novel homogeneous electrochemiluminescence biosensor

BACKGROUND

MicroRNAs (miRNAs) are important non-coding RNA entities that affect gene expression and function by binding to target mRNAs, leading to degradation of the mRNAs or inhibiting their translation. MiRNAs are widely involved in a variety of biological processes, such as cell differentiation, development, metabolism, and apoptosis. In addition, miRNAs are associated with many diseases, including cancer. However, conventional detection techniques often suffer from shortcomings such as low sensitivity, so we need to develop a rapid and efficient detection strategy for accurate detection of miRNAs.

RESULTS

We have developed an innovative homogeneous electrochemiluminescence (ECL) biosensor. This biosensor employs CRISPR/Cas12a gene editing technology for accurate and efficient detection of microRNA (miRNA). Compared to conventional technologies, this biosensor employs a unique homogeneous detection format that eliminates laborious probe fixation steps and greatly simplifies the detection process. By using two amplification techniques - isothermal amplification and T7 RNA polymerase amplification - the biosensor improves the sensitivity and specificity of the assay, providing excellent detection performance in the assay. This makes it possible to evaluate miRNA directly from a variety of biological samples such as cell lysates and diluted human serum. Experimental results convincingly demonstrate the extraordinary performance of this biosensor, including its extremely low detection limit of 1.27 aM, high sensitivity, reproducibility and stability.

SIGNIFICANCE

The application of our constructed sensor in distinguishing between cancerous and non-cancerous cell lines highlights its potential for early cancer detection and monitoring. This innovative approach represents a major advancement in the field of miRNA detection, providing a user-friendly, cost-effective, and sensitive solution with broad implications for clinical diagnosis and patient care, especially in point-of-care settings.

Construction of Multiply Guaranteed DNA Sensors for Biological Sensing and Bioimaging Applications

Nucleic acids exhibit exceptional functionalities for both molecular recognition and catalysis, along with the capability of predictable assembly through strand displacement reactions. The inherent programmability and addressability of DNA probes enable their precise, on-demand assembly and accurate execution of hybridization, significantly enhancing target detection capabilities. Decades of research in DNA nanotechnology have led to advances in the structural design of functional DNA probes, resulting in increasingly sensitive and robust DNA sensors. Moreover, increasing attention has been devoted to enhancing the accuracy and sensitivity of DNA-based biosensors by integrating multiple sensing procedures. In this review, we summarize various strategies aimed at enhancing the accuracy of DNA sensors. These strategies involve multiple guarantee procedures, utilizing dual signal output mechanisms, and implementing sequential regulation methods. Our goal is to provide new insights into the development of more accurate DNA sensors, ultimately facilitating their widespread application in clinical diagnostics and assessment.

Engineering Assembly of Plasmonic Virus-Like Gold SERS Nanoprobe Guided by Intelligent Dual-Machine Nanodevice for High-Performance Analysis of Tetracycline

Accurate detection of trace tetracyclines (TCs) in complex matrices is of great significance for food and environmental safety monitoring. However, traditional recognition and amplification tools exhibit poor specificity and sensitivity. Herein, a novel dual-machine linkage nanodevice (DMLD) is proposed for the first time to achieve high-performance analysis of TC, with a padlock aptamer component as the initiation command center, nucleic acid-encoded multispike virus-like Au nanoparticles (nMVANs) as the signal indicator, and cascade walkers circuit as the processor. The existence of spike vertices and interspike nanogaps in MVANs enables intense electromagnetic near-field focusing, allowing distinct surface-enhanced Raman scattering (SERS) activity. Moreover, through the sequential activation between multistage walker catalytic circuits, the DLMD system converts the limited TC recognition into massive engineering assemblies of SERS probes guided by DNA amplicons, resulting in synergistic enhancement of bulk plasmonic hotspot entities. The continuously guaranteed target recognition and progressively promoted signal enhancement ensure highly specific amplification analysis of TC, with a detection limit as low as 7.94 × 10-16 g mL-1. Furthermore, the reliable recoveries in real samples confirm the practicability of the proposed sensing platform, highlighting the enormous potential of intelligent nanomachines for analyzing the trace hazards in the environment and food.

A dual-mode biosensor based on silica inverse opal photonic crystals modulated electrochemiluminescence and dye displacement colorimetry for the sensitive detection of synthetic cathinone in water environment

To address the challenges posed by signal capacity limitations and the reliance of sensing methods on single analytical information, this study developed an electrochemiluminescence (ECL) and colorimetric dual-mode sensing platform for the precise detection of 4-chloroethcathinone (4-CEC) in water environments. Firstly, the accurate alignment of the reflection wavelength of appropriately sized silica inverse opal photonic crystals (SIOPCs) with the ECL emission wavelength of luminescent metal-organic frameworks (PCN-224) has been achieved via diameter modulation. This innovative design, which cleverly utilized the band-edge effect, improved the luminous intensity of the ECL sensor, leading to a significant boost in analytical performance. Secondly, the establishment of a colorimetric detection method for confirming the presence of 4-CEC in samples through visual observation of color changes was achieved by employing an aptamer-based dye displacement reaction, utilizing differential binding affinities between the aptamer and both the sulforhodamine B (SRB) and 4-CEC. Under the optimal experimental conditions, the dual-mode sensor demonstrated ECL detection of limits (LOD) of 2.6 × 10-13 g/L and colorimetric LOD of 6.5 ng/L for 4-CEC. These findings highlighted the tremendous potential of developing streamlined and efficient dual-signal readout platforms using ECL aptamer sensors for the precise determination of other Synthetic cathinones (SCs) in water environments.

Targeted-activation superparamagnetic spherical nucleic acid nanomachine for ultrasensitive SERS detection of lysozyme based on a bienzymatic-mediated in situ amplification strategy

Lysozyme (LYS) is a widely used bacteriostatic enzyme. In this paper, we built a sensitive and accurate Raman biosensing platform to detect trace amounts of LYS. The method is based on magnetic spherical nucleic acid formed by a combination of LYS aptamer (Apt) and magnetic beads (MBs). Meanwhile, this method utilizes a dual enzyme-assisted nucleic acid amplification circuit and surface-enhanced Raman scattering (SERS). In this sensing strategy, which is based on the specific recognition of Apt, magnetic spherical nucleic acids were associated with SERS through a nucleic acid amplification circuit, and the low abundance of LYS was converted into a high-specificity Raman signal. Satellite-like MB@AuNPs were formed in the presence of the target, which separated specifically in a magnetic field, effectively avoided the interference of complex sample environment. Under the optimal sensing conditions, the concentration of LYS exhibited a good linear relationship between 1.0 × 10-14 and 5.0 × 10-12 M and the limit of detection was as low as 8.3 × 10-15 M. In addition, the sensor strategy shows excellent accuracy and sensitivity in complex samples, providing a new strategy for the specific detection of LYS.

A CRISPR-Cas12a-based electrochemical biosensor for the detection of microphthalmia-associated transcription factor

A novel electrochemical biosensor that combines the CRISPR-Cas12a system with a gold electrode is reported for the rapid and sensitive detection of microphthalmia-associated transcription factor (MITF). The biosensor consists of a gold electrode modified with DNA1, which contains the target sequence of MITF and is labeled with ferrocene, an electroactive molecule. The biosensor also includes hairpin DNA, which has a binding site for MITF and can hybridize with helper DNA to form a double-stranded complex that activates CRISPR-Cas12a. When MITF is present, it binds to hairpin DNA and prevents its hybridization with helper DNA, thus inhibiting CRISPR-Cas12a activity and preserving the DPV signal of ferrocene. When MITF is absent, hairpin DNA hybridizes with helper DNA and activates CRISPR-Cas12a, which cleaves DNA1 and releases ferrocene, thus reducing the DPV signal. The biosensor can detect MITF with high sensitivity (with an LOD of 8.14 fM), specificity, and accuracy in various samples, such as cell nuclear extracts and human serum. The biosensor can also diagnose and monitor melanocyte-related diseases and melanin production. This work provides a simple, fast, sensitive, and cost-effective biosensor for MITF detection and a valuable tool for applications in genetic testing, disease diagnosis, and drug screening.

A Colorimetric/Fluorescent Dual-Mode Aptasensor for Salmonella Based on the Magnetic Separation of Aptamers and a DNA-Nanotriangle Programmed Multivalent Aptamer

Salmonella infection has emerged as a global health threat, causing death, disability, and socioeconomic disruption worldwide. The rapid and sensitive detection of Salmonella is of great significance in guaranteeing food safety. Herein, we developed a colorimetric/fluorescent dual-mode method based on a DNA-nanotriangle programmed multivalent aptamer for the sensitive detection of Salmonella. In this system, aptamers are precisely controlled and assembled on a DNA nanotriangle structure to fabricate a multivalent aptamer (NTri-Multi-Apt) with enhanced binding affinity and specificity toward Salmonella. The NTri-Multi-Apt was designed to carry many streptavidin-HRPs for colorimetric read-outs and a large load of Sybr green I in the dsDNA scaffold for the output of a fluorescent signal. Therefore, combined with the magnetic separation of aptamers and the prefabricated NTri-Multi-Apt, the dual-mode approach achieved simple and sensitive detection, with LODs of 316 and 60 CFU/mL for colorimetric and fluorescent detection, respectively. Notably, the fluorescent mode provided a self-calibrated and fivefold-improved sensitivity over colorimetric detection. Systematic results also revealed that the proposed dual-mode method exhibited high specificity and applicability for milk, egg white, and chicken meat samples, serving as a promising tool for real bacterial sample testing. As a result, the innovative dual-mode detection method showed new insights for the detection of other pathogens.