DNA Technology-assisted Signal Amplification Strategies in Electrochemiluminescence Bioanalysis

Locked Nucleic Acid-Enhanced Entropy-Driven Amplifier Combined with Catalytic Hybridization Reaction-Based DNA Circuit for Dual Amplified Detection of Single Nucleotide Polymorphisms and Asymmetric Encryption of Gene Information

Single-nucleotide polymorphisms (SNPs) play a pivotal role in investigations of disease-associated genes and in the genetic analysis of animal and plant varieties. Therefore, the detection of SNPs is essential for advancing biomedical diagnostics and therapeutics. Here, we report a locked nucleic acid (LNA)-enhanced dual signal amplification strategy for high-contrast detecting single-nucleotide polymorphisms (SNPs) in the KRAS_G12C gene. By integrating entropy-driven amplification with catalytic hybridization reaction, the proposed method achieves significant amplification of fluorescence and resonance Rayleigh scattering signals. The incorporation of LNA modification enhances the thermodynamic stability and reaction kinetics of the DNA computing circuit, resulting in superior sensitivity and specificity for SNPs detection. The method exhibits a low detection limit of 0.19 fM and a wide dynamic range from 1 fM to 0.1 nM for the KRAS_G12C gene. Compared to traditional DNA-based circuits, the LNA-modified system demonstrates enhanced discrimination of single-base mismatches and improved signal gain. Moreover, the proposed method was further demonstrated for its potential application in human serum samples. Impressively, this research not only presents a highly sensitive and selective platform for SNPs detection but also demonstrates its potential for molecular-level information encryption. The incorporation of LNA in dual signal amplification significantly elevates the intricacy and robustness of information encryption. Therefore, this study underscores the potential of DNA-based technologies to serve as a bridge between the era of biomedical research and the emerging Internet of things.

Gold nanomaterials: important vectors in biosensing of breast cancer biomarkers

Breast cancer (BC) is one of the most common malignant tumors in women worldwide, and its incidence is increasing every year. Early diagnosis and treatment are critical to improve the curability and prognosis of patients. However, existing detection methods often suffer from insufficient sensitivity and specificity, which limits their clinical application. Fortunately, the rapid development of nanotechnology offers new possibilities for diagnosing BC. For example, the unique physicochemical properties of gold nanomaterials (Au NMs), such as fascinating optical properties and quantum size effect, along with excellent biocompatibility and modifiability, enable them to manifest great potential in the field of biosensing, especially in the detection of BC biomarkers. Through fine surface modification and functionalization, Au NMs can accurately bind to specific antibodies, nucleic acids, and other biomolecules, thus achieving sensitive and precise detection of specific biomarkers. Here, we focus on the research progress of Au NMs as a key biosensing vector in BC biomarker detection. From four major perspectives of early diagnosis, prognostic evaluation, risk prediction, and bioimaging applications, we have thoroughly analyzed the broad application of Au NMs in BC biomarker detection and prospectively addressed its possible future trends. We hope this review will provide more comprehensive ideas for future researchers and promote the further development of this field.

Recent Advances in Electrochemiluminescence Biosensors for MicroRNA Detection

Electrochemiluminescence (ECL) as an analytical technology with a perfect combination of electrochemistry and spectroscopy has received considerable attention in bioanalysis due to its high sensitivity and broad dynamic range. Given the selectivity of bio-recognition elements and the high sensitivity of the ECL analysis technique, ECL biosensors are powerful platforms for the sensitive detection of biomarkers, achieving the accurate prognosis and diagnosis of diseases. MicroRNAs (miRNAs) are crucial biomarkers involved in a variety of physiological and pathological processes, whose aberrant expression is often related to serious diseases, especially cancers. ECL biosensors can fulfill the highly sensitive and selective requirements for accurate miRNA detection, prompting this review. The ECL mechanisms are initially introduced and subsequently categorize the ECL biosensors for miRNA detection in terms of the quenching agents. Furthermore, the work highlights the signal amplification strategies for enhancing ECL signal to improve the sensitivity of miRNA detection and finally concludes by looking at the challenges and opportunities in ECL biosensors for miRNA detection.

Europium Metal-Organic Framework with a Tetraphenylethylene-Based Ligand: A Dual-Mechanism Quenching Immunosensor for Enhanced Electrochemiluminescence via the Coordination Trigger

The effective applications of electrochemiluminescence (ECL) across various fields necessitate ongoing research into novel luminophores and ECL strategies. In this study, self-luminous flower-like nanocomposites (Eu-tcbpe-MOF) were prepared by coordination self-assembly using the aggregation-induced emission material 1,1,2,2-tetrakis(4-carboxyphenyl)ethylene (H4TCBPE) and Eu(III) ions as the precursors. Compared with the monomers and aggregates of H4TCBPE, Eu-tcbpe-MOF exhibits stronger ECL emission. Such enhanced electrochemiluminescence is due to coordination as the coordination-triggered electrochemiluminescence (CT-ECL) enhancement effect. In this study, a cubic-structured nanocomposite (Co9S8@Au@MoS2) was used as an efficient quencher, and a more sensitive ECL detection platform was achieved by two quenching mechanisms: resonance energy transfer and competitive consumption of coreactants. N,N-Diethylethanolamine (DBAE) was used as a coreactant, and DBAE has a faster electron transfer rate and stronger energy supply efficiency than the traditional anodoluminescent coreactant tripropylamine, which effectively improves the ECL signal intensity of Eu-tcbpe-MOF. Hence, a sandwich-type ECL immunosensor was prepared by employing a dual-quenching mechanism, utilizing Eu-tcbpe-MOF as the detection probe and Co9S8@Au@MoS2 as the quencher, achieving precise detection of carcinoembryonic antigen from 0.1 pg·mL-1 to 100 ng·mL-1 with a detection limit of 35.1 fg·mL-1.

Engineering of an adaptive tandem CRISPR/Cas12a molecular amplifier permits robust analysis of Vibrio parahaemolyticus

Seeking new molecular diagnostic method for pathogenic bacteria detection is of utmost importance for ensuring food safety and protecting human health. Herein, we have engineered an adaptive tandem CRISPR/Cas12a molecular amplifier specifically designed for robust analysis of vibrio parahaemolyticus (V. parahaemolyticus), one of the most harmful pathogens. Our strategy involves the integration of three crucial processes: recombinase polymerase amplification (RPA) for copy number amplification, terminal deoxynucleotidyl transferase (TdT) for template-free strand elongation, and CRISPR/Cas12a-mediated trans-cleavage of a reporter molecule. By combining these processes, the target genomic DNA extracted from V. parahaemolyticus is able to activate many CRISPR/Cas12a units (CRISPR/Cas12an) simultaneously, resulting in a greatly amplified target signal to indicate the presence and concentration of V. parahaemolyticus. This unique model offers more advantages compared to traditional amplification models that use one RPA amplicon to activate one CRISPR/Cas12a unit. Under optimized conditions, our method enables the detection of target V. parahaemolyticus within a linear range of 1 × 102-1 × 107 CFU/mL, with an impressive limit of detection as low as 12.4 CFU/mL. It is conceivable that the adaptive tandem CRISPR/Cas12a molecular amplifier could be adapted as routine diagnostic kits in future for in-field detection of pathogens.

Advances of Electrochemical and Electrochemiluminescent Sensors Based on Covalent Organic Frameworks

Covalent organic frameworks (COFs), a rapidly developing category of crystalline conjugated organic polymers, possess highly ordered structures, large specific surface areas, stable chemical properties, and tunable pore microenvironments. Since the first report of boroxine/boronate ester-linked COFs in 2005, COFs have rapidly gained popularity, showing important application prospects in various fields, such as sensing, catalysis, separation, and energy storage. Among them, COFs-based electrochemical (EC) sensors with upgraded analytical performance are arousing extensive interest. In this review, therefore, we summarize the basic properties and the general synthesis methods of COFs used in the field of electroanalytical chemistry, with special emphasis on their usages in the fabrication of chemical sensors, ions sensors, immunosensors, and aptasensors. Notably, the emerged COFs in the electrochemiluminescence (ECL) realm are thoroughly covered along with their preliminary applications. Additionally, final conclusions on state-of-the-art COFs are provided in terms of EC and ECL sensors, as well as challenges and prospects for extending and improving the research and applications of COFs in electroanalytical chemistry.

Photoelectrochemical sensors based on paper and their emerging applications in point-of-care testing

Point-of-care testing (POCT) technology is urgently required owing to the prevalence of the Internet of Things and portable electronics. In light of the attractive properties of low background and high sensitivity caused by the complete separation of excitation source and detection signal, the paper-based photoelectrochemical (PEC) sensors, featured with fast in analysis, disposable and environmental-friendly have become one of the most promising strategies in POCT. Therefore, in this review, the latest advances and principal issues in the design and fabrication of portable paper-based PEC sensors for POCT are systematically discussed. Primarily, the flexible electronic devices that can be constructed by paper and the reasons why they can be used in PEC sensors are expounded. Afterwards, the photosensitive materials involved in paper-based PEC sensor and the signal amplification strategies are emphatically introduced. Subsequently, the application of paper-based PEC sensors in medical diagnosis, environmental monitoring and food safety are further discussed. Finally, the main opportunities and challenges of paper-based PEC sensing platforms for POCT are briefly summarized. It provides a distinct perspective for researchers to construct paper-based PEC sensors with portable and cost-effective, hoping to enlighten the fast development of POCT soon after, as well as benefit human society.

Microtrap-assisted microfluidic magnetic separation and concentration for ultrasensitive immunoassays of biomarkers

Precise and accurate quantitation of important biomarkers is significant, especially in early-stage diseases diagnosis. To realized effective biosample preparation and trace-level biomarker detection, a microtrap-assisted microfluidic magnetic immunoassays (μMI) method was developed in this work. A microtrap was fabricated inside the straight microchannel of μMI device to help magnetic separation and concentration of immunocomplexes. These immunocomplexes were enriched in microtrap of μMI device to accomplish selective and sensitive biomarker detection. Horseradish peroxidase-labeled magnetic beads were employed to evaluate assay feasibility and microtrap effect on assay sensitivity. The microtrap-assisted μMI was then applied for model biomarkers detection. The limits of detection of μMI were 0.025 pg/mL for monocyte chemoattractant protein-1 (MCP-1) and 0.021 pg/mL for matrix metalloproteinase-9 (MMP-9), which corresponded up to 2014-fold sensitivity improvement compared to their standard microwell enzyme-linked immunosorbent assay (ELISA) results. In addition, the selectivity and reproducibility of microtrap-assisted μMI were confirmed. In clinical serum sample analysis, recoveries of 91.3%-106.7% with relative standard deviations less than 6.1% were obtained for MCP-1 and MMP-9, and method accuracy was verified by commercial ELISA kit. The developed μMI can accomplish ultratrace biomarker detection offering practical tool for laboratorial and clinical research.

Catalyst-Accelerated Circular Cascaded DNA Circuits: Simpler Design, Faster Speed, Higher Gain

DNA cascaded circuits have great potential in detecting low abundance molecules in complex biological environment due to their powerful signal amplification capability and nonenzymatic feature. However, the problem of the cascaded circuits is that the design is relatively complex and the kinetics is slow. Herein, a new design paradigm called catalyst-accelerated circular cascaded circuits is proposed, where the catalyst inlet is implanted and the reaction speed can be adjusted by the catalyst concentration. This new design is very simple and only requires three hairpin probes. Meanwhile, the results of a series of studies demonstrate that the reaction speed can be accelerated and the sensitivity can be also improved. Moreover, endogenous mRNA can also be used as a catalyst to drive the circuits to amplify the detection of target miRNA in live cells and in mice. These catalyst-accelerated circular cascaded circuits can substantially expand the toolbox for intracellular low abundance molecular detection.

Recent Progress in Plasmonic based Electrochemiluminescence Biosensors: A Review

Electrochemiluminescence (ECL) analysis has become a powerful tool in recent biomarker detection and clinic diagnosis due to its high sensitivity and broad linear range. To improve the analytical performance of ECL biosensors, various advanced nanomaterials have been introduced to regulate the ECL signal such as graphene, gold nanomaterials, and quantum dots. Among these nanomaterials, some plasmonic nanostructures play important roles in the fabrication of ECL biosensors. The plasmon effect for the ECL signal includes ECL quenching by resonant energy transfer, ECL enhancement by surface plasmon resonance enhancement, and a change in the polarized angle of ECL emission. The influence can be regulated by the distance between ECL emitters and plasmonic materials, and the characteristics of polarization angle-dependent surface plasmon coupling. This paper outlines the recent advances of plasmonic based ECL biosensors involving various plasmonic materials including noble metals and semiconductor nanomaterials. The detection targets in these biosensors range from small molecules, proteins, nucleic acids, and cells thanks to the plasmonic effect. In addition to ECL biosensors, ECL microscopy analysis with plasmonic materials is also highlighted because of the enhanced ECL image quality by the plasmonic effect. Finally, the future opportunities and challenges are discussed if more plasmonic effects are introduced into the ECL realm.

A SERS Biosensor Based on Functionalized Au-SiNCA Integrated with a Dual Signal Amplification Strategy for Sensitive Detection of Telomerase Activity During EMT in Laryngeal Carcinoma

Purpose

This paper aims to construct a surface-enhanced Raman spectroscopy (SERS) biosensor based on functionalized Au-Si nanocone arrays (Au-SiNCA) using a dual signal amplification strategy (SDA-CHA) to evaluate telomerase activity during epithelial-mesenchymal transition (EMT) in laryngeal carcinoma (LC).

Methods

A SERS biosensor based on functionalized Au-SiNCA was designed with an integrated dual-signal amplification strategy to achieve ultrasensitive detection of telomerase activity during EMT in LC patients.

Results

Labeled probes (Au-AgNRs@4-MBA@H₁) and capture substrates (Au-SiNCA@H₂) were prepared by modifying hairpin DNA and Raman signal molecules. Using this scheme, telomerase activity in peripheral mononuclear cells (PMNC) could be successfully detected with a limit of detection (LOD) as low as 10^-6 IU/mL. In addition, biological experiments using BLM treatment of TU686 effectively mimicked the EMT process. The results of this scheme were highly consistent with the ELISA scheme, confirming its accuracy.

Conclusion

This scheme provides a reproducible, selective, and ultrasensitive assay for telomerase activity, which is expected to be a potential tool for the early screening of LC in future clinical applications.

Programmable, Universal DNAzyme Amplifier Supporting Pancreatic Cancer-Related miRNAs Detection

The abnormal expression of miRNA is closely related to the occurrence of pancreatic cancer. Herein, a programmable DNAzyme amplifier for the universal detection of pancreatic cancer-related miRNAs was proposed based on its programmability through the rational design of sequences. The fluorescence signal recovery of the DNAzyme amplifier showed a good linear relationship with the concentration of miR-10b in the range of 10–60 nM, with a detection limit of 893 pM. At the same time, this method displayed a high selectivity for miR-10b, with a remarkable discrimination of a single nucleotide difference. Furthermore, this method was also successfully used to detect miR-21 in the range of 10–60 nM based on the programmability of the DNA amplifier, exhibiting the universal application feasibility of this design. Overall, the proposed programmable DNAzyme cycle amplifier strategy shows promising potential for the simple, rapid, and universal detection of pancreatic cancer-related miRNAs, which is significant for improving the accuracy of pancreatic cancer diagnosis.

Luminous MoS2 nanosheet-based electrochemiluminescence biosensor with biomimetic vesicle for miRNA-210 detection

In this work, a novel electrochemiluminescence (ECL) sensor has been developed to detect miRNA-210 in the serum of triple negative breast cancer (TNBC) patients. The luminous MoS₂ nanosheets were synthesized via the solvothermal method and served as ECL emitters for the first time. As a result, the ECL properties of as-prepared MoS₂ nanosheets were significantly improved. Furthermore, the biomimetic magnetic vesicles were used as capture platform in the ECL sensing strategy. Due to the highly efficient fluidity and magnetic property, the biomimetic vesicles with hairpin aptamers can capture target gene in the serum. After magnetic separation, the captured miRNA-210 can trigger the target-catalyzed hairpin assembly (CHA) sensing process on the magnetic electrode and hybridize MoS₂ nanosheets labeled probe DNA. The concentration of miRNA-210 can be quantified by the ECL enhancement of the MoS₂ nanosheets. This approach has achieved the sensitive detection for miRNA-210 in a range from 1 fM to 100 pM with the detection limit of 0.3 fM. The luminous MoS₂ nanosheets-based ECL sensing system with the biomimetic vesicles would provide a new pathway to explore 2D nanomaterials for developing a wide range of bioanalytical applications.

Preparation of a disposable electrochemiluminescence sensor chip based on an MXene-loaded ruthenium luminescent agent and its application in the detection of carcinoembryonic antigens

We developed a novel type of disposable ECL sensor chip for CEA detection in serum samples of healthy humans and cancer patients. The disposable ECL sensor chip has many advantages including convenience, rapid detection, low cost, and easy mass production.